Final Report

Inland Desalination: Concentrate Management and

Brine Beneficial Application

By

Lucas M. De Buren

Advisor

Ali Sharbat, Ph. D., P.E.

Presented to the Watershed Management Internship Program

Experiential Learning for USDA Careers

California Polytechnic University, Pomona

Pomona, CA

Abstract

The project is needed in order to investigate beneficial applications of innovative

methods for inland desalination and concentrate management. As of May 13th 2014,

nearly 60 percent of the state is officially in an “exceptional” drought — the highest

level, above “severe” — and meteorologists are seeing no immediate change in a

relentlessly dry forecast. Even more alarming is that scientists are warning that the

state’s cyclical droughts could become longer and more frequent as the climate

warms. Current methods for inland desalination, such as RO, require large amounts

of electrical energy and are very cost demanding, making them hardly accessible to

small and developing communities / countries. The analysis will provide concept

description, pros and cons, maturity assessment, and application potentials for

emerging technologies such as: FO, Membrane Distillation, EDM, and Thermo-Ionic

Technology. Disposal of concentrate, the byproduct of desalination, is also

problematic in inland communities. Therefore a report on the significance of salt

and nutrient recovery and the challenges is presents will be compiled. The objective

is to compile background information and develop a suggested protocol for

addressing the issue of Inland Desalination and Concentrate Management.

Review of volume reduction technologies

Improved Membranes

Researchers at the UCLA Henry Samueli School of Engineering and Applied Science

have developed a new application for nano-technology in RO systems. The new

membrane uses a cross-linked matrix of polymers with engineered nanoparticles

designed to attract water ions and repel contaminants. Unlike conventional RO

membranes, these integrated highly porous nanocomposite material act like a

sponge. The repulsion of contaminants by the nanocomposite material provides a

significant reduction in the fouling potential of the membrane as well as volume of

effluent concentrate. Initial case studies have shown a decrease in energy of 50%

required for water desalination or roughly a 25% decrease in energy use. Figures 1

and 2 show a microscopic photo of the membranes with and without

nanocomposite materials.

Figure 2. Conventional thin film composite RO membrane; polyamide thin film

formed over a porous polysulfone support.

Source: Hoek, 2011

Figure 3. Thin film nanocomposite RO membrane comprising a polyamide-particle

nanocomposite thin film formed over a porous polysulfone support.

Source: Hoek, 2011

Carbon nano-tubes (CNTs) have similar fluid transport characteristics as those in

water transport channels in biological membranes. The high selectivity of particles

capable of passing through the membrane decreases the amount of water rejected

into the concentrate stream. CNTs provide a strong invitation to water molecules

while rejecting salts and pollutants (Das et al. 2014). Furthermore CNTs can

increase membrane stability by increasing the compressive strength between layers

(Elimelech et al. 2011). As seen in Figure 3, the hollow pores allow the passage of

water without a loss of pressure due to friction. What is more impressive is that CNT

membranes can be used as highly trained ‘gate keepers’ for size controlled

separation of multiple pollutants (Das et al. 2014). Current research has been

focusing on development of the fabrication and functionalization of membranes.

Ratto et al. (2011) patented a CNT membrane capable of achieving an ion rejection

greater than 99%. Due to limited pilot testing and proprietary matarials, economical

tendencies and cost analysis cannot be completed at this point.

Figure 3. Visual Representation of Tip-functionalize nonpolar CNT.

Source: Das, Ali, & Hamid, 2014

The impeccable water transport properties of biological membranes, such as cell

walls, has lead to research for the incorporation of water-selective proteins into RO

membranes. The inclusion of water-selective properties would serve as water

directing channels. A case study incorporating Aquaporin Z (AqpZ) proteins showed

increased water transport efficiency relative to conventional RO membranes.

Authors postulated that by using AqpZ based biometric membranes a permeability

of two (2) orders greater than that seen in conventional SWRO systems can be

achieved (Tang, Zhao, Wang, Hélix-Nielsen, & Fane, 2013). Theoretically, biomimetic

membranes should offer the highest permeability, however due to lack of extensive

research this conclusion is solely based on transport velocity measurements of

water molecules through individual AqpZ channels rather than conventional

membrane tests. Despite almost excellent salt rejection capabilities these

biomaterials have been observed to be relatively unstable and develop severe

fouling, thus decreasing the durability of the membrane. At this moment there are

currently two companies developing membranes. Aquaporin A/S is developing a 2-

D membrane with embedded aquaporins to support pressures up to 10 bar, flux >

100 lmh. Danfoss AquaZ is developing 3-D membranes within which vesicles are

cross-linked tightly together, with space between them filled up, the water then

passes through several aquaporins; the objective of such a process is to achieve a

flow that is 5 to 10 times higher than normal. (Veerapaneni & Bond, 2011)

At this point nanotechnology is leading the way in the development of innovative RO

membranes for desalination. As presented in this paper many key fundamental

scientific and technical aspects have to be addressed prior to large-scale

implementation of such systems.

Improved online monitoring

Mineral scaling occurs when the concentration of sparingly dissolved mineral salts

such as gypsum, barium sulfate, calcium carbonate, silicon oxide, etc. near the

membrane surfaces rise above their solubility limits. As permeate recovery is

increased to offset cost associated with management of residual desalination, there

is also an increase in fouling propensity of brackish water desalination. As a result,

sparingly soluble salts precipitate as bulk on the membrane, leading to a significant

reduction in membrane performance and membrane life. If development of scaling

is detected at an early stage membrane cleaning can be effectively accomplished

through processes such as chemical cleaning (Ang et al. 2006) or feed flow reversal

(Bartman et al. 2008). Yet these processes require real-time membrane monitoring

information to detect the onset of mineral scaling (Bartman et al., 2011)

RO systems controller capable of responding to changes in feed water salinity and

compositions have been proposed, however such systems require early detection

and monitoring of membrane mineral scaling. In-situ monitoring techniques for the

study of mineral scaling and use in mineral scale and fouling detection in RO system

have been based on indirect ultrasonic crystal detection (Zang et al. 2006). Although

these methods are capable of detecting the buildup of fouling, they are incapable of

differentiating the type of foulant (i.e. particulate deposition, bacteria or surface

formed crystals). Furthermore in general there is insufficient reliability in the early

onset detection of membrane surface crystallization (Uchymiak et al. 2007 & 2009).

Thus a novel monitoring system must be developed that allows for real-time

membrane surface imaging.

