VATIS Update Waste Management . Sep-Oct 2008

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ISSN: 0971-5665

VATIS Update Waste Management is published 4 times a year to keep the readers up to date of most of the relevant and latest technological developments and events in the field of Waste Management. The Update is tailored to policy-makers, industries and technology transfer intermediaries.

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ISO 15270 will help expand plastics recycling

A new ISO International Standard will assist the emerging worldwide market for plastic recovery and recycling. Because plastic products are traded internationally and many of the plastic resin manufacturing companies and industrial users are multinational companies, the new “ISO 15270:2008, Plastics – Guidelines for the recovery and recycling of plastics waste” is of particular significance.

ISO 15270:2008 has been drafted to assist all plastics industry stakeholders in the development of: a sustainable global infrastructure for plastics recovery and recycling; and a sustainable market for recovered plastics materials and their derived manufactured products.

The standard establishes the different options for recovering plastics waste that arise from pre- and postconsumer sources. It will assist in the selection of methodologies and processes for the management of post-use plastics that may be approached using various strategies.

ISO 15270:2008 also establishes the quality requirements that need to be considered in all steps of the recovery process. Selection of any one of the available recycling options must be based on compliance with the following requirements:

• The need to minimize adverse environmental impact;
• Prior demonstration of sustainable commercial viability; and
• Secure access to viable systems for collection and quality control.

The standard also provides recommendations for inclusion in material standards, test standards and product specifications. Consequently, the process stages, requirements, recommendations and terminology presented in ISO 15270:2008 are intended to be of general applicability.


Malaysia pushes for registration of EHS

In Malaysia, producers and users of environmentally hazardous substances (EHS) will need to register with the Department of Environment (DoE) to provide the authorities with comprehensive data to monitor the use of such substances. Registration would be made mandatory if efforts to get industry players to do so voluntarily, beginning January 2009, fail to get support from the industry and key players, said the Natural Resources & Environment Minister, Datuk Douglas Unggah Embas.

Under the scheme, manufacturers and importers of EHS and importers of chemical mixtures or finished chemical products that contain such substances are encouraged to register with DoE, which will provide training to ensure that the chemicals are handled without causing harm to the environment, people, animals and plants. The scheme will enable the government to possess comprehensive data on EHS so that decisions can be made on how to manage these substances safely. A substantial portion of chemicals remains unregulated and no information pertaining to their health and environmental effects are available, the Minister said.


Delhi to force plastics makers to recycle

In India, the State Government of Delhi has got a shot in the arm to restrain the units violating plastic recycling and manufacturing rules after the Delhi High Court ordered restricted use of plastic bags in the city of New Delhi. The government believes that the order would act as a deterrent for such factories, as they would directly face contempt of court.

Reacting to the order of the Court, Environment, Forest and Wild Life secretary Mr. J.K. Dadoo said many of the city’s problems could be addressed if the plastics industry is to set up a modern recycling plant in the city, something they haven’t shown much interest in. “Now, if they don’t act, they would be violating court orders,” he said. The Court has asked the Delhi government to consider and implement the suggestions of Justice Chopra Committee. Quoting the Committee’s recommendations, the order says: “Reasonable rates may be fixed for the plastic waste to encourage rag pickers and others to collect and sell plastic bags waste.” Mr. Dadoo stated this too would be possible only when a system for procuring plastic waste is put in place. The Delhi Pollution Control Committee is hiring an economist for studying the extent of illegal plastic recycling and manufacturing.


China to regulate recycling of electronic waste

China recently approved a draft law on the management of electronic waste. The proposed regulation on the recycling and treatment of used electronic products and home appliances received approval of the State Council at a recent executive meeting.

The country will set up a mechanism to encourage recycling and centralized treatment of e-waste. This will be supported by a special fund, according to the proposed law. The regulation also stipulated the respective responsibilities of manufacturers, retailers, repair and customer service providers, as well as recycling companies in the collection and treatment of e-waste.


Pakistani waste management firm to work with ADB

Waste Busters, a Pakistani waste management firm, has been invited by the Asian Development Bank (ADB) to share its experience with other member states of ADB for providing a low-cost sustainable solution of solid waste management through public-private partnership.

Waste Busters has been selected as a model in integrated solid waste management at the international workshop titled “Urban Environment – Liveable Cities”, held in Manila, the Philippines, on 8 September. ADB has selected Waste Busters to implement its waste management practices in six districts of southern Punjab through the provincial government, under a loan agreement of US$500 million. The project involves community participation in door-to-door collection, construction of transfer stations and landfill sites.


Sri Lanka gets into waste export

The Board of Investment (BoI) of Sri Lanka has signed an agreement with Green keepers Ltd. to establish an export trading house to source industrial waste material. This project will recycle, process and export identified waste to recycling plants across the globe. The company will also focus on exporting organic food items, as well as environmentally friendly products such as coconut coir- and shell-based products from Sri Lanka to global markets

In the area of waste material export, the company will be working closely with BoI factories that manufacture garments, tyres and rubber-based products, and will later move to other types of waste that can be recycled. The venture, at an investment of US$100,000, will create over 30 employment opportunities in waste processing and help the country to dispose of a lot of industrial waste in an environment-friendly manner.


Viet Nam’s master plan for solid waste management

The Ministry of Construction (MoC) of Viet Nam has drafted a master plan on solid waste management in urban areas and industrial zones till 2020. MoC sources say that the master plan covers orientations and comprehensive and systematic action plans for solid waste management.

It also identifies problems to be solved, and defines the aims of the work in each stage of national development. The country has annually turned out about 15 million tonnes of waste, including 12.8 million tonnes of garbage from urban and rural households as well as 2.7 million tonnes of industrial waste. Annually, the medical sector generates close to 21,000 tonnes of waste, while the industrial and agricultural sectors discharge about 130,000 tonnes and 45,000 tonnes, respectively, of harmful waste including chemicals. Viet Nam buries most of its solid waste. According to Dr. Pham Sy Liem from the Viet Nam Construction Federation, however, only 17 out of the 91 dumping grounds in the country meet hygienic standards. Urban areas have seen some progress in solid waste management, but the problem is still quite serious in rural areas.


Waste management in Malaysia moves up

In Malaysia, the Housing and Local Government Ministry will take over the management of wastes from local councils starting this September. Minister Datuk Seri Ong Ka Chuan stated that it will be done in stages and the Ministry hoped to fully take over by year-end. The Solid Waste Management Board that had been set up for the purpose “will monitor the jobs carried out by the private waste management companies currently operating under contracts with their respective local councils,” said the Minister.

