Permeable reactive barrier for groundwater remediation

Download Permeable reactive barrier for groundwater remediation

Post on 26-Jun-2016

222 views

Category:

Documents

0 download

Embed Size (px)

TRANSCRIPT

  • Revie

    Permeable reactive barrier fo

    R. Thiruvenkatachari a, S. Vigneswaran a,*, R. Naidu b

    5. Mechanism of interaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148

    . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152

    small percentage of the total water distribution [1,2,3]. The

    Available online at www.sciencedirect.com

    Journal of Industrial and Engineering Ch14. PRB studies in Australia and New Zealand. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153

    Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154

    References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154

    1. Introduction

    Groundwater is a limited ecological resource representing a13.1. Use of oxidants . . . . . . . . . . . . . . . . . . . . . . . . . . . .13. In situ chemical oxidation (ISCO) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152

    . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15212. Sequential reactive media . . . . . . . . . . . . . . . . . . . . . . . . . .7. Zero-valent iron. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149

    8. Activated carbon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150

    9. Zeolites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150

    10. Alkaline materials-complexing agents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150

    11. Bioremediation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

    11.1. Organic carbon for denitrification and sulphate reduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1526. Treatment of inorganic and organic pollutants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1494.1. Conventional systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147a Faculty of Engineering, University of Technology, Sydney, P.O. Box 123, Broadway, NSW 2007, Australiab CRC CARE, University of South Australia, Australia

    Received 14 December 2006; accepted 26 October 2007

    Abstract

    This article aims to provide an overview of the upcoming technology of permeable reactive barriers for groundwater remediation. A

    comprehensive list of references and web-links are also provided for further in-depth understanding. A brief discussion on the Australian

    perspective on this emerging technology is also included.

    # 2008 Published by Elsevier B.V. on behalf of The Korean Society of Industrial and Engineering Chemistry.

    Keywords: Permeable reactive barriers; Groundwater; Remediation; Pollution

    Contents

    1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145

    2. Sources and types of groundwater contamination. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146

    3. Permeable reactive barrier. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147

    4. Configuration of PRBs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147

    4.2. Advanced methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147* Corresponding author. Tel.: +61 2 9514 2641; fax: +61 2 9514 2633.

    E-mail address: s.vigneswaran@uts.edu.au (S. Vigneswaran).

    1226-086X/$ see front matter # 2008 Published by Elsevier B.V. on behalf ofdoi:10.1016/j.jiec.2007.10.001w

    r groundwater remediation

    www.elsevier.com/locate/jiec

    emistry 14 (2008) 145156contribution from groundwater is vital; perhaps as many as two

    billion people depend directly upon aquifers for drinking water,

    and 40% of theworlds food is produced by irrigated agriculture

    The Korean Society of Industrial and Engineering Chemistry.

  • Groundwater can also be contaminated by diffuse sources

    over a wide area, for instance widespread use of fertilisers on

    gardens and fields. Diffuse contamination may have greater

    environmental impacts than contamination from point sources

    because a much larger volume of water is affected. Pollutants

    from point sources are generally related to urban development,

    while diffuse sources are generally rural in nature. Some of the

    examples of point and diffuse pollutions are given in Table 1.

    Analysts estimate that there are between 300,000 and

    400,000 sites in the USA contaminated with a wide variety of

    al and Engineering Chemistry 14 (2008) 145156groundwater. Due to the cap on surface water extractions in the

    MurrayDarling Basin and the scarcity of surface water

    resources in other areas, groundwater use across Australia has

    increased significantly in the last 10 years [4]. South Australia,

    New South Wales and Victoria use more than 60% of

    groundwater for irrigation, while Western Australia uses

    72% for urban and industrial purposes [5,6].

    Studies by [4,7] identified increased demand for water in

    Australia and called for proper management of groundwater.

