Groundwater, surface wa-ter, wastewater, drinking water: it’s all essentially the same stuff. Whichever

stage of the water cycle you care to look at, chemical engi-neers are to be found — either trying to stop water from becoming pol-luted in the first place, or cleaning up afterwards.

Cleaning up outdoorsMany water purification processes rely on naturally occurring micro-organisms to oxidize contaminants. One of the most basic techniques is to allow wastewater to flow through natural or artificial wetlands, where aquatic plants and the bacteria that live among their roots remove organic compounds and heavy metals.

Reed beds have been used success-fully for small-scale sewage treatment and for industrial wastewater, espe-cially as a polishing step after conven-tional biological treatment plants. Now a five-year study at Purdue University (West Lafayette, Ind.) has shown that artificial wetlands are also valuable for cleaning up surface water runoff — in this case from residential areas, though the principle could apply equally well to hard surfaces in industrial plants.

Purdue soil microbiologist Ron Turco and colleagues started their research in 1998 on three artificial ponds on a

newly renovated golf course on the university campus (top photo). Runoff water from nearby roads and parking lots flowed onto the golf course, through the constructed wetland, and into a recovering natural wetland. Contami-nants in the entering water included the herbicide atrazine, plus compounds involving chlorides, nitrates, ammonia, nitrogen, organic carbon, phosphorus, aluminum, iron, potassium and manga-nese. Of 17 chemicals present in mea-surable amounts, 11 were significantly reduced as the water passed through the wetland system.

Another outdoor water treatment option, this time chemical in nature, is RegenOx, an oxidizing reagent launched last year by Regenesis (San Clemente, Calif.) The company de-scribes it as a breakthrough technol-ogy for in-situ remediation of recalci-

trant soil and groundwater pollutants, such as chlorinated solvents, explo-sives and pesticides.

Standard in-situ oxidants such as potassium permanganate and Fenton’s reagent (a combination of hydrogen peroxide and an iron-based catalyst) are typically either too short-lived or too hazardous for general use, says the company, and may require specialized training, equipment and techniques. RegenOx, in contrast, is a safe, non-toxic formulation that can be injected directly into soil using widely-avail-able equipment. It uses several syner-gistic chemical processes to destroy a broad range of contaminants, says the company, and remains active for up to one month. Unlike other chemical oxi-dation technologies, RegenOx has no detrimental effect on groundwater.

(Continues on p. 24)

CHEMICAL ENGINEERING WWW.CHE.COM FEBRUARY 2006 23

Newsfront

MANAGING WATER POLLUTION

Equipment and ideas abound for cleaning up plant wastewater

and polluted groundwater

Moore Industries’ 555 controller (left) gives accurate control over chlorination and dechlorination

Moore Industries ABS Group Fluid Dynamics,

The AFP-ME submersible sewage pump (center) from ABS features anti-blocking hydraulic design, a high-ef-ficiency motor and reduced maintenance costs

For dosing and hydrating dry polymer used in wastewater treatment, Fluid Dynamics has introduced a packaged solution in the form of the dynaJET system (right)

Purdue University scientist Ron Turco has confirmed the value of artificially-

constructed wetlands in removing chemical contaminants from

surface run-off water

Purdue Agricultural

Communication/Tom Campbell

Arsenic, copper and oilArsenic has been in the news this year, as municipal and community water providers faced a U.S. En-vironmental Protection Agency (EPA) deadline of January 23 for reducing levels of this toxic element in drinking water from 50 parts per billion (ppb) to 10 ppb. The ruling affects around 4,100 small and community drinking-water systems in the U.S., most serving fewer than 10,000 people.

Pall Corp. (East Hills, N.Y.) says its membrane filtration technology has been verified to remove arsenic by NSF International Drinking Water Systems Center, a partner of the EPA’s Environmental Technology Verification Program. The Pall Aria microfiltration system (photo, top left) reduces arsenic to undetectable levels — below 2 ppb — and is the first microfiltration tech-nology verified to remove arsenic to the new EPA standard. It has been tested in several parts of the U.S., including Fallon, Nev., where arsenic was found at 160 ppb in drinking water.

Pall’s Aria system is already used to remove arsenic from industrial wastewater, as well as parasites such as cryptosporidium and giardia from drinking water. Addition of an iron-based coagulant, such as ferric chlo-ride, to the water causes the arsenic to become adsorbed onto positively charged ferric hydroxide particles, which are then removed by microfil-tration. The technology is said to have lower capital and operating costs than other methods of arsenic removal.