The duty will be taken over by the Ministry, as more allocation will be needed to carry out the task efficiently and effectively, said Datuk Ong. He added that 20 out of 216 landfills nationwide would be closed and 50 landfills would be upgraded.




Reclaiming PP, PS and ABS from mixed plastics

Mitsubishi Electric Corp. of Japan will start separating and recovering polypropylene (PP), polystyrene (PS) as well as acrylonitrile butadiene styrene (ABS) with a purity of 99 per cent or higher from the mixed plastics produced during the recycling of household appliances.

The recovered plastics will be used to make new products. Annually, about 6,400 t of PP, PS and ABS would be recovered. In general, the closed-loop recycle system that recovers plastics from waste household appliances to manufacture new products is believed to have advantages in economic efficiency and environmental load reduction. The throughput, however, is limited because the target plastics have to be separated and recovered manually from a mixture of several kinds of plastics. Moreover, the existing separation method has a problem in that only those plastic parts made of a single material and relatively easy to separate using a visual check can be separated.

Mitsubishi has developed a proprietary technology based on the specific gravity to separate and recover PP, which is lighter than water, from PS and ABS. It has developed and adopted the “electrostatic separation technology” to separate PS and ABS from each based on the difference in charging haracteristic. A mixture of plastics containing granular ABS and PS is first put into a cylindrical triboelectric charger.

Then, the charger is rotated so that ABS and PS rub against each other and get charged – PS is charged negative and ABS positive. Next, they descend between electrodes to which a voltage is applied so that ABS is attracted on the negative electrode while PS is collected on the positive electrode.

During this process, the separation accuracy lowers if the granular plastics are attracted and agglomerate by the electric force. The company maximized the quantity of triboelectric charge to prevent deterioration of accuracy. As a result, PS and ABS can be recovered with a purity of 99 per cent or higher.


A process to recycle just about anything

Plastics recycling might be taking a new shape outside an abandoned lumber warehouse at Akron in the United States. There, Polyflow Corp. has been testing a process that can convert waste plastic and rubber products into feedstock chemicals. “Contamination doesn’t matter,” said Mr. Joseph Hensel, Polyflow’s CEO. The process can use carpet, tyres, leftover compounds, polystyrene foam, and just about anything else.

Previous methods of making chemicals from recycled plastics or rubber tyres have been criticized because the energy needed to depolymerize the waste matches or exceeds any environmental savings produced by the overall process. A fully operational Polyflow plant, however, will provide about 90 per cent of its own energy needs, Mr. Hensel said. The technology used by Polyflow was developed in the late 1970s by Mr. Charles Grispin, an inventor who now works with Polyflow.

Only 6 per cent of the scrap items used by Polyflow currently are recycled, according to Mr. Hensel; the remaining 94 per cent usually ends up in landfills. In the Polyflow process, scrap is placed into a tank and cooked at nearly 540ºC until vaporized. When the vapour condenses, the resulting liquid contains aromatic chemicals including styrene
and benzene. The chemicals refined from the slurry liquid can be reused by petrochemical firms or used in paints, coatings, solvents or other products, said Mr. Hensel.

The process yields product on a ratio of roughly 70 per cent. In other words, 130,000 t of plastic and rubber waste input would yield roughly 90,000 t of industrial product. The scrap mixture needed to produce such results consists of 80 per cent polyethylene, polypropylene and polystyrene – in roughly equal parts – with the other 20 per cent coming from rubber or from nylon or other specialty plastics. Polyflow wants to license its technology and plant design to other firms.


Depolymerization of waste rubber and thermoplastics

An Indian inventor, Mr. N.S. Sutar, has filed for patent on a process of depolymerization of rubber waste, plastic waste (including PET and PVC), waste oil, foam and synthetic fabric into hydrocarbon fuels. In the process, the waste materials are physically disintegrated and progressively heated to temperature below 500ºC near to atmospheric pressure in a closed reactor.

The process uses a catalyst consisting of at least one metal oxide and one metal silicate, and an additive consisting of at least one ammonium compound, one sulphate compound and one nitrate compound. The process is claimed to enable depolymerization at much lower temperatures than those of existing processes and of a wide spectrum of thermoplastic materials, such as PET/PVC, eliminating formation of dioxins/toxic gases and terepthalic acid.

One preferred embodiment of the process uses a combination of copper oxide and aluminium silicate as catalyst, and a combination of ammonium formate, sodium nitrate and calcium sulphate as the additive. Contact: Mr. Nivrutti S. Sutar, 144, Gaurishankar Sadan, Rampeth, lsangameshwar, Ratnagiri District, Maharashtra 415 611, India.


Processed plastic waste as refinery fuel

Japan Energy Venturing has become a pioneer in the country to use processed waste plastic as a fuel for thermal cracking. Japan’s sixth largest refiner is the first refiner to adopt this technology. The company has a capacity to process 1,000 kl/ year of liquefied waste plastics to petrochemical products, mainly into naphtha, using the hydrogenation refining unit at its Mizushima refinery.

Using plastics waste as fuel will not only save feedstock cost but also result in a negative cost to the company because of savings on waste management.


PET bottle recycling

Krones AG, Germany, has obtained a European patent on a method and equipment for recycling used PET bottles. The invention essentially comprises the following steps:

• The bottles are comminuted into plastic flakes;
• The plastic flakes are sorted into at least two partial sets according to set criteria; and
• The sorted flakes are subjected to an individual recycling process, which includes a decontamination process.

The patent claims that the method and equipment separates the plastic flakes of the threaded part of the PET bottle – which are difficult to clean – are separated from the plastic flakes of the non-threaded part of the bottle – which are easier to clean – and are recycled in other specific recycling steps.


Cost-effective recycling of Styrofoam products

Synthetic polymer expanded polystyrene (EPS), better known by its trade name Styrofoam, is still widely used in disposable cups, fast-food containers and packaging material. EPS is very difficult to remove from the environment effectively because of its tendency to disintegrate easily. RecycleTech Corp. from the United States offers equipment that allows cost-effective recycling of EPS.

Most technologies for “densifying” EPS have a 40:1 compression ratio, while RecycleTech’s machines are said to achieve a 90:1 ratio. “We basically take the expansion out of the polystyrene,” explains Mr. Dan Chung, RecycleTech’s President. RecycleTech maximizes the compression by combining three existing approaches that have never before been used together: crushing, heating and compacting. Three independent tests of RecycleTech’s EPS recycling showed that it produced no harmful air emissions, says Mr. Bill Lindler, President of USSI, a consulting company.

