Municipal WastewaterThe illustration below provides a simplified process flow diagram for a typical municipal wastewater treatment plant. As shown, the typical plant is segmented into a "water processing" side, and a "sludge processing" side. Chemicals used in the water processing side include coagulants such as ferric chloride or alum, and sodium hypochlorite for chlorination and disinfection. Environmental regulations in many areas require that the effluent water be de-chlorinated before return to the environment using chemicals such as sodium bisulfite. On the sludge processing side, various chemicals are used including polymer sludge thickeners, among others.Refer to the headlined text (below the diagram), for additional generic discussion of chemical treatments in municipal wastewater.Municipal WasteSludgeSludge ConditionersWastewaterRemediationWastewater ReclamationGround Water Remediation

Municipal WasteOne of the major problems in wastewater treatment is the separation of solids from water. The solids come either from the wastewater or are created as the result of one of treatments -- biological or chemical. In general, the higher the degree of treatment, the larger the amount of sludge that is produced.SludgeThe residue that accumulates in sewage treatment plants is called sludge. Treatment and disposal of sewage sludge are major factors in the design and operation of all water-pollution control plants. Two basic goals of treating sludge before final disposal are to reduce its volume and to stabilize the organic materials. Stabilized sludge does not have an offensive odor and can be handled without causing a nuisance or health hazard. Smaller sludge volume reduces the costs of pumping and storage.Sludge is the solid material remaining after sewage treatment facilities purify wastewater from homes, business and industries. In some communities, runoff from roads, lawns, and fields is also sent through the facility.Treatment of sewage sludge may include a combination of thickening, digestion, dewatering, and disposal processes.Thickening is usually the first step in sludge treatment because it is impractical to handle thin sludge, a slurry of solids suspended in water. Thickening is usually accomplished in a tank called a gravity thickener. A thickener can reduce the total volume of sludge to less than half the original volume. An alternative to gravity thickening is dissolved-air flotation. In this method air bubbles carry the solids to the surface, where a layer of thickened sludge forms.Sludge digestion is a biological process in which organic solids are decomposed into stable substances. Digestion reduces the total mass of solids, destroys pathogens, and makes it easier to dewater or dry the sludge. Digested sludge is inoffensive, having the appearance and characteristics of a rich potting soil.Most large sewage treatment plants use a two-stage digestion system in which organics are metabolized by bacteria anaerobically (in the absence of oxygen). In the first stage the sludge is heated and mixed in a closed tank for about 15 days, while digestion takes place. The sludge then flows into a second tank, which serves primarily for storage and settling. As the organic solids are broken down by anaerobic bacteria, carbon dioxide gas and methane gas are formed. Methane is combustible and is used as a fuel to heat the first digestion tank as well as to generate electricity for the plant. Anaerobic digestion is very sensitive to temperature, acidity, and other factors. It requires careful monitoring and control.Sludge digestion may also take place aerobically--that is, in the presence of oxygen. The sludge is vigorously aerated in an open tank for about 20 days. Methane gas is not formed in this process. Although aerobic systems are easier to operate than anaerobic systems, they usually cost more to operate because of the power needed for aeration. Aerobic digestion is often combined with small extended aeration or contact stabilization systems.Both aerobic and anaerobic digestion convert about half of the organic sludge solids to liquids and gases.Digested sewage sludge is usually dewatered before disposal. Dewatered sludge still contains a significant amount of water--often as much as 70 percent--but, even with that moisture content, sludge no longer behaves as a liquid and can be handled as a solid material. Sludge-drying beds provide the simplest method of dewatering. A digested sludge slurry is spread on an open bed of sand and allowed to remain until dry. Drying takes place by a combination of evaporation and gravity drainage through the sand. A piping network built under the sand collects the water, which is pumped back to the head of the plant. After about six weeks of drying, the sludge cake, as it is called, may have a solids content of about 40 percent. It can then be removed from the sand with a pitchfork or a front-end loader. In order to reduce drying time in wet or cold weather, a glass enclosure may be built over the sand beds. Since a good deal of land area is needed for drying beds, this method of dewatering is commonly used in rural or suburban towns rather than in densely populated cities.Alternatives to sludge-drying beds include the rotary drum vacuum filter, the centrifuge, and the belt filter press. These mechanical systems require less space than do sludge-drying beds, and they offer a greater degree of operational control. However, they usually have to be preceded by a step called sludge conditioning, in