In order to overcome the limitations of RO systems controller and indirect

ultrasonic crystal detection, a novel ex-situ membrane monitor (MeMO) has been

recently developed (Uchymiak et al. 2009). The MeMo detector is capable of

delivering real-time images of a representative membrane surface, where the

operating conditions are matched to the conditions in the spiral-wound element of

the RO plan (Bartman et al., 2011). Through the use of an image analysis program

(operating either online, or in a post-processing mode) plant monitoring systems

would be capable of determining the amount of membrane surface coverage by

mineral salt scaling and the number of crystals present in the observation area,

representative of a spiral-wound element of the RO plan. With this monitoring

approach, when mineral scale coverage reaches a predetermined threshold, a

control signal can be sent to the plant control system in order to initiate any number

of cleaning strategies, adjustment of antiscalant dose or adjustment of product

water recovery.

Emerging Technologies

Effluent concentrate consists of mostly water, for example Salt Water Reverse

Osmosis (SWRO) concentrate is approximately 94% water. Thus extracting this

water can increase the amount of freshwater obtained, decrease the volume of the

waste to dispose of, and facilitate the precipitation and extraction of valuable salts

from the concentrate (Xu et al. 2013). Most of the technologies presented

hereinafter are emerging technologies whose production, operating and

maintenance costs need to be improved and demonstrated through bench or pilot

testing.

Forward Osmosis (FO)

Forward Osmosis (FO), which utilizes the natural phenomenon of osmosis, has

recently emerged, as a viable alternative to the cost and energy intensive process

required in RO. According to the “Global Desalination Report from Global Water

Intelligence” FO places at the top of coefficient of desalination reality with a score of

8.9. Coupled with the right technology, such as NF or magnetic field, FO systems can

completely separate water from draw solutes. Forward Osmosis is a membrane

process driven by the osmotic pressure gradient created across a semi-permeable

membrane by two flowing streams of varying concentration (i.e. the draw solution

and the feed), Figure 8 shows the typical set up for an FO system couples with a

magnetic field for solute rejection. Due to the natural driving force of the system the

energy required to transport the water across the membrane is almost negligible.

Thus making it appealing to application in small developing communities.

There are various aspects, which need to be refined for the large-scale application of

FO. For maximum water flux, most FO membranes are designed of asymmetric

structures with a thin dense active layer on a porous sub-layer. The presence of the

sub-layer in the systems causes internal concentration polarization (ICP) regardless

of which solution is ran along the sub-layer (i.e. draw solution or feed solution). The

immediate impact developed due to ICP is a decrease in the net driving force,

directly affecting the expected flux across membranes. Studies have shown that the

addition of a highly porous sub-layer could decrease ICP.

Figure 8. Schematic of a Forward Osmosis (FO) Unit.

Source: Su, Zhang, Ling, & Chung, 2012

The application of FO systems have not been thoroughly researched with the use of

brackish water, thus for the moment being we must rely on information obtained

through testing with seawater. Thus far the highest reported flux for seawater

desalination is about 15 L/m2h reported by Widjojo et al. (2011), with a 2.0 M draw

solution and a flat TFC polyamide membrane. Further increase in the flux is limited

due to the limiting effect of flux-dependent ICP. The very low retention of draw

solutes suggests that present designed may not be feasible in practical applications.

However work has been conducted to develop draw solutes, which can be easily and

completely separated from the water through Nanofilration (NF) (Ling and Chung

2011) or magnetic field compared with conventional salts. A draw solution

containing 0.12 g/mL polyacrylic acid sodium salt generated a water flux of 7.5

L/m2 h.

For FO to be feasible the draw solution must offer an osmotic pressure higher than

the feed (2.04 to 20.4 atm for brackish water and 27 atm for seawater). Therefore

the application of FO for desalination of inland brackish water has greater feasibility

than of seawater. In order to accurately evaluate the energy consumption of a FO

unit for any specific applications, the draw solution regeneration must be

considered, and thus far there has been limited research on the subject.

In conclusion ample amount of research is currently being conducted to establish FO

as a viable alternative to RO. Yet the efficiencies to separate draw solutes from

water using NF or magnetic separator are still not high enough for potable water.

This problem is increasingly prevalent as it is very difficult to simultaneously

enhance water-flux and solute rejection. As a result for FO to be considered as a

sustainably supply source of clean water further research must be conducted

Membrane Distillation (MD)

Membrane distillation (MD) uses low-grade heat sources to drive a thermal

separation and facilitate mass transport through a hydrophobic, microporous

membrane (Figure 9) (Lawson and Lloyd, 1997; Hendren et al., 2009; Qtaishat et al.,

2009; Cath, 2010). The vapor pressure gradient between the heated solution and

the cooled distillate on the opposite side of the membrane makes up the driving

force for mass transport (Xu et al. 2013) Laboratory experiments have show that

MD is capable of producing ultra-pure water at lower cost than conventional

distillation processes (Lawson and Lloyd, 1997; Hendren et al., 2009; Qtaishat et al.,

2009; Cath, 2010). The membrane itself is made up of multiple engineered materials

such as polytetrafluoroethylene (PTFE), polypropylene (PP),

polyvinylidenedifluoride (PVDF), carbon nanotubes, and ceramic membranes

(Cerneaux et al., 2009; Dume ́e et al., 2010; Gryta and Barancewicz, 2010; Singh and

Sirkar, 2012).

Figure 9. MD process using hydrophobic membrane.

Source: KmX Corp. 2014

A theoretical model was developed to predict the rejection of nonvolatile solutes,

including: sodium, silica, boron and heavy metals. The model showed that rejection

of these solutes is close to 100%, although some compounds more volatile than

water will advantageously diffuse through the membrane. (Cath et al., 2004; Cath et

al., 2005a; Winter et al., 2011).

Furthermore studies have shown that MC is capable of desalinating streams of high

salinity and can successfully recover crystals from solutions under extreme

conditions. (Ji et al., 2010). When coupling the system with the use of vacuum-

enhanced direct contact membrane distillation (VEDCMD) to treat two independent

brackish water RO concentrates Martinetti et al. (2007) discovered that the system

was capable of achieving up to 81% water recovery from the concentrates. An

increase in water recovery from effluent concentrate directly reduces the volume of

effluent concentrate. Total water recovery, including the initial RO recovery, were

greater than 98% for the first concentrate and greater than 89% for the second. The

total dissolved solids (TDS) observed in each concentrate stream were 7,500 and

17,500 mg/L respectively. An increase in feed water concentration could result in a

flux decrease due to membrane scaling and drop in partial vapor pressure

(Martinetti et al., 2007). Furthermore increasing the feed water concentration

would require more frequent chemical cleaning, considerably increasing operation

costs and effluent volume produced. MD membranes are more chemically resistant

to oxidation than traditional RO and NF membranes, which allows for more efficient,

chemically aggressive cleaning. (Xu et al. 2013)

The application of MD membranes to produce high water recovery and low

membrane fouling/scaling would prove as an attractive alternative to desalination

concentrate management at municipal sectors where low-grade heat is available.