Model XT-500 EPS Foam Densifier is recommended for mid- to largesized businesses, while XT-700 is meant for large-scale operations. XT-500 handles 500 lb (227 kg) per hour while XT-700 processes 700 lb (317 kg) of EPS. The latter handles EPS in both dry and wet conditions and is therefore appropriate for fish processing centres. XT-700 has a blower and silo also as additional components. Contact: RecycleTech Corp., 418 Falmouth Avenue, Elmwood Park, NJ 07407, United States
of America. Tel: +1 (201) 475 5000; Fax: +1 (201) 475 5001; E-mail: info @

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Tyre recycling technology uses microbiology

Recyclatech, a Scotland-based tyre recycling company, has developed a technique that can make rubber easily bondable with natural or synthetic rubber. The microbiological rubber devulcanization process that the firm developed generates a recyclate, which can be used in highvalue rubber products. Recyclatech technique is quite similar to a bug attacking the rubber and consuming the sulphur on the surface. As the process makes the rubber easier to be bonded with other natural or synthetic rubber, it allows the rubber to be remoulded and reused. The process is said to be ideal for waste tyres, disposal of which in landfills is either banned or getting difficult. Worn out tyres are reduced to small particles and put through the microbiological process.



Usable materials from e-waste

Developing e-waste recycling technologies is challenging because of the toxicity of many electronic components. According to the Silicon Valley Toxics Coalition, an environmental group, just one computer can contain hundreds of chemicals, including lead, mercury, cadmium, polyvinyl chloride and brominated flame retardants (BFRs). Some of these chemicals are known to cause cancer, respiratory illness and reproductive problems. Burning e-waste can produce toxic dioxins.

Much of the research into improving e-waste recycling focuses on technologies capable of capturing or creating usable materials from the printed circuit boards (PCBs) used in electronics. PCBs are by weight the most valuable component of waste electronics, says Ms. Renee St. Denis, Director of Product Take Back operations, Hewlett- Packard (HP). HP recycles more electronics than any other company operating in the United States, says the United States Environmental Protection Agency.

For the past five years, scientists at China’s Shanghai Jiao Tong University’s School of Environmental Science & Engineering have been investigating ways to improve the efficiencies of technologies capable of separating usable materials. The average metal content of PCBs is 28 per cent (by weight) – mainly, copper, lead and tin – points out Mr. Zhenming Xu. A tonne of PCBs has more than 10 times the concentration of precious metals in contentrich minerals, he says. Thus, PCB recycling is significant from the viewpoints of recovery of valuable materials and waste management.

Mr. Xu and his colleagues are focusing on how a technology known as corona electrostatic separation, which is widely used in the mining industry, can be used for separating waste PCBs. The technology separates materials on the basis of the particles’ ability to conduct electricity. Particles that conduct electricity are charged by electrostatic induction and attracted to an electrode. What Mr. Xu calls “ion bombardment” of the second electrode then pins the non-conductive particles to the surface of a rotating roll electrode. The new version of the technology, which is used with a two-step separation process, is reported to have improved production speeds by 50 per cent over the conventional electrostatic separation, while significantly reducing the percentage of PCBs that cannot be recycled.

Mr. Xu’s team shows how the nonmetal portions of waste PCBs can be used to produce what they call a “kind of non-metallic plate”. They contend that this plate’s chemical composition and mechanical performance are preferable to those of wood and that the material could be used for products such as sewer grates, park benches and fences.

The presence of BFRs – such as tetrabromobisphenol A (TBBPA, the main flame retardant used in PCB) – in this non-metal plate is a cause for concern. Use of TBBPA is not banned or restricted in any country, but the chemical could end up in the non-metal plate, together with any dioxin-like compounds that can form during e-waste processing.As BFRs cannot be removed from the plastics portions of electronic products, this “presents a significant recycling and reuse challenge,” Ms. St. Denis says. Mr. Xu concurs that further studies are needed to investigate the presence of BFRs in the non-metallic plate. He also points out that they “may be considered as a flame retardant for the non-metallic plate.”

A team of researchers from Turkey and Romania, led by Ms. Cornelia Vasile of Romania’s national Petru Poni Institute of Macromolecular Chemistry, has also presented a technique for waste PCBs processing. It used pyrolysis to produce a fuel oil from the waste and succeeded in removing “almost all of the hazardous toxic components” in their attempts to render it suitable for use by the petrochemical industry. Ms. Vasile contended that the process might be cost-effective if it could be integrated in a petrochemical plant using the existent installations and equipment. But the team is yet to approach companies to gauge their interest in the process, she said. The economics of the process is yet to be worked out. In the long run, “green” design and engineering focused on designing electronics products for recyclability and reducing their use of toxic materials should solve many of the problems currently associated with e-waste, maintains Mr. Ted Smith, chair of the non-profit Electronics TakeBack Coalition. He is convinced that forward-looking companies like HP are already beginning to make important headway in tackling these issues.



New eco-friendly mobile phones

Samsung Electronics, based in the Republic of Korea, has introduced eco-friendly mobile handsets that make use of bio-plastic materials for exterior construction and recycled material for packaging. The three ‘green’ mobile handset offerings from Samsung are: the F268, W510 and E200 Eco.

Company officials said that 40-50 percent of the mobile structure of the three new models is made out of naturally dissolving bio-plastic, which is made from corn starch, and the rest of the plastic required is derived from traditional materials for rigidity. The circuit boards of the models do not contain any brominated flame retardants or polyvinyl chloride, which are toxic materials affecting the environment.

The W510, released in the Republic of Korea, is Samsung’s first green mobile phone model with bio-plastic. This model is not made of any heavy metals – such as lead, mercury or cadmium – and has a water-soluble coating. F268, which was released in China, includes accessories such as a charger and headset that are also eco-friendly. This model has an alarm function that alerts users to unplug the charger when the device is finished charging. It follows the Energy Star requirements. E200 Eco, the latest in the series, was released in Europe.

The company is making an effort to develop more renewable and ecofriendly materials. It is also developing micro fuel cells that can power handsets with hydrogen, and has handset recycling programmes for phones of all brands in Republic of Korea, China, the United States and Canada. The materials from these phones are recycled as much as possible and reused in the manufacture of new phones, stated the company officials.


Software for e-waste management

Indian IT solutions provider Zylog Systems will soon launch ‘Recycle Accelerator’, its new software to manage electronics waste. Zylog Vice-president Mr. John Mehrmann said the software is primarily aimed at creating a database of products to be recycled and information on partners involved in the process. The new product would help in connecting all the partners – manufacturers, recyclers, collectors and buyers of materials – to exchange information and strengthen communication on tracking, among others.

Zylog Systems would be partnering with makers of electronic products and other service providers to start a network of stakeholders involved in the process of recycling e-waste, and is already in talks with some of them. Contact: Zylog Systems, 155, Thiruvalluvar Salai, Kumaran Nagar, Sholinganallur, Chennai 600 119, India. Tel: +91 (44) 3915 7000; Fax: +91 (44) 3915 7009.


