biological treatment of ammoniu m perchlorate...

82 © IWA Publishing 2016 Journal of Water Reuse and Desalination | 06.1 | 2016

Biological treatment of ammonium perchlorate-contaminated

wastewater: a review

Hongzhi Ma, Nyandwaro A. Bonnie, Miao Yu, Shun Che and Qunhui Wang

ABSTRACT

Absolute reduction of perchlorate has proven complex owing to the diverse characteristics of the

perchlorate ion. Technologies such as chemical reduction, ozone/peroxide, nanofiltration, and reverse

osmosis havehad limited success, high costs and arenot environmentally friendly. Agreat deal of research

and reviews on ion exchange and biodegradation have been carried out, but conditions for optimal

biodegradation are not yet well understood. The acceptability of biological treatment of perchlorate has

been limited due to challenges such as electron donor availability, which impacts on the environmental

sustainability of perchlorate biodegradation, the biomass inventory, secondary contamination of treated

water due to contact with micro-organisms between the treatment unit and the final effluent, and the

presenceofotherenergeticcompoundssuchasRoyalDemolitionExplosivesand2,4-dinitroanisole (DNAN)

in army PAX 21 production water and other competing electron acceptors such as nitrate and sulfate.

Therefore, thecurrent researchconcern isaboutoptimizationof thebiodegradationofperchlorate for large-

scale applicability. In addition to summarizing the strengths and weaknesses of developed and emerging

perchlorate treatment technologies, this review focuses on research developments in biological treatment

of ammoniumperchlorate, perchlorate reducingbacteria, factors affectingbiodegradationofNH4ClO4� and

previous research recommendations on efficient, effective, and stable biological treatment of perchlorate-

contaminated wastewater.

doi: 10.2166/wrd.2015.016

Hongzhi Ma (corresponding author)Nyandwaro A. BonnieMiao YuShun CheQunhui WangDepartment of Environmental Engineering,University of Science and Technology Beijing,Beijing 100083,ChinaandBeijing Key Laboratory of Resource-oriented

Treatment of Industrial Pollutants,Beijing 100083,ChinaE-mail: [email protected]

Key words | ammonium perchlorate, biodegradation of NH4ClO4- , perchlorate, perchlorate reducing

bacteria

INTRODUCTION

Perchlorate is among the most recently acknowledged group

of toxins called endocrine disrupters. It is manufactured as

perchloric acid and salts such as ammonium perchlorate,

magnesium perchlorate, sodium perchlorate, and potassium

perchlorate for use in various processes. These have been

significantly introduced into the environment in the form

of disinfectants, fertilizers, bleaching agents, blasting

agents, herbicides, and rocket propellants. The presence of

perchlorate in the environment is detrimental to human

health as it can alter hormonal balances and impede

human reproduction and development.

Exposure to ammonium perchlorate has been

reported to lead to hypothyroidism (Park et al. ;

Chen et al. ). The perchlorate ion competitively

inhibits iodide uptake by the thyroid glands, thus affect-

ing the functionality of the thyroid. Naturally occurring

chemicals, such as thiocyanate (in food and cigarette

smoke) and nitrate (in some food), are also known to

inhibit iodide uptake. This potentially leads to a

reduction in the production of thyroid hormones; triio-

dothyronine and thyroxin thyroid hormones (serum T3

and T4) and subsequently, increased production of thyr-

oid stimulating hormones (serum TSH) associated with

lower thyroidal hormone storage (Mattie et al. ).

Thyroid hormones play an important role in regulating

metabolism and oxygen consumption. They are critical

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83 H. Ma et al. | Biological treatment of ammonium perchlorate-contaminated wastewater Journal of Water Reuse and Desalination | 06.1 | 2016

for normal growth and development in fetuses, infants,

and young children.

Short-term exposure to high doses may cause eye and

skin irritation, coughing, nausea, vomiting, and diarrhea.

Long-term exposure could result in neuro-developmental

defects due to decreased thyroid hormones, thyroid hyper-

plasia resulting from severe/sustained iodine deficiency,

and ultimately, growth of tumors due to increased levels of

TSH, although tumor growth is a rare occurrence unless

in individuals susceptible to disruption of thyroid functions.

Research shows that chlorate and chlorite produced during

reduction of perchlorate can also cause hemolytic anemia in

laboratory animals, methemoglobin formation in mammals,

and toxicity in micro-organisms and plants (University of

Nebraska ; Baldridge et al. ; Braverman et al.

; National Research Council ; Mattie et al. ;

Park et al. ; Chen et al. ).

According to the National Research Council, the main

adverse effects of perchlorate ingestion are hormonal imbal-

ances, metabolic sequelae such as decreased metabolic rate

and slowing of the function of many organ systems at any

Figure 1 | Exposure–dose response continuum.

age, and abnormal fetus and child development. The model

in Figure 1 shows the exposure–dose response continuumcon-

sidered in the context of biomarkers (classified as measures of

exposure, effect, and susceptibility) and level of organization at

which toxicity is observed (United States Environmental Pro-

tection Agency (US EPA) ).

It should therefore be noted that even at microgram levels,

perchlorate causes toxicity to flora and fauna and affects

growth,metabolism, and reproduction in humans and animals.

Perchlorate contamination occurs in groundwater, surface

water, soil, anddrinkingwater sources. It has alsobeen found in

many nutritionally important foods such as dairy and human

milk, lettuce and other leafy green vegetables, forage, cereals,

cantaloupe, citrus fruits, canned foods, wines, beer, bottled

water, and humanurine, posing serious public health concerns.

Recent studies on perchlorate pollution status in China

indicate widespread contamination. The concentration of per-

chlorate in sewage sludge, rice, bottled drinking water, and

milk in various areas in China was found to be in the range

of 0.56–379.9 μg/kg, 0.16–4.88 μg/kg, 0.037–2.013 μg/L, and

0.30–9.1 μg/L, respectively (Shi et al. ). In theUSA, federal


and state agencies identified more than 400 sites including

California, Utah, Nevada, Texas, Arkansas, Maryland, Massa-

chusetts, Arizona, New York, the districts of Columbia, and

two commonwealths where drinking water, surface water,

groundwater, and soilwere found tobecontaminatedwith per-

chlorate, affecting drinking water supplies to more than 20

million people (US EPA ). Perchlorate contamination

has also been found in other parts of the world such as in

Israel, where widespread perchlorate contamination has

been found in the 40 m deep vadose zone near an ammonium

perchlorate manufacturing plant north of Tel Aviv, above the

central part of Israel’s coastal aquifer, with peak concen-

trations of 1,200 mg kg�1 sediment (Gal et al. ).

Ammonium perchlorate [AP (NH4ClO4)] is a form of high

grade perchlorate domestically produced for use in theDepart-

ment of Defense (DoD), and the National Aeronautics and

Space Administration (NASA). It has been used by the US

DoD as an oxidizer in munitions and missiles since the

1940s. Ammonium perchlorate has a limited shelf life, so

inventories must be periodically replaced with a fresh supply,

creating large quantities of ammonium perchlorate waste

that need to be disposed of. For instance, the end of the Cold

War left the US DoD with a projected 140 million pounds of

rocket propellant to be disposed of between 1993 and 2005

(US EPA ).

The ammonium ions initially present in the ground at con-

taminated sites generally biodegrade over time, whereas the

perchlorate ionpersists due to its poor reactivity and great solu-

bility and mobility in water. Furthermore, perchlorate

compounds and the perchlorate anion do not volatilize from

water to air. As a result, perchlorate plumes in groundwater

can be extensive. For example, the perchlorate plume at a

former safety flare site (the Olin Flare Facility) in Morgan

Hill, California, extends more than nine miles (US EPA ).

Figure 2 | Processes and pathways for the production of perchlorate and accompanying

intermediary oxychlorines (EPSC Abstracts Vol. 8, EPSC2013-799-1 2013).

PERCHLORATE OCCURRENCE AND SOURCES OFCONTAMINATION

Natural occurrence

Perchlorate is both a naturally occurring and man-made

anion (ClO�4 ). It occurs naturally, especially in arid regions,

and can be found as a natural impurity in nitrate salts used

to manufacture nitrate fertilizers. Contamination from mili-

tary and industrial sources is well documented but up to

now natural background levels are not well understood. A

number of possible processes through which perchlorate

can be naturally formed are being studied. Figure 2 shows

some of these processes and possible pathways of perchlor-

ate formation. Highly oxidizing species such as ClO and

ClO�2 can be generated from stable Cl� minerals by the

action of UV and from ClO4� minerals by the action of

cosmic γ and x-rays (Kounaves et al. ).

Currently, atmospheric formation by photochemical

reactions between chloride and ozone and perhaps ultra-

violet radiation is the working theory. After atmospheric

formation, perchlorate is dissolved in precipitation and

returns to the Earth’s surface. Atmospheric deposition

occurs from rain, washing compounds out of the atmos-

phere, and the settling out of dry airborne materials,

including dust.

In arid environments, where the rate of deposition

exceeds the rate of dissolution by ongoing precipitation, per-

chlorate can be incorporated into certain geologic

formations (Orris ), as shown in Figure 3. The samples

deriving from soil-caliche show 100% with perchlorate,

and the proportion of halite samples is 44%.

The rate of atmospheric deposition has long been

thought to be small, however recent studies show that

Figure 3 | Comparative assessment of the environmental sustainability of perchlorate treatment technologies for drinking water using consumables as the driving force (Choe et al. 2013).


perchlorate atmospheric deposition rates are about 10 times

larger than previously reported (Andraski et al. ). In this

study, atmospheric deposition ClO�4 flux was 343 mg ha�1

yr�1, which is approximately 10 times that for published

southwestern wet-deposition fluxes. The study further

proved that both wet and dry atmospheric depositions are

important contributors of perchlorate to the land surface.

The distribution of this naturally occurring ClO�4 in

deserts, arid and semi-arid regions has mainly been related

to evaporative concentration and unsaturated transport.

This process leads to higher ClO�4 and other ion concen-

trations in groundwater where the water table is relatively

shallow, and in areas with lower saturated thickness

(Böhlke et al. ; Balaji et al. ; Jackson et al. ;

Andraski et al. ).

Natural perchlorate deposits

Perchlorate has been known to be present naturally in

nitrate deposits in the Atacama Desert of northern Chile

since the 1880s. Initially, it was believed that the exten-

sively documented Chilean deposits were the only source

of naturally occurring perchlorate. However, based on iso-

topic composition, natural perchlorate indigenous to the

United States and other parts of the world can be distin-

guished from both synthetic perchlorate and perchlorate

derived from Chilean fertilizers (Böhlke et al. ; Jackson

et al. ). Various researches recently carried out show

widespread occurrence of natural perchlorate independent

of the Chilean deposits. These are summarized in Table 1

and serve as confirmation that perchlorate is produced

globally and continuously in the Earth’s atmosphere, that

it typically accumulates in hyper arid areas, and that it

does not build up in oceans or other wet environments

probably due to microbial reduction.