which chemicals are added to the liquid sludge to coagulate solids and improve drainability.The final destination of treated sewage sludge usually is the land. Dewatered sludge can be buried underground in a sanitary landfill. It also may be spread on agricultural land in order to make use of its value as a soil conditioner and fertilizer. Since sludge may contain toxic industrial chemicals, it is not spread on land where crops are grown for human consumption.Where a suitable site for land disposal is not available, as in urban areas, sludge may be incinerated. Incineration completely evaporates the moisture and converts the organic solids into inert ash. The ash must be disposed of, but the reduced volume makes disposal more economical. Air-pollution control is a very important consideration when sewage sludge is incinerated. Appropriate air-cleaning devices such as scrubbers and filters must be used.Obtaining cleaner water from treatment facilities inevitably means producing more sludge. Whether the sludge is used or disposed of, it is important to avoid creating additional environmental problems and to keep costs down. In the past, municipalities disposed of their sewage sludge in the least troublesome most affordable ways possible: they sent barges of sludge to be dumped at sea, buried it in landfills or burned it in incinerators. However, communities are now reassessing their sludge management practices because of increasing landfill tipping fees and closure costs, more stringent environmental standards, and increased public concern about air, land and water.This reassessment can uncover new problems. For example, to comply with stricter water quality standards, municipalities are forced to upgrade their treatment facilities. However, to produce a higher quality, cleaner effluent, these upgraded facilities produce lower quality sludge because more impurities are removed from the wastewater. The result of better treatment is more sludge of lower quality.Before sludge undergoes treatment such as dewatering or thickening, it must be stored and pretreated. Sludge storage is an important, integral part of every wastewater sludge treatment and disposal system. Sludge storage provides many benefits including equalization of sludge flow to downstream processes, allowing sludge accumulation during times of non-operation of sludge-processing facilities, and allowing a uniform feed rate that enhances thickening, conditioning, and dewatering operations.Sludge is stored within wastewater treatment process tankage, sludge treatment process systems, or separately in specially designed tanks. Sludge can be stored on a short-term or a long-term basis. Small treatment plants, where storage time may vary from several to 24 hours, may store sludge in wastewater clarification basins or sludge-thickening tanks. Larger plants often use aerobic digester, facultative lagoons, and other processes with long detention times to store sludge.Pretreatment of sludge is often necessary before dewatering or thickening can take place. It includes degritting and grinding. Sludge degritting involves the installation of grit removal and precessing facilities at the head works where raw wastewater first enters the treatment plant. As a result, there is reduced wear on influent pumping systems and primary sludge pumping, piping and thickening systems. Sludge grinding involves shearing of large sludge solids into smaller particles. This method is used to prevent problems with operation of downstream processes. In-line grinders reduce cleaning and maintenance down time of equipment. The grinders can shear sludge solids to 6-13 mm, depending on design requirements.With minor exceptions, such as pretreatment required by industrial wastewater and sewer ordinances, treatment plants have little control over the material they process. They must accept all incoming wastewater and purify it before discharging the effluent back into the environment. The wide variety of incoming wastewater and available treatment technologies determine the volume and makeup of wastewater treatment plant sludges. So, sludge quality depends on how clean the incoming wastewater is and which treatment methods are applied.Sludge ConditionersThere are many alternatives for sludge treatment, but most fall in the following categories: conditioning -- addition of chemicals or heat treatment to improve separation dewatering -- separation of solids and water stabilization -- use of biological processes to stabilize organic solids so they can be used as soil conditioners without nuisance or hazard reduction -- reduction of solids to a stable form by use of incineration or wet oxidationBefore sludge can proceed to dewatering or thickening processes, it must be conditioned. Sludge conditioning involves chemical or thermal treatment to improve the efficiency of the downstream processes. Chemical conditioning involves use of inorganic chemicals or organic polyelectrolytes, or both. Thermal conditioning is discussed elsewhere.The most commonly used inorganic chemicals in the US are ferric chloride and lime. Organic polymers, introduced during the 1960's, are used for both sludge-thickening and dewatering processes. Their advantage over inorganics is that polymers don't greatly increase the amount of sludge production: 1 kg of inorganic chemicals added will produce 1 kg of extra sludge. The disadvantage of polymers is their high cost.Municipal sludge is dewatered with belt presses, centrifuges or recessed chamber