A method for recycling mixed e-waste streams

Close the Loop Technologies Ltd., Australia, has filed for a European patent on a process for recycling mixed streams of waste electrical and electronic equipment (WEEE). The process facilitates substantial recycling of all material forming the WEEE, thus providing a near-zero landfill. The invention also covers an additive used in the process. The process is claimed to allow recycling of ink, toner, PU foam, plastic materials containing brominated flame retardants, plastic materials generally based on styrenes (e.g. PS, HIPS, ABS, PPO/PS, PPE/PS, ABS/PC) and polyamides (Nulon 6, Nylon 6, Nylon 12) and other engineering plastics, such as polyacetal, polycarbonate, PET, PBT and liquid crystal polymers. Contact: Close the Loop Technologies Pty. Limited, #208 Hume Highway, Somerton, VIC 3062, Australia.




New process could minimize water use

Environmental solutions provider Enva of Ireland has developed a water treatment process that could cut industrial water consumption by up to 90 per cent. The electrocoagulation process separates suspended and dissolved particles from water using an electric field. Coagulation is the process that coaxes particles to bind together into larger solids that will settle out of the water. Then, using another process called flocculation, the solids are separated out from a solution. The electro-coagulation cell has a capacity of 100 litres and has about 20 square metres of electrodes.

Dr. Frank Holland of Enva points out the benefits of the technique, which uses computers to minimize passivation and ensure continued operation of the electrodes: “For example, a laundry must have its final rinse with fresh water, so a volume of perhaps 25 per cent would have to be disposed of, and therefore the reduction would be 75 per cent. Equally, where very high purity water is needed throughout most of the application, recycling is reduced, and the key benefit in such cases of electro-coagulation is clean up of the water prior to discharge.”


Turning oil and gas field waste into valuable water supply

Each year, hydraulic fracturing produces billions of litres of wastewater while increasing the production rate of oil and gas wells. For example, Texas, the largest oil and gas producing state in the United States, annually discards over six billion barrels of oilfield wastewater into the state’s 50,000 permitted disposal wells. The wastewater disposed of in the wells is forever lost, placing even more stress on this water scarce region. Now, GE Water & Process Technologies and STW Resources Inc. (STW) have formed an alliance that will drastically reduce this water loss. Using a costeffective process, innovative and patented GE thermal evaporation technologies, the joint effort will help oil and gas customers recover up to 70 per cent of their hydraulic fracturing wastewater.

The GE-STW collaboration will first address the wastewater challenges in locations known for tough-to-treat wastewater. Using GE’s patented Evaporator and Brine Concentrator technology, it will help the regions reclaim approximately 70 per cent of their hydraulic fracturing wastewater. The reclaimed water will be reused or safely returned back to the environment. GE’s seeded-slurry, falling-film evaporators produce distilled water from highly saturated industrial waste streams, while its Brine Concentrator system allows recovery of wastewater for a variety of uses and help achieve zero liquid discharge.


Technology that cuts industrial water use

Aqueous Recovery Resources Inc. (ARR) in the United States has developed an innovative technology that effectively separates process oils, other liquids and uspended contaminants from industrial water. The patented system enables users to separate liquids by specific gravity, thus making significant savings in process water consumption by allowing reuse of the water as well as other process fluids, such as the separated oil. This savings of water also improves uptime, extends the use of detergents and significantly reduces the need to prepare water, thus saving on energy, ARR claims.

Called Suparator®, this ‘dynamic separation’ technology is based on the Bernoulli Principle. Unlike conventional water separation devices, it uses no moving parts or media to provide more than 99 per cent separation of polluting oils or liquid contaminants from water while it is still in the process tanks. This liquidliquid separation allows reuse of the recovered contaminants, like oil, as well providing a means of reuse of it as well. Further, Suparator is able to remove dirt and other unwanted foreign objects from the suspended oil before it can settle into the water tank and necessitates water and/ or detergent changes. The technology has been already deployed in pharmaceutical, automobile, plastics and petrochemical industries. Contact: Mr. Kim Kaplan, Aqueous Recovery Resources Inc., #300 Adams Street, Bedford Hill, New York, NY 10507, United States of America. Tel: +1 (914) 241 2827; Fax: +1 (914) 242 7346; E-mail: info


Bacterial process for waste fluid treatment

Industrial firms face pressure from regulators to reduce the pollution and toxicity of waste fluids as well as the amount of waste sent to landfill and climate change gas emissions. The MicrocycleTM technology from Microbial Solutions Ltd., the United Kingdom, could help them meet their targets with significant cost savings. The bacterial process turns used metal working fluids into grey water that is safe to dispose of in the sewerage system within seven to ten days and without producing methane.

The process employs a bioreactor containing non-pathogenic bacteria that together ‘eat’ the polluting and toxic elements in the metal working fluids. The bacterial consortium has been carefully selected following a worldwide search of hundreds of bacteria that survive naturally in machine sumps, where they eat metal working fluids. In their natural conditions, these bacteria can only survive in very low concentrations. After isolating complementary bacteria, which co-exist with these and eat different components of waste metal working fluids, the company has ensured that they can thrive in the bioreactors by providing an appropriate environment for them to grow and increase in biomass. The bacteria convert the wastes to biomass.

The process produces some carbon dioxide. The on-site process is provided on a ‘pay as you treat’ per litre basis, offering price certainty and stability to manufacturers. Contact: Microbial Solutions, Cherwell Innovation Centre, 77 Heyford Park, Upper Heyford, Bicester, Oxford OX25 5HD, England, United Kingdom. Tel: +44 (1869) 238098; E-mail: info@micro; Website: www.


Treatment of saline wastewater

Researchers at the School of Engineering, University of Santiago de Compostela, Spain, have proposed a sequencing batch reactor (SBR) treatment for saline wastewater from fish canning centres. Fish canning effluents have salt content, which may go up to 30 g sodium chloride per litre. Such effluent, previously diluted to desired concentration, was treated in an SBR where aerobic granular sludge was produced.

The formation of mature aerobic granules occurred after 75 days of operation with 3.4 mm of diameter, sludge volume index (SVI) of 30 ml/ g volatile suspended solids (VSS) and density of approximately 60 g VSS/l-granule. Treated organic loading rates were up to 1.72 kg COD/ (m3·d) with fully organic matter depletion.

