VATIS Update Waste Management . Jan-Feb 2007

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Waste Management Jan-Feb 2007

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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POPs encounter worldwide restriction

An international scientific committee has moved five compounds one step closer to joining the initial list of a dozen toxic chemicals targeted for reduction or elimination under the United Nations Stockholm Convention on Persistent Organic Pollutants (POPs). In November last year, the POPs Review Committee had finalized draft risk profiles, the second step in the approval process, for pentafluorooctane sulphonate, pentabromodiphenyl ether, chlordecone, lindane and hexabromobiphenyl. The committee now has to determine whether global action is required and, if so, whether each of these chemicals should be banned or restricted, as well as whether any specific exemptions should be permitted. Its final conclusions, which could take 2-3 years, will be sent to the conventions member governments for a formal decision.

The review panel, comprising scientists from 31 countries, also took the first step towards adding five more chemicals to the POPs list by ag-reeing to prepare draft risk profiles for the same. The newly proposed chemicals are a-hexachlorocyclohexane, -hexachlorocyclohexane, pentachlorobenzene, octabromodiphenyl ether and short-chain chlorinated paraffins.


India for integrated pollution control

The Indian Ministry of Environment and Forests plans to undertake capacity building for industrial management projects. The World Bank will provide financial assistance for the project under the Project Preparation Facility (PPF). The project will promote an integrated approach to pollution management, which will facilitate full remediation of polluted sites. It builds on a framework of regulatory incentives for pollution reduction, promotes partnership between public and private entities for improved compliance, enhances public awareness through better access to environmental information, and introduces measures for reducing environment and health risks to communities.


Japanese aid for Vietnamese organic waste management

Japan is assisting Viet Nam to find a solution to the solid waste management problem in Ha Noi city. According to a project agreement signed by the Ha Noi Peoples Committee and the Japan International Cooperation Agency, about US$3 million will be provided by Japan. The 3R Reduce-Reuse-Recycle Initiative is very popular in Japan.

The focus of the Implementation support for 3R Initiative for a sound material-cycle society project is to promote the practice of segregating domestic waste at the source, with organic and inorganic wastes to be separated by homes before collection by the Urban and Environment Co. of Ha Noi. Ultimately, the organic waste will be utilized for profitable economic activities such as the production of compost fertilizer, which will in turn substantially reduce the pressure on the currently overloaded landfills. The project activities will also promote environmental education among Ha Noi residents about the economic and environmental benefits of separation at source using means mass media and community meetings.


Thai venture for fuel from plastic

Three Thai companies Single Point Energy and Environment, PTT, and Bangchak Petroleum have joined hands to churn out crude oil from plastic waste. The companies have signed a memorandum of understanding to study polymer energy technology jointly and explore possible marketing strategies to sell the crude oil.

Mr. Mechai Viravaidya, chairman of Single Point, said the successful implementation of a polymer energy technology imported from Poland could help eliminate the countrys plastic waste, which is estimated to be about 7.5 million tonnes at present. It is estimated that plastic wastes could yield sufficient crude oil to reduce 12 per cent of Thailands oil imports. The imported machinery is capable of producing 4,500 l/d of crude oil from 6 t/d of plastic waste. Many garbage-collecting groups are reported to have shown interest in joining the programme. PTT senior executive vice-president Mr. Chaiwat Choorit said that the research centre of PTT would assist with the research. He said that he project is attractive since half of the crude oil could be turned into diesel, 20 per cent into petrol and 30 per cent into bunker oil.


Pollution control efforts in China

As part of its efforts to protect the marine environment from land-based pollution, China has prioritized the control of industrial pollution. It has implemented standard controls over industrial pollution sources, initiated a comprehensive pollution discharge registration drive, set up a dynamic registration database, set up an on-line monitoring system of major pollution sources, bolstered supervision and checks of main pollution sources, and broadened the pollution discharge permit system. The current focus is on formulating the environmental bearing capacity of major watersheds and various types of environmental functional zones in cities.

By sticking to the principle of laying equal emphasis on both pollution control and ecological conservation, various efforts have been made to reduce the environmental impact of agricultural activities in different localities. Rational use of pesticides and fertilizers has been strengthened in rural areas. Treatment and optimum use of waste produced by livestock and poultry breeding has been speeded up. Several measures have also been implemented to control pollution from ports and vessels. All the ports in coastal areas need to have recovery equipment for petroleum and wastewater collection.

Discharge of oil-containing wastewater is prohibited in harbours. In addition, strict measures have been enforced to control pollution from the exploitation of mineral resources in coastal regions.


Anti-POP plan in the Philippines

The Department of Environment and Natural Resources (DENR) of the Philippines has launched a national implementation plan (NIP) aimed at reducing and eliminating persistent organic pollutants (POPs). According to DENR Secretary Mr. Angelo Reyes, NIP serves as a guide to reduce and eliminate POPs. The launch of NIP has placed the Philippines among the first countries to prepare a national implementation plan in compliance with the Stockholm Convention. Among the measures planned under NIP are:
  • Outline the national objectives for the reduction and elimination of POPs production, importation, use and releases;
  • Design programmes to remove barriers to implementation of NIP;
  • Plan programmes for information exchange, public education, communication and awareness raising;
  • Enhance capacity through capability building;
  • Identify possible areas of exemption and prepare a report to justify it to the convention; and
  • Outline the needs for transfer of technology and know-how and / or enhanced use and development of indigenous knowledge and alternatives and the estimated cost of the needed investments.


Korea revises waste disposal law

The Ministry of Environment in the Republic of Korea has notified its decision to streamline criteria on the disposal of designated wastes by revising the implementation decree and accompanying rules of the waste material disposal law. The draft revision bill calls for waste plastic and waste synthetic rubber to be dropped from the list of designated wastes (substances that are harmful to humans or contaminate the environment). It has also excluded waste paint unmixed with benzene and other organic solvents from the list. As such, these wastes have to be reported to the government as regards the times of collection, transportation, storage and disposal in accordance with the law.

The draft also stipulates the education period that the dischargers of work site wastes and personnel in charge of wastes in small waste disposal facilities have to undergo. To expedite the reutilization of waste materials, the draft allows rice husk and rice bran which are mostly recyclable to be recycled without being reported to the authorities. It stipulates that scrap iron, rubber and waste lubricants be classified separately so that waste oil filters could be made suitable for reuse. The Ministrys estimates project substantial economic benefits arising from the relaxed controls.