However long-term pilot-scale experiments with real water are required to provide

a better understanding of the real life applications of these membranes.

Dewvaporation

Dewvaporation uses humidification-dehumidification process to desalinate effluent

concentrate. Through this process the amount of water contained in, therefore the

volume, effluent concentrate can be effectively reduced by as much as 90%. The

concentrate stream is evaporated by heated air (derived from combustible fuel,

solar, or waste heat from nearby power plant) and fresh water condenses as dew on

the face of a heat treatment wall. The process was developed at the Arizona State

University in conjunction with L’Eau LLC. In order to minimize capital cost and

prevent the development of corrosion the tower units are built of thin plastic films,

see Figure 10. Using this configuration reduces operating cost as the tower operates

at atmospheric pressure.

Figure 10. Dewvaporation Cell.

Source: L’Eau LLC, 2009

Dewvaporation has been pilot tested in treating reclaimed water RO concentrate

and produced water from oil and gas production. These studies showed that

through Dewvaporation effluent disposal volumes could be reduced by as much as

90% while generating high quality distilled water. The scaling potential for this

system is relatively low as evaporation occurs at the liquid air interface and not on

the heat transfer wall.

Although much of the energy required is drawn from the energy released by vapor

formation, the demand for extra energy is still a challenge. An economical study by

Beckman (2008) concluded the following: using an average multiple effect value of

3.2, the heat needed for 1000 gallons of distillate production would be 764kWh of

heat. At an average natural gas cost of $0.169 per kWh (Energy Cost) the operating

cost would be $129.12 per 1000 gallons in additional capital investment. As

aforementioned in this report the addition of geothermal energy to provide for low-

grade energy might make the municipal application much more feasible. However

there are currently no full-scale operational units, thus no data on O&M life cost.

Commercial Dewvaporation towers are available through Altela, Inc, which has

designed, manufactured and tested the AlterlaRainTM systems are based on the

Dewvaporation process for the treatment of produced water during oil and gas

exploration and production (Xu et al. 2013)

Thermo-Ionic

Thermo-Ionic technology combines a desalination unit and a concentration unit to

increase water recovery, thus reducing the amount of water lost in effluent

concentrate as well as reducing the volume of effluent concentrate. Currently there

are two commercially available systems: a) AquaSelTM, and b) Thermo-Ionic

TechnologyTM. Both of which will be discussed hereinafter.

a. AquaSelTM

AquaSelTM is a non-thermal concentrate concentrator (NTBC) for high water

recovery developed by General Electric (GE). The combination a desalination unit

and a concentration unit can potentially remove barrier to water recovery arising

from inorganic scale fouling. The desalination unit is operated to typically remove

80% or more of the total dissolved solids (TDS) in the feed water. The concentration

unit is then specifically designed and operated to reduce the volume of the waste

stream from the system. The heart of the process is an electrodialysis-reversal

(EDR) system that can be adapted for specific concentrate concentration application

to further concentrate the RO reject stream.

Figure 12. Pilot Study AquaSelTM System in Coca-Cola Plant.

Source: Technologies, 2011

After it has been desalted, the EDR product water is then re-introduced into the RO

system and the reject concentrate is discharged into an engineered precipitation

tank, where the precipitated solids are allowed to settle. As a result dry salt cakes

are produced in the precipitation tank. With simple retrofit any RO process would

be augmented to only discharge less than 1% of the feed water (Technologies, 2011)

A pilot study was conducted in an Asian Coca-Cola plant beginning in December

2011. Figure 8 shows a schematic of the system and Figure 9 shows an actual

representation of the system. The 36,000 GPD was operated for more than 1,000

hours and was able to achieve more than 99% of the RO concentrate from an

ingredient quality water treatment system used to manufacture Coca-Cola products.

The initial focus of the system will be for application in the food and beverage

industry ingredient water markets where RO concentrate typically contains a TDS of

2,000 – 4,000 mg/L and flow rates from 25 to 100 GPM. Although these are the

applications being targeted, systems can be customized for feed water salinity of

500 - 5,000 mg/L and flow rates from 20 to 125 GPM while maintaining a 95% or

higher recovery rate.(Technologies, 2011)

b. Thermo-Ionic Technology by Saltworks Technologies Inc.

Thermo-Ionic is a technology developed by Saltworks Technologies Inc. Utilizing a

hybrid design Saltworks incorporated thermo-ionic technology into an RO system to

provide low-cost concentrate (concentrate) management. Thermo-Ionic

desalination uses ionic gradient for treatment of concentrate stream, the process is

driven by the salt concentration gradient between hyper-saline solution and feed

water. Figure 15 shows a simple visual schematic of the process. The hyper-saline

solution is produced in a special evaporative unit that operates at a temperature

10°C warmer than the ambient wet bulb temperature. Because the unit relies on

salinity gradients for internal voltage generation, the net salt flux, or current

density, is lower than EDR, requiring more membrane area (Xu et al. 2013). Above

evaporation ponds, whose energy consumption is minimal, thermo-ionic technology

has shown to consume the least amount of energy in comparison to conventional

concentrate management methods. For example: concentrate with a concentration

greater than 300,000 ppm will consume 1.5 kWh/m3 using Thermo-Ionic. For deep

well injection of concentrate of comparable concentration the cost would nearly

double.

Figure 15. Visual Representation of Thermo-Ionic Process.

Source: Greentech Media 2014.

Further development of Thermo-Ionic Technology recently been conducted by SPX

Cooling Technologies. As a partner of Saltworks Technologies, SPX Cooling

Technologies have developed an air-cooled tower capable of achieving ZLD while

also harvesting precipitated salts. Although this technology has great potential for

application in RO concentrate treatment it is still at demonstration scale, thus

further bench-scale and pilot testing must be completed before any significant

recommendations can be made.