Up to 40 per cent ammonia nitrogen was removed via nitrification- denitrification when nitrogen loading rates were of 0.18 kg N/ (m3·d). The presence of salt in the treated effluent did not have any detrimental effect on the operation of the reactor once the aerobic granules were formed. Contact: Mr. R. Méndez, Department of Chemical Engineering, School of Engineering, University of Santiago de Compostela, Lope Gómez de Marzoa S/N, E- 15782, Santiago de Compostela, Spain. E-mail:


Novel anaerobic reactor to treat wastewater

Rubber Research Institute of India has developed a novel anaerobic process for processing wastewater for reuse in rubber latex production units. As in the conventional aerobic process, here too digestion of bio-particles in the wastewater takes place but in less time and expense. Aerobic process takes 30-40 days to process wastewater and consumes a large amount of space for treatment operations – something not ideal of small rubber processing units, the Institute said.

The new anaerobic process takes only a day to process wastewater and there are no offensive odours released in the process. The treated water can be used in rubber sheet production. An ultra-fast anaerobic reactor has been established at a model rubber processing unit. It will cost only Rs 650,000 (approx. US $13,500) to set up such in a rubber processing unit with daily capacity of 500 sheets.


Ecologically sustainable treatment of wastewater

Researchers at the School of Mechanical and Building Sciences, VIT University, India, have carried out a study on an ecologically sustainable wastewater treatment system. The system incorporates enhanced primary treatment, anaerobic digestion of coagulated organics, biofilm aerobic process for the removal of soluble organics and disinfection of treated water. An attempt was also made to study the reuse potential of treated water for irrigation and use of digested sludge as soil conditioner by growing marigold plants.

Ferric chloride dose of 30 mg/l was found to be the optimum dose for enhanced primary treatment with removals of COD and BOD to the extent of 60 per cent and 77 per cent, respectively. Efficient anaerobic digestion of ferric coagulated sludge was performed in 7 days of hydraulic retention time. Upflow aerobic fixed film reactor was found to be very efficient in removals of COD/BOD in the organic loading rate range of 0.25 to 3 kg COD/m3/ day with COD and BOD removals of 65-90 and 82-96, respectively.

Photo-oxidation followed by disinfection reduced by half the chlorine dose required for the disinfection of treated effluent. The treated water was found to be suitable for irrigation. The result also indicated that anaerobically digested sludge may be an excellent soil conditioner.



Groundwater bioremediation with emulsified oils

EOS Remediation LLC, a United States-based developer and manufacturer of advanced technologies for groundwater restoration, is the exclusive licensee for a technology on groundwater bioremediation developed by Solutions-IES. The technology uses oil emulsions for aquifer bioremediation where the oil droplets are smaller than the pores of aquifer. The addition of emulsified vegetable oils provides food for the micro-organisms, and stimulates biodegradation activity.

The proven EOS® technology is said to reduce substantially the cost to restore contaminated aquifers. It is claimed to be a significant advancement in the treatment of groundwater contaminated with chlorinated solvents, energetic materials, nitrates, oxidized heavy metals and radionuclides. Contact: EOS Remediation LLC, 1101 Nowell Road, Raleigh, NC 27607, United States of America. Tel: +1 (919) 342 2944; Fax: +1 (919) 873 1074; E-mail: nfo@eosremedi


Bioremediation of subsurface contaminants

Camp Dresser & McKee Inc., the United States, has patented an in situ treatment regime that includes methods of stimulating anaerobic biodegradation of subsurface contaminants, such as perchlorates, nitrates and halogenated volatile organic compounds. The methods include vaporizing a liquid electron donor to form a treating gas. The treating gas or hydrogen is directed to a subsurface site that includes one or more contaminants, thereby stimulating anaerobic degradation of the subsurface contaminants.

One method comprises the steps of vaporizing an electron donor to form an electron donor gas, mixing the electron donor gas with a carrier gas to form a treating gas with an electron donor component, and directing the treating gas to a subsurface injection site. The electron donor is a liquid at a temperature of 0ºC and a pressure of 1 Atm. The treating fluid stimulates anaerobic degradation of at least a portion of the contaminant, for example, a perchlorate compound. The amount of electron donor gas mixed with the carrier gas is controlled to prevent the electron donor component from condensing before the treating gas reaches the point of treatment.

The electron donor includes at least one member of the group consisting of an aldehyde, alkene, alkyne, amine, aromatic hydrocarbon, ester, organic acid, ethyl acetate, ketone, methanol, ethanol, propanol, butanol, etc. The invention also provides for the treatment of groundwater and perched water. The methods of the invention eliminate the need for costly pumping of groundwater and reduce the risk of bio-fouling of wells and equipment. The method does not require high amounts of energy, as is needed in thermal treatment methods. Usage of esters, alkenes, ketones and alcohols as electron donors is advantageous because these chemicals efficiently stimulate anaerobic degradation of nitrate and perchlorate.


Petroleum remediation product

Universal Remediation (UniRem) of the United States offers a new way of cleaning up oil spills using bioremediation product called Petroleum Remediation Product (PRP®). PRP is a natural and non-toxic product, consisting of tiny spheres of treated wax, which contains nutrients. When a wax sphere comes into contact with spilled oil, it “binds” with the hydrocarbons. Nutrients in the sphere help micro-organisms from the immediate environment flourish until they eat every droplet of oil. PRP will absorb and remediate, over time, more than 20 times its weight.

This natural, biodegradable oil spill powder can be used on any hydrocarbon spill application. For cleaning up an oil spill, PRP is used in with an apparatus, the BioBoom®, which is an oil spill containment system available in several sizes or tailored to a user’s requirements. The Bio-Boom is a flotation device that keeps the boom on top of the water and prevents the oil from spreading into non-polluted water.

The basic delivery system grew out of NASA biological encapsulation research and the orbital production of microspheres so uniformly precise that they provide calibration standards for scientific and industrial equipment. Industry scientists worked with NASA’s Jet Propulsion Laboratory and the Marshall Space Flight Centre to develop PRP. Uni- Rem later commercialized this technology by developing the systems to treat contaminants in a wide variety of situations.


Bioremediation using bacterivorous protozoa

Marine Biotechnology Institute of Tokyo, Japan, has secured a European patent on a bioremediation process that uses bacterivorous protozoa (particularly flagellates) to increase the efficiency of both in situ and bioreactor bioremediation processes involving the biodegradation of organic pollutants, including petroleum-derived hydrocarbons. The bacterivorous protozoa can be added alone or in combination with appropriate bacteria to contaminated sites or bioreactors to facilitate and enhance bioremediation.

When a bacterium that consumes the organic pollutant and a protozoan that eats such a bacterium are together added to the organic pollutant, the bioremediation by the bacteria is improved and accelerated, in spite of the bacterivorous characteristics of the protozoa. The invention is based on this new finding. It is a bioremediation process wherein the bacterivorous Heteromita protozoa are used to increase the efficiency of in situ or ex situ bioremediation process involving appropriate bacteria for the biodegradation of organic pollutants, such as petroleum-derived hydrocarbons.