Pollution is a health hazard in Viet Nam

The head of Viet Nams Ministry of Natural Resources & Environments environmental pollution monitoring section, Dr. Tran The Loan, says that 101 of 134 industrial and export-processing zones nationwide have not invested effectively in waste treatment. It is estimated that 15 million tonnes of solid wastes are annually released into the environment, of which 150,000 t are toxic chemicals. This figure is predicted to rise by 24-30 per cent by 2010 and does not include dust, sulphur dioxide, nitrogen dioxide and carbon monoxide, which are usually 20-435 times above safety levels at construction material manufacturing factories, 5-125 times at coal and metal plants, and 10-15 times at shipbuilding or mechanical factories.

Residents of areas such as Ho Chi Minh City, Hai Phong, Hanoi and Da Nang face the threat posed by the extremely dangerous wastes from these factories. Dr. Tran Dac Phu, vice-director of the Health Ministrys Preventive Health Department said that the incidence of diseases in polluted areas is increasing.



Separation and recovery of oil and plastic

Itec Environmental Group, the United States, is offering ECO2 system for recycling motor oil bottles and every other type of consumer plastics. The ECO2 system is based on a process developed and patented by the Kansas City Plant, which employs liquid and supercritical carbon dioxide. This process, licensed to Itec, was initially developed for blasting oil residues off empty plastic motor oil bottles, thereby enabling reuse of the residual oil and clean plastic.

ECO2 has proven to be superior to conventional plastic recycling processes. As the liquid carbon dioxide and special solvent are both reusable, no waste streams are created, unlike water-wash systems that collectively discharge billions of litres of wastewater into the environment each year. ECO2 generates FDA-approved clean plastics, which are in high demand in the plastics industry for uses such as in produce packaging.

Since this system has no adverse environmental impact, special waste permits are not essential, which in turn makes it less costly to start up. Overall, the operational costs of ECO2 system is 30 per cent less than traditional water-wash recycling systems, providing for higher profit margins. Furthermore, it can fully remove glue, labels, oil and dirt from plastic containers. The process even eliminates odours, making the plastic cleaner, more marketable than plastics cleaned with water-wash.

Contact: Itec Environmental Group Inc., 5300 Claus Road, P.O. Box 760, Riverbank, CA 95367, United States of America. Tel: +1 (209) 848 3900; Fax: +1 (209) 863 9839;



Dual-chamber granule grinder

Progressive Crumb, Australia, has introduced a dual-chamber grinder for recycling tyres. Utilizing brand new grinding and motor/torque technology, the granule grinder uses no more power than the old standard single-chamber grinder. Among the principal advantages of the machine is its ability to reduce up to 2 t/h of tyres to -30 mesh. The grinder utilizes a single 380/415/440/480 V, 50/60 Hz, 132 kW six-pole motor instead of three four-pole motors, thus reducing electrical power consumption in the plant by a minimum of 400 A. Further, the unit requires less space than the earlier models and the amount of cabling required for plant set-up is also less.

Contact: Progressive Crumb, 25 Baronga Road, Avoca Beach, New South Wales, Australia. Tel: + 61 (2) 43 81 0166; Fax: +61 (2) 43 81 0377




FRP recycling using subcritical water hydrolysis

In Japan, Matsushita Electric Works Ltd. is reported to have successfully developed a technology based on subcritical water for hydrolysing and regenerating fibre-reinforced plastic (FRP) resin, which has been very difficult to recycle. Styrene-fumaric acid copolymer, a functional polymer recovered from this process using a unique method, holds promise as a high-value-added polymer material in a wide spectrum of applications. The value of this functional polymer has been evaluated to be about 5-10 times higher than the market price of styrene and organic acid, which are original components of the FRP resin. Furthermore, while it is common for recycled chemical materials to exhibit lower performance levels, the new material exceeded the value of the original raw materials. Matsushita plans to continue its research for commercialization of this high-value-added functional polymer.


Recycling plastics recovered from electrical wastes

A comparative study undertaken by the Waste and Resources Action Programme (WRAP), a non-profit organization based in the United Kingdom, has found the patented CreaSolv process to be the best technology for recycling waste plastics from electrical and electronic goods. The process, developed by the Fraunhofer Institute for Process Engineering and Packaging IVV in Germany, together with CreaCycle GmbH, achieves a recycling rate of 95 per cent.

Electrical and electronic waste contains a varied mixture of plastics, which makes it difficult to recycle. Moreover, the plastics tend to be contaminated with heavy metals or brominated flame-retardants. The technologies in use so far have not been able to separate these toxins. Fillers, stabilizers and pigments are also present, posing problems at the time of recycling. The pathbreaking Fraunhofer technique allows reuse of even plastics containing highly toxic substances and pollutants. Additionally, the properties of plastics thus recovered are as good as new ones in all relevant areas.

Appliances are broken up in a giant mill and then the metals and circuit boards are separated to obtain a mixture of shredded plastics, fibres, wood and foam. Recyclable polymers are removed from the scrap mixture with an environment-friendly solvent. Insoluble contaminants and hazardous substances are separated, as there is a market even for these in the chemical industry.


Scrap tyres used to filter wastewater

Dr. Yuefeng Xie, an associate professor of environmental engineering at Penn State Harrisburg, the United States, has developed a method that uses crumb rubber to filter wastewater. According to Dr. Xie, crumb rubber derived from waste tyres can be used as an efficient filter media to treat wastewater.

Traditional wastewater filtration with gravity downflow granular filters commonly employs sand or anthracite as the filter medium. A major problem with these filters is that upon back-washing, the larger particles settle at a greater rate than the smaller ones. This causes the top of the filter bed to hold the smallest particles and the bottom to hold the largest, with the small/medium particles at the top filter layer tending to clog quickly. Dr. Xie proved that in the case of crumb rubber, the larger solids reside at the top layer of the filter while the smaller solids rest at a lower level, thereby minimizing the clogging problem.

Studies have shown that the crumb rubber filter is much more cost-effective than conventional sand or anthracite filters. Moreover, because crumb rubber filters have much higher water filtration rates and lighter weight in comparison with sand or anthracite, they may even be used in mobile treatment units that are employed in disaster relief operations.


New catalytic plastics recycling technology

Tokarz, Poland, has developed a new technology that converts plastic wastes into liquid fuels through depolymerization. T-technology can even convert the wastes into an oil fraction and operates without the need for high pressure. T-technology is being mooted as an alternative to plastic waste granulation or incineration, as the process converts the material back into its original form a mixture of gaseous hydrocarbons with chain lengths from C1 to C4 which can be further processed in refineries or used as a fuel oil fraction for heating houses.