Electrochemical conversion of concentrate wastes into valuable chemicals

Recent research has incorporated the use of electro-separation technology referred

to as electrodialysis metathesis (EDM) followed by a crystallized and precipitator to

treat brackish water RO effluent concentrate stream. This process was patented at

The University of Southern Carolina (Patent PCT/US2005/032419) and licensed to

Veolia for international commercialization. This system is composed of a traditional

RO system, followed by the EDM process. The concentrated reject from the RO are

placed though the EDM process, which further concentrates the salts into two

separate concentrate streams; one rich in calcium chloride and the other in sodium

sulfate. A resultant blowdown (Morillo et al., 2014), of the two concentrate streams

can be mixed together to precipitate calcium, sulfate, or gypsum. Any additional

dilute of the EDM can be returned to the RO feed for further processing without

additional risk of membrane scaling.

The main difference between EDM and typical ED is the use of five solution

compartments (including the electrolyte circuit) and four membranes, rather than

two of each in the repeating unit. Furthermore the repeating unit comprises one

diluate compartment, two concentrate compartments, one NaCl solution

compartment, one ordinary anion exchange, one ordinary cation exchange, one

monovalent selective anion exchange and one monovalent selective cation (Bond et

al., 2011).

Pilot testing has shown that EDM coupled with RO configurations are capable of

achieving a 99% water recovery rate (Davis et al., 2006). Furthermore due to the

small amount of water lost to the concentrate EDM can result is zero brine

discharge, reducing disposal costs, especially in brackish water RO plants. Scale-up

from pilot scale tests can be easily achieved, as all processes involved are available

on a commercial scale. Through the use of EDM brackish water RO plants are also

capable of turning concentrate wastes into valuable chemicals such as Na2SO4 and

CaSO4.

Estimates based on pilot-scale studies carried out by The University of South

Carolina indicate that EDM is economically possible with the recovery of

commercial salts. However individual studies of influent water conditions must be

completed prior to any recommendation, as capital costs are high due to the

multiple techniques required; ED (M), brine concentrators, crystallizers and brine

purification treatments (Morillo et al., 2014).

Salt Recovery Methods

Conventional methods for inland concentrate management are: disposal into

surface waters and/or municipal sewers, evaporation ponds, deep-well injection,

irrigation of halophyte plants, and algae production. From these methods only

irrigation of halophyte plants and algae production provide recovery for

concentrate obtained upon desalination of brackish water. Recent research has

shown that it is possible to: a) precipitate metals and nutrients (salts) out of

concentrate using chemical and biological processes, and b) increase salt recovery

via various techniques including zero liquid discharge (ZLD), pelletized softening,

SAL-PROCTM process, and selective salt recovery. For example pellets produced as a

result of chemical precipitation processes could be used as construction materials,

animal feed supplements, and soil remediation. Moreover selective precipitation

(removal) of the carbonate series may help reduce the CO2 footprint of desalination.

The importance of the development of salt recovery systems is beyond providing

a cost-effective method for concentrate disposal, the separation and marketing of

salts is a direct step towards developing an environmentally sustainable solution

where water recovery is maximized and landfill use is minimized.

Zero Liquid Discharge (ZLD)

Zero Liquid Discharge (ZLD) refers to the process by which all liquid is removed

from the concentrate stream (no water is left in the discharge). The end product of a

ZLD system is a solid residue of precipitate salt, which needs to be tested for

delivery to the appropriate solid waste disposal facility. Toxicity test and other

applicable tests will determine type of the landfill that can ultimately handle the

disposal of the waste. ZLD systems are attractive because they reduce the volume of

residue. Several ZLD technologies have been successfully implemented in industrial

water treatment processes. However the ZLD concept is relatively new in the

application to large-scale RO systems. Developmental technologies such as Salt

Solidification and Sequestration (SAL-PROCTM) are currently being tested to provide

zero liquid discharge in large-scale RO systems.

Combination ZLD systems combine mechanical or thermal evaporation for

volume reduction and forced circulation crystallizers (FCC). Typically used in direct

combination with high recovery RO systems, they are capable of producing high-

quality product water. However, crystallizers are mechanically complex and have

high capital and O&M costs (high energy demand). As small inland desalinations

strive to reduce energy costs, ZLD technologies might not be a viable option, unless

renewable sources of energy can be implemented to offset the energy requirement.

Furthermore there are a series of public health and ecosystem health concerns exist

for the regulations, which govern concentrate management, including the use of

solid residual processing processes. These concerns derive from minimal permit

requirements for operation of solids residual-producing process equipment for

disposal of concentrate derived from membrane desalination and are similar to

requirements for the implementation of wastewater treatment systems.

Chemical Precipitation Process

The chemical components in concentrate stream can be used for additional

applications after being extracted through physical or chemical processes. For

example in Eliat, Israel there is a dual-purpose plant in operation that produces

desalinated water and high-quality table salt (Ravizky and Nadav, 2007) The

desalination plant uses a mixed feed of 80% seawater and 20% Brackish Water

Reverse Osmosis (BWRO) concentrate from adjacent plants. Both feeds are blended

together and then placed in multiple evaporation ponds prior to being processed at

the salt factory of the company. The production of high-quality salt has not been

limited to RO concentrate. In a recent report by Takana et al. (2003) it was

discussed that by using a hybrid system composed of ED to treat concentrate from a

Salt Water Reverse Osmosis (SWRO) plant as raw material for salt production may

provide significant energy reduction, up to 20%, and be more advantageous than

using seawater. The preferential selectivity of monovalent ions over multivalent

ions (i.e. Na+ over Ca2+, Cl- over SO4-) required the use of special grade monovalent

permselective IX membranes in ED stacks. As a result Takana was able to produce

food-grade NaCl from concentrate stream. Electrodialysis was also used by Davis

(2006) to reduce the salinity of a SWRO reject stream prior to recycling to SWRO.

From the pre-concentrated SWRO concentrate salable sodium chloride; magnesium

hydroxide and bromine were extracted.

A bench study conducted by Baruzzaman et al. (2009) showed that through the

application of ED in combination with bipolar membranes (BMED) it is possible to

recover acid, base and hypochlorite which could be used directly onsite for water

purification purposes. An economic evaluation found that this approach might be

feasible for inland wastewater reuse facilities, which have limited access/option for

concentrate disposal. In this process monopolar cation- and anion- exchange

membranes are installed together with bipolar membranes in alternating series in

an ED stack (Xu et al.) The application of such system might be limited by the

contamination of acid and base products by salt ions, as they are likely to permeate

the bipolar membrane in the presence of a high concentration of acids and bases.