Rapid bioremediation of soil perchlorate

In the United States, researchers from CDM and Geomatrix Consultants have developed a rapid process for the on site bioremediation of perchlorate in soil and groundwater. The process was applied to a now-defunct ammunitions factory site in Massachusetts that used to manufacture various explosives and related products containing energetic compounds, including perchlorate. Remediation of perchlorate in site soil and groundwater is being conducted to meet the regulatory requirements and allow planned redevelopment activities to proceed.

The general approach to perchlorate remediation of shallow soil at the site includes excavation of affected soils followed by ex situ bioremediation. Glycerine was chosen for use as an electron donor because of its stability, safety, low cost and regulatory acceptance. However, fullscale bioremediation operation with glycerine initially resulted in inconsistent results. To eliminate this and to optimize the biotreatment process, more studies were performed in the field, determining the factor(s) that influenced inconsistent breakdown of perchlorate in site soils.

Total Kjeldahl nitrogen was determined to be a major factor limiting perchlorate biodegradation. Adding di-ammonium phosphate (DAP) resulted in consistent and complete perchlorate removal, usually within two weeks of incubation, with an average per day destruction rate of about 200 µg/kg. Soil processing rates were gradually increased over the year to the current 2,000-2,500 tonnes of soil processed per day. The total unit treatment cost for the process is approximately US$35/ tonne. The glycerine-DAP process is at present playing a major role in the remediation of this 1,000-acre former industrial site.


A promising process for oil spill bioremediation

It has been well established that most crude oils are substantially biodegradable, especially components like short linear alkanes or simple aromatic hydrocarbons. However, the heavy fraction, made up of long-chain saturated and polyaromatic hydrocarbons and a considerable fraction of asphaltenes and resins, is generally recalcitrant to degradation. Scientists from the Spanish Council for Research working at the Research Station at Zaidín, Granada, investigated in situ crude oil degradation after an oil spill. They found that indigenous micro-biota (microscopic living organisms of a region) of the Galician shore is able to degrade heavy crude oil fractions.

The team’s goal was to assess the response of the natural bacterial population after the spill and to find evidences of crude oil degradation taking place at the contaminated sites. They used stable isotopes (13C/12C) to determine the origin of dissolved inorganic carbon (DIC) in control and contaminated coastal marine water samples. Crude oil is very depleted in 13C; therefore, its biodegradation product carbon dioxide (CO2) will also be more 13C depleted as compared with the typical marine DIC and dissolved CO2 in the atmosphere.

The anomalous DIC isotopic composition of certain samples taken along the shore of a contaminated site showed degradation of a depleted 13C source (crude oil), pointing to a natural population oxidizing this carbon source into CO2. This could be reproduced in the laboratory using water samples taken from the contaminated shore, after nitrogen and phosphorus amendment. The results confirmed the presence of microbiota that degrade the contaminant. Further study of specific organisms present at the site revealed several populations able to degrade polycyclic aromatic compounds, such as phenanthrene or naphthalene.


Bioremediation of petroleum pollutants

Mr. Felix A. Perriello, an inventor in the United States, has secured a European patent on a bioremediation process that employs alkaneusing bacteria to degrade pollutants comprising petroleum compounds. In situ or ex situ approach may be used to reduce or eliminate petroleum pollutants from liquid, gas and solid sources.

For instance, petroleum concentrations in contaminated sites are reduced by contacting the petroleum pollutants with butane-utilizing bacteria in the presence of oxygen to degrade the petroleum pollutants by cometabolism or direct metabolism. Suitable alkane-utilizing bacteria for the process include Pseudomonas, Variovorax, Nocardia, Chryseobacterium, Comamonas, Acidovorax, Rhodococcus, Micrococcus, Aureobacterium, Aeromonas, Stenotrophomonas, Alcaligenes, Gordona, Shewanella, Clavibacter, Cytophaga, Sphingobacterium, Corynebacterium and Phyllobacterium.



Bioremediation of paraffin deposition in oil well tubing

Paraffin deposition in oil well tubing is a major problem, which causes enormous production loss. Conventional techniques for the control of paraffin deposition in oil well tubing are highly expensive and plagued with related problems. The Oil and Natural Gas Corporation (ONGC), India, has been practicing scraping of oil well tubing. However, at times the scraper wire breaks and blocks the oil well tubing. In such a case, the scraper has to be removed at high costs. The Energy and Resources Institute (TERI), India, and ONGC’s Institute of Reservoir Studies (IRS) jointly developed a thermophilic, paraffindegrading bacterial strain (PDS-10) for preventing paraffin deposition inside the oil well tubing. Application of these microbes has successfully prevented paraffin deposition in well tubing.

Besides PDS-10 technology, the joint venture between ONGC and TERI, ONGC-TERI Biotech Ltd., will also offer technologies such as OilZapper and Microbial enhanced Oil Recovery (MEOR). TERI’s Oilzapper is a microbial product that eliminates oil spills and manages oily sludge. MEOR is also a microbial method, developed by TERI and IRS, for enhanced oil recovery from stripper oil wells, wherein a set of microbes mobilizes crude oil trapped in the pores in oil reservoirs. Contact: Mr. Rajiv Chhibber, The Energy and Resources Institute, Darbari Seth Block, IHC Complex, Lodhi Road, New Delhi 110 003, India. Tel: +91 (11) 2468 2100, Ext. 2324; Fax: +91 (11) 2468 2144; Email:



Bioremediation in heterogeneous porous media

Ms. Xin Song and Dr. Eric A. Seagren of the Department of Civil and Environmental Engineering, University of Maryland, the United States, have devised a quantitative framework, based on a set of dimensionless numbers, to capture the effects of competing interfacial and biokinetic processes, and define limits on the application of in situ bioremediation. An integrated numerical modelling and an experimental approach was utilized to evaluate the quantitative framework. Experiments were conducted to examine the transport and biodegradation of naphthalene in a saturated, heterogeneous, intermediate- scale flow cell with two layers of contrasting hydraulic conductivities.

The experiments were carried out in two phases: Phase I, simulating intrinsic biodegradation; and Phase II, simulating an engineered in situ bioremediation. In Phase I, dispersion was identified as the overall rate-limiting process based on the proposed quantitative framework. In Phase II, two engineered perturbations to the system were examined for their abilities to enhance in situ biodegradation. In the first perturbation, nitrogen and phosphorus were spiked into the influent solution in excess of the required stoichiometric amounts. There was no significant impact, as dispersion, not biokinetics, was the overall rate-limiting process. However, in the second perturbation, advection was increased, resulting in increased longitudinal and vertical transverse dispersion, thereby reducing the rate-limiting process and enhancing the overall biotransformation rate.