Tokarzs processing line accepts up to 25 per cent of plastic waste besides PE and PP within the total mass of the waste material and can handle mixed and highly contaminated plastics of variable quality. About 360-450 t of plastic waste can be processed monthly using the Tokarz line with two modules. Each module needs only the energy generated by 20 l/h of fuel oil and 30 kWh of electricity.


New method for greener plastics

In the United States, scientists at Carnegie Mellon Universitys Centre for Macromolecular Engineering recently announced the discovery of an improved version of a process commonly used to make plastics. Besides making plastic manufacturing faster and cheaper, the new process could also help reduce the amount of industrial waste produced.

About half of the everyday plastics including styrofoam and plexiglass is produced using radical polymerization. The scientists worked with a slightly different version of this reaction, the atom transfer radical polymerization, that allows precise control over polymer structure. It is possible to add functionality to the polymer in a designed fashion by adding a few monomers to a polymer chain at a time. The research team found that adding simple chemical additives such as sugars and vitamin C could reduce the amount of an essential copper catalyst by 500-fold, eliminating the long and expensive task of removing excess catalyst in the product. It also minimizes the amount of toxic waste produced in the manufacturing process, lessening its impact on the environment.



Cost-effective biomedical waste processing system

Biomedical Technology Solutions Inc., the United States, is offering the only cost-effective system approved for on-site treatment and disposal of both sharps and red bag waste for low- to medium-volume medical waste generators. About the size of a desktop copier, Demolizer II is a compact system that can be used in doctors offices, dentists offices, nursing homes, veterinary clinics and other healthcare facilities. It provides a safer, simpler and low-cost solution for treating medical wastes.

The external surfaces of Demolizer II do not get hot and the unit does not emit any odour. After treatment, the sharps and red bag waste are sterile while the syringes are destroyed by melting. Demolizer II is a reconfigured, improved version of the original Demolizer biomedical waste processing system, which was developed 13 years ago.


Gasification system

United Recycling Technology Inc., the United States, offers a gasification system for the treatment and disposal of medical wastes. The pyrolytic reactor heats up medical wastes to temperatures exceeding 704C by burning a mixture of natural gas and the volatile organics off-gas produced by the heated waste itself. A gas burner indirectly heats the waste in the process chamber, producing a carbon char that is much reduced in weight and volume. Entrained particulate carbon in the gas stream is captured, which, along with the carbon treatment residue from the reaction chamber, may be either recycled as carbon black or disposed as solid waste.

Contact: Mr. Aram Sarkissan, United Recycling Technology Inc., 6230, May Field Avenue, La Crescenta, California, CA 91213, United States of America. Tel: +1 (818) 9572 821.

Website: www.

Solar ovens sterilize bio-infectious wastes

In Costa Rica, Universidad Nacional and Hospital San Vicente de Paul have jointly launched a project that is promoting the use of solar ovens to attain the temperature necessary for sterilizing biological wastes at hospitals. The simple and low-cost pro-cess sterilizes on-site, thereby eliminating the hazard of transporting these wastes, while allowing hospitals to dispose of the waste as common biological inert waste.
Furthermore, the solar oven entails low-cost maintenance, is very durable (lasting approximately 30 years) and uses the energy provided freely and abundantly by nature. Capable of achieving temperatures of 180-200C, the oven can help poor and remote communities reap the benefits of improved environmental and human health as toxic compounds such as furans, diphenyls and dioxins that result from combustion processes are not produced by this technology.

Contact: Dr. Edio Ricci, Laboratorio Secado Solar, Universidad Nacional, Apartado Postal 86-3000, Heredia, Costa Rica Tel: + 506 262 3174, 277 34 82



Biomedical waste reactor and sterilizer

Safe Alternatives Corp., the United States, offers a patented reactor/sterilizer for disinfecting contaminated medical and biological wastes. The system employs at least one shredder/grinder to reduce the size of the solid waste to be disinfected. A freezer or ice-maker is used to trap disinfecting concentrations of ozone from an ozone generator in ice, which is added to the waste prior to the shredding or grinding step. The biological and/or medical waste is treated with ozone-containing ice by admixing the ice with the waste and allowing the ice to melt, thereby releasing ozone and exposing the waste to effective concentrations of ozone to achieve disinfection.

In preferred embodiments, the instant biomedical reactor/sterilizer has both a coarse shredder/grinder as well as a fine shredder/grinder. The shredder/grinder generates a slush/slurry of ice-containing ozone and waste. As the temperature of the slurry increases, the ice melts and the entrapped ozone gets released in a sustained manner, mixing with and disinfecting the waste.


Rotoclave for treating red bag wastes

Hopkins hospital, the United States, is utilizing a rotoclave to dispose of infectious wastes in eco-friendly manner. In this system, steam of high pressure is used to sterilize wastes in a rotating drum.

After the waste is loaded into the rotoclave, steam heated to about 135C is injected into the waste, as the drum begins to rotate. The combined effect of steam treatment and agitation breaks down and sterilizes the waste. Each load of waste is subjected to 30 minutes of treatment. The treated waste, with its volume about 80 per cent less than the original, appears like mulch and is moved to a landfill.



Recycling fluorescent tubes

In Canada, researchers at Direct Energy and the University of Calagary have found a way to eliminate mercury present in discarded fluorescent light bulbs from getting into landfills. A bulb-eating machine developed by them not only crushes the glass from the bulbs, but also removes mercury, a neurotoxin, from the fluorescents.
The system works by grinding the spent fluorescent tubes, filtering out the bulbs mercury and contaminated air, and storing the glass shards for disposal. The captured mercury, about 0.15 mg in each 4 ft fluorescent tube, is sent to a designated hazardous waste facility.

Furthermore, the glass volume from 1,200 fluorescent lamps is reduced into a single 182 l barrel for disposal, which cuts the transportation costs because of a lower number of truck loads needed for disposal. The only drawback to this solution is the milky-coloured crushed glass, which cannot be mixed with clear glass, cannot be recycled. Mr. Hans Lu, the environmental management coordinator at the University of Ca-lagary, said that they are on the lookout for a company that would accept the glass for recycling.