Anthropogenic sources

Perchlorate is used in a variety of commercial, chemical,

and industrial processes. The pervasive contamination of

Table 1 | Natural perchlorate occurrence

Site Analyzed substances Perchlorate concentrations Source of perchlorate Reference

Amargosa Desert,Nevada

Soil, leaves fromshrubs, rain, dust

Shallow soils had high levels ofperchlorate – 10–20 grams perhectare in the top 30 cm

Atmospheric wet and drydeposition

Andraski et al. ()

Southwestern UnitedStates (arid andsemi-arid)

Discrete depthsubsurface soiland sediment

Peak concentrations ranged from1.6 to 13 micrograms perkilogram dry solid (μg kg�1)

Atmospherically depositedchloride (Cl�)

Balaji et al. ();Jackson et al. ()

High plains of Texasand New Mexico

Groundwater Generally low (<4 ppb),although some areas areimpacted by concentrations upto 200 ppb

Atmospheric deposition andmeteoric ClO4 thataccumulated in theunsaturated zone over the last2–10,000 years

Rajagopalan et al.()

Antarctic Soil and ice fromseveral Antarcticdry valleys

Concentrations reach up to1,100 μg/kg

Atmospheric deposition Kounaves et al. ()

North America(ContinentalUnited States,Alaska, and PuertoRico)

1,578 compositewet depositionsamples

Perchlorate concentrationsvaried from <5 ng/L to a highof 102 ng/L with a mean of14.1± 13.5 ng/L

Wet atmospheric deposition Rajagopalan et al.()

Annual perchlorate flux averagedat 65± 30 mg/ha-year andranging from 12.5 (TX) to 157mg/ha-year

Arctic Devon Island icecap

Concentrations varied between 1and 18 ng L�1

Stratospheric formation bychlorine radicals reacting withozone year round (perchlorateconcentrations the total ozonelevel)

Furdui & Tomassini()

Tropospheric formation(perchlorate was correlatedwith the chlorideconcentrations duringsummer)

Chilean AtacamaDesert

Cultivated anduncultivatedsoils, superficialrunning water

Concentrations ranging from290± 1 to 2,565± 2 μg/kg insoils with highestconcentration in humber stonesoil. Concentrations in waterranged from 744± 0.01 to1,480± 0.02 μμg/L

Wet and dry deposition Calderón et al. ()


perchlorate arises from its application in a wide range of

processes. Salts of chlorate have been used as defoliants,

leading to speculation that these could be sources of per-

chlorate in groundwater (Brown & Gu ).

Ammonium perchlorate has been used as a primary

oxidizer in solid propellants for missiles, munitions, and

rockets for many years now because it has a high

oxygen content and decomposes to the gaseous phase’s

products, water, HCI, N2, and 02, leaving no residue.

The one disadvantage in its use as an oxidizing agent is

that it does not function well in solid fueled rockets

after it adsorbs too much water, requiring significant

proper disposal and replenishment (Brown & Gu ).

When rockets are successfully launched, the intense


heat leads to nearly complete reaction of the perchlorate.

Therefore, release of perchlorate to the environment often

occurs when its intended use does not occur, such as in

dismantling and disposal of rockets, accidental release

from manufacturing facilities, or unsuccessful rocket

launches.

Currently, no suitable replacements for perchlorate as

an oxidizer have been found that can satisfy defense/mili-

tary, aeronautics and space administration logistics,

performance, safety and environmental requirements.

Studies on the use of ammonium dinitramide and other

nitramines and nitramides are ongoing, although existing

alternative energetic oxidizers show significant cost, avail-

ability, and performance issues if used in fielded weapon

systems (Strategic Environmental Research and Develop-

ment Program a, b). Owing to their use in

military applications, many countries consider the amounts

that they make confidential.

Overall, perchlorate salts are essential constituents of

composite propellants, underwater explosives, and pyro-

technic compositions. These are used in fireworks,

airbag initiators for vehicles, matches, signal flares, blast-

ing agents, and in some disinfectants. Perchlorate

contamination investigation in groundwater and surface

water from Sivakasi and Madurai in the Tamil Nadu

State of South India showed that concentrations of per-

chlorate were <0.005–7,690 μg/L in groundwater,

<0.005–30.2 μg/L in surface water, and 0.063–0.393 μg/L

in tap water. Levels in groundwater were significantly

higher in the fireworks factory area than in the other

locations, indicating that fireworks and safety match

industries are principal sources of perchlorate pollution

(Isobe et al. ). In agriculture they are used in fertili-

zers, as additives in cattle feed, and have also been

found in some herbicides as an incidental byproduct in

the manufacture of sodium chlorate used in agricultural

herbicides and defoliants. In textile industries, perchlorate

has been found in finished leather, fabric fixers, and dyes.

Further, perchlorate salts are used in lubricating oils, elec-

troplating, aluminum refining, the manufacture of rubber,

paint, enamel production, and magnesium batteries

(Motzer ). Pulp and paper industries which use

sodium chlorate are also possible sources of perchlorate

contamination. For use in the paper industry, sodium

chlorate is converted to C102 by reduction with hydrogen

peroxide in the presence of sulfuric acid. The C102 is then

used as a bleaching agent.

It has been reported that laboratory grade sodium chlor-

ate contains 0.2% perchlorate on a weight basis, while the

analytical reagent grade chemical has 200–900 ppm (Burns

et al. ).

Although authoritative reference works indicate that

technical grade sodium chlorate is 99.5% pure (McKetta &

Weismantel ), given the large quantities of sodium chlor-

ate used annually by the pulp and paper industry, sodium

chlorate cannot be ignored as a possible source of perchlor-

ate contamination in the environment.

In farming regions, the main source of perchlorate

contamination of soil is fertilizers. However, very high

levels of perchlorate contamination of soil and sediments

have been reported to occur from DoD and other federal

facilities. In groundwater contamination, perchlorate

occurs as a result of percolation of rainwater through con-

taminated sand or soil. It also may be released to surface

water from runoff or erosion of contaminated sand or soil.

Furthermore, water-gel and emulsion blasting agents con-

taining perchlorates used in difficult rock blasting,

underground and trenching, deep boreholes, and other

applications that require extra energy over conventional

agents, could lead to a higher incidence of incomplete

combustion and become a source of perchlorate contami-

nation if applied where surface and groundwater can be

affected.

Human exposure

Ingestion of contaminated food, milk, and drinking water

has been reported to be the primary pathway for human

exposure to perchlorate. Other modes of exposure, although

minor, include adsorption through the skin and inhalation.

Perchlorate being an inorganic compound and completely

ionized in water, the potential for dermal absorption

through intact skin is unlikely.

However, the primary pathway for workers in industrial

and commercial production facilities or commercial use of

perchlorate salts is inhalation of ammonium perchlorate

dust. Occupational exposure in ammonium perchlorate pro-

duction facilities has been shown to be higher than potential


exposures from drinking water or food sources (Gibbs et al.

; Braverman et al. ).

Table 2 | Drinking water standards for perchlorate

State Drinking water perchlorate standard

Nevada 18 μg/L

Arizona 14 μg/L

New York 5 μg/L

California 6 μg/L

Texas 4 μg/L

New Mexico 1 μg/L

Massachusetts 1 μg/L

Maryland 1 μg/L

PERCHLORATE DRINKING WATER STANDARDS

The amount of perchlorate safe for humans is an issue of

major scientific deliberation. In addition to perchlorate con-

tamination being detected in the United States, China, and

Israel, it has also been detected in Japan’s Tome river water-

shed (Kosaka et al. ) in concentrations ranging from

0.08 to 2,300 mg/L in the upper watershed and

0.73–25 mg/L in the middle and lower portions of the water-

shed and in Korea (Quinones et al. ) at concentrations

ranging from 0.15 to 60 mg/L in the Nakdong river water-

shed and 0.08–2.3 mg/L in the Yongsan river. Despite

perchlorate contamination being an international problem,

most nations lack definitive drinking water regulations for

perchlorate.

Following the discovery of perchlorate in drinking water

sources in various states in the USA and recognition that a

perchlorate dose of 6 mg kg�1 body weight d�1 or more

administered to hyperthyroidism patients over a 2-month

period could lead to fatal bone marrow disorders in 1992,

perchlorate was added to the EPA contaminant candidate

list in 1998 (US EPA ).

After a number of studies, researches, and consul-

tations among the National Research Council, DoD,

National Academy of Science, and the Environmental

Protection Agency in January 2006, the EPA Superfund

office issued guidance for a drinking water-equivalent

level of 24.5 μg/L perchlorate to be considered as the pre-

liminary remediation goal (PRG) in order to minimize

health risks (Kucharzyk et al. ). The EPA’s Chil-

dren’s Health Protection Advisory Committee (CHPAC)

however suggested that the PRG of 24.5 μg/L does not

protect infants, who are highly susceptible to neuro-

developmental toxicity and may be more exposed than

fetuses to perchlorate. While noting that perchlorate is

concentrated in breast milk and that nursing infants

could receive daily doses greater than the reference

dose if the mother was exposed to 24.5 ppb perchlorate

in tap water, the CHPAC recommended the level to be

lowered.

In October 2008 the EPA issued an Interim Drinking

Water Health Advisory for perchlorate of 15 ppb and

announced a delay on the decision about whether to set a

drinking water standard for perchlorate until it received

advice from the NRC (US EPA ).

As of 2009, no national drinking water standard for per-

chlorate had been set. The promulgation of a national

primary drinking water regulation for perchlorate has

hence proven to be a multi-year process, especially due to

economic considerations.

Owing to the EPA’s reluctance to set a national drinking

water standard for perchlorate, individual states have set

their own advisory levels, as shown in Table 2.

TREATMENT METHODS

Wastewater and drinking water treatment to remove/destroy

perchlorate can be achieved by both biotic and abiotic

methods. Perchlorate is highly toxic, soluble, relatively

stable, and mobile in water. It is also highly soluble in polar

organic solvents, slow to react, and ammonium perchlorate

has a limited shelf life. Table 3 summarizes the physical

and chemical properties of common perchlorate salts.

Perchlorate compounds and the perchlorate anion do not

volatilize from water to air. Owing to these properties, most

well-known processes have had little success especially with

respect to environmental and economic considerations.

Previous reviews on most physical and chemical pro-

cesses, namely, chemical and electrochemical reduction,

adsorption on activated carbon, granular activated carbon

(GAC) or metal ions, ion exchange, membrane processes

Table 3 | Physical and chemical properties of perchlorate compounds

Property Ammonium perchlorate Sodium perchlorate Potassium perchlorate Perchloric acid

CAS No. 7790-98-9 7601-89-0 7778-74-7 7601-90-3

Formula NH4ClO4 NaClO4 KClO4 HClO4

Formula weight 117.49 122.44 138.55 100.47

Color/Form White, orthorhombic crystals White, orthorhombiccrystals; whitedeliquescent crystals

Colorless crystals or white,crystalline powder; colorless,orthorhombic crystals

Colorless, oily liquid

Melting point Decomposes/explodes 480 WC 525 WC �112 WC

Density 1.95 g/cm3 2.52 g/cm3 2.53 g/cm3 1.768 g/cm3

Solubility 200 g/L of water at 25 WC 209.6 g/100 mL of water at25 WC

15 g/L of water at 25 WC Miscible in coldwater

Additionalsolubilityinformation

Soluble in methanol; slightlysoluble in ethanol, acetone;almost insoluble in ethylacetate, ether

209 g/100 mL water at15 WC; 284 g/100 mLwater at 50 WC; soluble inalcohol

Soluble in 65 parts cold water,15 parts boiling water;practically insoluble inalcohol; insoluble in ether

Not provided

Source: National Library of Medicine. Specialized Information Services. 2004. Hazardous Substances Data Bank.


such as reverse osmosis (RO), electrodialysis, ultrafiltration

(UF) and nanofiltration (NF) indicate that these have had

limited application in perchlorate removal. This is attributed

to high costs, non-selectivity, slow reduction rates, rapid

accumulation of active sites in the presence of competing

anions like nitrates, their need for extreme reaction con-

ditions (temperature, pressure, and pH), and generation of

large volumes of concentrated waste streams (with perchlor-

ate and total dissolved solids (TDS)) that cannot be easily

disposed of or require further reduction processes before dis-

posal (Hatzinger ; Bardiya & Bae ; Ye et al. ).

For instance, electrochemical reduction, despite showing

great promise in complete destruction of the perchlorate

ion, is inapplicable on a large scale as it is very slow, as is

chemical reduction. Ion exchange merely transfers perchlor-

ate from water to the resin, making it a non-selective and

incomplete process since it is a physico-chemical process

based on exchanging an anion (typically Cl�) with the per-

chlorate ion in the water as shown by the equation below:

R4NþCl� þ ClO�

4 , R4NþClO�

4 þ Cl�

In a review, Bardiya & Bae () found that perchlorate-

laden spent resins with perchlorate 200–500 mg L�1

required regeneration resulting in the production of concen-

trated brine 6–12% NaCl or caustic waste streams. Further

research and subsequent application of selective anion

exchange is fortunately progressing well.