BOC Edwards (Wilmington, Mass.) targets semiconductor fabricators with wastewater treatment technolo-gies to remove mixed metals such as copper, cobalt, nickel and palladium, concentrate fluoride wastes and re-duce wastewater volumes. Chemi-cal-mechanical planarization (CMP) processes generate large volumes of wastewater containing low concentra-tions of copper. The BOC Edwards Cu-NoSS (Copper, No Suspended Solids) system uses patent-pending fluidized bed technology to selectively remove copper ions without pretreatment or the need to capture suspended solids.

The compact equipment is available to treat waste volumes up to 45 gal/min.

Organoclays — natural clays such as bentonite that have been chemi-cally modified using quaternary amines — can be used to remove oil and other organic compounds from water by adsorption. Biomin, Inc. (Ferndale, Mich.) markets organoclays under the Oilsorb name for removing oil, grease, polychlorinated biphenyls (PCBs), benzene, phenolic compounds and other poorly soluble hydrocarbons. Organoclays are typically used in con-junction with activated carbon, and in the same types of adsorber vessel, but are much more effective than carbon alone at removing organics, says the company.

One petroleum refinery in Califor-nia which used a simple dissolved air flotation (DAF) unit to remove oil and sediments from parking-lot and plant runoff frequently found itself in viola-tion of local discharge standards, says Biomin. Installation of cartridge fil-ters followed by two adsorber vessels, each containing 35,000 lb of Oilsorb, allowed the plant to treat 2,000 gal/min of wastewater and reduce the oil concentration to below 5 ppm.

Microbes bad and goodHarmful microorganisms may need to be eliminated from both treated waste-water and water intended for drink-ing or process use. At the WEFTEC wastewater treatment exhibition and conference in Washington, D.C., last October, Calgon Carbon Corp. (Pitts-

burgh, Pa.) announced a contract from the Washington (D.C.) Suburban Sani-tary Commission to supply ultraviolet (UV) disinfection equipment to the Potomac Water Filtration Plant. When installed, the 12 Sentinel 48 UV reac-tors will form the largest UV drinking water disinfection installation in the U.S., treating up to 300 million gal/day. Installation will begin in 2007.

Also at WEFTEC, Calgon Carbon launched a new UV wastewater dis-infection system. The C3500 UV sys-tem is the largest in the company’s C3Series product line, and uses new energy-efficient 500 W low-pressure UV lamps. The C3500 is designed for applications in high-flow municipal wastewater, combined sewer overflow (CSO), sanitary sewer overflow (SSO), and water reuse.

JMAR Technologies, Inc. (San Diego, Calif.) offers the BioSentry, a laser-based device that detects and classifies water-borne micro-organisms without the need for consumables or reagents. It uses multi-angle light scattering (MALS) to generate an optical “signa-ture” that is characteristic of the type of organism concerned. The BioSentry has adjustable alert thresholds which can trigger the unit to take water samples for laboratory validation. The system uses an optical process-ing technique licensed from N.A.S.A.’s Goddard Space Flight Center (Green-belt, Md.). The system is being tested at a water utility, on a cruise ship, and at a beverage plant.

Not all microorganisms, however,

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24 CHEMICAL ENGINEERING WWW.CHE.COM FEBRUARY 2006

Pall’s Aria microfiltration system (left) reduces arsenic levels in drinking water to below 2 ppb. It is the first microfiltration technology verified to remove arsenic under new EPA regulations

The Rosemount Analytical Model TCL (right) measures total chlorine in water, including seawater. It is signifi-cantly cheaper to run than previous-

generation total chlorine systems

Pall Corp.

Emerson Process Management

are harmful. For monitoring biologi-cal activity in wastewater treatment, LuminUltra Technologies Ltd., (Fred-ericton, New Brunswick, Canada) last year launched a range of instruments based on measurement of the mol-ecule adenosine triphosphate (ATP), the primary energy carrier in living cells. The system is quick, easy to use and works with both aerobic and an-aerobic microbes, the company says.

Pathogenic organisms are frequently dealt with using chlorine. Moore Indus-tries’ (North Hills, Calif.) new 1/4 DIN-sized 555 controller (photo, p. 23, left) is designed especially for chlorination, as

well as dechlorination with sulfur diox-ide. It is easy to set up, says the com-pany, and handles proportional flow control, residual chlorine control, and compound loop control with lag times. The front panel is NEMA 4X rated for protection from water and corrosion, and the controller has simple menus, a clear display and large, back-lit keys.

