VATIS Update Waste Management . Nov-Dec 2006

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Waste Management Nov-Dec 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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China ratifies global convention on marine pollution

Ratification of the 1996 Protocol on the Convention of Marine Pollution by Dumping of Waste and Other Matter by Chinas National Peoples Congress Standing Committee concurs with the building of an environmentally friendly society proposed by Chinas 11th Five-Year Programme (2006-10), said Mr. Sun Zhihui, director of Chinas State Oceanic Administration. It also indicates the countrys resolution to manage the dumping of waste into the ocean and presents an image of responsibility to the international community regarding marine environment protection, he said.

The Convention on the Prevention of Marine Pollution by Dumping of Waste and Other Matter, generally known as the London Convention, was passed in 1972 and came into force in 1975. The 1996 Protocol is meant to replace the 1972 Convention as it is much more restrictive. It aims to protect and preserve the marine environment from all sources of pollution by introducing the precautionary approach.

China will further amend its marine dumping regulations, including the Regulations of the Peoples Republic of China on Control over Dumping of Waste in the Ocean as soon as the protocol takes effect. It will also improve its technical standards of marine dumping management, Mr. Sun said. The country has listed seven wastes or other matter that are not considered dumping, including dredged material, fish waste, sewage sludge, inert organic material of natural origin, vessels and platforms, and bulky items primarily comprising iron, steel, concrete and similarly harmless materials.


Unattended stockpiles of organic pollutants in Pakistan

In Pakistan, Mr. Makhdoom Ishfaq Ahmad, Environment Minister of Punjab, has said that the province has persistent organic pollutants (POPs) in the form of 167 stockpiles of unattended obsolete pesticides and about 279.45 tonnes of mixed pesticides stocked in poorly maintained stores. He said the ministry completed the inventory of POPs with the cooperation of environment protection agencies and the United Nations Development Programme (UNDP) during the past two years, as mandated under the Stockholm Convention, for the formulation of a National Implementation Plan for eliminating POPs. All stakeholders had been included in the decision making process for building up capacity to combat the menace of POPs at the provincial level, he said.

Inaugurating a one-day provincial workshop on National Implementation Plan for POPs, organized by UNDP, the Pakistan Environment Protection Agency and the Punjab Environment Protection Department, the minister said the inventory of dioxin and furan indicated existence of numerous sources of emission of these gases. The total emission of dioxin in Punjab was estimated at 5,809 g toxic equivalent per year, whereas the inventory of polychlorinated biphenyls identified thermal and hydraulic oils as major sources.


Aid to Bangladesh for medical waste treatment

Japan will provide about US$87,400 (Taka 6.1 million) for a project for collection and treatment of medical waste in Dhaka city. A grant contract to this end was signed by Mr. Masayuki Inoue, Japanese Ambassador to Bangladesh, and Kh. Anisur Rahman, Exec. Director of PRISM Bangladesh, in a ceremony attended by officials from the Japan International Cooperation Agency (JICA) Bangladesh office and Dhaka City Cooperation (DCC).

In response to a request from the Government of Bangladesh, the Government of Japan conducted a study on Solid Waste Management in Dhaka City through JICA in 2003-06. Consequently, PRISM Bangladesh and DCC had started medical waste management services in two wards in Dhaka city in 2004. So far, the service has achieved remarkable outcome. Under the new grant, Japan will support PRISM Bangladesh to further those efforts jointly with DCC and JICA. PRISM will use the Grant Assistance for Grassroots Human Security for promoting collection, transportation and treatment of disposals, reducing health hazards, and training skilful staff on medical waste management.


Indian state adopts stricter rules for hazardous waste

Industries generating hazardous waste have to now comply with stricter regulations notified by the State Pollution Control Board of Karnataka, India. Among other measures of the Hazardous Waste (Management and Handling) Rules, factories have to display large digital signboards at the entrance indicating the quantity and nature of the hazardous waste generated. This move complies with directions issued by the Supreme Court in connection with a public interest litigation.

The Board has said that every hazardous waste-generating unit and those recycling or reprocessing such waste has to register themselves with the Board. This applies to collection, reception, treatment, transport and storage of waste, and those violating the rules may be closed down. The digital signboards at factory gates should measure 6 ft by 4 ft, and have to show updated data on the quantity and nature of hazardous substances handled, the waste generated and details about wastewater and emissions into the air. The Board has banned burning of both hazardous and non-hazardous industrial waste or dumping them in open places.


Dell and Nokia lead in e-waste management

Ranked on their use of toxic chemicals and electronic waste (e-waste) policies, only Dell and Nokia have managed to get 7 out of 10 points each, according to a Greenpeace report entitled Guide to Greener Electronics released recently. The third place goes to Hewlett-Packard, followed by Sony Ericsson, Samsung, Sony, LG Electronics, Panasonic, Toshiba and Fujitsu Siemens Computers, taking 4th to 10th slots. Lenovo is at the bottom, garnering points only for chemicals management and providing some voluntary product take-back programmes. The Greenpeace report intends to clean up the electronics sector and get manufacturers to take responsibility for their products full lifecycle, including the e-waste their products generate. The report does not rank companies on labour standards, energy use or any issues other than waste-related ones.

The scorecard will provide a dynamic tool to green the electronics sector by setting off a race to the top, said Mr. Iza Kruszewska, a toxics campaigner for Greenpeace International. The guide will be updated every quarter.

According to the report, Nokia leads the way on eliminating toxic chemicals: all its mobiles are free of polyvinyl chloride (PVC) since end-2005 and all new components will be free of brominated flame retardants from the start of 2007. Dell has also set ambitious targets for eliminating these harmful substances from its products. Commenting on its 13th rank, a Motorola spokesperson said, Our policy is to meet or exceed all applicable environmental, health, safety, legal and other requirements in the countries in which we do business. We believe the evaluation provides an incomplete picture of the companys true environmental performance.


GEF helps China phase out persistent organic pollutants

The World Bank has approved US$ 32.7 million in grants from the Global Environment Fund (GEF) for two projects that help China phase out three persistent organic pollutants (POPs). The Bank said POPs were a major environmental concern and the Chinese government has taken rapid action to eliminate key POPs targeted for elimination worldwide.

The first project, Polychlorinated Biphenyls (PCBs) Management and Disposal Demonstration Project, was approved by the World Bank board in December last year as a pilot policy with institutional and disposal measures to eliminate PCBs in Zhejiang. PCBs are broadly used in electrical equipment and cause widespread contamination of their storage sites. The project would demonstrate environmentally sound policies, and cost-effective methods for safely disposing of PCBs and PCB waste as well as decontaminating PCB sites. The total cost of the project would exceed US$35 million, of which more than half was funded by China.