Evidence obtained from a growing number of bench-

scale tests also show the potential effectiveness of phyto-

remediation of perchlorate-contaminated soils, surface,

and groundwater (Susarla et al. a, b, c, ;

Nzengung et al. , ; Nzengung & Wang ; Nzen-

gung & McCutcheon ).

Laboratory research involving testing with several wet-

land species, including Typha latifolia (cattail), Spirodela

polyrhiza (L.) Shield (duck weed), microbial mats, and

Myriophyllum aquaticum (parrot feather), as well as several

terrestrial plants, including black willow (Salix nigra and

Salix caroliniana), eastern cottonwood (Populus deltoides),

eucalyptus (Eucalyptus cinerea), loblolly pine (Pinus taeda),

French tarragon (Artemisia dracunculus), and spinach (Spi-

nacia oleracea) (Susarla et al. a, b, c, ;

Nzengung & Wang ; Nzengung et al. , ; Nzen-

gung & McCutcheon ) have been carried out.

Bench-scale studies have identified the predominant

mechanisms of phytoremediation of perchlorate as: (1)

uptake and phytodegradation, (2) uptake and phytoaccumu-

lation by some plant species, and (3) rapid rhizodegradation.

As uptake and phytodegradation is a slower process, it poses

an ecological risk resulting from the temporal phytoaccumu-

lation of some fraction of the perchlorate being taken up and


transported mainly to plant leaves. In bench-scale tests,

uptake may account for the removal of 5–25% of the per-

chlorate present in the root zone of plants (Susarla et al.

).

Constructed wetlands are also increasingly being used

for the remediation of groundwater or surface water

impacted by industrial chemicals and wastes such as landfill

leachate and explosives such as TNT or Royal Demolition

Explosives (RDX). The increased application is due to the

low capital and operation and maintenance (O&M) costs

associated with this mostly passive technology. Recent suc-

cessful trials of small-scale wetland reactors suggest that

full-scale use of constructed wetlands could be a cost-effec-

tive method to deal with large volumes of perchlorate-

contaminated water sources such as groundwater.

Membrane technologies which employ a semi-per-

meable membrane that prevents the passage of certain

ions to treat water, such as UF, NF, and RO, although

having been reported to be effective for perchlorate removal

are not suitable for large-scale applications because of foul-

ing issues, costliness, and the generation of large volumes of

reject streams. Electrodialysis, being the most effective

membrane technology, has extremely high operational

costs (Srinivasan & Sorial ). Table 4 summarizes the

strengths and weaknesses of various perchlorate treatment

technologies.

Generally, technologies that have been successfully used

to treat perchlorate contamination have primarily involved

anion exchange or biological treatment, although anion

exchange requires supplementary treatment before disposal.

This need for auxiliary treatment of the concentrated brines

has resulted in great interest in chemical reduction for many

seeking economical and efficient ways of remediation of per-

chlorate contamination in water. Chemical reduction has

been limited due to the fact that perchlorate does not

appreciably react at ambient temperature with chemical

reducing agents commonly used in remediation, such as sul-

fite, dithionite, or zero-valent iron (ZVI). Determining a

stable remediation procedure has been challenged by the

discovery that some weaker reducing agents react with per-

chlorate at measurable rates, whereas stronger reducing

agents fail to react at all.

Despite biological reduction and ion exchange being

more established than other methods, there is still not a

single technology that can be directly applied to a drinking

water treatment system for complete removal of perchlorate

(Srinivasan & Sorial ), an indication that an integration

of these technologies may have to be adopted for a com-

pletely effective and economical perchlorate reduction.

Choe et al. () analyzed the environmental sustain-

ability of ion exchange, biodegradation, and catalytic

reduction perchlorate reducing technologies using a life

cycle assessment. Resource consumption/consumable

during the operation phase was used as the major driving

force for environmental impacts. The analysis indicated

that the environmental impacts of heterotrophic biological

treatment were 2–5 times more sensitive to influent con-

ditions (i.e., nitrate/oxygen concentration) and were 3–14

times higher compared to ion exchange. Catalytic treatment

using carbon-supported Re–Pd had a higher (ca. 4,600

times) impact than others, but was within 0.9–30 times the

impact of ion exchange with a newly developed ligand-com-

plexed Re–Pd catalyst formulation. Autotrophic biological

treatment was the most environmentally beneficial among

all methods (Choe et al. ).

Figure 3 shows the three perchlorate reducing technol-

ogies and their potential impact on the environment

measured as kg CO2 equivalent per kg of ClO�4 treated, an

indication of the global warming potential of these

technologies.

BIODEGRADATION OF AMMONIUM PERCHLORATE

Microbial reduction of perchlorate was observed as early as

the 1950s, but research into this has only been conducted

during the recent past several years. Biodegradation was

recognized by the Air Force Research Laboratory (AFRL)

in 1989 as a potential process for treating dilute ammonium

perchlorate waste streams and for remediating contami-

nated soil and groundwater.

Perchlorate can be anaerobically biodegraded under

reducing conditions. In these reactions, perchlorate serving

as an electron acceptor is readily reduced to water, carbon

dioxide, and chloride in the presence of an appropriate

food source (electron donor) and redox conditions. The

initial steps in perchlorate destruction are the reduction of

perchlorate to chlorate and subsequently the reduction of

Table 4 | Strengths and weaknesses of perchlorate treatment technologies

Technology Strengths Weaknesses Other remarks

Tailored granular activatedcarbon (T-GAC)

Proven effective technology Not a destructive technology Spent carbon (all adsorptive sitesused) can be disposed of bylandfill or incineration.Landfill may cause perchlorateto desorb from the carbon andcontaminate off-site areaswhereas incineration destroysthe perchlorate ion andreduces the GAC to a smallamount of ash with nosecondary toxic contaminantsto manage

No regeneration brine is createdduring treatment – a highlyadsorbent carbon materialactivated by heating andcoated with a thin layer of asurface-active substance is usedto adsorb the negativelycharged perchlorate ion

Carbon tailoring has limitedadsorption capacity forperchlorate removal hence noteffective for large-scaleapplication and high perchlorateconcentrations

Can be regenerated for reuse Quaternary ammonium monomersimprove capacity over what isachieved with organic polymersbut have not yet been approvedfor use in potable water treatment

Not as effective as othertechnologies, hence is only bestas retrofit of existing systems suchas IX

Spent GAC may require treatmentprior to ordinary or hazardouswaste disposal

GAC adsorption for perchloratemight require pretreatment forremoval of suspended solids,silica, or mica from streams to betreated

Ability to remove perchlorate canbe reduced by water-soluble co-contaminants with a high polarity

Ion exchange (IX)regenerate systems

Proven technology for large-scaleapplication that can be usedfor both high and low CLO4

concentrations as well asgroundwater with high totalsolids (TS), though is morecost-effective when theperchlorate concentration islow

Costly non-destructive technology Can be used as a polishing stepfor biological treatmentprocesses or electrodialysis

(continued)


Table 4 | continued


Regenerable systems offer theadvantage of small footprints,high regeneration efficiencies,and automated operation

Non-selectivity as it generatesperchlorate-laden brine wastestreams that require additionaltreatment, hence can be highlycostly

Resin beds can be clogged byorganics, TDS, calcium, or iron inthe influent

Ion exchange single usesystems (use of non-regenerable resins)

Proven technology for large-scaleapplication that can be usedfor both high and low CLO4

concentrations as well asgroundwater with high TS

Costly and non-destructivetechnology

Selectivity (use of resins withhigh affinities for perchlorate)would reduce long-termoperating costs

Do not generate a perchlorate-laden waste stream (brine) thatis created during resinregeneration

Need substitution of exhaustedresins, which must be removedfrom the facility and sent fordisposal

Resins can cause fouling, plugging,channeling, bacterialcontamination, agglomeration,and compaction problems

Resin beds can be clogged byorganics, TDS, calcium, or iron inthe influent

Electrochemical – capacitivedeionization

More energy-efficient thancompeting technologies likethermal processes

Non-destructive, very slow andhighly costly, hence notapplicable for large scale

The resulting brine can betreated through catalytictreatment and biologicalreduction

Uses less energy with loweroperating pressures than RO

Small electrochemical energy limitcapacity, hence is efficient onlyon low perchlorateconcentrations

No bothersome membranes Regeneration of the electrodesyields concentrated brine

Phytoremediation (use ofplants to removecontaminants from soiland groundwater)

Low cost high public acceptance Relatively slow process Choice of the plant species isimportant and there is limitedresearch and data

Little disturbance to theenvironment

Possible ecological risk due totemporal phytoaccumulation ofsome fraction of the perchloratetaken up and transported mainlyto plant leaves and finally/alsopossibility of inclusion into thefood chain

Can treat other common co-contaminants, such aschlorinated solvents, explosives

Depth and climatic restrictions asclimate greatly impacts plantgrowth

No secondary waste production

(continued)


Table 4 | continued


Electrolysis Destruction of perchlorate intoharmless by-products andleaves the water contaminantfree

High electrical energy requirements Still an emerging technology, notfully proven yet; limitedresearch

No brine or other waste stream

Ultraviolet laser reduction Complete destruction of lowperchlorate concentrations

Not effective for high perchlorateconcentrations

Still an emerging technology, notfully proven yet; limitedresearch

Catalytic reduction is faster thanbiological reduction

Membrane technologies

RO (<0.0001 microns poresized membrane)

Proven and effective inperchlorate removal

Non-destructive technology hencerequires further treatment ofreject

To ensure water palatability post-treatment may require sodiumchloride or sodiumbicarbonate

Can treat high-TDS water andconcentrated brines

High capital, O&M costs

Automated systems Only applicable as standalone forlow perchlorate concentrations

Can be used as a pretreatment orpolishing technology for othersystems

Generate high volumes of rejecthence unsuitable for large scale

Non-ionic selectivity in the semi-permeable membrane can alterthe pH of the effluent stream andmake it corrosive

Membrane resilience and fouling

Needs higher operating pressurethan other membranetechnologies due to small poresizes of membrane filters, henceincreased need for power supply

Ultrafiltration (0.1–0.005microns pore size);nanofiltration (0.005–0.0001 microns pore size)

Lower energy requirements thanRO due to large pore sizes

UF membrane pore sizes are toolarge to remove perchlorate(0.00035 microns)

Nanofiltration membrane haslimited success in perchlorate ionremoval

Expensive, fouling issues and wastestreams that require furthermanagement

Electrodialysis Most effective membranetechnology

Non-destructive and generatescontaminated waste streams thatrequire further treatment/disposal

When high TDS is aconsideration, pretreatmentwith IX resin membranes ispossible

(continued)


Table 4 | continued


Can manage high TDS Extremely high operation/energycosts

Capable of high recovery (moreproduct and less brine than IX)and is not affected by non-ionic substances such as silica

The resulting concentrate mayrequire larger volumes of waterfor treatment before disposal

Permeable membrane has lowselectivity for perchlorate ions

Fouling issues


chlorate to chlorite (Figure 4). These steps are mediated by

chlorate reductase and are followed by the dismutation of

chlorite into chloride and O2, which is catalyzed by a con-

served enzyme known as chlorite dismutase (Figure 5). The

dismutation of chlorite to chlorine and oxygen is known to

be common to all perchlorate-reducing bacteria (PRB). A

widely accepted perchlorate-reducing pathway, especially

in the use of acetate, a common electron donor, is:

ClO�4 ! ClO�

3 ! ClO�2 ! Cl� þO2

Both aerobic and anaerobic biological wastewater treat-

ment can be achieved under either suspended growth

systems or attached growth systems.