filter presses. Applications such as primary clarification, secondary clarification, phosphorous removal, sludge thickening, and sludge dewatering can experience performance improvements through the use of polymers.Sludge conditioning is an integral part of any sludge management program. The benefits include: Enhances the release of water Speeds the solid/liquid separation process, and Decreases sludge volume while increasing its solids contentThe primary function of sludge conditioners - whether organic or inorganic - is to flocculate, or agglomerate, suspended particles in wastewater. The mechanisms by which the two classes of conditioners achieve this goal, however, differ.Inorganic sludge conditioners first stabilize the particles through charge neutralization. This overcomes the electrical repulsive forces of the particles. They are then free to agglomerate and settle. The result is a metal hydroxide precipitate with entrained particles.Organic polymers flocculate particles by a mechanism called bridging. In this process, a few segments of the polymer chain attach themselves to the sludge particle surface. The unattached segments extend into the bulk of the solution, where they can attach to additional particles and thereby flocculate the sludge. Charge neutralization is not required with organic flocculants.Traditionally, inorganic chemicals (primarily alum and ferric chloride) have been used for sludge conditoning on plate and frame press dewatering systems.. But inorganic salts can severely corrode dewatering equipment, creating costly operational nad maintenance problems.Plants have discovered an alternative to the use of inorganic flocculants, mainly synthetic organic polymers. These polymers have none of the corrosive properties of inorganic salts, and greatly reduce operator safety concerns.Inorganics commonly comprise as much s 20% of a dewatered sludge on a dry weight basis. Organic polymers are rarely required in concentrations exceeding 1% of the sludge, so the amount of sludge that must be disposed of is far less when polymes are used for sludge conditioning.Inorganics frequently cause extreme pH fluctuations, where as polymers eliminate the need for pH adjustment. Also, smaller volumes of polymer are required, and solution makeup is easily automated for safer operation.Correct conditioning of the feed sludge makes available for dewatering both the free water originally contained in the sludge, and the intercellular water previously chemically bound. It also ensures the capture of the finest particles present, as the floc aggregates with the larger particles. Increasing the particle size is necessary because the filter belts are made of meshes with apertures larger than the smallest, natural particles.It was the development of consistent quality high-grade polymeric reagents that allowed belt filter presses to reach their present performance levels. This is particularly true for biological sludge dewatering where the use of synthetic polymers is essential. Polymer conditioning is regarded as an art by many press operators with respect to proper dosage amounts. Polymer manufacturers recommend starting with the least amount and increasing gradually. Overdosing does not improve conditioning and may cause blinding (clogging), of the filter belt openings as well as destruction of the floc. Furthermore, because polymers are expensive, the amount used should be restricted to only that amount necessary to do the job.Some installations have found ways to cut polymer dosage. One municipal treatment plant discovered that, by adding potassium permanganate to remove sulfides before adding the polymer, they not only remove bad odors but also were able to cut back on polymer dosage and increase throughput from 60 gpm to 90 gpm.There are different types of polymers used for chemical conditioning. Chemical conditioning improves sludge dewatering. Choice of chemical conditioners is very much dependent on the characteristics of the sludges and the type of dewatering devices. Lime, alum, ferric chloride and polyelectrolytes are commonly used chemical conditioners. Each one has different flocculating characteristics in terms of time and the mixing energy required. In the case of municipal sewage, dewatering characteristics can vary with the seasons, the loading rates o the wastewater treatment facility, and the operation of the plant. It is advantageous to have a conditioning system that incorporates the flexibility to vary the detention time and mixing energy to suit the slurry characteristics.WastewaterThe reuse of treated municipal wastewater is becoming more common as technology for purification improves and the cost and supply of fresh water climbs. In arid areas reuse is becoming a reality as is demonstrated at the following facilities.U.S. Filter's Operating Services group has a 20-year, public-private partnership to design, build, finance, own and operate a 12 million gallons per day (mgd) water reclamation facility in Honolulu.The agreement, valued at $140 million, is an example of the incremental business US Filter has obtained by combining previously separate wastewater treatment companies, in this case, Zimpro, Memcor and IWT. U.S. Filter is spearheading the multifaceted water reclamation project, which involves accepting up to 13 mgd secondary effluent from the adjacent Honolulu Wastewater Treatment Plant, in order to produce 12 mgd for beneficial reuse.The facility uses multi-media filtration, microfiltration and reverse