Removal of NOx and HCN contaminants

AirProtekt, the United Kingdom, has installed and commissioned a combined Regenerative Thermal Oxidation (RTO) system and a Selective Catalytic Reduction (SCR) system to remove nitrogen oxides (NOx) and other gaseous contaminants, such as hydrogen cyanide (HCN), from the manufacturing facility of SGL Carbon Fibres (SGLCF) in Muir of Ord, in the north of Scotland. SGLCF, a subsidiary of the SGL Group based in Germany, produces carbon fibre for a variety of engineering applications.

To assist in handling the additional emissions, including fugitives from SGLCF’s upgraded production facility, AirProtekt was selected to supply a third RTO system in combination with a new SCR system. The main purpose of the new combined system is to treat and remove pollutants such as NOx and HCN. The chemical reactions during the heating process generate NOx, HCN, carbon monoxide, carbon dioxide, ammonia and volatile organic compounds in exhaust gases. These exhaust gases are extracted using RTO systems that reduce the levels of contaminants prior to discharge through stacks, which are the main sources of emissions from the carbon fibre manufacturing process.


Scientists use sunlight to make fuel from carbon dioxide

Scientists at Sandia National Laboratories in New Mexico, the United States, have found a way of using sunlight to recycle carbon dioxide (CO2) and produce fuels such as methanol or petroleum. The Sunlight to Petrol, or S2P, project basically reverses the combustion process, recovering the building blocks of hydrocarbons. These can then be used to synthesize liquid fuels. The researchers report that the technology already works and can help reduce greenhouse gas emissions, although large-scale implementation can be a decade or more away.The Sandia team originally developed the Counter-Rotating Ring Receiver Reactor Recuperator (CR5) to generate hydrogen for use in fuel cells. If the rings of the device are exposed to steam instead of CO2, they will generate hydrogen.

S2P uses CR5 to divide CO2 into carbon monoxide (CO) and oxygen, and CO – a building block for making hydrocarbons – is used to make the fuel. Lab experiments have shown that the process works. The prototype being developed will be about the size and shape of a beer keg. It will contain 14 cobalt ferrite rings, each about 1 ft in diameter and turning at 1 rpm. An 88 m2 solar furnace will blast sunlight into the unit to heat the rings to about 1,427ºC. At that temperature, cobalt ferrite will release oxygen. When the rings cool to about 1,093ºC, they are exposed to CO2. Ashe cobalt ferrite is now missing oxygen, it snatches some from the CO2, leaving behind just carbon monoxide that can then be used to make methanol or petroleum. With the cobalt ferrite thus restored to its original status, the device is ready for another cycle.


NOx removal

Branch Environmental Corporation, the United States, provides several different technologies for removing nitrogen oxides (NOx) from air or flue gas. The best treatment method will depend on the conditions of operation. The technologies offered are:

• Selective catalytic reduction, or SCR: SCR systems use a catalytic design to react ammonia (NH3) injected into the air stream with the NOx present. This approach needs an operating temperature of 160º-320ºC, depending on the catalyst used. For flue gas that is already in this range, the SCR system will be a suitable choice. Systems use about 1.5 wt. NH3/wt.NOx.

• Wet scrubbing: This system has the lowest initial cost. As NOx absorbs in water,it reacts to form NO (insoluble form) that will slowly reoxidize to NO2. In a conventional scrubber, 60-70 per cent removal occurs. To improve this, several possible chemicals can be introduced into the towers combined with a very long contact time. The cost of the special chemicals required is a disadvantage. Further, there will be a wastewater treatment requirement.

• Wet-phase catalyst: To avoid the high chemical cost, a special surface catalyst media was developed. This system employs conventional scrubber chemistry with a caustic solution, operates at ambient temperature, and can handle variable loads.

The surface catalyst is relatively expensive initially, so the best choice will depend on concentration of NOx, temperature, required efficiency, and so forth. Contact: Branch Environmental Corporation, 3461 Route 22, Somerville, New Jersey, NJ 08876, United States of America. Tel: +1 (908) 5261 114; Fax: +1 (908) 5262 881.


New catalyst for diesel NOx reduction

In the United States, a new diesel engine catalyst that can remove smog-causing nitrates of oxygen (NOx) without costly liquid ammonia injection systems and platinum coatings has been developed by researchers at Argonne National Laboratories and licensed for production by a start-up company Integrated Fuel Technologies Inc. (IFT).
IFT plans to use the material in its emissions-reducing products for large diesel engines.

Argonne’s tests show the catalyst, which uses a ceramic brick coated with a specially formulated cerium oxide compound, can reduce NOx emission by 95 per cent or more. The catalyst is installed in the vehicle’s emissions system and works on particulate matter, or soot, removed from the exhaust by a particulate trap. It uses the vehicle’s diesel fuel to reduce the NOx in the soot to harmless nitrogen. Most other NOx treatment systems, especially for larger engines (such as diesel V6 and V8 engines used in pickup trucks, SUVs and some luxury cars) inject liquid ammonia (urea) into the exhaust stream to knock down the NOx. The process requires addition of a urea tank, pump and delivery system and periodic refilling of the urea tank. Eliminating the urea system reduces a vehicle’s weight, which improves its fuel efficiency. Because it uses a relatively plentiful element (although a rare earth metal, cerium is one of the more plentiful elements on Earth), does not require special pumps or electronics and has a useful life of about 400,000 miles, the system is inexpensive compared with other NOx treatments.


Treating digester off-gas from ethanol production

Ethanol production from dry and wet milling processes is projected to increase in the United States, with the recent introduction of the Energy Independence and Security Act of 2007. As ethanol production goes up, so will waste emissions from fermentation processes. Merichem Gas Technology Product offers its trade-marked LO-CAT technology as a viable alternative for removing hydrogen sulphide (H2S) from digester gas produced as part of wet milling processes. LO-CAT treated digester gas helps maximize the use of valuable natural resources. Ethanol production energy costs could be reduced by more than half if energy in put is supplemented by the use of LO-CAT cleaned digester off-gas. Every 1,000 SCF of treated digester off-gas could yield about
0.6 MMBtu, equivalent to US$6.96, in saved natural gas cost. Actual energy savings may vary based on the availability and composition of treated digester gas.