Suspended-growth systems include systems like continu-

ous-flow stirred-tank reactors (CSTRs), most sequencing

batch reactors (SBRs), and activated sludge systems (ASSs).

Attached growth systems include biological trickling fil-

ters and rotating biological contactors, which were

Figure 4 | Wolinella succinogenes HAP 1 metabolic perchlorate-reducing pathway.

developed to improve the functionality of trickling filter and

biological tower systems following the discovery of light-

weight plastic media. Owing to the greater heights, trickling

filters using plastic media are often termed biological

towers. Trickling filter systems have also been described as

trickle filters, trickling biofilters, biofilters, biological filters,

biological trickling filters, roughing filters, intermittent filters,

packed media bed filters for packed bed reactors (PBRs),

alternative septic systems, percolating filters, attached

growth processes, fluidized bed reactors, and fixed film pro-

cesses, depending on system characteristics.

The key advantage of attached growth systems over sus-

pended growth reactors is their ability to maintain high

densities of biomass within the reactor, even in the presence

of rapidly flowing groundwater or wastewater, hence there

preferred application in groundwater and drinking water

perchlorate treatment. Suspended growth systems have

mainly been studied and applied in high strength and indus-

trial perchlorate treatment.

Other biological wastewater treatment systems appli-

cable include the moving bed biological reactor (MBBR),

which is an attached growth activated sludge process

designed to achieve a high quality effluent (20BOD/30SS/

ammonia) within a small footprint with low capital cost,

low sludge production, and no return activated sludge

stream requirement; and the integrated fixed-film activated

sludge system (IFAS), which is an integration of the biofilm

carrier technology (MBBR) within a conventional ASS.

Perchlorate degradation to levels needed for drinking

water has been achieved using fixed and fluidized bed bio-

reactors, with most studies conducted in the laboratory.

Biological removal of perchlorate has also been evaluated

Figure 5 | Enzymes involved in biological perchlorate reducing pathway.


in biofilm reactors using different carrier media including

plastic, sand, Celite, and GAC for fixed bed reactors, and

sand and GAC for fluidized bed reactors. Advantages of

using GAC as a carrier medium include the widespread

application of GAC in drinking water treatment plants

where existing GAC filters can easily be retrofitted to oper-

ate as biologically active carbon (BAC) reactors (Brown

et al. ; Min et al. ; Choi et al. ). GAC supports

the growth of biofilms, and its sorptive capacity should be

able to enhance biological perchlorate removal indirectly

by lowering the concentration of oxygen, the competing

electron acceptor, through chemisorption. Application of

sorptive support media is advantageous for biofilm reactors

exposed to transient operating conditions, such as variable

influent DO levels, reactor backwashing, and periods with-

out electron donor addition (Choi et al. ).

The design and development of biological systems for

perchlorate removal has evolved over time. In the early

1990s, the AFRL developed the first reactor, a suspended

growth system reactor, which treats wastewater generated

when high pressure water is used to remove solid fuels

from rockets and missiles, a process often termed ‘hog

out’ (Attaway & Smith ). The CSTR design was

tested at pilot scale at Tyndall Air Force Base in Florida

and then installed at the Thiokol rocket production facility

in Brigham City, Utah, in 1997. The original Thiokol

system consisted of two anaerobic CSTRs (6,000 and

2,700 L) and associated equipment for electron-donor

feed and pH adjustment, process control, and effluent clar-

ification and discharge. In 2002, two 3,800-L reactors were

added to increase capacity and permit the simultaneous

treatment of three different effluent streams containing

ammonium perchlorate, potassium perchlorate, and

mixed nitrates, respectively. A cheese whey and yeast

extract mixture was initially used as an electron donor,

but it was later replaced with molasses to reduce cost

and improve efficiency. The expanded system is capable

of treating ∼3,600 kg perchlorate/month from influent


concentrations ranging from 4,000 to 5,000 mg/L

(achieved by diluting the concentrated wastewater) to

effluent concentrations below the minimum reporting

level (MRL) for this matrix (∼400 μg/L) (Air Force

Research Laboratory ). In 2003, Hodgdon Powder

Co. constructed a dual anaerobic CSTR system, the

second suspended-growth reactor system, at its gunpowder

manufacturing facility in Herington, Kansas. This system,

consisting of two 9,500-L molasses-fed reactors designed

to process 9,500–19,000 L of wastewater daily, is success-

fully treating gunpowder processing wastes containing

perchlorate at influent levels >3,000 mg/L to effluent

levels that are below the MRL of ∼20 μg/L.

In 2004, the California Department of Health Services

issued a conditional approval of biological removal of per-

chlorate from drinking water sources using fixed bed BAC

reactors.

PBRs for perchlorate treatment have also been tested in

the laboratory (Logan & LaPoint ; Min et al. ) and

a few pilot-scale studies have also been completed with the

most extensive pilot testing being at the Texas Street Well

Facility in Redlands, California (Min et al. ). The

PBR design has not yet been applied at full scale for per-

chlorate treatment, although tests with flow rates as high

as 76 L/min have been conducted (Xu ). All laboratory

and pilot tests show that the PBR can effectively remove

perchlorate to a non-detectable level. However, for it to

be practical at full scale, a reliable method is needed to con-

trol the biomass inventory within the reactor over long

periods, while maintaining perchlorate levels below appli-

cable standards.

In addition to biomass inventory, biological treatment

has been faced by the challenge of contact between micro-

organisms in the treatment unit and the final effluent result-

ing in secondary contamination of treated water. Research

shows that this challenge can be overcome by use of an

ion exchange membrane bioreactor (IEMB). Using glycerol

as a carbon and energy source, a perchlorate concentration

as high as 250 mg L�1 was efficiently reduced to chloride.

Despite high perchlorate concentrations in the feed render-

ing the anion exchange membrane significantly less

permeable to perchlorate, the presence of bacteria in the

bio-compartment significantly increased the flux through

the membrane. Results also suggested minimal secondary

contamination (<3 mg C L�1) of the treated water with the

optimum feed of glycerol (Fox et al. ).

PERCHLORATE REDUCING MICRO-ORGANISMS

A number of micro-organisms have been identified that have

the capability to reduce both perchlorate and chlorate. Most

identified bacterial strains that reduce perchlorate are facul-

tative anaerobes, mostly Gram-negative. Dissimilatory (per)

chlorate reduction has also been reported in various strains

including denitrifying bacteria (DB). Many nitrate reducing

bacteria in pure cultures reduce chlorate and perchlorate

(which is usually referred to as (per)chlorate) by means of

membrane-bound respiratory nitrate reductases and assimi-

latory nitrate reductases (Coates & Achenbach ).

However, not all DBs can reduce perchlorate. Enzymatic

reduction of chlorate to chlorite (ClO�2 ) by nitrate reductase

occurs as a competitive reaction between nitrate and chlor-

ate in certain DBs.

Several other microbial isolates have also been obtained

that are capable of biodegrading perchlorate through cell

respiration, but few of these have been individually tested

for perchlorate removal to the required low levels of less

than 18 μg/L.

Kim & Logan (), while studying microbial

reduction in pure and mixed culture PBRs, found that per-

chlorate can be reduced approximately from 20 mg/L to

non-detectable (<4 μg/L) levels in acetate-fed columns

inoculated with Dechlorosoma sp. strain KJ or mixed cul-

tures. Flow into the reactor inoculated with the pure

culture was at an initial loading rate of 0.24 cm/min

(0.06 gpm/ft2), corresponding to an empty bed contact

time (EBCT) of 117 min. This was gradually increased to a

maximum of 13.6 cm/min (3.35 gpm/ft2; EBCT¼ 2.1 min)

over 83 days of operation in order to determine a minimum

EBCT for complete perchlorate removal. Hydraulic loading

rates for the reactor inoculated with mixed culture were

varied from 0.24 to 0.45 cm/min (0.06 to 0.11 gpm/ft2), cor-

responding to EBCTs of 43–118 min (detention times of

18–51 min).

It was demonstrated that detention times of PBRs can be

substantially reduced using the isolate KJ as compared to a

mixed culture, but larger concentrations of acetate, an

Figure 6 | Microscopic view of Wolinella succinogenes HAP 1.


electron donor, are required to reduce perchlorate to the

low levels necessary for drinking water. Perchlorate removal

to non-detectable levels, according to the study, required a

minimum EBCT of only 2.1 min for the column inoculated

with KJ, vs. 31 min for the mixed culture column. Acetate

was used at a molar ratio of C2H3O�2 =ClO

�4 of 2.9 (n¼ 6)

for the mixed culture, while more than twice as much acet-

ate was consumed on average (6.6± 2.0, n¼ 156) by the

pure culture (Kim & Logan ).

Despite research focus on PRB, bacteria that degrade

perchlorate can be broadly divided into four groups. The

choice of any one strain or mixed culture for use in a

wastewater treatment facility depends on the characteristics

of the wastewater (nitrate, ammonium and salt content, dis-

solved oxygen level), available carbon sources/electron

donors and climatic conditions of the facility location, or

energy considerations to maintain the required operation

parameters for a given bacteria. These groups are given

below.

PRB

These can reduce both perchlorate and chlorate. The

majority fall into two distinct monophyletic subgroups:

Dechloromonas and Dechlorosoma and most were ident-

ified by Achenbach et al. () as a β-subclass of

Proteobacteria. In the analysis it was shown that the

majority of the PRB in the Rhodocyclus assemblage that

form the two distinct monophyletic subgroups, namely,

Dechloromonas and Dechlorosoma, fall under the β-Proteo-

bacteria subclass of the Proteobacteria in the 16S rDNA

sequence whereas the W. succinogenes strain HAP-1 exclu-

sively represents the ϵ-Proteobacteria subclass.

They include but have not been limited to: Dechloro-

soma, which has recently been renamed Azospira based

on the very high (99.9%) 16S rRNA gene sequence identity

between the type strainDechlorosoma suillum and Azospira

oryzae; and Dechloromonas such as the hydrogen utilizing

strains Dechloromonas sp. JM isolated from hydrogen utiliz-

ing autotrophic consortium but incapable of utilizing

carbohydrates as an electron donor (Miller & Logan

), and Dechloromonas sp. JDS5 and Dechloromonas

sp. JDS6 isolated from a perchlorate-contaminated site

(Shrout et al. ).

Most PRB are facultative anaerobes except for Woli-

nella succinogenes HAP 1 (Wallace et al. ) and

Dechlorospirillum anomalous strain WD, which are

micro-aerophilic (Coates et al. ). All PRB are strict

respires and require an e� acceptor for growth. Most are

heterotrophic micro-organisms that need a carbon source

and can utilize alternate e� acceptors such as O2, nitrate,

and chlorate in preference to perchlorate. Most PRB prefer

neutral pH and mesophilic temperature. The majority have

been isolated under facultative anaerobic conditions using

streak plate or shake tube method with perchlorate or chlor-

ate as the e� acceptor. All perchlorate reducers completely

reduce perchlorate to O2 and Cl� without accumulation of

chlorate, chlorite, and O2. Figure 6 shows a microscopic

view of Wolinella succinogenes HAP 1.

Chlorate reducing bacteria

These can reduce only chlorate but not perchlorate.

Examples include Ideonella dechloratans (Malmqvist et al.

), Pseudomonas chloritidismutans strain ASK-1

(Wolterink et al. , ), and Alicycliphilus denitrificans

strain BC (Weelink et al. ).

High chlorate accumulating perchlorate reducing

bacteria

These can reduce both perchlorate and chlorate with transi-

ent accumulation of chlorate which can be utilized by

conventional PRB and chlorate reducing bacteria (CRB) in


a syntrophic association. Examples include Dechloromonas

PC1 (Nerenberg et al. ) and Dechlorosoma sp. HCAP-C

(Dudley et al. ).

DB

These are not significant players in perchlorate reduction in

nature, since perchlorate reduction is not a preferred energy-

yielding pathway of denitrifiers. Although DB are able to

reduce chlorate, the reaction is not coupled with growth.