(Strathmann, 2010)

For systems where multiple salts are recovered and where there is a wide

range of solubility, the processing may involve multiple stages of concentration and

treatment steps that can recover salts from lowest to highest solubility. See

“Selective Salt Recovery” section, when performing cost-analysis on individual

systems and potential recoverable profit from saleable salts a solubility limit might

be established due to the cost of additional stages required to recover salts of high

solubility.

Biological Precipitation Process

Conventional mining techniques have now been in practice for over a few

centuries, during this time period we have been able to mine the best and most

concentrated ores, however this is slowly coming to a stop. In the future, we will be

forced to extract from less concentrated ores at higher costs. Furthermore with a

rapidly depleting source of fossil fuels, energy intensive mining might no longer be

feasible. Modern tech-driven society would not be able to survive without a cheap

supply of materials, thus we must look for alternative sources of mineral

production. Researcher Damian Palin has recently proposed a new method of salt

extraction from saline water using natural bacterial metabolic processes.

Palin isolated a strand capable of accumulating minerals from their

environment over time. As the bacteria metabolize they create an electrical field,

attracting metals from their local environment. These metals build up on the surface

of the bacteria; once the bacteria are encased in metal the bacteria perish and metal

precipitate is formed. Figure 1 shows the bacterial at the beginning of the

experiment and Figure 2 shows the bacteria encased in metal precipitate after a

one-hour period.

Figures 1 & 2. Initial & final still of bacteria precipitating metals.

Source: Palin, 2012

Singapore, a leading place for desalination technologies, has proposed to produce

900 million liters per day of desalinated water by 2060. This will produce an

excessive amount of desalination concentrate. If the most advanced recovery

technologies were implemented (94% recovery), this would equal to approximately

54 million gallons of concentrate daily, causing dire consequences to the local

ecology and environment where the concentrate is disposed.

At lab scale, metals like calcium, potassium and magnesium have been

precipitated from out of desalination concentrate. In terms of magnesium the

amount of concentrate would create a $4.5 billion mining industry for Singapore, a

country that lacks natural resources and relies heavily on imports. Considering this

is only one of the metals being precipitated it is obvious that not implementing this

technology would be detrimental to building a sustainable future. This technology

would provide access to clean potable water, reduce ecological impact and create a

mining industry in a way that hasn’t existed before; a mining industry that doesn’t

defile the Earth.

Pelletized Lime Softening

To maximize water recovery, technologies such as Pelletized Lime Softening

(PLS) are being evaluated to improve the recovery rate of RO systems to about

92.5% to 95%. Research has shown that with the implementation of a conventional

softening Intermediate Concentrate Chemical Stabilization (ICCS) reactor it is

feasible to achieve a 94% overall recovery on brackish surface water and

groundwater. Intermediate Concentrate Chemical Stabilization technologies are

implemented between the primary and secondary RO systems (Figure 3) to

precipitate sparingly soluble ions such as silica, calcium and barium.

Figure 3. Schematic of two-stage RO system with ICCS.

Pelletized softening ICCS works though the addition of microsand in an up-

flow reactor. The sparingly soluble salts react with the microsand and precipitate as

“pellets.” The PLS system provides a reduction in the chemical footprint and the

volume of residuals produced as a result of ICCS. Water born emissions of nitrate

and ammonium from pellet systems were shown to be approximately 46% and

47%, respectively, less than that from conventional softening system (Wan & Li,

n.d.). Due to their excellent, highly pure and nearly dry composition, 5-10%

moisture after air dry (He et al. 2011) the pellets can be reused or recycled in

various applications. Furthermore pilot studies have shown virtually complete

softening with no conceivable post softening problems.

A recent study established that PLS ICCS can lower environmental impact

due to a reduction in the consumption of chemicals, energy and residual handling

requirements. (He et. al. 2011) Pilot studies have shown that PLS is capable of

reducing the hardness range, iron and manganese concentrations. For a case study

the following quantities were reported.

Well 6 Well 3

Parameter Raw Finished Raw Finished

pH 7.1-7.8 8.2-8.9 7.3 8.0-8.4

Hardness (mg/L) 188-210 60 - 72 212-253 53-81

Iron (mg/L) 0.51-0.96 0.03-0.10 0.07 0.00

Manganese (mg/L) 0.28-0.36 0.015-0.019 0.28 0.018

Table 1. Water Quality Before and After Pelletized Treatment.

Source: Snedecor et al. 2008

Residual Pellets can be used as nutrient sources in animal feed (chicken

factories), cement (aggregate) and metal industry and road construction (asphalt).

Residual pellets contain some or all of the key elements that cement plants add

during cement manufacturing process. The addition of these residuals could

decrease the total volume of supplemental materials cement manufactures would

have to purchase, decreasing invasive mining techniques currently in practice. The

“dry” nature of the pellets makes them attractive to cement manufactures as this

reduces the need for any dewatering processes.

In the spring of 2006 U.S. Water Services develop and placed into

production the first dry grind ethanol plant designed and operated with ZLD to the

environment in central California. An environmentally sensitive area, the San

Joaquin Valley does not allow any aqueous industrial discharge. Therefore in order

to the build the water plant in this prime agricultural location, the development on a

process for re-using the discharge from the cooling tower, pretreatment and process

streams was required. The U.S. Water Services designed a process using CLD to

precipitate many of the minerals from the water. The minerals, which are rich in

calcium, are then added to the dried distillers grains with soluble supplementing the

nutrient value of this valuable animal feed byproduct of ethanol production.

Pellet Application Study 1- Soil Remediation

Pellets produced as a by-product of ZLD processes may be used in soil

remediation. An example of soil remediation is through the use of CaCl2 for sodic

(high SAR) soils instead of gypsum, which is cheaper and well accepted. Rainfall on

sodic soils is not allowed to soak into the soil and is therefore lost by evaporation.

Due to these characteristics the soil does not support agriculture, and rainfall is lost

to the local areas, as the water cannot enter local ground water pathways. By adding

calcium salts, it is possible to change the hydraulic conductivity of the soils to

produce increased rates of infiltration and reduce the amount of rainfall lost, in turn

significantly increasing the supply of usable water (Mickley, 2008).

Recent research has shown that soil remediation techniques can be achieved

through the use of calcium and magnesium chloride for sodic soils (Mickley, 2008).

These products, however, are more costly than gypsum. Even through more

expensive chemicals may be more efficient and perform at a higher level farmers are

still reluctant to pay more money for remediation. In this example, a large-scale

need (soil remediation) could gather large, long-term benefits that include increase

in agricultural yields and reduce water loss due to evaporation of rainfall.