    The report also revealed that groundwater resource in Australia

    has been highly committed in some places, or of poor quality in

    others, and poorly investigated in others [8]. If not managed

    properly, groundwater resources are highly vulnerable to

    widespread contamination. There are many reports of serious

    incidents of groundwater contamination due to accidental

    spills, or unsatisfactory disposal of industrial chemicals,

    agricultural practices, mining activities, etc.

    Attempts at large-scale groundwater cleanup began in

    earnest in the 1980s and the results of early remediation efforts

    seldom produced the expected reduction in contamination

    levels. Studies by the U.S. Environmental Protection Agency

    (EPA) [9,10] found that the commonly used pump-and-treat

    (P&T) technologies (pump the water and treat it at the surface)

    rarely restored sites that had contaminated groundwater to

    background conditions. This was confirmed in a much more

    extensive 1994 National Research Council (NRC) study that

    explicitly reviewed 77 sites across the United States where full-

    scale pump-and-treat was being used [11,12]. One of the most

    promising remediation technologies is the use of permeable

    reactive barriers (PRBs) filled with reactive material(s) to

    intercept and decontaminate plumes in the subsurface. In the

    last decade, there has been an explosion of activities directed at

    the development and implementation of PRBs. This study

    presents a comprehensive review on PRBs technology.

    2. Sources and types of groundwater contamination

    Broadly, groundwater contaminants come from two cate-

    gories of sources:

    (a) Point Sources and

    (b) Distributed, or Non-Point Sources.

    Localised sources are known as point sources of contam-

    ination. The contaminant interacts with the moving ground-

    water and the soil and spreads out to form a plume moving in

    the same direction as the groundwater. The resulting ground-

    water contamination plume may extend several hundred metresTerri

    wateor etory, and the Pilbara are entirely dependent on ground-

    r. Most of the countrys premium wine districts rely onregions like arid zones of South Australia, the Northernthat relies largely on groundwater. Australia has 25,780 GL of

    groundwater suitable for potable, stock and domestic use, and

    irrigated agriculture that can be extracted sustainably each year.

    It is extensively used for urban water supplies, agriculture,

    irrigation, industry and mining. In Australia, some of the

    R. Thiruvenkatachari et al. / Journal of Industri146ven further away from the source of pollution.toxic chemicals, representing clean up cost in the range of $500

    billion to $1 trillion [11]. Many of these sites experience

    groundwater contamination by complex mixtures of chlori-

    nated solvents, fuels, metals, and/or radioactive materials.

    Europes groundwater is polluted in several ways: nitrates,

    pesticides, hydrocarbons, chlorinated hydrocarbons, sulphate,

    phosphate and bacteria. Some of the most serious problems are

    pollution by nitrates and pesticides. The key findings of

    Australia: State of the Environment Report [13] highlighted that

    Australias inland waters are under increasing pressure from

    over-extraction, algal blooms, catchment modification, habitat

    destruction and pollution. Also, the experiences from Europe

    and North America suggest that groundwater pollution in

    Australia will become a more serious issue in the future. There

    are many well-documented cases of groundwater pollution in

    Australia. The most significant diffuse contaminant of ground-

    water throughout each state and territory in Australia is nitrates,

    due to their adverse affects on people, animals and the

    environment [14,15]. The main source of nitrate contamination

    is through the application of fertilizers for cropping and pasture

    [15]. Direct discharges of nitrogen compounds from on-site

    sanitation and from sewer effluent also exacerbate the problem.

    In many areas, the concentration is greater than the Australian

    Drinking Water Guidelines [16] level of 50 mg/L nitrate (as

    nitrate), resulting in groundwater that is unfit for drinking. In

    some of the more contaminated areas, the concentration is in

    excess of 100 mg/L [15].