These bacteria are not likely to grow on chlorate because

of the accumulation of toxic chlorite after reduction of the

chlorate by the nitrate reductase, which prevents growth.

Examples include Rhodobacter capsulatus, Rhodobacter

sphaeroides (Roldan et al. ), halophilic archaea Halo-

ferax denitrificans, Paracoccus halodenitrificans and

A. denitrificans strain BC.

Requirements of PRB

Electron acceptors

PRB have been reported to utilize inorganic e� acceptors

such as nitrate, bromate, chlorate, and O2 in preference to

perchlorate. Fortunately, if chlorate reducing bacteria are

present in the culture, chlorate will not pose a great hin-

drance since the CRB will reduce chlorate though not

perchlorate. In perchlorate-contaminated drinking water,

the dominant competing electron acceptors are typically

oxygen and nitrate. Consequently, significant perchlorate

reduction can only occur after complete removal of nitrate

and O2. When perchlorate is the sole e� acceptor, increas-

ingly higher reduction is observed.

Many studies on simultaneous reduction of perchlorate

and nitrate have been carried out and all point to the above

conclusion (Roldan et al. ; Okeke et al. ; Cang

et al. ; Lehman et al. ; Ricardo et al. ). A study

on simultaneous perchlorate and nitrate reduction by a

mixed microbial culture in suspension showed that the nitrate

reduction rate was 35 times higher than the maximum per-

chlorate reduction rate. While investigating the biological

degradation of nitrate and perchlorate using a mixed anoxic

microbial culture and ethanol as the carbon source, it was

found that perchlorate reduction was inhibited by nitrate,

since after nitrate depletion the perchlorate reduction rate

increased by 77% (Ricardo et al. ). It was also shown

that under ammonia limiting conditions, the perchlorate

reduction rate decreased by 10%, whereas the nitrate

reduction rate was unaffected. Ammonium ions higher than

0.4% have been found to significantly affect perchlorate

reduction of ion exchange regenerant brines.

High concentrations of salts such as sodium bicarbonate

or sodium phosphate have an inhibitory effect on the growth

of the perchlorate reducers, hence inhibiting biodegradation

of perchlorate. Cang developed two cultures capable of

degrading perchlorate and nitrate in high salt solutions

from marine inoculums. The growth conditions to maintain

these cultures in a healthy state required the maintenance of

strictly anaerobic conditions and the addition of trace

metals, Na2S and phosphate (Cang et al. ).

PRB do not utilize other inorganic e� acceptors such as

sulfite, sulfate, selenate, Mn-IV (except strain GR-1), and

Fe-III, and most of the PRB are unable to use organic elec-

tron acceptors. Therefore, their presence in the wastewater

has minimal or no effect on the rate of biodegradation of

perchlorate by the PRB as is the case for nitrate, chlorate,

and oxygen.

Electron donors

PRB can use a wide variety of organic (ethanol, fatty acids,

and vegetable oils) and inorganic e� donors (Ju et al. ).

Acetate is the most commonly used single organic e� donor.

Other organic e� donors include acetic acid, lactate, pyru-

vate, casamino acids, fumarate, succinate, methanol,

ethanol, fructose, cellobiose, mannose, xylose, pectin,

n-alkanes, 1-hexene, and liquefied petroleum gas. The

majority of PRB are, however, unable to use carbohydrates,

benzoate, catechol, glycerol, citrate, and benzene.

Although ClO�4 removal has been reported to be suc-

cessful in studies using organic donors, the organic

residual is a concern because it could stimulate bacterial

growth in water distribution systems and interfere with

chlorination processes, producing disinfection byproducts.

Inorganic electron donors can overcome the disadvan-

tages of organic substrates, and thus are currently the

focus of study for biological reduction of ClO�4 . Inorganic

e� donors utilized by some PRB include H2, H2S, soluble


and insoluble ferrous (Fe-II) iron, ZVI, elemental sulfur (S◦)

and S2O2�3 (Son et al. , ; Ju et al. ; Ahn et al.

).

It has been recently shown (Ahn et al. ) that pre-

treatment of the army’s insensitive melt-pour explosive,

PAX-21, production wastewater with ZVI can convert the

energetic compounds present in PAX-21 to products that

can serve as electron donors for PRB. PAX-21 mainly con-

tains ammonium perchlorate, RDX, and 2,4-dinitroanisole

(DNAN). ZVI reduction experiments showed that DNAN

was completely reduced to 2,4-diaminoanisole and RDX

was completely reduced to formaldehyde. Anaerobic batch

biodegradation of the ZVI-treated PAX-21 wastewater

resulted in removal of 30 mg L�1 perchlorate to non-

detectable levels within 5 days. Formaldehyde was the pri-

mary electron donor for perchlorate respiring bacteria,

affirming that integrated iron-anaerobic bioreactor systems

can be effective and cost-effective in the biological treatment

of perchlorate in army PAX-21 production wastewater (Ahn

et al. ).

More reliable and effective perchlorate removal can also

be achieved by use of the calcium ion. Large amounts of

Ca2þ have been reported to result in earlier initiation and

faster completion of perchlorate removal. Ca2þ can delay

pH increase by combining with OH� and consequently

extends biodegradation time. If ZVI and Ca2þ co-exist in a

system, empty bed residence time can be decreased, and

more reliable and effective perchlorate removal perform-

ance achieved (Liang et al. ).

Nutritional requirements

Microbial organisms responsible for perchlorate reduction

need a carbon source just like most micro-organisms. Var-

ious substances have been used as carbon sources in

biological removal of perchlorate, and the choice of any

one carbon source depends on the wastewater character-

istics, availability, and the cost implications.

Several PRB require trace metals, molybdenum, iron,

and selenium. Lack of vitamins or trace minerals in the

growth/isolation medium causes a visible decrease in the

degradation rate. Kucharzyk et al. (), in a study on max-

imizing microbial degradation of perchlorate using a genetic

algorithm, noted that in the case of Dechlorosoma sp. strain

KJ, when 1 mL/L of trace minerals and 0 mL/L of vitamins

were applied the degradation rate was only 7.5 mg/L/min.

This may be caused by the lack of microelements, such as

molybdenum, which are important for perchlorate degra-

dation (Kucharzyk et al. ). Protein nutrients such as

brewer’s yeast, cottonseed protein, or cheese whey and mol-

asses have also been used as nutrient sources (Okeke &

Frankenberger ). Yeast extract has a stimulatory effect

on the growth of these bacteria.

These micro-organisms are capable of utilizing various

components of the organic matter in wastes generated

from agro-industrial processes as a carbon source for

growth and for synthesis of cellular biomass as well

(Okeke & Frankenberger ). This would go a long way

in reducing the costs of substrate requirements during

large-scale wastewater treatment.

FACTORS AFFECTING BIODEGRADATION OFAMMONIUM PERCHLORATE

Several studies on biodegradation of perchlorate have been

carried out and reports on isolation of PRB published. How-

ever, conditions for optimal performance of the PRB have

not yet been well understood. The performance of PRB

under electron donor limited conditions, oxygenated con-

ditions, and chemically oxidizing conditions needs

extensive research in order to optimize microbial perchlor-

ate reduction. Some of the already studied factors affecting

performance of PRB are shown in Figure 7.

Oxygen

Oxygen hinders perchlorate and chlorate reduction by both

pure and mixed cultures because PRB utilize oxygen as an

electron donor in preference to perchlorate, as mentioned

earlier. This is also applicable to dissolved oxygen levels.

For instance a 12-h exposure of 6–7 mg L�1 dissolved O2

to a suspended culture of Azospira sp. KJ caused inhibition

of perchlorate reduction even after complete removal of

the O2. Severe inhibition has also been reported with

micro-aerophilic W. succinogenes HAP 1, D. anomalous

strain WD and strains JDS5 and JDS6 (Wallace et al.

; Coates et al. ). Simultaneous reduction of

Figure 7 | Factors influencing microbial perchlorate reduction (Bardiya & Bae 2011).


perchlorate and oxygen is therefore necessary to ensure

anaerobic conditions essential for the proper activity of

the perchlorate reductase. A sufficient supply of an elec-

tron donor is therefore imperative for continued

perchlorate reduction in oxygenated conditions. This is

an added cost to the operation and maintenance of a waste-

water treatment system, hence there is a need for cheaper

and available electron donors. Biological perchlorate

reduction can also be enhanced by use of chemisorption

using granulated active carbon as mentioned earlier in

the section Biodegredation of ammonium perchlorate

(Choi et al. ). Using a sorptive biofilm support

medium in the reactors can enhance biological perchlorate

removal under dynamic loading conditions. As shown in

the reactions below, in a redox reaction to account for

the reduction of oxygen produced by dismutation, 8 mole

of electrons are required to reduce 1 mole of perchlorate

to chloride and the produced oxygen to water (Sawyer

et al. ).

ΔGo0 Kj=eeqð Þa

Reduction and dismutation of perchlorate

Hþ þ e� þ 1=4ClO4� ! 1=4Cl� þ 1=2H2Oþ 1=4O2

� 109:40

Reduction of oxygen

Hþ þ 1=4O2 ! 1=2H2O� 78:72

Complete reduction of perchlorate

Hþ þ e� þ 1=8ClO4� ! 1=8Cl� þ 1=2H2O� 94:06

aCalculated for pH¼ 7 (Sawyer et al. ).


This remains so even in the case of oxygen production

due to microbial cell activity of perchlorate grown bacteria.

When perchlorate grown bacteria are used in perchlorate

reduction, the addition of chlorite yields oxygen outside

the cell. However, the organisms appear to be capable of rid-

ding themselves of oxygen produced (even in pure culture)

to protect oxygen sensitive perchlorate reducing enzymes,

presumably using c-type cytochromes (Rikken et al. ).

Perchlorate reduction by mixed lactate (electron donor)

enrichment culture (LEC) cannot be slowed by the addition

of oxygen in the presence of a sufficient electron donor

quantity. Experiments conducted where oxygen was added

to active perchlorate degrading microcosms that were

designed such that electron donor would not be limiting,

as lactate (400 mg/L) was supplied to the microcosms in suf-

ficient quantity to completely reduce the added perchlorate

plus 15.8 mg oxygen, showed that, after 8 h incubation with

perchlorate followed by room air being injected into the

microcosm headspace, the addition of 0.28 mg, 1.1 mg,

2.8 mg, and 5.6 mg oxygen (1 mL, 4 mL, 10 mL, and

20 mL room air, respectively) did not adversely affect per-

chlorate degradation (Shrout & Parkin ). This

indicates that perchlorate reduction in a diverse, in situ, bac-

terial environment can still take place in the presence of

molecular oxygen with a sufficient supply of an electron

donor. However, if environmental conditions are more oxi-

dized (indicated by a higher redox potential), the rate and

extent of perchlorate degradation will be decreased.

Nitrate

The effect of nitrate on perchlorate reduction appears to be

more complex than that of oxygen. Close similarity in the

reduction potential of the NO�3 =N2 pair (E◦¼ 1.25 V, with

the ClO�4 =Cl

� pair (E◦¼ 1.28 V) makes nitrate an excellent

competitor to perchlorate. Consequently, several PRB differ

significantly in their response toward the two e� acceptors.

The simultaneous reduction of perchlorate and nitrate and

the sequential reduction of the two e� acceptors have

been extensively reported in the literature both for the

pure and enriched cultures. The literature indicates that

the two can be simultaneously reduced in the presence of

electron donors, but the perchlorate reduction rate

decreases slightly in the presence of nitrate. Among the

pure cultures, D. agitata strain CKB, W. succinogenes

HAP-1 and Perc1ace can reduce nitrate and perchlorate

simultaneously, but only Perc1ace can grow with nitrate

reduction (Okeke & Frankenberger ; Choi & Silverstein

). In the majority of cases, the presence of nitrate causes

a longer lag in perchlorate reduction, and perchlorate

reduction starts only after complete removal of nitrate.