Getting value from waste electronics

Canadas Global Electric Electronic Processing Inc. (GEEP) transforms obsolete electronics into useable raw materials, such as metals, glass and plastic. The primary step of the labour-intensive recycling process is manual stripping of the electronic product to separate circuit boards, glass screens, plastic shells, wiring and other components. Machines are then used to grind and shred the pieces. Glass, copper, silver and gold are sold as raw materials and returned to the manufacturing cycle, as are most of the plastics.

The companys latest acquisition is a machine that will turn plastic scrap into diesel fuel to drive generators that power the other machines used in the recycling process. The waste-to-fuel process is reported to be efficient and works at low pressures, and temperatures of around 250-350C. As a result, less than 1 per cent of all the materials carted to GEEP will end up in a landfill.


Eco-friendly gold recovery process

Haber Inc., the United States, has successfully employed its Haber Gold Process (HGP), a proprietary technology for the environmentally friendly processing of electronic scrap and precious metal-bearing ores, at its Massachusetts gold processing facility. The first bulk run consisted of 31.75 kg of Ghanaian concentrate that was processed in a Haber mobile unit, designed for use in remote areas.

The process consisted of loading the unit with the gold concentrate, adding HGP lixiviant, rotating the drum for approximately 3 h, then vertically articulating the drum and decanting by gravity. This was followed by pumping the gold solution into an open vessel. The tailing was then rinsed, decanted and pumped into the vessel. The HGP recovery solution was then added and stirred for approximately 2 min, which immediately precipitated fine particles of gold. The solution was then passed through a filter where the gold metal was deposited on the filter pad. The gold produced by the HGP process weighed about 7.1 g. Assays are being performed on the concentrate, before and after processing, to determine the recovery efficiency. The mobile unit reportedly performed well and the operational information derived from the testing confirmed all of the chemical parameters established through earlier laboratory work.

Contact: Peter R. DAngelo, Haber Inc., 58 Medford Street, Arlington, MA 02474, United States of America. Tel: +1 (781) 6432 727; Fax: +1 (781) 6436 164;




PBDEs and PCBs in gadgets and homes

A recent research report has stated that older computers and air inside older automobiles can be significant sources of toxic polybrominated diphenyl ether (PBDE) flame retardants, while newer homes can harbour unidentified sources of PCBs.

According to Mr. Stuart Harrad, an environmental chemist at the University of Birmingham in the United Kingdom and the lead author of the study, older computers are a significant source of the lighter PBDEs, considered as more toxic than the heavier PBDEs. Mr. Harrad and co-author Mr. Sadegh Hazrati came across the new data while monitoring PBDE levels in an office where a computer purchased in 1998 was replaced with a newer model. After the new computer was put in place, total PBDE concentrations in the office air dropped by more than 75 per cent, from 431 pg/m3 to below 95 pg/m3.

The sharp drop recorded is particularly noteworthy, as the researchers did not measure levels of congeners the heavier PBDE compounds associated with the Deca formulation of PBDEs used in electronic products. In recent months, other researchers have also reported that both older computers and television sets can be significant sources of the lightweight PBDEs associated with the commercial Penta formulation, which was banned in Europe and abandoned in the United States since 2004.


Catalyst to remove dioxins

SK Corporation of the Republic of Korea has obtained a United States patent for a catalyst that helps remove dioxins. The catalyst is made by recycling a spent catalyst discharged from an oil refinerys hydro-desulphurization process. The spent catalyst comprises gamma alumina support, with high contents of vanadium impregnated over a large surface area. It is mixed with tungsten-impregnated titania, to prepare a catalyst comprising suitable metal components. The catalyst features excellent dioxin removal and low preparation cost because of recycling the spent catalyst. The preparation of the new catalyst consists of the following steps:
  • Pretreating the spent catalyst on an alumina support by thermally treatment followed by washing with water. The spent catalyst consists of 5-30 weight percentage of vanadium, with molybdenum, nickel, sulphur, iron, silicon and phosphorous making up the rest.
  • Homogenizing the treated spent catalyst with tungsten-impregnated titania by mixing the two with addition of water and acid.
  • Dehydrating the mixture to remove excess moisture and active metal components.
  • Drying the dehydrated mixture, followed by grinding the dried mix.
  • Forming a catalyst body either by extruding the grinded mixture or by coating the grinded mixture to a structure, followed by drying and then calcining the dried structure.


Control of dioxin emissions from incineration

Teller Environmental Systems Inc., the United States, has developed a method to control dioxin emissions from incineration processes. In this patented technique, the combustion flue gas stream containing dioxins, some of which are in the vapour phase, is cooled to between 100C and 110C. With this temperature-reducing step, about 98-99 per cent of the dioxins originally present in the vapour phase appear as either suspended particulates or deposits on other suspended particulates. These particulates are subsequently captured and thermally destroyed.

Cooling is accomplished by water sprays, and in a particularly preferred embodiment the gas is cooled in an upflow quench reactor. The suspended particulates, in the size range of 0.05-1.0 m, are captured by target particulates in the 3-20 m range to form larger particulates, and may then be captured by conventional devices such as baghouses, etc. A key feature of this method is in determining the hitherto unknown vapour pressure data of the dioxins.


Phytoremediation for soil decontamination

Researchers at the University of Waterloo, Canada, have investigated a multi-process phytoremediation system for removing persistent organic pollutants and metals from contaminated soils. Among the key benefits of phytoremediation are that it is low cost; green; solar-powered and suitable for large, medium and small sites.
To improve the remediation, multiple complementary techniques that target different aspects of persistent organic pollutants (POPs) and metal removal have been combined. The enhanced multi-process system shows improved and accelerated remediation kinetics, leading to more rapid and complete removal of POPs and metals from soil. More importantly, the multi-process system not only removes POPs from the soil, but generally results in their metabolism to non-toxic molecules. It also brings metals into biomass that can be removed from the soil. The system for decontaminating soil involves the following components:
  • Land farming: For aeration, physical volatilization and photochemical degradation;
  • Microbial remediation: Bacteria that start the degradation of organic contaminants; and
  • Phytoremediation (plant growth) with plant growth promoting Rhizobacteria (PGPR): Rapid growth of plants, including roots, for effective partitioning of POPs and metals out of the soil.

A key feature of this system is that the complementary processes build on each other so that remediation is rapidly initiated and sustained throughout the growth season. The PGPR prevents production of stress ethylene and synthesize auxin. This promotes vigorous root growth even under stress conditions. Based on successful results from trials, the team predicts that sites heavily contaminated with POPs and/or metals can be remediated in 2-5 years. In addition, the cost of such a clean-up will be a fraction of that of other remediation practices.