The second project, the Demonstration of Alternatives to Chlordane & Mirex in Termite Control Project, was approved by the Bank recently to eliminate the use of two highly toxic pesticides. The first project of its kind in the World Bank or GEF portfolio, it would help China phase out the use of 15,000 kg of chlordane and mirex, close its largest manufacturing facility, and adopt modern termite control methods based on integrated pest management. The project would cost US$27.7 million, half of which would come from China.


Japans help to Viet Nam in e-managing dangerous waste

Two Japanese organizations have offered a non-refundable aid package to Viet Nams Ho Chi Minh City for a pilot project on e-managing dangerous waste. Under this project, the Japanese International Cooperation Agency and an environment centre in Japan will install a computer system and a software for the city to quickly deal with huge industrial solid wastes discharged by at least 2,000 major and 9,000 small and medium enterprises.

The system includes a server for the municipal Natural Resources and Environment Department (NRED) and seven other computers for the municipal Export Processing Industrial Zone Management and waste treatment establishments. The new initiative will enable NRED, the enterprises that discharge waste and waste treatment establishments to become well informed immediately after a discharge instead of three months, as at present. NRED will be able to control the total volume of dangerous waste, the process of waste transportation and treatment, the quality of treatment technology and the volume of untreated waste.


Malaysias master plan for waste management

The Malaysian Cabinet has approved the National Solid Waste Management Master Plan, which will provide the direction for an integrated approach to waste management in the country. Datuk Seri Ong Ka Ting, the Housing and Local Government Minister, said the plan includes the formation of a department under his ministry to coordinate waste management efforts in the country.
Whatever happens, next year will see the implementation of the Bill and greater coordination between all parties involved in waste management, said Datuk Ong after the launch of the Plastic Coding System and the Malaysian Plastics Forum. On the long-term direction of the master plan, he said it represented the movement from the base of a triangle to its tip. Recycling represents the broad base of the triangle where most waste should be dealt and the middle part of the triangle consists of waste that is treated. At the very tip should be what goes to the landfill, Datuk Ong said.


China stresses polluter responsibility

The Chinese government is to make producers, distributors and users of domestic appliances and electronic products responsible for the growing amount of high-tech junk. A policy issued by the State Environmental Protection Administration (SEPA) aims to curb pollution in the process of recycling mountains of discarded household appliances and electronic goods. The previous system of disposing of electronic waste in scattered family workshops had posed a grave threat to Chinas fragile environment and human health.

The new policy of polluter responsibility encourages manufacturers to reduce the use of toxic materials, label their products with information on toxins, and prolong the operating life of components. It is also possible that consumers might be charged for electronic waste treatment, said a SEPA official, adding that specific rules would be drawn up to allot responsibilities to producers, retailers and users.


Hospitals in Indian state reach pact for waste disposal

In Patna, the capital of Bihar in India, 52 private hospitals and nursing homes have entered into an agreement with Indira Gandhi Institute of Medical Sciences (IGIMS) for the proper disposal of biomedical waste. For a nominal fee, the waste from these hospitals will be carried away from their premises for incineration or shredding at IGIMS heavy-duty biomedical waste management system consisting of an incinerator, an autoclave and a shredder.

As per the pollution norms, hospitals and nursing homes must make arrangements for the safe disposal of waste. Since it is expensive and capital intensive, small hospitals were reluctant to set up their own incinerators. Instead, they have now decided to send their waste to the IGIMS waste disposal machines. The hospitals have to pay just Rs 3 (US$0.07) per bed per day. Rockwell Industrial Plants Ltd., which has supplied and runs the waste management system, collects the fees, while IGIMS also receives a commission of 10 per cent from the total collection.

Since the cost is calculated on the basis of the number of beds, several private hospitals are reported to have fudged their bed numbers. Moreover, majority of the waste still gets thrown in a drain, by the roadside or at a garbage dump, said a city doctor. The IGIMS machines, which are very powerful and can run round-the-clock, are being run only for a couple of hours daily to get rid of the waste that is coming in.


Viet Nam allows the import of 20 categories of scrap

The Ministry of Natural Resources and the Environment (MoNRE) in Viet Nam has recently permitted the import of 20 categories of scrap for recycling. The Law on Environment Protection prohibits importing used transport means for recycling domestically. However, MoNRE is trying to develop local heavy industries by allowing them to import several kinds of scrap, including scrap steel and iron. The ministry has also permitted the import of slag for making cement. The decision was made after the Ministry of Construction confirmed that this kind of material did not pollute the environment and requested that the MoNRE allow the import of this material. Other types of scrap that will also be allowed into Viet Nam include copper, lead, nickel, aluminium, crushed glass and waste paper.



New ASU plant for recycling waste plastic

The waste plastic recycling plant of Showa Denko K.K. in Kawasaki, Japan, started production from July 2006. The plant is using waste plastic to produce raw material gases such as hydrogen, which are then used to produce ammonia. Under a long-term contract with Showa Denko to supply oxygen and nitrogen, Japan Air Gases has invested in the waste plastic recycling plant through a new Air Separation Unit (ASU), which integrates the latest energy saving technologies, and will achieve significant improvement of power consumption. With the installation of the new ASU, Showa Denko aims for further improvement in cost efficiency of the recycling plant, by scrapping one of its two proprietary ASUs.

Showa Denkos waste-plastic recycling plant is a zero-emission unit that decomposes used plastic from domestic wastes at high temperature employing a unique two-stage heating system. It transfers output elements into raw material gases for ammonia production. With this plant, approximately 50 per cent of the main raw materials necessary for Showa Denkos ammonia production are generated from gases produced by the waste plastic recycling plant.


New method for plastic bottle recycling

A new method for making certain polymers promises to devour extensive quantities of post-consumer polyethylene terephthalate (PET) waste, according to GE Plastics, the United States. The company is launching a polybutylene terephthalate (PBT)-based polymer, Valox iQ, and a PBT/polycarbonate alloy, Xenoy iQ, that uses the wastes as raw materials. This novel chemistry enables up to 85 per cent of the PBT-based polymers content to come from the wastes.

The established approach to making PBT employs butanediol (BDO) and either terephthalic acid or dimethyl terephthalate. GEs process breaks down PET waste into an un-named monomer mix that can be reacted with BDO. The level of BDO needed is cut to 15 per cent, which is much less than that required with conventional technology. By relying upon recycled materials, the approach reduces CO2 emissions by at least 1.7 kg/kg of resin and saves as much as 8.5 bbl of crude oil/1,000 kg of resin, claims GE. Had the technology had been used for entire PBT production in 2005, it would have consumed 562,000 t of PET waste, or the equivalent of 22.5 billion bottles, according to the company. Valox iQ is competitive economically, selling for only a small premium over conventional PBT.

GE Plastics new manufacturing processes that pose less environmental impact and the ready availability of a consistent, high-quality supply of waste PET were key drivers behind the new process. Basically, the process starts with cleaned and flaked post-consumer PET wastes, such as water and soda bottles, photographic film stock, etc. The process route is reported to be straightforward and can be easily retrofitted to existing production sites.