Recent research indicates that absolute perchlorate

reduction in a wastewater treatment facility faced with a high

concentration of nitrate and sulfate can be achieved using a

two-staged hydrogen-based membrane biofilm reactor

(MBfR) system (Figure 8) (Zhao et al. ) and also by using

enzyme-based technologies (Figure 9) (Hutchison et al. ).

In Figure 8, the NO3� surface loading was controlled in

each stage and with an equivalent NO3� surface loading

larger than 0.65± 0.04 g N/m2-day, the lead MBfR removed

about 87± 4% of NO3– and 30± 8% of ClO�

4 . This reduced

the equivalent surface loading of NO�3 to 0.34± 0.04–0.53±

0.03 g N/m2-day for the lag MBfR, in which ClO�4 was

reduced to non-detectable levels. SO2�4 reduction was elimi-

nated without compromising full ClO�4 reduction using a

higher flow rate that gave an equivalent NO�3 surface loading

of 0.94± 0.05 g N/m2-day in the lead MBfR and 0.53± 0.03 g

N/m2-day in the lag MBfR. The lead MBfR biofilm was domi-

nated by DB,Dechloromonas, Rubrivivax, and Enterobacter,

whose main function was to reduce nitrate, whereas the lag

MBfRwas dominated by PRB, Sphaerotilus,Rhodocyclaceae,

and Rhodobacter, with the main function of perchlorate

reduction as nitrate loading being small (Zhao et al. ).

Figure 9 shows the removal of perchlorate in the co-occur-

renceofnitrate using cell-free bacterial enzymes as biocatalysts.

In this study, crude cell lysates and soluble protein fractions of

Azospira oryzae PS, as well as soluble protein fractions encap-

sulated in lipid and polymer vesicles were used. Perchlorate

was removed by the soluble protein fraction at higher rates

than nitrate and perchlorate reduction even in the presence

of 500-fold excess nitrate (Hutchison et al. ).

Salinity

Perchlorate reduction is drastically affected at salt concen-

trations as low as 1%, and is completely inhibited at

salt concentrations above 4% (Coates et al. ). Microbio-

logical treatment of perchlorate containing solutions has not

Figure 9 | Perchlorate reduction using free and encapsulated Azospira oryzae enzymes

in the presence of nitrate (Hutchison et al. 2013).

Figure 8 | Two-staged MBfR for perchlorate reduction in the presence of nitrate and sulfate (Zhao et al. 2013).


been reported thus far to occur at the high salinities typical

of perchlorate-contaminated ion exchange brines. A per-

chlorate degrading isolate obtained by Logan et al. ()

had an optimal salinity of 1% and grew only at <2%

NaCl. Non-salt-tolerant PRB is completely inhibited at sali-

nities over 2–4% (Michaelidou et al. ; Gingras &

Batista ), but salt-tolerant PRB that is acclimated to

high salinity has been shown to reduce perchlorate at

appreciable rates in high salinity, although the rates are

indirectly proportional to the salt concentrations.

Owing to the high ionic strength of industrial waste-

waters containing high NaCl concentrations, it is very

difficult to remove perchlorate as high ionic strength ofwaste-

water has been reported to hinder the perchlorate reduction

activity of perchlorate reducers. The inhibitory effects of

high ionic strength can be dealt with by (1) diluting thewaste-

water until the inhibitory effect dissipates and (2) using PRB

strains that are tolerant of high ionic strength. However, the

dilution process is operation and capital intensive, leaving

the use of salt tolerant PRB the more economical option. In

a recent study on perchlorate reduction using salt tolerant

bacterial consortia, it was found that although the perchlor-

ate reduction rates decreased with increasing NaCl

concentration, salt tolerant-PRBl consortia could reduce per-

chlorate to 75 g-NaCl L�1 (Ryu et al. ).

Temperature

Perchlorate reduction has been reported to occur over a wide

range of temperatures (10–40 WC), however, optimal

reduction proceeds between 28 and 37 WC. The temperature

range for bacteria growth of W. succinogenes HAP 1 was

20–45 WC, with an optimum at 40 WC. Perchlorate reduction

by the perchlorate respiring bacteriumPerc1acewas achieved

in the temperature range of 20–40 WC, and with optimum

activity at 25–35 WC (Okeke & Frankenberger ).

pH

Most PRB require a neutral pH of around 6.8–7.2 for growth

and optimal perchlorate reduction, although perchlorate

Table 5 | pH ranges for PRB

PH range for PRB

Pure or mixed culture Perchlorate reduction Bacteria growth Reference

HAP-1 N/A 6.5–8.0, optimum 7.1 Wallace et al. ()

Perclace 6.5–8.5, optimum 7.0–7.2 N/A Okeke & Frankenberger Jr (); Coates & Achenbach ()

Mixed culture 5.0–9.0, optimum 7.0 N/A Wang et al. ()

CKB N/A 6.5–8.5, optimum 7.5 Herman& Frankenberger ()

Acinetobacter N/A 6.0–7.5, optimum 6.8–7.2 Stepanyuk et al. ()

Mixed culture 6.6–7.5, optimum 7.1 Wide range Attaway & Smith ()


reduction occurs throughout the pH range from 5.0 to 9.0.

Rates of perchlorate removal by a unit mass of bacteria

have been reported to be significantly different at various

pHs, with a maximum rate at pH 7.0 (Wang et al. ).

The optimal PRB growth for W. succinogenes HAP 1

occurs at a pH of 7.1, whereas the optimal perchlorate

reduction rate in a mixed culture occurs at a pH of 7.0.

Table 5 shows a summary of pH ranges for both pure and

mixed heterotrophic PRB (Wang et al. ).

CONCLUSION

Perchlorate, being poorly reactive and highly soluble in

water, can persist in the environment for long periods of

time. Conventional physical and chemical water and waste-

water treatment processes are inapplicable for the removal

of the perchlorate ion. Treatment options that have been

used to remove the perchlorate ion have necessitated

additional steps to treat or dispose of the concentrated per-

chlorate residual waste stream that is generated, leaving

biological treatment as the only viable method that can com-

pletely remove ClO�4 from wastewater effluents.

To curb challenges limiting wide acceptability of biode-

gradation, effective biological treatment of perchlorate

wastewater in large-scale applications such as army

munition production can be achieved through integration

of two or more treatment options, such as inclusion of tai-

lored GAC in biological reactors, whose main

disadvantage is the long-term need for further treatment of

explosive-laden spent carbon or disposal by landfill/

incineration.

Biomass inventory and secondary contamination of

treated water may be addressed through the integration of

ion exchange with a membrane bioreactor as an IEMB

system. Electron donor availability and electron competition

can be reduced by pretreatment of army PAX-21 production

wastewater with ZVI before biodegradation, as ZVI pre-

treatment breaks energetic compounds into compounds

that can be used by PRB as electron donors. ZVI can be

combined with Ca2þ for a more reliable, fast, and effective

perchlorate removal efficiency, as the Ca2þ reacts with

OH� delaying the pH increase, hence extending biodegrada-

tion time. Electron competitors such as sulfate and nitrate

can also be dealt with by using two-staged hydrogen-based

MBfR systems and also by using enzyme-based technologies.

However, further research and pilot-scale application on

the aforementioned recommendations is a necessity.

ACKNOWLEDGEMENTS

The present research was supported by theMajor Science and

Technology Program for Water Pollution Control and

Treatment (2012ZX07201002-6), National Scientific Funding

of China (51378003), International Cooperation Project

(2013DFG92600), Beijing Higher Education Young Elite

Teacher Project.

REFERENCES

Achenbach, L. A., Michaelidou, U., Bruce, R. A., Fryman, J. &Coates, J. D. Dechloromonas agitata gen. nov., sp. nov.


and Dechlorosoma suillum gen. nov., sp. nov., two novelenvironmentally dominant (per)chlorate-reducing bacteriaand their phylogenetic position. Int. J. Syst. Evol. Microbiol.51, 527–533.

Ahn, S. E., Cha, D. K. & Kim, B. J. Detoxification of PAX-21ammunitions wastewater by zero-valent iron for microbialreduction of perchlorate. J. Hazard. Mater. 192, 909–914.

Ahn, S. C., Hubbard, B., Cha, D. K. & Kim, B. J. Simultaneousremoval of perchlorate and energetic compounds inmunitions wastewater by zero-valent iron and perchlorate-respiring bacteria. J. Environ. Sci. Health A 49 (5), 575–583.

Air Force Research Laboratory Operation Implementation ofAmmonium Perchlorate Biodegradation. Airbase &Environmental Technology Division, Wright-Patterson AirForce Base, Ohio, USA.

Andraski, B. J., Jackson, W. A., Welborn, T. L., Böhlke, J. K.,Sevanthi, R. & Stonestrom, D. A. Soil, plant, and terraineffects on natural perchlorate distribution in a desertlandscape. J. Environ. Qual. 43, 980–994.

Attaway, H. & Smith, M. Reduction of perchlorate by ananaerobic enrichment culture. J. Indust.Microbiol.12, 408–412.

Attaway, H. & Smith, M. D. Propellant wastewater treatmentprocess. U.S. Patent 5, 302, 285.

Balaji, R., Anderson, T. A., Orris, G. J., Rainwater, K. A.,Rajagopalan, S., Sandvig, R. M., Scanlon, B. R., Stonestrom,D. A., Walvoord, M. A. & Jackson, W. A. Widespreadnatural perchlorate in unsaturated zones of the SouthwestUnited States. Environ. Sci. Technol. 41, 4522–4528.

Baldridge, M. G., Stahl, R. L., Gerstenberger, S. L., Vicki, T. &Reinhold, J. H. In utero and lactational exposure ofLong-Evans rats to ammonium perchlorate (AP) disruptsovarian follicle maturation. Reproductive Toxicol. 19,155–161.

Bardiya, N. & Bae, J.-H. Dissimilatory perchlorate reduction:a review. Microbiological Res. 166, 237–254.

Böhlke, J. K., Sturchio, N. C. & Gu, B. Perchlorate isotopeforensics. Anal. Chem. 77 (23), 7838–7842.

Braverman, L. E., He, X. & Pino, S. The effect of low doseperchlorate on thyroid functions in normal volunteers.Thyroid 14 (9), 691.

Braverman, L. E., He, X. & Pino, S. The effect of perchlorate,thiocyanate, and nitrate on thyroid function in workersexposed to perchlorate long-term. J. Clin. Endocrinol. Metab.90 (2), 700–706.

Brown, G. M. & Gu, B. The Chemistry of Perchlorate in theEnvironment. Chemical Sciences and EnvironmentalSciences Divisions, Oak Ridge National Laboratory, OakRidge, Tennessee, USA, pp. 17–47.

Brown, J. C., Snoeyink, V. L., Raskin, L. & Richard, L. Thesensitivity of fixed-bed biological perchlorate removal tochanges in operating conditions and water qualitycharacteristics. Water Res. 37, 206–214.

Burns, D. T., Chimpalee, N. & Harriott, M. Flow-injectionextraction- spectrophotometric determination of perchloratewith Brilliant Green. Anal. Chim. Acta 217, 177–181.

Calderón, R., Palma, P., Parker, D., Molina, M., Godoy, F. A. &Escudey, M. Perchlorate levels in soil and waters fromthe Atacama Desert. Arch. Environ. Contam. Toxicol. 66 (2),155–161.

Cang, Y., Roberts, D. J. & Clifford, D. A. Development ofcultures capable of reducing perchlorate and nitrate in highsalt solutions. Water Res. 38, 3322–3330.

Chen, Y., Sible, J. C. & McNabb, F. M. A. Effects of maternalexposure to ammonium perchlorate on thyroid function andthe expression of thyroid-responsive genes in Japanese quailembryos. Gen. Comp. Endocrinol. 15, 196–207.