osmosis processes supplied by U.S. Filter companies to treat secondary effluent now discharged into the Pacific Ocean. These processes will generate two grades of water. One grade is a high-purity water that will be sold to power and petro refining companies at nearby Campbell Industrial Park. The other grade will be used for irrigation purposes.The reuse of wastewater, as a concept, includes many treatment applications includingat its least demandingirrigation, through cooling tower makeup and boiler feed to complex treatment allowing recycling the wastewater in an industrial process ("closed loop"). There is no general treatment scheme for reclaimed water facilities. The optimum treatment must be determined based on the characteristics of the wastewater stream, whether of municipal or industrial origins.Two examples of treatment of industrial wastewater are cited below to demonstrate the technological creativity now being employed.While cartridge filters are extensively used in industrial applications to help industry meet these guidelines few are used in municipal wastewater treatment. The details and forecasts for industrial wastewater treatment are covered in the chapters of the applicable industry.In one Florida power generating facility tertiary effluent (treated urban wastewater) is used, after further treatment, as boiler feed. The makeup demineralizer system consists of softening/clarification and gravity filtration with provisions for feeding lime, soda ash, alum, sodium hypochlorite and polymer. Filter effluent is further processed through activated carbon beds and cartridge filters before being fed to the RO, after which it enters a four bed demineralizer. Seasonal Total Nitrogen levels and turbity of the secondary effluent, under normal circumstances may be considered acceptable for RO systems. However, values for TOC and BOD were not included in the design analysis. The wastewater was chlorinated to maintain a 1.0 Cl2/l residual. This free chlorine rapidly dissipated as it reacted with the ammonia and organics in the wastewater, resulting in a zero chlorine residual by the time the wastewater entered the pretreatment system, providing an ideal environment for biological growth.The clarifier-softener's operation at a high pH was having no effect on the organic matter, which is typically removed at lower pH conditions. Consequently the clarifier was converted to an alum clarification mode, operating at pH 6.0-6.2 using 85 mg/l aluminum sulfate to coagulate the high concentration of colloidal organic matter in the influent. As a result the SDI was improved to the 2.8-3.5 range, allowing trouble free RO operation.Wastewater produced from an oil field in Southern California forms 90 percent of the oil pumped from the reservoir. Historically, produced water has been treated for discharge or re-injected into the oil field. In the present case a 50 MW cogen plant, the water is treated for power plant uses, notably cooling tower makeup and boiler feed. The steam produced is injected into the oil reservoir to enhance oil recovery. Average plant water use is approximately 200 m3/hr (53,000 gph). The first stage of treatment is air flotation (IAF) followed by lime softening, with parallel silica removal in a high rate clarifier. Most of this clarified softened water (130 m3/hr-34,000 gph) is used in cooling tower makeup. The remainder is filtered, passed through RO units and two bed ion exchange units. Silica removal is achieved by dosing magnesium chloride to the unit.It was originally intended that the clarifier effluent, after gravity filtration, would be adequate for the RO units. Unfortunately, while the turbidity was typically low, the SDI's were above 6.0, leading to increased membrane fouling. The high SDI's were found to be due to 1-10 m sized particles of aluminum silicate and silt, present in the produced water, and not removed by either the IAF or clarification upstream. The SDI's were finally reduced by installing pressure filtration with volcanic pumice as the media, downstream of the gravity filters. Poly aluminum chloride is added directly upstream of these filters as coagulant. The system has now been working for over seven years.RemediationPump and treat (P&T) is a general term for any method that removes impacted groundwater and treats it outside of the subsurface environment. Treatment methods vary, but the basic action is to pump the water from the subsurface contaminant source and treat it above ground. This type of ex situ treatment is a baseline against which other remediation methods are usually compared.Originally, the use of groundwater extraction and ex situ treatment was the only means to remediate chemically contaminated groundwater. Typically this was accomplished through one or more pumping or extraction wells, with the water being treated by any one or a combination of physical and biological methods. Treatment options include air stripping ultraviolet oxidation, physical-chemical separation, granular-activated-carbon adsorption, bioreactors and ion exchange. Cartridge filters are used in conjunction with many of these systems.For successful remediation, surface treatment of pumped groundwater must be consistent with the type and concentration of contaminants, and the volume of water to be treated. Pump and treat is typically used for contaminants that are dissolved in groundwater, However, removal of free-phase light or dense, non-aqueous phase liquids (LNAPLs, DNAPLs, or, in general, NAPLs) may