From plastic to diesel

Clyvia Technology GmbH, Germany, has successfully converted 3 tonnes of plastics into 2,000 litres of diesel fuel. In this latest test run, a mixture of three kinds of plastics were utilized plastic sheeting for agricultural purposes, industrial plastics waste produced during the manufacture of electric fencing, and plastic materials segregated from domestic waste collection. These materials were first heated to a temperature of 270C and then fed into a pilot plant reactor. The plastics were then subjected to the fractional depolymerization process developed by Clyvia, a process that is similar in operation to the cracking of crude oil. Gas-chromatographic analysis of the resulting product has shown that the fuel produced meets the quality requirements for diesel and heating fuel.

A sample batch has been submitted to an independent accredited research laboratory in order to confirm that the resulting product conforms with DIN norms. Although the test run was conducted using a mixture of different types of plastics, Clyvia expects that the plant would be able to process various types of plastics individually. Isolating the different types of plastics will allow Clyvia greater control over the quality of the end product.


Granulator to reduce size of rubber bales

The new Vulcanator Model KM30 from Franklin Miller Inc., the United States, reduces whole bales of natural and synthetic rubber to small bits. This 150 hp unit features large throat and split clam shell design that allows for easy maintenance of cutters and screens. As the low-friction design minimizes heat rise, no cooling system is needed. This unit is invaluable in rubber processing, as it greatly reduces rubber dissolving time and processing time, and thereby reduces costs.

The Model KM30, built for heavy-duty operation, is capable of processing larger and heavier bales up to six times faster than previous units. The housing is constructed of heavy steel with a high level of precision incorporated into every component. An auxiliary flywheel helps this unit rip through even the toughest bales. Optional features include automatic controller, infeed and discharge conveying system, and pneumatic evacuation system.

Contact: Franklin Miller Inc., 60 Okner Parkway, Liv-ingston, NJ 07039, United States of America. Tel: +1 (973) 535 9200; Fax: +1 (973) 535 6269




Separation of mixed plastic waste into different phases

Baker Hughes GmbH of Germany has secured United States Patent for a method that enables a simple and economic separation of plastic waste mixtures. The method provides for the continuous mechanical separation of mixed plastic waste into heavy and light plastic phases for feedstock and material recycling, respectively.

The plastic waste mixture is first comminuted, preferably to less than 20 mm. Size reduction is normally a one-stage procedure but may also include several stages depending on material sizes and types. If required, this operation is followed by magnetic separation and/or eddy current separation to remove separable metals. The comminuted plastic waste mixture is then mixed with a separation liquid in a mixing tank. The heavy phase impurities (such as sands, metals, etc.) are separated from the suspension through the outlet at the bottom.

The suspension is directed from the mixing tank to a hydrocyclone, preferably a flat-bottom cyclone. Any remaining unwanted heavy-phase impurities together with the heavy phase undesirable plastics is separated from the balance of plastic waste materials as hydrocyclone underflow. The heavy products from the underflow of the mixing tank and from the hydrocyclone underflow may be further reprocessed and the remaining quantity disposed of.

The hydrocyclone overflow directly reaches a sorting centrifuge in which the remaining plastic waste mixture is subjected to further separation. The products discharged from the centrifuge include a plastic waste fraction (free of PVC) made up of heavier phase plastic, which can be used for feedstock recycling, e.g. in a blast furnace as reducing gas generating agent. The quantity will amount to approximately 35-40 per cent of the total plastic waste treated. A fraction of light plastic waste obtained can be utilized at higher added value for material recycling. The quantity available amounts to about 40-55 per cent of the total.


Continuous plastic recycling system

The PlastiCycler recycling system, developed by Polymer Recovery Systems in the United States, is designed to upgrade virtually any rigid post-consumer or post-industrial plastic. It is simple to install, operate and maintain, has a low initial invesment and the operation is cost effective. The finished product from the PlastiCycler is a clean, dry flake suitable for extruding or moulding.

The heart of the system is a washer/ dryer that incorporates a series of drums that rotate on a horizontal axis. As the drums rotate, material flows through the system, passing through a series of washing, de-watering and drying stages. In the wash stage, hot water is continually sprayed on the material. The combination of attrition and heated water provides exceptional cleaning. Contaminants pass through the wire mesh of the drums and are collected in a sedimentation tank. The dewatering stage allows free moisture to fall off of the material as it tumbles in the drum. Drying is by hot air passed through the drums as the material tumbles inside.

The PET system is designed to upgrade post-consumer PET. As with the HDPE system, the PET system incorporates two stages of air classification for effective removal of labels and other contaminants from the finished product. Production rate for PET and HDPE systems is in the range of 1,000-2,000 lb/hour. The polystyrene system is designed to process up to 400 pounds per hour.

Contact: Polymer Recovery Systems Inc., 945 Short Street, Eau Claire, WI 54701, United States of America.Tel: +1 (715) 835 3233; Fax: +1 (715) 833 2464




Unlocking the riddle of LCD re-use

Lliquid crystal display (LCD) screens are usually composed of two glass sheets, between which a thin film of viscous liquid crystal material is deposited. The material is a mixture of 15 to 20 different compounds. The liquid crystals that LCDs contain are potentially hazardous and there are no viable recovery techniques or fully safe disposal options.

Scientists in the United Kingdom are to play a pivotal role in new research aimed at averting a growing environmental problem caused by discarded LCDs. The scientists in the Department of Chemistry at the University of York have won a major competition to investigate ways of extracting and recycling liquid crystals from waste LCD devices. They are part of a consortium supported by the Resource Efficiency Knowledge Transfer Network and the Displays and Lighting Knowledge Transfer Network. Once recovered, the liquid crystal mixture will be recycled in to different LCDs or the mixture will be separated into individual components for re-sale, said Dr. Avtar Matharu of the Department of Chemistry at the university.

Contact: The Communications Office, University of York, Heslington, York, YO10 5DD, United Kingdom. Tel: +44 (1904) 432029; Fax: +44 (1904) 434466

Recycling firms tackle SAs rising e-waste problem

In South Africa, companies such as Universal Recycling specialize in dealing with scrap metal that includes electronic scrap. Universal Recycling specializes in handling complex metals by various processes, including heavy-media separation, shredding, sorting, milling, grinding and magnetic separation. It converts the metallic part of the e-waste into secondary raw materials for foundries, mills, smelters and refiners.

A 1200 hp Becker shredder is used to shred the material into small fragments. The next step is to size the material, as different sizes react differently to the various processes that follow shredding. During the shredding process, the shredded material is put over a magnetic drum and the ferrous part is removed and sold to the local rolled steel or the foundry industry. At the same time, large volumes of air are circulated through the shredder and recovered in a cyclone and scrubbing system where only clean air is released into the atmosphere. The various sizes of recovered ferrous-free metals and inorganics are further processed.