Contact: Mr. Bruce M. Greenberg, Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1, Canada. Fax: +1 (519) 7460 614




Degradation of PCBs

Researchers at the Chinese University of Hong Kong have reportedly employed ultraviolet-catalysed photolysis to degrade polychlorinated biphenyls (PCBs). Photolysis of five PCB congeners PCB 28, PCB 52, PCB 101, PCB 153 and PCB 180 individually and in combination were carried out using 2-propanol, methanol and ethanol as solvents. It was observed that, in general, the disappearance of the parent congener increased with UV intensity.

Results of photolysis of the PCB mixture showed that PCB 52 was formed and accumulated after 4 h of photolysis. Addition of sodium hydroxide increased the photolysis rate of the PCB mixture. Complete removal of the PCB in mixture can be achieved within 90 minutes under optimum conditions. Gas chromatography-mass spectrometry was used to determine the intermediates of the photolysis of PCBs under optimized conditions.

For the PCB congeners and mixture studied, the major photolytic intermediates were less chlorinated congeners, and biphenyl was the main product with minor amounts of hydroxylated PCBs, and methylated, dimethylated and ethylated biphenyls. A prolonged photolysis could further degrade biphenyls.


Thermochemical destruction of PCBs in waste insulating oil

In the Republic of Korea, scientists have studied the feasibility of thermochemical destruction of polychlorinated biphenyls (PCBs) present in waste insulating oil using a batch reactor and two different (vertical and horizontal) types of continuous reactors. A simple batch reactor was first designed and built to examine the applicability of thermo-chemical destruction of PCBs. It was evidenced from the batch test results that the destruction of PCBs in the insulating oil (40 per cent PCBs, w/w) was accomplished via abiotic dechlorination and mineralization of PCBs with quicklime at 600C under nitrogen environment. PCB destruction efficiencies of about 99.95 per cent were obtained. The reaction was exothermic, by which the reactor temperature suddenly increased up to 750C at the incipient 30 min of the experiment. Two major end products, calcium chloride and carbon, were identified.

For a practical purpose, two continuous reactors were developed and tested. The observed continuous test results demonstrate that over 99.99 per cent of PCB destruction efficiency has been achieved when excess quicklime was used. Specifically, the horizontal continuous reactor was suitable as regards the ease of solid transfer, which is essential for complete destruction of PCBs and for full-scale applications.



Electrochemical processing

AMT Tech Co. Ltd., the Republic of Korea, has developed an electrochemical system for industrial wastewater processing. In this system, nitrogen is separated from wastewater using electrolysis and then discharged into air while the organic constituents are eliminated by the indirect oxidation method.

By using an insoluble catalyst electrode as the anode and a selective catalyst electrode as the cathode, the electrochemical apparatus eliminates nitrogen, cyanogens and COD by converting them into nitrogen, carbon dioxide, water, etc. by means of electrochemical oxidation and reduction reactions. As the oxidation and reduction reactions can be generated simultaneously, it is possible to achieve the high efficiency of the electrochemical reaction of the oxidation-reduction reactions. The oxidation-reduction reactions can occur simultaneously at one electrode as both positive and negative are simultaneously formed at the front and back of the electrode. Nitrates are converted into ammonia by reduction at the cathode and the ammonia then converted into nitrogen by oxidation at the anode, then released into air.

Contact: AMT Tech Co. Ltd., Republic of Korea. Tel: +82 (32) 6770800; Fax: +82 (32) 6798744



Low-energy wastewater treatment

Researchers at the Fraunhofer IGB, Germany, have developed a rotating disk filter that efficiently controls the thickness of the particle layer formed during filtration by rotation of its filter disks. Hereby, the filter opens up new applications for membrane filtration such as industrial and municipal wastewater treatment.

The rotating disk filter is a dynamic membrane filter comprising a cylindrical housing, in which a stack of membrane disks is attached to a rotating hollow shaft. By applying a slight over-pressure of 0.2-1.5 bar, the filtrate passes through the separation layer on the membrane disk outside and is drawn off through or along the hollow shaft. The particle layer on the membranes is controlled by means of the centrifugal force field created. This enables the laminar particle layer, adhering on the filter disk and thereby rotating together with the disks, to flow off. The particle layer is thus continuously renewed. The benefits of this process are:
  • High specific filtrate fluxes;
  • Robust against blockages and clogging;
  • Low energy consumption;
  • Long operating times; and
  • Easy to clean.

Contact: Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB, Nobelstrasse 12, 70569 Stuttgart, Germany. Tel: +49 (711) 970-00; Fax: +49 (711) 9704 200



Total removal of contaminants

UVPS Environmental Solutions Ltd., the United Kingdom, has developed a system capable of removing 100 per cent of contaminants from waste discharges such as industrial wastewaters or water produced from an oil rig. The technology uses an activated catalyst in the presence of UV light to remove and destroy a wide range of dissolved chemicals, pesticides, micro-organisms and other toxins, which have so far been difficult or prohibitively expensive to treat. The patented technology can provide solutions for the destruction of contaminants such as hydrocarbons, volatile organic compounds, nitrogen oxides and waste chemicals. The UVPS system is 100 per cent effective and has applications in many industries, such as oil and gas, food and beverage, water treatment, and healthcare.


Treating wastewater containing RDX and perchlorate

In the United States, researchers at the University of Delaware and the Army Engineering Research and Development Centre have investigated the use of zero-valent iron for treating wastewaters that contain RDX and perchlorate at both elevated and moderately elevated temperatures, with chemical addition through batch and column experiments. RDX in the wastewater was fully removed in an iron column after 6.4 min. Increasing the temperature to 75C decreased the required retention time to 2.1 minutes for complete RDX removal. Perchlorate in the wastewater was fully removed by iron added at an elevated temperature of 150C in batch reactors in 6 hours without pH control. Significant reduction of perchlorate by zero-valent iron was also achieved at a more moderate temperature (75C) through the use of a 0.2 M acetate buffer.

Based on the evaluation results, the researchers have proposed two new processes for treating wastewaters containing RDX and perchlorate. The first is a temperature- and pressure-controlled batch iron reactor, with subsequent oxidation in an industrial wastewater treatment plant. The second method involves reduction by consecutive iron columns with heating and acid addition capabilities, followed by oxidation.

Contact: Mr. S. Y. Oh/Mr. D. K. Cha/Mr. P. C. Chiu, Department of Civil & Environmental Engineering, University of Delaware, DE 19716, United States of America.