Pellet Application Study 2 – Dust Suppression

Calcium chloride and magnesium chloride are two types of salts used for dust

suppression. Moisture is required to keep fine particles in unpaved roads and

construction projects together, as it coats and binds all particles. Furthermore

calcium chloride is able to absorb large amounts of water and retains the water due

to high surface tension, which reduces evaporation. These characteristics allow

calcium chloride to hold soil particles with a strong thin film of moisture that

reduces friction between particles, increasing compaction rate. Once compacted, the

surface tension creates a cohesive force that is able to hold the consolidated base

together and performs a soil stabilization function.

The ideal application for this use of concentrate would be implemented for the life

of the desalination plant. However in most cases dust suppression, for the

application of unpaved roads and construction, the amount of salts recovered would

be much greater than required.

Pellet Application Study 3 – Hot-Mix Asphalt (HMA) Production

Traditionally, lime fines have been used to treat HMA ingredients in order to

improve the long-term interactions (bonds) between the asphalt cement and

aggregates. These improvements are due to the limes’ ability to inhibit any water

from softening the asphalt and/or enhancing the physical interaction between the

asphalt cement and aggregates. These improvements have been achieved by the

combination of lime fines with either the aggregate or asphalt cement prior to

preparation of HMA mix. While favorable characteristics from adding lime fines into

HMA have been achieved using current methodologies, problems have been found

due to the clumping of lime fines and fines becoming airborne.

Lime fines have been identified as a health hazard due to the ability of the

fines to become airborne during the mixing process. Long-term exposure to may

lead to emphysema, pneumonia, chronic bronchitis, and lung cancer. Furthermore

methodology used to marinate aggregate with lime fines also causes other health-

related issues. Issues arise from the premature application of lime fines to

aggregate, as the aggregate is allowed to “sit” on the ground for weeks or months. As

a result, lime fines have seeped into the ground, flowed into near aquifers, and also

contaminated groundwater. The presence to lime fines has been linked to the death

of local fish as well as drinking water contamination. Subsequent processing of

contaminated water sources also cause increased cost as Ca+2 account for a majority

of the fouling developed in membrane systems. Manufacturers have admitted that

when 1.5% powdered lime is added by current methods that only 1% of the lime is

incorporated into the finished product.

Producing lime pellets through PLS is beneficial as it provides a more

manageable form to improve the use in asphalt manufacturing, paving and in soil

conditioning with minimal health concerns associated with small particulates.

Furthermore encased microsand particulate provide an additional source of “fine”

aggregate reducing the need for virgin material during HMA production.

It should be noted that salts made for these examples lime pellets would

need to meet product specifications for or undergo environmental testing for the

application. Furthermore, a concern with PLS ICCS is the impact of intake water

quality. Research has shown that conventional systems are more efficient at

processing a greater range of water quality, where using pellet softening intake

water quality may impact performance. Therefore the application may be limited to

water quality and susceptible to cost increases for pretreatment of water.

SAL-PROCTM

Salt Solidification and Sequestration (SAL-PROCTM) is a patented process

(Geo-Processors USA, Inc.) where valuable salts and chemical compounds are

extracted from inorganic saline waters. The saline feed water is initially pre-treated

using solar evaporation or desalination process supplemented by conventional

mineral and chemical processing steps. The steps lead to a significant reduction in

the salt load and volume, which minimize the requirements for concentrate

discharge.

The model for this process consists of two subsystems, including one or

more selective salt recovery steps coupled with RO desalination, thermo-mechanical

concentrate concentration, and crystallization steps. A simplified schematic of the

system can be seen in Figure 4. The model allows for the selection of an appropriate

ZLD process scheme. The ZLD processes use multiple steps and incorporate lime

and soda ash to precipitate mixed salts. The overall system has been shown to

recover the entire concentrate flow and generate high-quality water as a result.

However, the incorporation of desalting technologies is required to reduce the

volume significantly while highly concentrating water entering the SAL-PROC.

Pilot testing has shown that a number of saline waste streams can be

Gypsum Magnesium Hydroxide Sodium Chloride Salt Calcium Chloride

converted into marketable products while achieving ZLD. Typical recovered

marketable products include: gypsum, magnesium hydroxide, sodium chlorite,

calcium carbonate, sodium sulfate, and calcium chloride. Through the use of SAL-

PROC Jibril and Ibrahim (2001) produced, at laboratory scale, sodium bicarbonate

(NaHCO3), sodium carbonate (Na2CO3), and ammonium chloride (NH4Cl) from

concentrated NaCl solutions. The production of marketable products would allow

developing/stand-alone communities to offset the cost of RO systems.

Saline Water

Pre- Concentration

(Solar Evaporation or Desalination Process – e.g. RO system)

SAL-PROC

Process

Zero Liquid Discharge

Figure 4. Simplified Process Schematic of SAL-PROC Proces.

Selective Salt Recovery

This is a process to recover sodium chloride crystals and sodium chloride

crystals and sodium carbonate decahydrate crystals from concentrated concentrate.

The invention relates to a process for selectively recovering salts from a mixed salt

concentrate, in particular the recovery of sodium chlorine crystals and sodium

carbonate from a concentrate generally rich in these salts. An initial pre-

concentration process is carried out where the concentrate is concentrated and in

the process CO2 is removed from the concentrate. Some of the sodium bicarbonate is

Products

converted into sodium carbonate initially. During the process, the concentrated

concentrate is pumped into a sodium chloride crystallizer where the concentrate is

heated and further concentrated to form sodium chloride crystals. The sodium

chloride crystals produced are separated from the concentrate to yield a sellable salt

product. As a result of sodium chloride crystallization the first mother liquor

(affluent concentrated concentrate post sodium chloride crystallization) is then

directed to a sodium carbonate decahydrate crystallizer where the liquor is cooled

and concentrated resulting in the formation of sodium carbonate decahydrate

crystals and a second mother liquor. The second mother liquor is split into two

streams; one stream is directed back to the sodium chloride crystallizer for a second

time, while the other stream is waster or further treated using other technologies.

Figure 5 provides a visual representation of the selective salt recovery process

outlined above.

Figure 5. Simple Schematic of Selective Salt Recovery

The recovery of the salts described above and any other salts that may be

recovered through the use of this process may require beneficiation to maximize

commercial value. For example, it may be appropriate to improve the quality of

sodium chloride by dissolution and re-crystallization, a process often done with sea

salt. Applying such processes may broaden the applications of the sodium carbonate

decahydrate crystals.