Recycling of printed circuit boards

NEC Corporation, Japan, has introduced a new recycling system for printed circuit boards (PCBs). The process consists of removing components, removing solder and pulverizing, and separating boards from the components. NECs system is designed to recover all materials of PCBs mounted with components as high-grade valuable resources (metallic resources, filling materials for plastic products, etc.) and recycle these resources for high value-added applications.

The system first removes components by heating and external force, and then removes the solder on the board surface through surface polishing and heat shock processes. It later separates copper and mixed powder of glass fibres and resins (GR powder) from the remaining part of the board during pulverizing and separating processes. The key features of the technology are:
  • It allows recovery of all high-grade valuable resources from PCBs that were considered difficult to recycle.
  • The apparatus can be used as a small-scale, on-site system, and a large-scale system can be set up by increasing the number of units.
  • The apparatus, which has a small footprint and simple structure can be manufactured, at a low cost.

Contact: Intellectual Assets Sales Department, NEC Corporation, NEC Bldg., 7-1, Shiba 5-chome, Minato-ku, Tokyo 108-8001, Japan.


Recyclable circuit boards

In Australia, Griffith University scientists have developed the worlds first recyclable circuit boards to help tackle the growing problem of e-waste. Griffith Universitys Centre for Wireless Monitoring and Applications research team, led by Prof. David Thiel, has developed a technology called Circuits in Plastic. This technology is recyclable and uses less toxic materials than traditional printed circuit boards.

It is clean and green. There is zero use of chemicals during the circuit board manufacturing process, meaning less by-products end up in landfills, said Prof. Thiel. Circuits in Plastic had the advantage of being a one-stage manufacturing process compared with three stages for conventional circuit boards. The new technology can reduce the cost of circuits by up to 15 per cent compared with lead-based circuit boards.



Thermal desorption for soil remediation

Researchers at Deep Green SA, Brussels, have developed Thermopile, a thermal desorption process to address soils contaminated with petroleum hydrocarbons and polycyclic aromatic hydrocarbons in a controlled batch system. The technology brings down contaminants to natural levels or to levels where the contaminated material is treatable with a traditional thermal desorption unit.

The system differs from most indirect thermal desorption systems by its high energetic efficiency. Contaminated soil is placed in a pile or in a modular container in which perforated steel pipes are installed in a hexagonal pattern. The pipes are heated by hot gases (about 600C) from the afterburner to bring the soil contaminants up to the desorption temperature. The desorbed pollutants are drawn by convection and diffusion into the heating pipes via the perforations. Inside the pipes, the desorbed gases mix with the heating gases and are extracted by a fan to the afterburner, where the hydrocarbons in gaseous phase are oxidized. These hydrocarbon-bearing vapours provide a part of the energy needed to heat the soil itself.

The pilot unit is also equipped with a purge that allows the evacuation of a part of the gases circulating in the system after the afterburner produces clean gases. Additional gas treatments can be applied as required by the type of contaminants and the emissions limits imposed. Internal soil combustion can occur while treating soils of high energetic content. This phenomenon reduces treatment duration while increasing treatment efficiency when the soil reaches temperatures up to 700C.


Ultrasound removes pollutants from soil

Researchers at Australias Commonwealth Scientific and Industrial Research Organization (CSIRO) say ultrasound can be used to destroy toxic or carcinogenic persistent organic pollutants (POPs) that commonly contaminate industrial land. Ultrasound technology has been shown effective in cleaning of contamination from oil refineries, power stations and aluminium factories.

POPs include polychlorinated biphenyls and dichloro diphenyl trichloroethane. They can spread in water and air, and accumulate in the food chain. Cleaning POPs is difficult, as incineration can produce toxic breakdown products, while treating the soil chemically needs large amounts of energy or substances almost as toxic as those being cleaned up. Mr. Andrea Sosa Pintos and colleagues developed a prototype system that works more effectively. Polluted soil is mixed with water and passed through a chamber that blasts the mixture with ultrasound. The team tested their system on sand spiked with pollutants and samples collected from industrial sites, and found their procedure destroyed up to 97 per cent of contaminants in just a few minutes.


Thermal photolytic destruction for dioxin control

Researchers in the Environmental Science and Engineering Group of the University of Dayton Research Institute, the United States, have designed a thermal photolytic destructor (TPD) based on an innovative technology to control combustion emissions of toxic combustion by-products such as polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and other chlorinated hydrocarbons.


The technology is based on the principle the rates of photochemical reactions of chlorinated hydrocarbons and other pollutants can be increased from 10 to 10,000 times by moderate heating. Dioxins prove particularly susceptible to this acceleration. The effects of reaction temperature, time, and photolysis wavelength and intensity have been determined for representative pollutants from different classes and performance models developed. The success of the research has led to the development of solar concentrator systems for decontamination of polluted air and water streams.

The TPD system uses high-energy mercury arc lamps and operates at temperatures ranging from 300 to 600C. The energy cost is modest and the main cost of operation is maintenance of the lamps, which is also reasonable. The system is suitable particularly for treating effluent streams containing halogenated hydrocarbons at mildly high temperatures.

Contact: Office for Technology Partnerships, University of Dayton Research Institute, 300 College Park, Dayton, OH 45469 0102, United States of America. Tel: +1 (937) 2293 515; Fax: +1 (937) 2293 873.


Superior solutions for hazardous POPs

A chemical process technology from Hydrodec, Australia, has reportedly created a paradigm shift in the sustainable management of persistent organic pollutants (POPs), both at the source of production and in the environment. Hydrodecs technology can be applied to re-manufacture POPs chemicals into high-value end products. For example, it completely converts pentachlorophenol or hexachlorobenzene into benzene. The process helps avoid the substantial environmental and economic costs of traditional hazardous POP destruction techniques, which have high energy consumption, as well as the financial burden and environmental hazard of storing POPs.

Hydrodecs technology does not produce any residual hazardous material or by-products, and achieves greater than 99.9999 per cent destruction of any hazardous halogenated compounds. Relative to many other available technologies, this closed loop, single pass, continuous process is low-temperature, cost-effective and rapid.

Contact: Hydrodec Australia Pty. Ltd., Level 6/90, Mount Street, P.O. Box 784, North Sydney, NSW 2059, Australia. Tel: +61 (2) 9959 5390; Fax: +61 (2) 9959 5760



Control of dioxin emission in cement clinker plant

The partial gas extraction stream of a cement clinker production line can contain unacceptable levels of the waste gas pollutants dioxin and/or furan, especially when raw materials and/or fuel containing chlorine compounds are used and the partial gas extraction is de-dusted in an electrostatic dust collector (E-filter). KHD Humboldt Wedag AG, Germany, has been accorded a United States Patent for a comparatively simple and cost-effective emission control method for cement clinker production lines.