Nanotech membrane for water desalination

A new reverse osmosis (RO) membrane developed by researchers at the UCLA Henry Samuel School of Engineering and Applied Science is reported to reduce the cost of sea-water desalination and wastewater reclamation. The membrane, developed by a team led by Prof. Eric Hoek, uses a unique cross-linked matrix of polymers and engineered nanoparticles designed to draw in water ions but repel nearly all contaminants. These membranes have a nano-structure to create molecular tunnels through which water flows more easily than contaminants.

Unlike the existing commercial RO membranes, which just filter water through a dense polymer film, the new membrane contains specially synthesized nanoparticles dispersed throughout the polymer, known as a nanocomposite material. Prof. Hoek stated that the nanoparticles are designed to attract water and are highly porous, soaking up water like a sponge while repelling dissolved salts and other impurities. The water-loving nanoparticles embedded in the membrane also repel organics and bacteria, which tend to clog up conventional membranes.


TDS removal from tannery wastewater

Researchers from the Council of Scientific and Industrial Research, India, have developed an aerobic process for removing total dissolved solids (TDS) from tannery wastewater. Preliminary experiments have shown that a bacterial cocktail reduced TDS levels of tannery wastewater by approximately 16 per cent over 15 days. Later attempts to reduce the retention time resulted in about 11 per cent reduction in the TDS levels of electro-floated tannery effluent and approximately 8 per cent reduction in the raw effluent within a period of 48 hours by one bacterial isolate. The aerobic biological process has been awarded a patent in the United States.


Removal of heavy metals from effluents

Researchers at Tianjin University, China, have employed magnetotactic bacteria (MTB) technology for removal of heavy metals from wastewater. Traditional methods of removal such as chemical precipitation, solvent extraction and ion exchange become less effective at metal ion concentrations of 100 mg/l, which involve high capital and operational costs as well as the generation of secondary wastes. Under such circumstances, application of MTB becomes a feasible alternative. MTB can synthesize unique intracellular structures called magnetosomes by uptaking iron (FeIII) ions from culture medium. This feature enables them to navigate along the geomagnetic or applied magnetic field lines.

The team studied the effect of performance parameters such as initial pH, temperature, biomass concentration and adsorption duration in the biosorption of copper (Cu II) ions by MTB. Experimental results show that the pH value and concentration of biomass exert important influence on the sorption process, and the optimum scopes are 1~9 and 2.0~5.0 g/l, respectively. The magnetic field-magnetotactic bacteria technology promises to have great application potential in the area of wastewater treatment, with several advantages such as high efficiency, low power, low cost, no secondary pollution, etc.


Resource recovery

Japanese researchers have developed a new treatment method for wastewater containing various harmful ions such as arsenite, arsenate, boric, fluoride and fluoroboric ions through hydrothermal mineralization using calcium hydroxide as a mineralizer. Total recovery of the ions is attained irrespective of the initial concentration and oxidation number of these harmful ion species in wastewater. Though the oxo-anions are of high toxicity to human health and the environment, they are an important resource for plating or advanced material manufacturing industries, from which the wastewater containing these oxo-anions is generated.

Contact: Mr. T. Itakura, Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Japan; Or Mr. R. Sasai/Mr .H. Itoh, EcoTopia Science Institute, Nagoya University, Japan.



Degradation of pollutants in groundwater

Researchers at the Fraunhofer Institute for Interfacial Engineering and Biotechnology, Germany, have developed a two-stage system for the treatment of soil and groundwater contaminants tetrachloroethene (PCE) and trichloroethene (TCE). PCE and TCE, owing to their widespread industrial use, are priority pollutants commonly present in soil and groundwater. Under anaerobic conditions, these chemicals can be rapidly transformed to cis-1,2-dichloroethene (cDCE) by reductive dehalogenation. Anaerobic transformation of cDCE to vinyl chloride and ethene is significantly slower. However, under aerobic conditions, cDCE can be co-metabolized at much faster rates.

In the economic two-stage process, the pollutants are reductively dehalogenated under strict anaerobic conditions in the first stage. Under these conditions cDCE accumulates and is co-metabolically mineralized in the aerobic stage.

Contact: Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB, Nobelstrasse 12, 70569 Stuttgart, Germany. Tel: +49 (711) 970-00; Fax: +49 (711) 9704 200



Bacteria lunch on soil pollutants

A cross-disciplinary team of biologists, chemists, environmental sci-entists and ecologists from Canada and the United States, led by Ms. Anne Vonderheide at the University of Cincinnati, has demonstrated that microbes can clean up polybrominated diphenyl ethers (PBDEs). These soil-dwelling bacteria are capable of rapidly breaking down the organic contaminants. The researchers showed that mixed bacterial cultures extracted from contaminated soils can use PBDEs as their sole nutrient source.

Ms. Vonderheide said that almost total loss of the parent compounds occurred within a few minutes. The speed of the microbial degradation implied that only one of the expected degradation products could be found using a combination of atomic and molecular spectrometry. Ac-cording to Ms. Vonderheide, further studies of the metabolic pathways would challenge even the most established and reliable instrumental techniques. The experiments were performed in water. In a real environment, Ms. Vonderheide stated, the bacteria would be interacting with different carbon sources, organisms and many other factors that could impact their ability for PDBE degradation. More work is needed to evaluate the process in natural settings.


Cleaning soil hydrocarbons

Caltex Pacific Indonesia (CPI) has employed bioremediation techniques to reduce the impact of crude hydrocarbon contamination at the Minas site in Indonesia. Land farming was selected owing to its cost-effectiveness, compliance with the governments regulatory requirements and clean-up successes at numerous sites. Excavated soil is spread and processed (land farmed) by tilling, irrigated, fertilized and monitored. When the total petroleum hydrocarbon (TPH) level in the soil meets acceptable regulatory concentrations, the soil is removed from the facility and redistributed in predetermined areas based on specific criteria. The average cycle time of the process is five months.

In CPIs Minas field alone, five bioremediation sites operate continuously, processing about 45,000 m3 of soil per year, with a cumulative treatment of about 150,000 m3 of soil from 1997 to 2005. Process optimization has led to the development of more land farming sites, use of different equipment and alterations in operating methods. New innovations are being tested to in-crease efficiency, reduce overall cycle time and increase capacity.