Recovery of sodium chloride and sodium carbonate decahydrate from

mixed concentrate has various advantages. Compared to known processes, this

process generates little to no waste material, requires little or no reagents to

recover the salts and does not require evaporation ponds, this is crucial as there

minimal space requirement for salt recovery.

Recoverable Salts

An analysis conducted by Mickley in 2006 (Table 2) showed that there are many

applications for the major recoverable salts and many have sufficient value to make

their recovery economically attractive. Recoverable products are largely site-

specific, thus each site will require in-depth analysis to determine any issues prior

to development of concept. Areas such as the southwestern United States would

benefit from recovery of these products as lack of cost-effective concentrate

disposal inhibits the building of desalination plants. Thus conception of systems

capable of recovering salts would provide alternative sources of revenue, making

inland desalination more economically attractive.

Table 2. List of recoverable salts and their potential application

Chemical Formula Name Application Areas

CaCO3 Calcium carbonate Paper coating pigment, fillers for plastics

and rubbers, special inks, paints and

sealants

CaSO4 + 2H2O Gypsum Remediation of sodic soils, manufacture of

building products

CaSO4 + 2H2O + Mg(OH)2

Slurry

Gypsum magnesium hydroxide Wastewater treatment, pH buffering, soil

conditioner for sodic soils

CaCl2 (liquor) Calcium chloride Dust suppression, road base stabilization,

sodic soil remediation, cement and concrete

stabilizer, construction industry

KNaSO4 Glacerite Potassium fertilizer

Mg(OH)2 slurry Magnesium hydroxide Water and wastewater treatment,

environmental, animal stock feed, feedstock

for magnesium metal production, fire

retardant and refractories and acid

neutralizer

xMgCO3 + yMg(OH)2 +zH2O Magnesium carbonate light Fire retardant, feedstock for magnesium

production, filler for paper manufacturing,

rubber and paint

NaOH Caustic soda Many applications industrially, including

basic feedstock for chemical processes, pH

adjustment

NaCl Halite Food and industrial processes, chloralkali

production, bulk salt supple

Na2CO3 Soda ash Water treatment, chemical industry

Na2SO4 Thenardite Surfactants manufacture, detergent

manufacture, glass manufacture,

remediation of calcareous soil

NaOCl Sodium hypochlorite Disinfection, chemical industries, pool

chlorine, water pretreatment

NaClO4 Sodium chlorate Paper bleaching, chemical industries

NH4Cl Ammonium chloride Fertilizers, metal work, expectorant in

medicines, yeast nutrient

NaHCO3 Sodium bicarbonate Fire retardant / extinguisher, food

processes as baking soda, neutralization of

acids and bases

Based on information from www.geo-processors.com

Economical Opportunities for Recoverable Salts

Case Study 1

Recovery of salts from concentrate could provide revenue generation

(offsetting costs). A possible use for recovered salt is for the de-icing of roads during

the winter months. According 2012 United States Geological Survey Mineral

Commodity Summaries (USGS, 2012), about 21.7 million metric tons of salt were

consumed nationally for this purpose in 2010–2011. Approximately 22% of the salt

used was imported. The salt generated from desalination concentrate stream can be

used to supplement the salt deficiency in the United States. According to the USGS a

probable revenue generation of $32 per ton as rock salt or $8 per ton as salt in

concentrate could be achievable.

Given acquired data by the USGA the average salinity of brackish water is

expected to be around 15 g/L. A rough estimate results in the salt production of 1.53

millions tons per year from a 10 million gallon per day desalination plant

(approximate plant production from desalination plant in Alamogordo, New

Mexico). Therefore, one plant could produce approximately 5% of the salt consumed

for winter deicing in the United States. When all brackish water desalination plants

across the United States are taken into consideration, the salt generation for winter

deicing would exceed the yearly needs. Although transportation costs would have to

be considered, as most brackish water desalination plants are located in warmer

areas such as California, Texas, Florida and Arizona where deicing is most often not

needed, the reduction in importation costs of salt for deicing purposes would far

outweigh these costs. In order to provide a economical report a cost-benefit analysis

must be completed by an independent agency to determine feasibility of salt for

deicing.

Case Study 2

To depict change in potential operating costs possible with the recovery and

sale of salts the following case was considered (Mickley, 2006). The total income

from the sale of salts averages $60 per ton based on all the salts produced, the local

landfill cost is $60 per ton and the concentrate is 1 MGD in volume with a salinity of

4,200 mg/L. The total amount of recoverable salts from the concentrate in 1 year

would then be 12.2 million pounds (6100 tons). To landfill this amount of solids

(neglecting any additional solids produced from the chemical treatment of

concentrate stream to produce the solids) at $60 per ton would cost more than

$366,000.00 per year. Instead, if the solids could be sold at an average price of $60

per ton, they would produce an income of roughly $366,000.00 per year. Depending

on the location and type of salt produced the generated income would change, for

example if anhydrous 94–97%, flake or pellet, calcium chloride was produced the

income stream would be over $1.67 million.

This additional revenue represents a substantial offset for typical operation

and maintenance costs. Due to early maturity of such salt recovery systems there is

lack of data for the additional capital and O&M expenses required to concentrate

precipitate and produce a marketable salt for comparison with this hypothetical

system.

Conclusion

In conclusion, there are many methods currently being developed to deal

with effluent concentrate control through either volume reduction or salt recovery.

One major concerns that has arisen out of this study is the development of

individual technologies, as most of them have only been tested at either lab or pilot

scale. Thus there is little information to determine economic feasibility of the

application in large-scale municipal systems. Furthermore to determine the

feasibility of each technology an intensive study of the quality of influent water and

concentrate must be performed to implement the correct technology. Lastly, the

most beneficial salts from concentrate processing are often more costly to produce

than the salts that are currently used. This creates a rising challenge to develop this

market, therefore a we must focus developing a shift from the short-term focus on

chemical cost to an understanding and appreciation of long-term benefits and

overall lower “total cost” associated with other salts, in particular salts produced as

pellets from desalination concentrate.

Contaminants of Emerging Concern (CEC’s)

Contaminants of Emerging Concern (CECs) has been a big issue for wastewater

treatment plants around the world. The common CECs consist of various

environmentally harmful substances such as alkylphenols, flame retardants,

hormones, personal care products, pharmaceuticals, steroids, and pesticides. These

CECs are often detected in drinking water supplies if the wastewater plant for that

particular area is not designed specifically to remove CECs from the water. It

requires a secondary advanced treatment process such as Reverse Osmosis (RO)

systems. However, wastewater treatment systems without the secondary advanced

treatment processes are still able to remove CECs, but it is unable to remove it all.