be simultaneously accomplished through the use of specialized pumping techniques.Pump and treat systems are relatively easy to design, install and operate using standard hydrogeologic and engineering practices. The technique is readily accepted by regulators and the groundwater remediation community. Where geologic conditions are favorable, the pumping systems can accomplish rapid mass-removal from areas of the groundwater plume where contaminants are most heavily concentrated. The technique also allows full capture of a plume at its leading edge, which prevents further migration. For this reason, pump and treat will continue to be the principal means of plume containment and control.Once extraction wells have brought contaminated water to the surface, treatment is relatively straightforward, provided that appropriate methods have been selected and the capacity of the treatment facility is adequate.Figure XI-1summarizes the applicability of various treatment technologies to groundwater contaminated by any of the major categories of inorganic and organic contaminants. Conventional technologies that have evolved from industrial wastewater treatment and that have been implemented at full scale for treatment of contaminated groundwater fall into two main categories: Biological - Biological treatment methods use microorganisms to degrade organic compounds and materials into inorganic products. The methods may be applicable for treatment of groundwater contaminated by organic compounds if concentration is low enough and the biological processes are not inhibited. The best established biological treatment methods include (1) activated sludge systems (2) a sequencing batch reactor, (3) powdered activated carbon in activated sludge (biophysical system), (4) rotating biological contactors, and (5) an aerobic fluidized bed biological reactor. Physical/Chemical - Physical, chemical, or a combination of physical andchemical methods can be used to remove contaminants from groundwater. The most commonly used methods include (1) air stripping, (2) activated carbon, (3) ion exchange, (4) reverse osmosis, (5) chemical precipitation of metals, (6) chemical oxidation, (7) chemically assisted clarification, (8) filtration, and(9) ultraviolet (UV) radiation oxidation.In 1991, Waste Management purchased 742 acres of land located amidst a natural wetland in Savannah, GA to build, own and operate a landfill. The landfill currently consists of two sites:a 20 acre non-subtitle D landfill (closed) and a 90 acre subtitle D landfill, which was permitted for eight cells. In July 1996, a closure certificate was issued on the non-subtitle D landfill with a requirement to monitor for 30 years. With the challenge of a remote site layout, Waste Management was required to (a) haul soil for daily cover and (b) ship leachate off-site for special (and costly) treatment.David Remick, General Manager of Waste Management, reduced the cost of hauling soil over county roads through the installation of an innovative 1800 foot conveyor that spanned the wetlands, to transfer soil used for covering at the landfill. This was a "first" for a landfill operation.Remick's decision was to treat the leachate on-site, using Pall Rochem reverse osmosis technology. The specific system selected incorporates the Disc Tubemodule, which consists of a chamber of hydraulic discs interleaved with ultrasonically welded, long-lasting membrane cushions as well as a cartridge filter. These filter modules are the heart of the RO system. In the reverse osmosis process, pressure is applied to leachate to force the pure water molecules through a semipermeable membrane. The majority of toxic organic and metal materials along with bacteria are unable to pass through the membrane. The result is a pure permeate stream (water) and a much smaller concentrate stream (contaminant).Wastewater ReclamationThe reuse of treated municipal wastewater is becoming more common as technology for purification improves and the cost and supply of fresh water climbs. In arid areas reuse is becoming a reality as is demonstrated at the following facilities.U.S. Filter's Operating Services group is undertaking a 20-year, public-private partnership to design, build, finance, own and operate a 12 million gallons per day water reclamation facility in Honolulu.In 1988, the City of Harlingen sought to attract new industry to expand its economic base. The Lower Rio Grande Valley appealed to Fruit of the Loom as the site of a new textile bleaching and dyeing production facility. Labor and land were in plentiful supply, but the limited water supply from the Rio Grande combined with the water's natural salinity seemingly formed a barrier to building the plant in Harlingen.Fruit of the Loom required two million gallons per day of water with exacting requirement for hardness, dissolved solids, pH, and mineral concentrations for their startup operations.Working in partnership, the industry and the utility arrived at a solution which delivered specially treated wastewater from the Harlingen wastewater treatment plant as process water to the adjacent Fruit of the Loom plant.Harlingen Water Works System contracted out the design and construction of a reverse osmosis plant. Two separate one mgd trains were on line by 1991. The partnership has proved so successful that Harlingen Water Works has now embarked on a project to double the total output, from two mgd to four mgd.The reuse of wastewater, as a concept, includes many treatment applications