In the new method, the partial gas stream, after cooling and electrostatic dust removal, is extracted in quantities that are lower than the sum of the volume of secondary air drawn through the rotary kiln and the volume of tertiary air drawn past the rotary kiln. The partial gas extracted is recirculated solely in the area of the clinker cooler in which the recuperation air is removed from the clinker cooler. The recirculated partial gas stream initially acts as cooling gas in the recuperation zone of the clinker cooler, before flowing into the rotary kiln. The partial gas extraction is purified in such a way that the dioxins and/or furans are destroyed upon contact with the hot cement clinker. The cooler section joining the recuperation zone of the clinker cooler is cooled in that fresh air is blown in so that the cooler exhaust air extracted from said cooler section is free of pollutants.


Indirect heated thermal desorption

Midwest Soil Remediation Inc., the United States, has successfully treated contaminated soils using its high capacity indirect thermal desorption unit (TDU). The units first project involved treating 32,000 t of solvent contaminated soil. The soil had chlorinated solvents up to 1,000 ppm and was treated to less than 10 ppb. Soil throughput was sustained at an average of near 50 t/h. The soil was heated to greater than 230C. These conditions translate to about 25 t/h capacity range for PCB/dioxin soil treatment. Petroleum-contaminated soils with similar moisture levels (10 per cent) would have a capacity of 30-40 t/h. These demonstrated production rates set a new standard in indirect heated thermal desorption and will substantially reduce the operating cost.

After a reconfiguration, the TDU has completed the treatment of 82,000 t of PCB-contaminated soil with 300 mg/kg to 1,000 mg/kg PCBs to less than 0.02 mg/kg total PCB. In the process, contaminated materials are fed continuously into an indirectly heated thermal processor to desorb contaminants such as organic chemicals and mercury. Treated solids are discharged to a clean stockpile after cooling and wetting.

The contaminants are transferred with an inert carrier to the off-gas treatment system for condensation and recovery. The system pressure is kept negative to prevent unwanted emissions. A portion of the treated off-gas is purged, and the balance returned to the dryer as the carrier gas. This vent is at a very low purge gas flow rate, typically less than 100 scfm. The process vent gas can be cleaned to any required emission standard.
Multiple stack tests have shown PCB chute-to-stack removal efficiencies greater than 99.999999 per cent; over 500 times better than ERA guidelines for PCB incinerators. This high control efficiency is combined with an extremely low air emission flow rate from the TDU to yield a low total organic emission rate measured at less than 0.4 g/day when feeding soil contaminated with PCB. Contact: Midwest Soil Remediation Inc., 23872 N. Kelsey Road, Lake Barrington, IL 60010, Illinois, United States of America.




Combined process for treating dyeing wastewater

In the Republic of Korea, researchers from Kyungpook National University, Andong National University and Kyungil University investigated a combined treatment process for textile wastewater. The process consists of moving-bed biofilm reactor (MBBR) treatment and chemical coagulation. The pilot-scale MBBR system comprises three MBBRs (anaerobic, aerobic-1 and aerobic-2, in series), each reactor filled with 20 per cent (v/v) of polyurethane-activated carbon (PU-AC) carrier for biological treatment followed by chemical coagulation with ferrous chloride (FeCl2).

In the MBBR process, 85 per cent of COD and 70 per cent of colour (influent COD = 807.5 mg/l and colour = 3,400 PtCo unit) were removed using relatively low MLSS concentration and short hydraulic retention time (HRT = 44 h). The biologically treated dyeing wastewater was subjected to chemical coagulation. After coagulation with FeCl2, 95 per cent of COD and 97 per cent of colour were removed overall. The study showed that combined process of MBBR and chemical coagulation has promising potential for dyeing wastewater treatment.


Treatment of pharma wastewater and removal of antibiotics

A joint study by researchers from Oak Ridge National Laboratory, the United States, and Tsinghua University and the Research Academy of Environmental Science, China, has evaluated both anaerobic and aerobic treatment of high-strength pharmaceutical wastewater. A batch test was performed to study the biodegradability of the wastewater, and the result indicated that combined anaerobic-aerobic treatment was effective in removing organic matter from the high-strength pharmaceutical wastewater. Based on the batch test, a pilot-scale system comprising an anaerobic baffled reactor followed by a biofilm airlift suspension reactor was designed.

At a stable conditions, effluent COD from the anaerobic baffled reactor ranged from 1,432 to 2,397 mg/l at a hydraulic retention time (HRT) of 1.25 day, and 979 to 1,749 mg/l at an HRT of 2.5 day when the influent COD ranged from 9,736 to 19,862 mg/l. As a result, effluent COD of the biofilm airlift suspension reactor varied between 256 and 355 mg/l at HRTs of 5.0 to 12.5 h. The antibiotics ampicillin and aureomycin, with influent concentrations of 3.2 and 1.0 mg/l ,could be partially degraded in the anaerobic baffled reactor at a removal efficiencys of 16.4 and 25.9 per cent with an HRT of 1.25 day, and 42.1 and 31.3 per cent with HRT of 2.5 day, respectively.


Smaller, cheaper wastewater plant

ITT Industries, the United States, has developed a dual-stage MBR system targeted at industrial wastewater applications in pharmaceutical, chemical, food and beverage, and other manufacturing sectors. The system is a continuous process. It takes wastewater with high BOD, suspended solids and other contaminants to yield an effluent suitable for direct discharge into surface water bodies and low grade re-use applications.

Membrane bioreactors employ the physical barrier provided by an ultrafiltration membrane instead of a settling tank to separate solids from liquid. Thus, the effluent is of significantly higher quality and hardly any additional treatment is needed prior to disposal or re-use. In the ITT dual-stage MBR system, the biological treatment portion of the process is kept separate from the membrane filtration stage. Parameters such as aeration rate can be controlled to reduce cleaning and power costs.

Contact: ITT Industries, 4 West Red Oak Lane, White Plains, NY 10604, United States. Tel: +1 (914) 641 2000; Fax: +1 (914) 696 2950.


Treatment of spent wash and black liquor mixture

The Council of Scientific & Industrial Research, India, has obtained a United States patent for a process for treating an effluent mixture of spent wash and black liquor. In the process, the effluent is mixed with a flocculating agent (a mixture of salts of Group III, transition metals, natural earths and a metal oxide), followed by treatment with a combination of ion exchange resins.

The process treats the effluent mixture for a period of 1-60 minutes at ambient temperature, allowing it to settle for a 5-240 minutes, separating the supernatant, contacting the supernatant with a mixture of ion exchange resin for a period of 5-30 minutes, allowing it to settle, and separating the supernatant to get the treated effluent. Indion 840 is a strong acid macroporous cation exchange resin having styrene matrix while Indion-930 A is a strong base macroporous Type I anion exchange resin with polyacrylic links. The adsorption on these resins is reversible.