The EPA published studies of removal of CECs from water and wastewater

using different treatment technologies that common wastewater treatment plants

are using today. These studies give data of 16 of the 200 CECs in the database. These

CECs include Bisphenol A, Caffeine, Carbamazepine, DEET (pesticide), Diclofenac,

Estradiol, Estrone, Galaxolide, Gemfibrozil, Ibuprofen, Iopromide, Naproxen,

Nonylphenol, Sulfamethoxazole, Tri(chloroethyl) phosphate, and Tricosan. The

treatment systems include Full-Scale Activated Sludge Treatment, Granular

Activated Carbon Adsorption, Chlorine Disinfection, Ultraviolet Disinfection, Ozone

Disinfection, and RO.

The EPA’s studies show data for three different water supplies, drinking

water, treated effluent, and municipal wastewater. Each supply shows the minimum

and maximum removal which helps show which treatment system is capturing the

most CECs on average. The tables show that the RO system has the least amount of

difference between minimum and maximum removal and the highest amount of

removal.

The United States Department of the Interior Bureau of Reclamation and 14

local and state agency partners did a Southern California Regional Brine-

Concentrate Management Study to examine CECs as well. This study, also known as

a Phase 1, assesses the brine-concentrate in southern California which includes

brine-concentrate management technologies, regulatory environment, existing

infrastructure, and future needs. A Phase 1 is needed in order to completely

understand how the areas of the region are being affected. At the end of this Phase 1,

a Phase 2 recommendation is included. A Phase 2 consists of the actual process to

remove the CECs once the Phase 1 has been reviewed and assessed.

The objective of this Phase 1 is to identify and categorize the CECs, define and

characterize RO concentrate water quality, and identify treatment technologies that

can help reduce CECs in the areas. In this particular area, southern California, the

CECs that are shown to be entering public water supplies in trace quantities are

metals, Disinfection By-Products (DBPs), synthetic and naturally occurring

hormones, pesticides and herbicides, pharmaceuticals, personal care products

(PCPs), and industrial and household chemicals. The data also states that there has

not been any evidence for association between a low-dose exposure to the CECs

listed and human health effects. However, wildlife and the natural environment

have been affected by the CECs. The CEC that has been receiving the most attention

is Alkylphenolic Ethoxylates (APEOs) due to the amount it is found in the

wastewater.

Other CECs that the California Department Department of Public Health

(CDPH) wants to monitor are Endocrine-Disrupting Chemicals (EDCs), PCPs, and

pharmaceuticals. These CECs are not in the regulation for monitoring, but because of

past discoveries of them being in the drinking water it has led to raise concern.

Then, looking more deeply at the different CECs that have shown up in the

wastewater in the region, the Phase 1 lists all the different CECs said to have been

found in the region, sorted by category. It also describes which types of water

treatment systems are able to remove some or all of these CECs. Because this region

doesn’t have regulations for the CECs, there is a vast amount of different CECs

showing up in the wastewater. That also means that the treatment requirements for

CECs are unknown by the majority of wastewater treatment plants. RO systems

have proved to have the highest total dissolved solids (TDS) in the region which

confirms previous studies of the RO systems.

To look at the removal process more closely, CEC removal can be broken up

into three different groups; Physical-Chemical (P-chem) Treatment Process,

Biological Treatment Process, and Natural Treatment System. With each of these

three groups, there are another handful of different process within that, each with

their pros and cons to removing CECs. But it is proven that even with all these

process, no one process can remove the CECs alone. Due to the vast number of CECs

being emitted into the wastewater, it needs several treatment processes to go

through.

The most efficient way to design a wastewater treatment system is to clearly

and carefully identify which CECs are needed to be removed, then pick the proper

waste water treatment system because each system is specific to the CECs being

removed.

The American Water Resources Association published a Water Resources

Impact issue regarding CECs directly and their impact to the environment we live in.

It clearly identifies the sources of the CECs and determines where they will most

likely end up and how it effects that environment. Susan Glassmeyer describes the

cycle of the CECs, from where they are created, to where they end up. A CECs life

begins from the user, travels through a water system which will most likely end up

in some sort of treatment facility, which will then be discharged into a natural

waterbody (i.e. river), which can then be picked up by the next treatment system

downstream, then to the next user. This cycle shows that humans can be exposed to

CECs, but there aren’t studies to state the effect to humans.

Stephan Frank describes how CECs should be less of a concern because there

aren’t studies to prove the harm of them to human life. Being that we live in a

heavily industrial society, we should worry about the things we know, such as the

harmful contaminants we know to effect human life. He believes that the people

should concentrate on solving the crumbling infrastructure and not cloud the issue

with a new problem of different small amounts of different chemicals that aren’t

known to be any effect to us.

Tamim Younos, Valerie Harwood, Joseph Falkinham III, and Hua Shen

describe how pathogens in natural and engineered water systems are effected by

the CECs in detail. They also describe in closer detail to Susan’s CEC cycle in how the

CECs end up in the water source for human use. The CECs they describe pose an

impact to wildlife and are being detected in a variety of water supplies around the

country. The effect on humans is still unknown.

David Norris and Alan Vajda attempt to address the effect on health in

humans and wildlife and see the trends in different human populations due to the

CECs in their systems. Observations show no direct effect to human health but they

do show that these chemicals appear through natural excretion by each of us and by

inappropriate disposal methods.

Laurie Peterson-Wright defines the causes for these CECs to be inside us and

determines where they are coming from. He believes that the CECs are coming from

industrial facilities because there is no monitoring of them to begin with. Since there

aren’t regulations preventing industries from discharging these CECs, then they

don’t see a reason to treat the water before release. With that being said, this is how

the CECs are ending up in the human body system. The real question is, are they of

harm to us? And if so, how much exposure is okay?

Brenda Ortigoza Bateman, Ralph Thonstad, and Daniel Danicic tell another

way to reduce the amount of pharmaceuticals, another common CEC, from the

wastewater. Pharmaceuticals prove to be one of the more difficult CECs to remove

from wastewater. In minimizing the risk of them being in the wastewater,

communities around the United States have implemented programs to offer to take

back pharmaceuticals in preventing them being flushed down the drain. This

program brings up another issue, resources. With all these pharmaceuticals being

returned, someone needs to sort them, document them, and handle them. This can

prove to be extremely work intensive, which requires more money to complete.

There needs to be a more efficient way to this process to maximize the effectiveness.

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