Emerson (Irvine, Calif.) has in-troduced the Rosemount Analytical Model TCL (photo, p. 24, top right), a total chlorine analyzer that the company says considerably reduces the trouble and expense of replacing reagents. The Model TCL, which con-

sists of a sample conditioning system, an analyzer and a sen-sor, has significantly lower costs of ownership compared to pre-vious-generation total chlorine systems. It uses readily avail-able, low-cost reagents — dis-tilled vinegar and potassium io-dide — that need to be replaced

only once every two months, compared to replacement every week or month for previous chlorine analyzers. It also measures chlorine continuously, rather than periodically — which is important for any analyzers that forms part of a control loop, points out John Wright, Rosemount Analytical's vice president of marketing.

Wastewater treatmentABS (Malmö, Sweden) is a global company supplying pumps, mixers, agitators, aerators, compressors, con-trol systems and services to the water industry. ABS has recently focused

WATER POLLUTION CONTROL SPECIALISTSABS edlinks.che.com/5826-561Biomin edlinks.che.com/5826-562BOC edlinks.che.com/5826-563Calgon Carbon edlinks.che.com/5826-564Dow Biocides edlinks.che.com/5826-565Emerson Process Management edlinks.che.com/5826-566Fluid Dynamics edlinks.che.com/5826-567JMAR edlinks.che.com/5826-568Larox edlinks.che.com/5826-569LuminUltra edlinks.che.com/5826-570

Moore Industries International edlinks.che.com/5826-571Nalco edlinks.che.com/5826-572Neptune Chemical Pump edlinks.che.com/5826-573Pall Corp. edlinks.che.com/5826-574Purdue University edlinks.che.com/5826-575Regenesys edlinks.che.com/5826-576USFilter edlinks.che.com/5826-577Water Maze edlinks.che.com/5826-578

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on complete solutions for wastewater treatment, but the company is already well-known for components such as NOPON submersible aerator mixers and disc diffusers, typically supplied by ABS high-speed turbocompressors, and AquaVision control and monitor-ing systems. A recent introduction is the AFP-ME submersible sewage pump (photo, p. 23, center), which fea-tures an innovative hydraulic design for blockage-free pumping, and lower power consumption thanks to high-ef-ficiency motors.

Siemens Water Technologies has re-cently announced many new wastewa-ter treatment technologies through its USFilter business (Waukesha, Wis.). Among these are the Agar integrated fixed-film activated sludge (IFAS) pro-cess developed by Wise Water Tech-nologies Ltd. (Netanya, Israel). Using proprietary plastic media and wedge-wire screens, the Agar process signifi-cantly increases the biological treat-ment capacity of the system without increasing the physical basin size.

Also from USFilter, the Envirex Diamond edition membrane diffuser overcomes the shortcomings typical of other membrane diffusers, such as reduced oxygen transfer efficiency, a narrow operating range of air flow-rates, high pressure drop and short life. It has a unique diamond-shaped aperture configuration which allows it to handle air flows up to 5 SCFM per diffuser, compared to 3–4 SCFM for diffuser types. Its custom-specified EPDM material is 50% stronger than that of other typical diffusers, and has a low soluble oil content for longer product life.

Nalco Co. (Naperville, Ill.) supplies many chemicals and additives used in water and wastewater treatment. The company’s Ultrion, for instance, is a liquid cationic coagulant that clarifies water more efficiently than alum, with less caustic or lime, over a broad range of pH, alkalinity, temperature, color and turbidity. It can be used by plants currently using alum, ferric chloride, ferric sulfate, aluminum chloride or any other inorganic coagulant used for water or wastewater clarification. Benefits include lower total solids in treated water, fewer pH adjustment problems, lower sludge volumes and

easy coagulant handling. For mem-brane filters, Nalco offers anti-scaling and other additives, plus monitoring systems to prevent under- and over-dosing, and detect leaks.

Fluid Dynamics, Inc. (Boulder, Colo.) has introduced the dynaJET dry poly-mer preparation system, designed to accurately meter and completely hy-

drate dry polymer in the treatment of industrial and municipal wastewater (photo, p. 23, right). The device uses a blower to convey the polymer pow-der into a spray chamber, where it is thoroughly wetted. There is a choice of sizes, polymer delivery and storage configurations. ■

Charles Butcher

www.woodgroup-esp.com

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