Innovative point-of-use copper abatement system

Metron Technology Inc., the United States, has brought out the semiconductor industrys first point-of-use (POU) solution for abating copper from a chemical mechanical planarization (CMP) systems effluent stream. AquareusTM was developed jointly by Applied Materials and BOC Edwards. The systems simplified treatment process enables chipmakers to comply with the most stringent liquid discharge limits at a lower cost and with less risk than complex back-pad methods. Providing greater than 99 per cent removal efficiency and over 3,000 h mean time between failure (MTBF), Aquareus can save up to US$0.15 per wafer, or up to 30 per cent in treatment cost compared with centralized back-pad systems.

Aquareus uses a highly selective, fluidized bed, ion exchange resin technology that handles high flows from a broad range of CMP chemical slurries, with minimal service or maintenance. Two-year intense testing with copper CMP slurry has demonstrated exceptional reliability and efficiency. A typical CMP tool running in production generates effluent containing about 100 kg/y of copper.

Aquareus concentrates copper by a factor of 200:1 for better efficiency and cost-effectiveness than back-pad copper abatement methods. The systems POU design allows process flexibility and incremental growth capability as semiconductor fab operations expand.

Contact: Metron Corporate Headquarters, 655 River Oaks Parkway, San Jose, CA 95134-1907, United States of America. Tel: +1 (408) 719 4600; Fax: +1 (408) 719 0452.


Improving the cleanliness of plating solution

The Republic of Koreas Research Institute of Industrial Science and Technology is offering technology and apparatus for removing sludge in plating solutions and electrolytes. Sludge in plating solutions as well as ions that produce sludge can be effectively removed by applying co-precipitation-acidification method. Potential applications for the method include plants using electrolytes, electroplating facilities and chemical manufacturing centres. Benefits of this technology include sludge re- duction to 1/10th that of conventional technology, which in turn improves productivity and prevents product defects.

Contact: Research Institute of Industrial Science & Technology, San 32 Hyoja-dong, Nam-gu Pohang 790-600, Republic of Korea. Tel: +82 (54) 279 6333; Fax: +82 (54) 279 6099




Decolourization of effluent from pulp mill bleach plant

In the United States, two field trials at pulp mills have shown that the Fe-tetraamido macrocyclic ligand TAML) catalyst is effective for both in-process and post-process (end-of-pipe) treatment of coloured wastewater, compared with hydrogen peroxide (H2O2) alone. In the presence of pulp fibre in a caustic extraction stage tower, Fe-TAML/H2O2 removed more than 30 per cent colour without affecting pulp quality. In a sewer system carrying caustic extraction filtrate, Fe-TAML/H2O2 removed approximately 50 per cent colour.

The Fe-TAML technology is competitive with other technologies for pulp mill wastewater treatment, offering many important advantages, including: the catalyst is non-toxic, used in very small amounts, does not generate sludge and can work with as little as five minutes contact time; implementation is easy, with simple delivery mechanisms; and minimal capital cost.



Anaerobic bioremediation of chlorinated solvents

When injected into the subsurface to stimulate microbial populations, inexpensive food sources such as ethanol, sodium lactate or sugars are rapidly consumed by microbes and normally persist for less than a month, requiring multiple injections per year to sustain reductive dechlorination activity. Injection of pure vegetable oil or emulsion with larger droplets could block soil pore throats and reduce soil permeability, making injection difficult and limiting the contact between ground water and vegetable oil surfaces.

Mr. W.A. Newman of Remediation and Natural Attenuation Services Mr. R.C. Pelle of P2 Environmental, both in the United States, have found that a kinetically stable soybean oil emulsion consisting entirely of submicron droplets is the answer. The product, dubbed Newman Zone, is a blend of fast and slow-release food sources consisting of 4 per cent sodium lactate (rapidly utilized food source), 50 per cent soy oil (slow-release food source) and food-grade stabilizing agents. The product can be applied in the field as an electron donor without any amendment.

The researchers applied Newman Zone at a former adhesives manufacturing facility contaminated with TCE and 1,1,1-TCA. About 23,600 kg of Newman Zone was injected as a dilute emulsion containing 4.09 per cent vegetable oil by volume. Three years after injection, total organic concentrations ranging from 20 mg/l to 61 mg/l were measured in the treatment area, indicating that the emulsion continued to support reductive dechlorination from a single injection after a period of more than three years.


Cleaning up aquifiers with edible oil

Researchers from Clemson University and Savannah River National Laboratory (SRNL) are testing vegetable oil as a way to stop contaminants from getting into groundwater aquifers. They say the method could help clean up chlorinated solvents, which are among the most common groundwater contaminants caused by industry.

The oil is injected through hydraulic fractures made 20 to 30 feet into the ground. The injected vegetable oil draws in oil-based contaminants that have leaked from pipes or tanks. If mixed with water, the contaminants separate as droplets, small amounts dissolving into the water and making it hazardous. But, if another oil is introduced, these contaminants steer clear of the water and are drawn towards the edible-oil source.

Some microbes in the ground subsurface will degrade solvents. The edible oils create the right conditions for those kinds of microbes to flourish, so they seek out the contaminants and break them down. We hope the oil will both trap and destroy contaminants underground, said Mr. Larry Murdoch, a Clemson University geologist. Since February, SRNL investigators have been monitoring levels of contaminant vapours and other indicators to determine whether the oil is attracting the contaminants at the test site. Mr. Murdoch said preliminary results are exciting enough, suggesting the process is working as anticipated.


Biological in situ soil decontamination

Zentrum fr Innovation & Technik in Nordrhein-Westfalen GmbH (ZENIT), Germany, offers biological on site soil decontamination that does not interfere with the natural soil structure and can be tailored to individual requirements. The process is also suitable for small areas. ZENIT is seeking industrial partners or consulting engineers for technical co-operation to carry out joint projects.

ZENITs biological in situ soil decontamination consists of modules that are individually adjustable. Adapted micro-organisms are utilized to degrade the pollutants in the soil. Bio-filters are available to clean air and wastewater. It is possible to combine the process with ground air and ground water treatment, and integrate a suitable vacuum technology into this low-cost solution.

Contact: Ms. Ivn Landa, Centre dInnovaci I Desenvolupament Empresarial, Passeig de Gracia 129, 08008 Barcelona, Spain. Tel: +34 (93) 567 48 87; Fax: +34 (93) 476 72 14



On site remediation of chlorinated solvents in groundwater

Consiglio Nazionale Delle Ricerche, an Italian research group, has developed an anaerobic in situ bioremediation technology for the removal of toxic and harmful contaminants from polluted groundwater. The technology is particularly suited for the treatment of chlorinated aliphatic hydrocarbons (such as perchloroethylene and trichloroethylene). The research group is seeking technical cooperation with industries or other research institutions for commercialising the technology.