Remediation of petroleum spill site

In Taiwan, researchers have conducted microcosm experiments at a site where methyl tert-butyl ether (MTBE) and benzene, toluene, ethylbenzene and xylenes (BTEX) have been detected in the groundwater. The trials evaluated the feasibility of using indigenous micro-organisms to biodegrade MTBE under aerobic, co-metabolic, methanogenic and iron-reducing conditions. Results indicate that the intrinsic biodegradation of MTBE and BTEX causes a decrease in their concentrations. The indigenous micro-organisms are able to biodegrade MTBE in aerobic conditions using MTBE as the sole primary substrate. Tri-butyl alcohol, the biodegradation by-product detected, can also be biodegraded by the indigenous micro-organisms.

Results show that the addition of BTEX at low levels could also enhance MTBE removal; however, no MTBE removal was noticed in iron-reducing and methanogenic microcosms, possibly due to the effects of low levels of dissolved oxygen within the plume. The low levels of iron reducers and methanogens in the aquifer also indicate that iron reduction and methanogenesis are not the dominant biodegradation patterns in the contaminant plume. Though results suggest that in situ or on-site aerobic bioremediation using indigenous micro-organisms would be a feasible technology to clean up this MTBE-contaminated site, additional laboratory evaluation is required to identify appropriate substrates and oxidation-reduction conditions to enhance the biodegradation of MTBE.


Styrene degradation

At the Fraunhofer Institute for Interfacial Engineering and Biotechnology, Germany, researchers have studied the biological degradation of styrene using a trickle-bed bioreactor. The trickle-bed bioreactor contained a polyamide textile filter bed (13.6 l) for immobilizing micro-organisms. Air containing styrene was passed upwards through the system. A counter-current of liquid from a circuit trickled on to the filter bed. This provided the bacteria with mineral nutrient. The feed quantity depended on ammonium consumption. Temperature was maintained at 25C while the pH was between 7.0 and 7.4.

The trickle-bed filter was inoculated with a mixed culture of three styrene-metabolizing bacteria Pseudomonas putida VLB 120, Rhodococcus sp. ETB 2 and a strain VLB 150 of unknown taxonomy. The degradation performance of the biofilter was studied for various volume flow rates of input gas (0.6-1.8 m3/h) and styrene concentrations (50-1,050 mg/m3). Very high elimination rates were noted in phases of operation with exponential bacterial growth. No substrate inhibition occurred at the filter loadings studied.

Contact: Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB, Nobelstrasse 12, 70569 Stuttgart, Germany. Tel: +49 (711) 970-00; Fax: +49 (711) 9704 200



New bioremediation technology

ARS Technologies Inc., the United States, is a leading expert in subsurface atomized injection involving the injection of a bioinoculum, engineered micro-organisms, oxygen releasing compound, lactate and sugars, and/or nutrient solution that enhance or promote bioremediation efforts for site clean-up. In the patented liquid atomization injection process, a stream of bioinoculum fed into the injection gas stream is atomized and penetrates the formation surrounding the injection point. Advantages of applying the substrate in this manner include:
  • More uniform distribution within the subsurface;
  • Large radii of injection influence;
  • Reduction of bio-fouling locally around the injection wells; and
  • Higher volume of substrate that can be delivered into the subsurface as the silt/clay layers existing within the formation will become fractured.

ARS atomized bioinjection technique, coupled with Pneumatic Fracturing, may also enhance greater groundwater flow in the area affected, resulting in the ability to create more favourable growth conditions through the injection of nutrients and biosubstrates.

Typical injection radii of influence ranges up to 25 feet in unconsolidated material and 45 feet in consolidated material.

Contact: ARS Technologies Inc., 98, North Ward Street, New Brunswick, New Jersey, NJ 08901, United States of America. Tel: +1 (732) 2966 620; Fax: +1 (732) 2966 625;



Microbial cocktail to clean up hydro- carbon pollutants

BioPetroClean (BPC), Israel, offers proprietary technology to efficiently remove all toxic and emulsified hydrocarbons. BPC technology uses a bacterial cocktail, a mixture of naturally occurring bacteria that feed on petroleum hydrocarbons in combination with a proprietary supplemental nutrient-mix and controlled oxygen and pH to ensure optimal biodegradation. The microbial mixture can be adjusted to work efficiently on different types of oil contamination, thus allowing the process to be tailored to address individual requirements. The versatile process from BPC can be easily adapted to meet various applications, including decontamination of wastewater, soil, and oil storage and transportation tanks.
The closed loop control system is completely modular and the remediation systems capacity can easily be expanded (without the need for duplicating the complete system) by modifying parameters and system modules. The BPC bioremediation system is also able to treat salt and fresh water in open or closed environments, including pools, beaches, lagoons or closed containers, while fully complying with environmental regulations.

Contact: BioPetroClean, Tel Aviv, Israel.




Low-emission diesel engine

Honda Motor Co. Ltd. has developed a next-generation diesel engine with exhaust gas emissions on par with a petrol engine. The new diesel engine, using a revolutionary catalytic converter, achieves reductions in nitrogen oxides (NOx) emissions to a level that complies with the stringent Tier II Bin 5 requirements of the United States EPA. The converter features the worlds first system that uses the reductive reaction of ammonia generated within the converter to detoxify NOx by turning it into harmless nitrogen (N2).

The new catalytic converter uses a two-layer structure one layer adsorbs NOx from the exhaust gas and converts a portion of it into ammonia, while the other layer adsorbs the resulting ammonia and uses it later in a reaction that converts the remaining NOx in the exhaust into N2.

Ammonia is a highly effective reagent for reducing NOx into N2 in an oxygen-rich, lean-burn atmosphere. This ability to generate and store ammonia within the catalytic converter has enabled Honda to create a compact, lightweight N2 reduction system for diesel engines. The system also features enhanced NOx reduction at 200-300C. Along with developing superior technology for cleaning exhaust gas, Honda plans to address other technical issues in developing clean diesel engines.


Low-temperature oxidation of CO

In the United States, researchers at Ohio State University have developed a low-temperature process for the oxidation of carbon monoxide (CO) using Co/ZnO2 catalyst. This process is intended to help in the production of hydrogen with 10 ppm or less of CO. The catalyst is capable of oxidizing CO to CO2, with very high selectivity.

Furthermore, this catalyst was able to obtain complete conversion of 600 ppm CO at room temperature in lean conditions at GHSV=20,000/h, and 100 per cent conversion of much higher CO concentrations (1.5 per cent) in lean conditions at a temperature as low as 135C. The catalyst has great potential to be used for CO removal from hydrogen streams, lean exhaust, and enclosed areas such as underground coal mines.