including at its least demanding irrigation, through cooling tower makeup and boiler feed to complex treatment allowing recycling the wastewater in an industrial process ("closed loop"). There is no general treatment scheme for reclaimed water facilities. The optimum treatment must be determined based on the characteristics of the wastewater stream, whether of municipal or industrial origins.Three examples of municipal wastewater reuse are cited below to demonstrate the technological creativity now being employed.Case History 1 - Hyperion Treatment Plant, City of Los Angeles. Design capacity, 18.4 m3/second (292,000 gpm), with treated wastewater discharged to the Pacific Ocean. California statutes (Title 22) permit wastewater to be further treated to achieve a turbidity of >2 NTU, disinfected, and used for irrigation of municipal parks, golf courses and for industrial needs. The West Basin Recycling Facility, with an ultimate design capacity of 4.4 m3/second (1162 gpm), will be the largest water recycling facility in the U.S. The present plant takes 0.66 m3/second (174 gpm) secondary effluent from Hyperion and treats it to Title 22 standards, however refineries were unable to switch to reclaimed water because of the high levels of ammonia. (Hyperion Treatment Plant does not nitrify.) The presence of ammonia is unacceptable since it is highly corrosive to Admiralty Brass used in the refinery heat exchangers. In response the recycle water to these facilities was further treated in nitrifying systems, Dgremont's "Biofor" system, guaranteed to remove 90 percent of influent ammonia. Breakpoint chlorination is used to remove the remainder of ammonia.Case History 2 - A cogeneration plant, 250 MW, is located in Jacksonville, FL. Final design was to use recycled paper mills' wastewater for cooling tower makeup (CTMU), with the whole facility to operate as a zero liquid discharge system (ZLD). The CTMU system included a Dgremont high rate Clarifier/Thickener, and a unit with a softening function. The cooling tower blowdown was to be treated in another clarifier followed by dual media filtration, then concentration by RO, with final concentration to dry salt cake by evaporation/crystallization. Foaming, high silt density indices, and failure of crystallization presented special challenges.Case History 3 - At a Florida power generating facility tertiary effluent (treated urban wastewater) is used, after further treatment, as boiler feed. The makeup demineralizer system consists of softening/clarification and gravity filtration with provisions for feeding lime, soda ash, alum, sodium hypochlorite and polymer. Filter effluent is further processed through activated carbon beds and cartridge filters before being fed to the RO, after which it enters a four bed demineralizer. Seasonal Total Nitrogen levels and turbidity of the secondary effluent, under normal circumstances may be considered acceptable for RO systems. However, values for TOC and BOD were not included in the design analysis. The wastewater was chlorinated to maintain a 1.0 Cl2/l residual. This free chlorine rapidly dissipated as it reacted with the ammonia and organics in the wastewater, resulting in a zero chlorine residual by the time the wastewater entered the pretreatment system, providing an ideal environment for biological growth.Ground Water RemediationThe site remediation industry is only 20 years old. It has witnessed distinct fluctuations in its development. At the outset, regulatory pressure was the principal market driver. We thought the remediation industry could solve all problems, if only we could develop the right technologies. All contaminated groundwater could be cleaned up to drinking water standards. No contamination could be considered non-threatening. Cost was not a primary factor. However, over time we came to understand that there were limits to our capabilities. New technologies, in which we had placed great faith, proved to have limitations, including bioremediation, which was embraced with enthusiasm in the mid-1980s. "Natural attenuation," the process of natural biodegradation accompanied by monitoring, is the most recent remediation concept and the buzzword of the moment, though it is being approached with caution.The largest future expenditures will continue to be devoted to solving groundwater contamination, and to a lesser extent soil contamination, at landfills. Cleanup at military bases and weapons manufacturing sites will remain a major element of this market. Expenditures to remediate military sites are currently heavily dominated by the U.S., as Russia, China and other military powers have not yet made a concerted effort to address this problem. The power industry, suffering from contamination from radioactive waste and manufactured gas residues, will continue to be another important remediation market (the U.S. currently represents over two-thirds of expenditures). The petroleum industry, with contamination resulting from recovery through distribution and underground storage, also will figure prominently. In addition, the chemical industry and forest products will be significant, followed by mining, metals, and electronics.The world market for the remediation of groundwater and soil contamination will grow from $18 billion in 1997 to $25 billion in 2002. It amounted to $7 billion in the U.S. alone in 1997. The Americas will remain the largest market but will lose market share as Asia and Central and Eastern Europe significantly increase expenditures.