Choe, J. K., Mehnert, M. H. & Guest, J. S. Comparativeassessment of the environmental sustainability of existingand emerging perchlorate treatment technologies fordrinking water. Environ. Sci. Technol. 47 (9), 4644–4652.

Choi, H. & Silverstein, J. Inhibition of perchlorate reductionby nitrate in a fixed biofilm reactor. J. Hazard. Mater. 159,440–445.

Choi, Y. C., Li, X., Raskin, L. & Morgenroth, E. Effect ofbackwashing on perchlorate removal in fixed bed biofilmreactors. Water Res. 41, 1949–1959.

Choi, Y. C., Li, X., Raskin, L. & Morgenroth, E. Chemisorption of oxygen onto activated carbon can enhancethe stability of biological perchlorate reduction in fixed bedbiofilm reactors. Water Res. 42, 3425–3434.

Coates, J. D. & Achenbach, L. A. Microbial perchloratereduction: rocket fuelled metabolism. Nat. Rev. Microbiol. 2,569–580.

Coates, J. D., Michaelidou, U. & Bruce, R. A. The ubiquityand diversity of dissimilatory perchlorate reducing bacteria.Appl. Environ. Microbiol. 65, 5234–5241.

Dudley, M., Salamone, A. & Nerenberg, R. Kinetics of achlorate-accumulating, perchlorate-reducing bacterium.Water Res. 42, 2403–2413.

Fox, S., Oren, Y., Ronen, Z. & Gilron, J. Ion exchangemembrane bioreactor for treating groundwater contaminatedwith high perchlorate concentrations. J. Hazard. Mater. 264,552–559.

Furdui, V. I. & Tomassini, F. Trends and sources of perchloratein Arctic snow. Environ. Sci. Technol. 44 (2), 588–592.

Gal, H., Ronen, Z., Weisbrod, N., Dahan, O. & Nativ, R. Perchlorate biodegradation in contaminated soils and thedeep unsaturated zone. Soil Biol. Biochem. 40, 1751–1757.

Gibbs, J. P., Ahmad, R. & Crump, K. S. Evaluation of apopulation with occupational exposure to airborneammonium perchlorate for possible acute or chronic effectson thyroid function. J. Occup. Environ. Med. 40, 1072–1082.

Gingras, T.M.&Batista, J. R. Biological reductionof perchloratein ion exchange regenerant solutions containing high salinityand ammonium levels. J. Environ. Monit. 4, 96–101.

Hatzinger, P. B. Perchlorate biodegradation for watertreatment. Environ. Sci. Technol. 39, 239A–247A.

Herman, D. C. & Frankenberger Jr, W. T.. Bacterial reductionof perchlorate and nitrate in water. J. Environ. Qual. 28,1018–1024.

http://dx.doi.org/10.1016/j.jhazmat.2011.05.104



http://dx.doi.org/10.1080/10934529.2014.859455

http://dx.doi.org/10.1080/10934529.2014.859455

http://dx.doi.org/10.1080/10934529.2014.859455

http://dx.doi.org/10.1080/10934529.2014.859455

http://dx.doi.org/10.2134/jeq2013.11.0453



http://dx.doi.org/10.1007/BF01569673

http://dx.doi.org/10.1007/BF01569673

http://dx.doi.org/10.1021/es062853i



http://dx.doi.org/10.1016/j.reprotox.2004.07.002



http://dx.doi.org/10.1016/j.micres.2010.11.005

http://dx.doi.org/10.1016/j.micres.2010.11.005

http://dx.doi.org/10.1021/ac051360d

http://dx.doi.org/10.1021/ac051360d

http://dx.doi.org/10.1210/jc.2004-1821

http://dx.doi.org/10.1210/jc.2004-1821

http://dx.doi.org/10.1210/jc.2004-1821

http://dx.doi.org/10.1016/S0043-1354(02)00243-9

http://dx.doi.org/10.1016/S0043-1354(02)00243-9

http://dx.doi.org/10.1016/S0043-1354(02)00243-9

http://dx.doi.org/10.1016/S0043-1354(02)00243-9

http://dx.doi.org/10.1016/S0003-2670(00)80398-0

http://dx.doi.org/10.1016/S0003-2670(00)80398-0

http://dx.doi.org/10.1016/S0003-2670(00)80398-0

http://dx.doi.org/10.1007/s00244-013-9960-y

http://dx.doi.org/10.1007/s00244-013-9960-y

http://dx.doi.org/10.1016/j.watres.2004.04.020



http://dx.doi.org/10.1016/j.ygcen.2008.08.014




http://dx.doi.org/10.1021/es3042862












http://dx.doi.org/10.1038/nrmicro926

http://dx.doi.org/10.1038/nrmicro926






http://dx.doi.org/10.1021/es902243b


http://dx.doi.org/10.1016/j.soilbio.2008.02.015

http://dx.doi.org/10.1016/j.soilbio.2008.02.015

http://dx.doi.org/10.1097/00043764-199812000-00007

http://dx.doi.org/10.1097/00043764-199812000-00007

http://dx.doi.org/10.1097/00043764-199812000-00007

http://dx.doi.org/10.1097/00043764-199812000-00007

http://dx.doi.org/10.1039/b107358n



http://dx.doi.org/10.1021/es053280x

http://dx.doi.org/10.1021/es053280x

http://dx.doi.org/10.2134/jeq1999.00472425002800030036x

http://dx.doi.org/10.2134/jeq1999.00472425002800030036x


Hutchison, J. M., Poust, S. K. & Kumar, M. Perchloratereduction using free and encapsulated Azospira oryzaeenzymes. Environ. Sci. Technol. 47 (17), 9934–9941.

Isobe, T., Ogawa, S. P. & Sugimoto, R. Perchloratecontamination of groundwater from fireworks manufacturingarea in South India. Environ. Monit. Assess. 185 (7),5627–5637.

Jackson, W. A., Bohlke, J. K., Gu, B., Hatzinger, P. B. & Sturchio,N. C. Isotopic composition and origin of indigenousnatural perchlorate and co-occurring nitrate in thesouthwestern United Stated. Environ. Sci. Technol. 44,4869–4876.

Ju, X., Sierra-Alvarez, R., Field, J. A., Byrnes, D. J., Bentley, H. &Bentley, R. Microbial perchlorate reduction withelemental sulfur and other inorganic electron donors.Chemosphere 71, 114–122.

Kim, K. & Logan, B. E. Microbial reduction of perchlorate inpure and mixed culture packed-bed bioreactors. Water Res.35 (13), 3071–3076.

Kosaka, K., Asami, M., Matsuoka, Y., Kamoshita, M. & Kunikane,S. Occurrence of perchlorate in drinking water sourcesof metropolitan area in Japan. Water Res. 41, 3474–3482.

Kounaves, S. P., Stroble, S. T. & Anderson, R. M. Discovery ofnatural perchlorate in the Antarctic dry valleys and its globalimplications. Environ. Sci. Technol. 44 (7), 2360–2364.

Kounaves, S. P., Carrier, B. L. & O’Neil, G. D. Destruction oforganics on Mars by oxychlorines: Evidence from Phoenix,Curiosity, and EETA79001. EPSC Abstracts, Vol. 8,EPSC2013-799-1.

Kucharzyk, K. H., Crawford, R. L., Cosens, B. & Hess, T. F. Development of drinking water standards for perchlorate inthe United States. J. Environ. Manage. 91, 303–310.

Kucharzyk, K. H., Crawford, R. L., Paszczynski, A. J., Soule, T. &Hess, T. F. Maximizing microbial degradation ofperchlorate using a genetic algorithm: media optimization.J. Biotechnol. 157, 189–197.

Lehman, S. G., Badruzzaman, M., Adham, S., Roberts, D. J. &Clifford, D. A. Perchlorate and nitrate treatment by ionexchange integrated with biological brine treatment. WaterRes. 42, 969–976.

Liang, S., Shi, Q., Gao, X., Yang, H. & Wang, S. Perchlorateremoval by autotrophic bacteria associated with zero-valentiron: effect of calcium ions. J. Chem. Technol. Biotechnol. 90,722–729.

Logan, B. E. & LaPoint, D. Treatment of perchlorate- andnitrate-contaminated groundwater in an autotrophic, gasphase, packed-bed bioreactor. Water Res. 36, 3647–3653.

Logan, B. E., Wu, J. & Unz, R. F. Biological perchloratereduction in high-salinity solutions. Water Res. 35 (12),3034–3038.

Malmqvist, A., Welander, T., Moore, E., Ternstrom, A., Molin, G.& Stenstrom, I. M. Ideonella dechloratans gen. nov., sp.nov., a new bacterium capable of growing anaerobically withchlorate as an electron acceptor. Syst. Appl. Microbiol. 17,58–64.

Mattie, D. R., Strawson, J. & Zhao, J. Perchlorate Toxicityand Risk Assessment. University of Nebraska, US Air ForceResearch, Springer, USA, pp. 169–196.

McKetta, J. J. & Weismantel, G. E., Eds. Encyclopedia ofChemical Processing and Design, Vol. 51. Marcel Dekker,New York, USA. p. 180.

Michaelidou, U., Achenbach, L. A. & Coates, J. D. Isolationand characterization of two novel (per)chlorate-reducingbacteria from swine waste lagoons. In: Perchlorate in theEnvironment (E. D. Urbansky, ed.). Kluwer Academic/Plenum, New York, USA, pp. 271–283.

Miller, J. P. & Logan, B. E. Sustained perchloratedegradation in an autotrophic, gas-phase, packed-bedbioreactor. Environ. Sci. Technol. 34, 3018–3022.

Min, B., Evans, P. J., Chu, A. K. & Logan, B. E. Perchlorateremoval in sand and plastic media bioreactors.Water Res. 38,47–60.

Motzer, W. E. Perchlorate: problems, detection, andsolutions. Environ. Forensics 2, 301–311.

National Research Council Health Implications ofPerchlorate Ingestion. National Academies Press,Washington, DC, USA.

Nerenberg, R., Kawagoshi, Y. & Rittmann, B. E. Kinetics of ahydrogen-oxidizing, perchlorate-reducing bacterium. WaterRes. 40, 3290–3296.

Nzengung, V. A. & McCutcheon, S. C. Phytoremediation ofperchlorate. In: Phytoremediation: Transformation andControl of Contaminants (S. C. McCutcheon & J. L.Schnoor, eds). Wiley-Interscience, Hoboken, NJ, USA,Chapter 29.

Nzengung, V. A. & Wang, C. Influences onphytoremediation of perchlorate- contaminated water. In:Perchlorate in the Environment (E. T. Urbansky, ed.). KluwerAcademic/Plenum, New York, USA, pp. 219–229.

Nzengung, V. A., Das, K. C. & Kastner, J. R. Pilot Scale in SituBioremediation of Perchlorate-Contaminated Soils at theLonghorn Army Ammunition Plant. Contract #DAAA09-00-C-0060.

Nzengung, V. A., Penning, H. & O’Niell, W. L. Mechanisticchanges during phytoremediation of perchlorate underdifferent root zone conditions. Int. J. Phytoremediation 6,63–83.

Okeke, B. C. & Frankenberger Jr, W. T. Molecular analysis ofa perchlorate reductase from a perchlorate-respiringbacterium Perc1ace. Microbiol. Res. 158, 337–344.

Okeke, B. C. & Frankenberger Jr, W. T.. Use of starch andpotato peel waste for perchlorate bioreduction in water. Sci.Total Environ. 347, 35–45.

Okeke, B. C., Giblin, T. & Frankenberger Jr, W. T. Reductionof perchlorate and nitrate by salt tolerant bacteria. Environ.Pollut. 118, 357–363.