Contact: Ms. Catherine Wendelken, Technology Licensing & Commercialization, Ohio State University, 1960 Kenny Road, Columbus OH 43210 1063, United States of America. Tel: +1 (614) 2921 315; Fax: +1 (614) 2928 907



Removal of volatile organic pollutants

Mr. Kamalesh K. Sirkar, an eminent chemical engineering professor at the New Jersey Institute of Technology, the United States, was recently feted by the Research and Development Council of New Jersey with one of its highest awards. He was honoured for his patented process to remove volatile organic pollutants from waste gas streams produced by manufacturing processes before the toxic pollutants are released to the atmosphere. Mr. Sirkar holds the patent with Mr. Jyh-Yao Raphael Li, the co-inventor of the process and a post-doctoral fellow at the Institute.

The chemical engineers developed a method and apparatus for removing potentially toxic organic compounds from a multi-component gas and vapour mixture. Using the new method, up to 98 per cent of volatile organic pollutants can be captured and the treated gas safely let out. The method employs an air/waste gas stream flowing through the bores of hollow fibres as fine as human hair. Simultaneously, a vacuum pulls pollutants out through the membrane coating on the outer surface of the hollow fibres. The invention can be used in several industries, from printing plants to wastewater facilities.

Contact: Ms. Sheryl Weinstein, Office of Communications, New Jersey Institute of Technology, 440 Fenster Hall, University Heights, Newark, New Jersey 07102-1982, United States of America. Tel: +1 (973) 596 3436; Fax: +1 (973) 642 4555



NOx removal systems

Eaton Corp., the United States, has developed systems for removing nitrogen oxides (NOx) from exhaust streams. In the invention, after ad-sorption, a NOx adsorber is isolated from the main exhaust flow, and desorption induced by raising the temperature. The desorbed NOx is combined with a reductant and reduced over a catalyst. Preferably, the reductant is synthetic gas produced in an on-board reformer. The catalyst need never be exposed to the main exhaust flow an advantage for catalysts sensitive to water, oxygen or sulphur.

In another aspect of the invention, a recirculating flow can be induced through a NOx adsorber during the regeneration cycle. Recirculation can induce greater desorption at a given temperature, provide a source of heat for the adsorber and allow a higher conversion rate with a fixed amount of catalyst. A further aspect of the invention relates to vehicle-mounted adsorbers with provisions for heating.


Methanol from CO2

Researchers at the Korea Institute of Science and Technologys Nano-Tech Research Centre are developing a process to convert carbon dioxide (CO2) into methanol, in an effort to sequester the greenhouse gas from combustion processes. In the Camere process, CO2 reacts with hydrogen (H2) over a ZnAl2O4 catalyst at 600-700C and atmospheric pressure to form carbon monoxide (CO) and water, by means of a reverse water-gas-shift reaction. The product gas is dried to remove the water, before feeding a methanol synthesis reactor. There, CO combines with unreacted H2, over a CuO/ ZnO/ZrO2/Al2O3 catalyst at 250-300C and 50-80 atm pressure, to form methanol. Several companies have expressed an interest in the process, mainly for the CO2 to CO conversion step rather than the full process.


Biotrickling filter cuts operating costs

Researchers at the University of California, the United States, have modified an existing caustic chemical scrubber (16,000 m3/h) at the orange county sanitation district into a biological trickling filter. Continuous operation for more than eight months have shown that the converted scrubber removes more than 97 per cent of hydrogen sulphide (H2S) with contact times as low as 1.6 s, which is comparable to those of chemical scrubbers, states Mr. Marc Deshusses, associate professor in the Department of Chemical and Environmental Engineering.

The study showed that the total annual savings in operating costs (chemicals and electricity) are US$30,000 for the trickling filter as compared with chemical scrubbing a pay-back on investment after 1-2 years. In the biotrickling filter, waste gas from a sewage plant is passed through a packed bed of polyurethane foam cubes inoculated with a biofilm of H2S-degrading bacteria. The bacteria metabolize the H2S into sulphate. According to Mr. Deshusses, nearly 100 per cent conversion is possible.


Abatement of NOx and diesel soot

Researchers from the Polytechnic of Turin, Italy, have developed a system for nitrogen oxides (NOx) and diesel soot abatement. They have developed nanostructured catalysts of perovskite-type (ABO3, where A= La, K, and B=Ni, Cr, Co, Cu) for the simultaneous removal of soot and NOx. A series of catalysts were prepared via the solution combustion synthesis method, a highly exothermic and self-sustaining reaction. They were first submitted to physical and chemical characterization. The catalysts were then analysed by X-ray diffraction to assess their purity, crystalline structure and approximate crystal grain size.

A detailed investigation was carried out on these oxides by temperature programmed oxidation of soot and reduction of NOx (TPO/R) tests in fixed bed microreactors by assessing the effect of the operating parameters. The encouraging results obtained with the catalytic activity tests proved to be effective in the simultaneous removal of soot and NOx, the two prevalent pollutants in diesel exhaust gases in the temperature range of 350-450C. The best compromise between soot and NOx abatement was shown by the catalyst La0.8K0.2Ni0.95Cu0.05O3, which could promote soot combustion and appreciable NOx reduction below 380C, the maximum temperature reached in the exhaust of a diesel engine.

Contact: Mr. Guido Saracco, Scienza dei Materiali e Ingegneria Chimica, Politecnico di Torino, Corso Duca degli Abruzzi 24, Torino 10129, Italy.


Recycling of partially used sorbent

Less than half the available calcium is converted to a calcium sulphate when limestone or hydrated lime is used in pulverized or fluidized bed combustors for removal of sulphur dioxide (SO2). The partially utilized sorbent cannot remove SO2 any further and is disposed of or partially reactivated by hydration. Dry sorbent processes are thus less competitive with other more expensive SO2 control technologies. Researchers at the Ohio State University in the United States have designed a process for the reactivation of partially used calcium-based sorbents for increased SO2 removal and sorbent utilization in coal-fired combustors. The higher sorbent use in this reactivation process could significantly improve sorbent-based flue gas de-sulphurization.

Contact: Ms. Catherine Wendelken, Technology Licen- sing and Commercialization, Ohio State University, 1960 Kenny Road, Columbus OH 43210 1063, United States of America. Tel: +1 (614) 2921 315; Fax: +1 (614) 2928 907




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