Sour gas is routed to a LO-CAT absorber, the type of absorber varying with the product gas H2S specification. The conventional liquid full scheme is used when about 99.99 per cent H2S removal efficiency is required. In fact, as low as 1 ppm by volume H2S can be achieved in the treated gas. The Venturi-mobile bed option is used when moderate H2S removal efficiency is required and low-pressure feed gas – less than 15 psi – is treated.

In the absorber, sour digester gas is contacted with LO-CAT solution. H2S is absorbed from the gas into the LO-CAT solution where a chelated iron catalyst promotes the reaction to convert H2S to elemental sulphur. Treated gas then exits at the top of the absorber and sulphurrich LO-CAT solution flows to the oxidizer. In the oxidizer, the solution gets mixed with air, and elemental sulphur settles to the bottom of the vessel. Oxygen in the air oxidizes (regenerates) the chelated iron in the solution, returning it to its active state. In its active state, iron and LO-CAT solution are recycled to the absorber to remove more H2S.


Oxidizer systems for halogen VOC control

RETOX® regenerative thermal oxidizers (RTO), from Adwest Technologies in the United States, provide VOC abatement of 99 per cent and greater. The oxidizers come with a corrosion resistant ceramic heat exchanger rated at 95 per cent primary heat recovery. This provides flameless, zero NOx and fuel-free operation at 3 per cent and greater inlet VOC loadings. Compact, shop assembled, skid mounted RETOX RTO modules are available from 700 to 75,000 cfm flow rates with low-pressure-drop, corrosion resistant ceramic heat transfer media and automatic PLC controls. Specialized RTO metallurgy from stainless steel to titanium construction with customized acid gas scrubber packages are available for halogenated chemical, coating and pharmaceutical processes.

Special features include the utilization of rapid cold RTO start-ups, the use of flameless RTO combustion for virtually zero NOx by-products, and development of simple low-cost poppet valves with soft step seating to ensure zero leakage. The virtual total shop assembly and compact, low-profile modular design provides for rapid installation. RETOX RTOs only require one fan to operate, thus reducing maintenance time as well
as costs. Contact: Adwest Technologies, 1175 North Van Horne Way, Anaheim, CA 92806-2506, United States of America. Tel: +1 (714) 632 9801; Fax: +1 (714) 632 9812; E-mail:


Controlling NOx emissions from diesel engines

The BlueMAX urea-based selective catalytic reduction (SCR) system from Nett Technologies, the United States, has been put by the Environmental Protection Agency on the National Clean Diesel Campaign’s Emerging Technologies List. The system is approved for Emerging Technology applications on nonroad, 4-cycle, heavy-duty diesel Caterpillar engine models in the 75- 450 kW (100-600 hp) power ranges, originally manufactured from 1996 through 2008. The BlueMAX SCR system is offered as a direct-fit design; this simplifies the installation and offers a cost-effective and customized solution to a sophisticated emission control problem.

BlueMAX SCR system is designed to effectively control nitrogen oxides (NOx) emissions from medium- and heavy-duty diesel engines. It uses a urea control strategy that relies on a NOx concentration measurement by a sensor stationed before the SCR catalyst. Based on the NOx sensor signal, in combination with an engine air mass flow sensor and temperature sensor, the necessary urea dosing rate is calculated by the control algorithm. The Blue- MAX SCR system can also control diesel particulate matter, hydrocarbons and carbon monoxide.


Injection mixer boosts removal of H2S in sour gas

For natural gas applications, the specification of the export gas is typically 2-4 ppmv for hydrogen sulphide (H2S) and 2.5 mole per cent for carbon dioxide (CO2). For refinery off-gas, the feed gas concentrations are typically in the 2-4 mole per cent range for both gases, with the outlet specification typically set to 50 ppmv for H2S. Therefore, with the less strict regulations set to the outlet CO2 concentration, selective H2S removal is a regulatory requirement for many sour gas treatment applications.

ProPure AS, Norway, has developed and qualified its injection mixer, originally designed for H2S scavenging of sour gas, into a co-current contactor for selective H2S removal. The development and qualification of the selective H2S removal technology, called ProPure Compact Alkanolamine Plant (ProCAP), has been sponsored by StatoilHydro, Total, ConocoPhillips and Gaz de France. Pilot testing has been carried out at Gaz de France’s gas storage and processing plant at real natural gas process conditions with pressures 70-100 bar, and at StatoilHydro’s refinery for selective H2S removal from refinery off-gas.

In comparison with a conventional counter-current absorber, the Pro- Pure co-current contactor unit is far more compact. It consists of an injection mixer, downstream contactor pipeline and gas-solvent scrubber. The key ProPure concept is to reduce CO2 absorption to make possible higher solvent loading capacity of H2S. This needs low gas-solvent contactor residence time and larger gas-solvent exposure area, which is effected by initially establishing a high exposure area between the gas and solvent droplets by the use of a one-shot mixer concept. In the downstream gas-solvent knock-out scrubber, the exposure between the solvent and the CO2-rich sour gas is minimal so that there is minimal CO2 mass transfer from the gas to the solvent and H2S-flashing
from the solvent.




Natural Processes and Systems for Hazardous Waste Treatment

This book discusses the various natural processes for the attenuation and degradation of hazardous compounds and application of these processes in inexpensive natural systems. Major attenuation processes covered include: sorption and sequestration, biodegradation and assimilation processes, photoprocesses, phyto-processes, oxidation-reduction, and physical processes. The book presents extensive up-to-date references, numerous illustrations, tables, and case studies.

Contact: Publications Marketing Department, American Society of Civil Engineers, 1801 Alexander Bell Drive, Reston, VA 20191-4400, United States of America. Tel: +1 (703) 295 6163; Fax: +1 (703) 295 6278.

Electronic Waste Management

Electronic Waste Management brings to the readers an up-to-date review, by a group of leading experts in the management of electrical and electronic wastes, of the scale of the e-waste problem, the impact of recent legislations, and current and future methods for treatment, recycling and disposal of this waste. While the emphasis is on European practice, comparisons with other countries such as the United States, Japan and China are made.

Contact: Sales & Customer Services, Royal Society of Chemistry, Thomas Graham House, Science Park, Milton Road, Cambridge CB4 0WF, United Kingdom. Tel: +44 (1223) 432360; Fax: +44 (1223) 426017.

Principles of Wate and Wastewater Treatment Processes

This is the third book in the Water and Wastewater Process Technologies Series. The book outlines the main operations that are involved in the separation, degradation and utilization of organic and inorganic matter during water and wastewater treatment. The module provides a descriptive introduction to unit operations that are further described with design and operational details in later books in the series.

Contact: IWA Publishing, Alliance House, 12 Caxton Street, London SW1H 0QS, United Kingdom. Tel: +44 (20) 7654 5500; Fax: +44 (20) 7654 5555; Website:


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