The process involves stimulation of the degradation activity of naturally occurring bacteria through the subsurface injection of food-grade nutrients and/or carbon sources. These bacteria can respire chlorinated compounds using them as terminal electron acceptors in their energy metabolism. This novel form of anaerobic respiration, called reductive dehalorespiration or reductive dechlorination, results in the removal of chlorine substituents from the molecule and in the end the formation of non-chlorinated products.

For reductive dechlorination to occur at significant rates in groundwater, it is necessary to stimulate the activity of dechlorinating bacteria present in the aquifer by providing them with a suitable electron donor. This can be typically accomplished by injecting appropriate amounts of selected innocuous food-grade organic compounds in the contaminated groundwater (using common groundwater wells). These organic compounds are used by naturally occurring bacterial communities to convert toxic chlorinated solvents into non-chlorinated end products.

Contact: Ms. Ivn Landa, Centre dInnovaci I Desenvolupament Empresarial, Passeig de Gracia 129, 08008 Barcelona, Spain. Tel: +34 (93) 567 48 87; Fax: +34 (93) 476 72 14



Bacterial treatment for wastewater

A vastly improved method of bacterial wastewater treatment, capable of degrading the most toxic and difficult pollutants, has been devised by the EUROENVIRON BIOMAC project of the European Union.

The new system employs bacterial mixtures in granular form, capable of breaking down even the most toxic wastes or deal with high pollutant concentration. The system uses 50 per cent less energy than conventional ones and will cost 30 per cent less, since the wastewater can be treated much faster than before.

The BIOMAC technology selects an optimal combination of bacteria for specific types of pollutants, and produces this mixture in a sufficiently large volume, while retaining the same mixture of strains. The system is computer-controlled and has been tested from the laboratory scale up to industrial through the EUREKA project.

Contact: Mr. Enga Luye, Belair Biotech Ltd., rue des bains 33,1211 Genve 8, Switzerland. Tel: +41 (79) 467 4093; Fax: +41 (22) 322 2400



Bioremediation of contaminated soil

Quantum Environmental Group of Canada provides ex situ treatment and disposal of contaminated soils using environmentally sustainable methods. Contaminated soil is excavated and transported to the facility where it is spread in piles on a treatment pad for processing. The treatment pads are designed to protect the surrounding environment from contamination through a built-in system that collects any leachate or toxic materials that seep out of the contaminated soil. The pads are constructed using a hydrocarbon-resistant, high-density polyethylene liner overlaid with granular material and a 75 mm thick layer of asphalt.

A sophisticated leak detection and water treatment system has been built into the treatment pads so that leachates and water runoff are collected and routed through a series of settling ponds to capture suspended solids. The treated water is then filtered through an engineered wetland and carbon vessel for further polishing before final discharge. The water is tested regularly to ensure that it meets regulatory norms.


Compost bioremediation technology

Under the LIFE ENVIRONMENT project of the European Union, Ekotek, Spain, has developed and demonstrated the technical and economic feasibility of compost bioremediation technology for the reclamation of soils polluted with different types of organic pollutants. This innovative, environment-friendly and cost-effective technology is based on the stimulation of the growth and the activity of autochthonous microbial populations by adding a specially designed compost to the soil.

Micro-organisms in highly contaminated soils develop effective genetic regulatory systems that respond to the presence or absence of specific pollutants, and many of them have the capacity to degrade such pollutants.

However, contaminated soils usually present a low microbial activity, basically because of the lack of optimal environmental conditions such as low concentrations of organic matter, low oxygen, nitrogen and/or phosphorus availability, etc. In the compost bioremediation process, soil environmental conditions are optimized by adding a specifically designed compost, which contribute with biodegradable organic matter (nutrients), a high concentration of degrading microflora, and acts as a bulking agent. Compost is specifically designed for each site according to soil characteristics and contaminants, using a mixture of organic waste such as poultry manure, cow dung, sawdust, barks, vegetable waste, etc. Before composting, a portion of the polluted soil is added to the mixture to act as an inoculum of adapted degrading micro-organisms. The result is a bio-augmented organic material rich in autochthonous degrading populations of micro-organisms and nutrients that will accelerate the bioremediation process. This material is then mixed with the polluted soil and biopiles are prepared.

Main advantages of the process are:
  • It achieves higher clean-up levels than the conventional bioremediation.
  • The treatment takes up to 40 per cent less time than other bioremediation processes.
  • Adaptability of micro-organims is not an issue as it uses indigenous micro-organisms.
  • It needs less manipulation and maintenance requirements, reducing the treatment costs.


Enhanced bioremediation of low permeability soils

Frac Rite Environmental, Canada, has demonstrated how soil hydraulic fracturing using its Frac RiteTM process can accelerate the degradation of contaminants by overcoming the limitations of unfavourable geology. A pilot-scale field trial of fracture-enhanced bioremediation, which combined the use of hydraulic soil fracturing and a natural polymeric organic bio-amendment called chitin, was conducted at a site in Kentucky, the United States. The results showed that chitin favourably impacted redox conditions and was responsible for the reduction of dichloroethylene and trichloroethylene by up to 70 per cent in four months.

The Frac Rite process was developed to hydraulically fracture low permeability soils and rock to accelerate the recovery or treatment of sub-surface contaminants. Fracturing is conducted using proprietary down-hole fracturing equipment. The resulting network of fractures in the soil contain high permeable sand to keep the fractures open as well as to act as pathways for the fast recovery or in-place treatment of contaminants.

The Frac Rite process can also be used for injecting biological amendments or chemical reagents with the sand in order to degrade contaminants while also providing enhanced soil permeability. The process has been proven to be a cost-effective alternative to conventional remediation.

Contact: Frac Rite Environmental Ltd., 5325 3rd Street S.E., Calgary, Alberta T2H 1J7, Canada. Tel: +1 (403) 265 5533; Fax: +1 (403) 265 5648




Bioremediation of petroleum products

Chemical oxidation is transitioning from an innovative technology to a common remediation technique for clean-up of hydrocarbon impacted soils, groundwater and bedrock. Concerns regarding the implementation of chemical oxidation include safety during application and disruption of natural contaminant attenuation. These concerns stem from the exothermic nature of the oxidation process and sterilizing effects of the oxidants on microorganisms in the soil.

Lessard Environmental Inc. of the United States has developed a process called Biologically Enhanced Chemical Oxidation (BECO), which integrates chemical oxidation and bioremediation as a concurrent and co-located process. Implementation of BECO is both temporally flexible and spatially scaleable. The process integrates the oxidation and bioremediation by increasing temperature below surface, raising available oxygen and nutrients, and by modifying contaminant distribution during remedial additive applications.