Orris, G. J., Harvey, G. J., Tsui, D. T. & Eldrige, J. E. Preliminary analyses for perchlorate in selected naturalmaterials and their derivative products: US GeologicalSurvey Open-File Report 03-314, 6 pp.




http://dx.doi.org/10.1007/s10661-012-2972-7

http://dx.doi.org/10.1007/s10661-012-2972-7

http://dx.doi.org/10.1007/s10661-012-2972-7

http://dx.doi.org/10.1021/es903802j



http://dx.doi.org/10.1016/j.chemosphere.2007.09.045

http://dx.doi.org/10.1016/j.chemosphere.2007.09.045

http://dx.doi.org/10.1016/S0043-1354(01)00014-8

http://dx.doi.org/10.1016/S0043-1354(01)00014-8






http://dx.doi.org/10.1016/j.jenvman.2009.09.023

http://dx.doi.org/10.1016/j.jenvman.2009.09.023

http://dx.doi.org/10.1016/j.jbiotec.2011.10.011

http://dx.doi.org/10.1016/j.jbiotec.2011.10.011



http://dx.doi.org/10.1002/jctb.4365



http://dx.doi.org/10.1016/S0043-1354(02)00049-0

http://dx.doi.org/10.1016/S0043-1354(02)00049-0

http://dx.doi.org/10.1016/S0043-1354(02)00049-0

http://dx.doi.org/10.1016/S0043-1354(01)00013-6

http://dx.doi.org/10.1016/S0043-1354(01)00013-6

http://dx.doi.org/10.1016/S0723-2020(11)80032-9

http://dx.doi.org/10.1016/S0723-2020(11)80032-9

http://dx.doi.org/10.1016/S0723-2020(11)80032-9

http://dx.doi.org/10.1021/es991155d





http://dx.doi.org/10.1006/enfo.2001.0059

http://dx.doi.org/10.1006/enfo.2001.0059



http://dx.doi.org/10.1080/16226510490439990

http://dx.doi.org/10.1080/16226510490439990

http://dx.doi.org/10.1080/16226510490439990

http://dx.doi.org/10.1078/0944-5013-00213

http://dx.doi.org/10.1078/0944-5013-00213

http://dx.doi.org/10.1078/0944-5013-00213

http://dx.doi.org/10.1016/j.scitotenv.2004.12.041

http://dx.doi.org/10.1016/j.scitotenv.2004.12.041


Park, J.-W., Rinchard, J., Liu, F., Anderson, T. A., Kendall, R. J.& Theodorakis, C. W. The thyroid endocrinedisruptor perchlorate affects reproduction, growth, andsurvival of mosquito fish. Ecotoxicol. Environ. Safety 63,343–352.

Quinones, O., Oh, J., Vanderford, B., Kim, J. H., Cho, J. & Snyder,S. A. Perchlorate assessment of the Nakdong andYeongsan watersheds, Republic of Korea. Environ. Toxicol.Chem. 26 (7), 1349–1354.

Rajagopalan, S., Anderson, T., Fahlquist, L., Rainwater, K. &Ridley, M. Widespread presence of naturally occurringperchlorate in high plains of Texas and New Mexico.Environ. Sci. Technol. 40, 3156–3162.

Rajagopalan, S., Anderson, T., Fahlquist, L., Rainwater, K. &Ridley, M. Perchlorate in wet deposition across NorthAmerica. Environ. Sci. Technol. 43 (3), 616–622.

Ricardo, A. R., Carvalho, G., Velizarov, S., Crespo, J. G. & Reis,M. A. Kinetics of nitrate and perchlorate removal andbiofilm stratification in an ion exchange membranebioreactor. Water Res. 46, 4556–4568.

Rikken, G. B., Kroon, A. G. M. & van Ginkel, C. G. Transformation of (per)chlorate into chloride by a newlyisolated bacterium: reduction and dismutation. Appl.Microbiol. Biotechnol. 45 (3), 420–426.

Roldan, M. D., Reyes, F., Moreno-Vivian, C. & Castillo, F. Chlorate and nitrate reduction in the phototrophic bacteriaRhodobacter capsulatus and Rhodobacter sphaeroides. CurrMicrobiol. 29, 241–246.

Ryu, H. W., Nor, S. J., Moon, K. E., Cho, K. S., Cha, D. K. & Rhee,K. I. Reduction of perchlorate by salt tolerant bacterialconsortia. Bioresour. Technol. 103, 279–285.

Sawyer, C. N., McCarty, P. L. & Parkin, G. F. Chemistry forEnvironmental Engineering, 5th edn. McGraw Hill,New York, USA.

Shi, Y., Zhang, P., Wang, Y., Shi, J., Cai, Y., Mou, S. & Jiang, G. Perchlorate in sewage sludge, rice, bottled water andmilk collected from different areas in China. Environ. Int. 33,955–962.

Shrout, J. D. & Parkin, G. F. Influence of electron donor,oxygen, and redox potential on bacterial perchloratedegradation. Water Res. 40, 1191–1199.

Shrout, J. D., Scheetz, T. E., Casavant, T. L. & Parkin, G. F. Isolation and characterization of autotrophic, hydrogenutilizing, perchlorate-reducing bacteria. Appl. Microbiol.Biotechnol. 67, 261–268.

Son, A., Lee, J., Chiu, P. C., Kim, B. J. & Cha, D. K. Microbialreduction of perchlorate with zero-valent iron. Water Res. 40,2027–2032.

Son, A., Schmidt, C. J., Shin, H. & Cha, D. K. Microbialcommunity analysis of perchlorate-reducing cultures growingon zero-valent iron. J. Hazard. Mater. 185, 669–676.

Srinivasan, R. & Sorial, G. A. Treatment of perchlorate indrinking water: a critical review. Sep. Purif. Tech. 69, 7–21.

Stepanyuk, V. V., Smirnova, G. F., Klyushnikova, T. M., Kanyuk,N. I., Panchenko, L. P., Nogina, T. M. & Prima, V. I.

New species of the acinetobacter genus-acinetobacterthermotoleranticus sp. Nov. Mikrobiolog. 61, 490–500.

Strategic Environmental Research and Development ProgramCP-1403 a Synthesis, Evaluation, and FormulationStudies in New Oxidizers as Alternatives to AmmoniumPerchlorate in DoD Missile Propulsion Applications.

Strategic Environmental Research and Development Program CP-1404 b Robust, Perchlorate-Free Propellants withReduced Pollution.

Susarla, S., Bacchus, S., Wolfe, N. L. & McCutcheon, S. C. aPhytotransformation of perchlorate and identification ofmetabolic products in Myriophyllum aquaticum. Int. J.Phytoremediation 1, 96–107.

Susarla, S., Bacchus, S., Wolfe, N. L. & McCutcheon, S. C. bPhytotransformation of perchlorate using parrot-feather. SoilGroundwater Cleanup February/March, 20–23.

Susarla, S., Bacchus, S., Wolfe, N. L. & McCutcheon, S. C. cPotential species for phytoremediation of perchlorate.EPA/600/R-99/069.

Susarla, S., Bacchus, S., Harvey, G. & McCutcheon, S. C. Phytotransformation of perchlorate-contaminated waters.Environ. Technol. 21 (9), 1055–1065.

University of Nebraska Perchlorate State of the ScienceSymposium. University of Nebraska Medical Center, Omaha,Nebraska, 29 September–1 October. http://www.unmc.edu/coned.

US Environmental Protection Agency (US EPA) Availablefrom: http://www.epa.gov/drink/contaminants/unregulated/perchlorate.cfm (accessed 11 November 2009).

US Environmental Protection Agency (US EPA) Availablefrom: http://www.epa.gov/fedrgstr/EPA-WATER/2009/August/Day-19/w19507.pdf (accessed 19 August 2009).

Wallace,W.,Ward,T.,Breen,A.&Attaway,H. Identificationofananaerobic bacteriumwhich reduces perchlorate and chlorate asWolinella succinogenes. J. Indust. Microbiol. 16, 68–72.

Wang, C., Lippincott, L. & Meng, X. Kinetics of biologicalperchlorate reduction and pH effect. J. Hazard. Mater. 153,663–669.

Weelink, S. A. B., Tan, N. C. G., ten Broeke, H. & van denKieboom, C. Isolation and characterization ofAlicycliphilus denitrificans strain BC which grows onbenzene with chlorate as the electron acceptor. Appl.Environ. Microbiol. 74, 6672–6681.

Wolterink, A. F. W. M., Schiltz, E., Hagedoorn, P. L., Hagen, W.R., Kengen, S. W. M. & Stams, A. J. M. Characterizationof chlorate reductase from Pseudomonas chloritidismutans.J. Bacteriol. 185, 3210–3213.

Wolterink, A., Kim, S., Muusse, M., Kim, I. S., Roholl, P. J. M., vanGinkel, C. G., Stams, A. J. M. & Kengen, S. W. M. Dechloromonas hortensis sp. nov. and strain ASK-1, twonovel (per)chlorate-reducing bacteria, and taxonomicdescription of strain GR-1. Int. J. Syst. Evol. Microbiol. 55,2063–2071.

Xu, J. Microbial degradation of perchlorate: principles andapplications. Environ. Eng. Sci. 20, 405–422.

http://dx.doi.org/10.1016/j.ecoenv.2005.04.002



http://dx.doi.org/10.1897/06-469R.1

http://dx.doi.org/10.1897/06-469R.1



http://dx.doi.org/10.1021/es801737u

http://dx.doi.org/10.1021/es801737u




http://dx.doi.org/10.1007/s002530050707

http://dx.doi.org/10.1007/s002530050707

http://dx.doi.org/10.1007/BF01570161

http://dx.doi.org/10.1007/BF01570161

http://dx.doi.org/10.1016/j.biortech.2011.09.115

http://dx.doi.org/10.1016/j.biortech.2011.09.115

http://dx.doi.org/10.1016/j.envint.2007.05.007

http://dx.doi.org/10.1016/j.envint.2007.05.007




http://dx.doi.org/10.1007/s00253-004-1725-0

http://dx.doi.org/10.1007/s00253-004-1725-0






http://dx.doi.org/10.1016/j.seppur.2009.06.025

http://dx.doi.org/10.1016/j.seppur.2009.06.025

http://dx.doi.org/10.1080/15226519908500007

http://dx.doi.org/10.1080/15226519908500007

http://dx.doi.org/10.1080/09593332108618049

http://www.unmc.edu/coned



http://www.epa.gov/drink/contaminants/unregulated/perchlorate.cfm

http://www.epa.gov/drink/contaminants/unregulated/perchlorate.cfm

http://www.epa.gov/fedrgstr/EPA-WATER/2009/August/Day-19/w19507.pdf

http://www.epa.gov/fedrgstr/EPA-WATER/2009/August/Day-19/w19507.pdf

http://dx.doi.org/10.1007/BF01569924

http://dx.doi.org/10.1007/BF01569924

http://dx.doi.org/10.1007/BF01569924



http://dx.doi.org/10.1128/AEM.00835-08



http://dx.doi.org/10.1128/JB.185.10.3210-3213.2003

http://dx.doi.org/10.1128/JB.185.10.3210-3213.2003

http://dx.doi.org/10.1099/ijs.0.63404-0



http://dx.doi.org/10.1089/109287503768335904

http://dx.doi.org/10.1089/109287503768335904


Ye, L., You, H. & Yao, J. Water treatment technologies forperchlorate: a review. Desalination 298, 1–12.

Zhao, H. P., Ontiveros-Valencia, A., Tang, Y., Kim, B. O., Ilhan,Z. E., Krajmalnik-Brown, R. & Rittmann, B. Using a

two-stage hydrogen-based membrane biofilm reactor (MBfR)to achieve complete perchlorate reduction in the presenceof nitrate and sulfate. Environ. Sci. Technol. 47 (3),1565–1572.

First received 15 February 2015; accepted in revised form 16 May 2015. Available online 8 July 2015

http://dx.doi.org/10.1016/j.desal.2012.05.006

http://dx.doi.org/10.1016/j.desal.2012.05.006

http://dx.doi.org/10.1021/es303823n




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