    Recent incidences of reported pesticide contamination of

    groundwater in this country are listed in the [5] report. In most

    affected areas, pesticides were detected in at least 20% of

    samples, indicating significant contamination. However, sys-

    tematicmonitoring of pesticide contamination of groundwater in

    Australia is limited indicating inadequate data on the quantities,

    locations and types of pesticides used, as well as knowledge gaps

    in the fate of pesticides in local environments [17].

    Table 1

    Examples of point and diffuse pollutions

    Point source Non-point or diffuse pollution

    Municipal landfills, industrial waste

    disposal sites, leaking gasoline storage

    tanks, leaking septic tanks, and accidental

    spills and leaks of petroleum products and

    of dense industrial organics

    Atmospheric deposition,

    contaminated sediments,

    and many land activities

    that generate polluted runoff,

    such as agriculture

    (pesticides and fertilisers),

    logging, and onsite sewagedisposal

  • re

    pe

    su

    gr

    un

    sy

    re

    co

    th

    tr

    ni

    4.1.

    T

    appl

    T

    reac

    funn

    zone

    cont

    al and En PRBs can degrade or immobilize contaminants in situwithout any need to bring them up to the surface. Hence no

    need for expensive above ground facilities for storage,

    treatment, transport, or disposal other than monitoring wells.

    After the installation the above ground can be re-used for

    other purposes. Also, as the contaminants are not brought to

    the surface; there is no potential cross media contamination.

    They also do not require continuous input of energy, becausea natural gradient of groundwater flow is used to carry

    contaminants through the reactive zone. Only periodic

    replacement or rejuvenation of the reaction medium might

    be required after its reactive capacity is exhausted or it is

    clogged by precipitants and/or microorganisms. However, the

    drastically reduced operating costs offsets the higher

    construction cost that are typical for PRBs, which results

    in an overall reduction in the life cycle cost of this technology.

    Degradation of most of the contaminants is achieved ratherthan mere change of phase of contaminants. The barrier

    provides effective contaminant remediation, much more than

    simple migration control of the pollutants.

    Technical and regulatory problems related to ultimatedischarge requirements of effluent from pump-and-treat

    systems are avoided with the PRB technology.

    However, so far, limited data are available on the

    performances of reactive barriers with different materials

    and their comparative performances. Limited long-term field

    testing data are available and field monitoring is in its infancypum[1rrier to the groundwater, but it is a barrier to the

    ntaminants. PRBs are designed to be more permeable than

    e surrounding aquifer materials so that contaminants are

    eated as groundwater readily flows through without sig-

    ficantly altering groundwater hydrogeology.

    PRBs potentially have several advantages over conventional

    p-and-treat methods for groundwater remediation.har

    baThe concept of PRBs is relatively simple. A permeable

    active barrier material consisting of permanent, semi

    rmanent or replaceable reactive media is placed in the

    bsurface across the flow of path of a plume of contaminated

    oundwater, which must move through it as it flows, typically

    der its natural gradient, thereby creating a passive treatment

    stem. As the contaminant moves through the material,

    action occur that transform the contaminants into less

    mful (non-toxic) or immobile species. The PRB is not acontaminant(s) into environmentally acceptable forms to

    attain remediation concentration goals down-gradient of the

    barrier3. Permeable reactive barrier

    This technology termed as Permeable Reactive Barriers is

    defined [9] as:

    An emplacement of reactive media in the subsurface

    designed to intercept a contaminated plume, provide a flow

    path through the reactive media, and transform the

    R. Thiruvenkatachari et al. / Journal of Industri8].The choice between the two configurations depends on

    both the hydrogeological characteristics of the site and the

    reactive material cost [19]. When a high cost reactive material

    is used, funnel-and gate configuration is preferred since the

    reactive zone requires less material. However, construction

    cost of continuous type barrier is much cheaper than funnel-

    and-gate system. Hence a balance must be struck between the

    cost of reactive material and the construction cost of the

    barrier, in accordance with the target pollutant and level of

    removal to be achieved. Multiple reactive medium in

    succession or in series can be insta...

Recommended

View more >