Remediation progresses as an integrated couplet of remedial additive applications and biological activity. The stimulated microbial activity reduces the total quantity of oxidant and number of applications required for remediation with oxidant alone. Heterotrophic plate counts during the remediation projects typically increase from baseline concentrations of 102 to 103 CFU/ml to concentrations of 105 to 107 CFU/ml following BECO application events.



Catalyst for purifying industrial exhaust gases

A group of Japanese researchers from Materials Research Institute for Sustainable Development, Advanced Manufacturing Research Institute and NGK Insulators Ltd has succeeded in developing a highly porous platinum-alumina catalyst for use in industrial exhaust gas purifiers with the characteristic of high temperature resistance coupled with a high efficiency. The reaction temperature of this catalyst is 100C lower than the reaction temperatures of the catalysts currently in use, and the thermal resistance has been improved to approximately 200C.

The process employed freeze-drying as a low-cost and simple process to dry the gel. The new highly porous platinum-alumina ceramic body named platinum-alumina cryogel has high durability at high temperature and improved catalytic activity. The process uses Boehmite sol, a low-cost aluminum hydroxide, as the starting material for the catalyst. Use of chelating agents such as oxalic acid and malonic acid, when adding the platinum source to the sol, protects the platinum ion, contributing to suppression of platinum black precipitation, and producing a homogeneous dispersion of ultra fine platinum particles (~ 1 nm).

The pore structure constitutes most of the volume of the manufactured cryogel, but even when it is a multi-porous body with low bulk density (~0.06 g/cm3), structural destruction by water is not observed. There are no observable changes before and after wetting in the separately measured pore distribution curve, which indicates that it is possible to employ a conventional immersion method to support the fine catalyst metal particles. These new characteristics cannot be observed in the currently used aerogel, which also presents a large volume composed of pores.


Chemical switch cuts costs, improves safety

The BIONOxSOLVERTM, developed by Bionomic Industries Inc. in the United States, provides an easy-to-handle, safe, high-efficiency NOx scrubbing solution that eliminates the production of hydrogen sulphide gas. ChemResearch Co. (CRC) has employed it to reduce labour and improve safety.

Since 1998, CRC had used sodium sulphide chemistry in the scrubber at the end of its dedicated aluminium pre-cleaning process. The automated line cleans and etches the parts using various cleaner and acid baths. When the parts come out of the acid baths, a large volume of NOx is released. Sodium sulphide use, coupled with sodium hydroxide, generates scale build-up on the scrubber tank and packing, making cleaning and maintaining the system labour-intensive. The safety of the tank itself is a concern as it is inside another lined tank.

As a result of the switch to BIONOx-SOLVER, CRC has cut its labour costs by about 75 per cent. Now the scrubber is easier to maintain, as there is little to no scale build-up. Elimination of gloves, aprons, respirators and cartridges required for handling sodium sulphide gave additional savings, besides savings in water and the electricity consumption.

Contact: Bionomic Industries, 777 Corporate Drive, Mahwah, NJ 07430, United States of America. Tel: +1 (201) 529 1094; +1 (201) 529 0252.


Ultra-low emission combustion device

Researchers from Georgia Tech, the United States, have created a new combustor designed to burn fuel in a wide range of devices with near-zero nitrogen oxide (NOx) and carbon monoxide (CO) emissions. The device has a simpler design than existing state-of-the-art combustors and could be built and maintained at a much lower cost, making it more affordable in everything from power plants and jet engines to home water heaters.

The Stagnation Point Reverse Flow Combustor from Georgia Tech burns fuel with emissions of NOx below 1 ppm and CO lower than 10 ppm. It burns fuel in low temperature reactions that occur over a large portion of the combustor. By eliminating all high-temperature pockets through better control of the flow of the reactants and combustion products within the combustor, the device produces far lower levels of NOx and CO and avoids acoustic instabilities.

Georgia Techs design eliminates the complexity associated with premixing the fuel and air by injecting the fuel and air separately into the combustor while its shape forces them to mix with one another and with combustion products before ignition occurs.

Contact: Ms. Megan McRainey, Institute Communications & Public Affairs, Georgia Institute of Technology, 177 North Ave., Wardlaw Centre, Atlanta, GA 30332-0181, United States of America. Tel: +1 (404) 894 6016; Fax: +1 (404) 894 7214



Corona-induced chemical scrubber

Beltran Inc., New York, has secured a United States patent on an emission treatment system for removing nitrogen oxides from flue gases. In the pre-treatment portion, the system includes a continuous plasma reactor that receives and modifies the gaseous effluent by applying a plasma discharge. The plasma discharge decomposes the majority of the effluent to nitrogen (N2) and oxygen (O2) and oxidizes nitric oxide (NO) to nitrogen dioxide (NO2). A pre-conditioning section further modifies the effluent by washing with a mildly alkaline solution for removing ozone and lowering the process temperature. A continuous chemical scrubber uses an absorbent medium to substantially eliminate NO2 from the effluent and release N2 and O2.

A non-thermal plasma discharge apparatus is used to decompose the gaseous mixture. At the plasma discharge treatment stage, the major portion of the incoming NO is decomposed to N2 and O2, and the balance is oxidized to NO2, which, at the chemical scrubbing stage, is removed by a caustic sodium sulphite aqueous scrubbing system. The outlet concentrations of both NO and NO2 from the plasma discharge/chemical scrubbing system (corona-induced chemical scrubber) are below the detection limit of the chemiluminescent NOx analyser. At least two dielectric materials, such as barium titanate and glass, can be used in the non-thermal plasma discharge unit for decomposing NOx. The dielectric materials are packed into the annular space of the plasma reactor to form a dielectric barrier.


New technology cuts NOx and costs in coal-fired cyclone boiler

Beltran Inc., New York, has secured a United States patent on an emission treatment system for removing nitrogen oxides from flue gases. In the pre-treatment portion, the system includes a continuous plasma reactor that receives and modifies the gaseous effluent by applying a plasma discharge. The plasma discharge decomposes the majority of the effluent to nitrogen (N2) and oxygen (O2) and oxidizes nitric oxide (NO) to nitrogen dioxide (NO2). A pre-conditioning section further modifies the effluent by washing with a mildly alkaline solution for removing ozone and lowering the process temperature. A continuous chemical scrubber uses an absorbent medium to substantially eliminate NO2 from the effluent and release N2 and O2.

A non-thermal plasma discharge apparatus is used to decompose the gaseous mixture. At the plasma discharge treatment stage, the major portion of the incoming NO is decomposed to N2 and O2, and the balance is oxidized to NO2, which, at the chemical scrubbing stage, is removed by a caustic sodium sulphite aqueous scrubbing system.

The outlet concentrations of both NO and NO2 from the plasma discharge/chemical scrubbing system (corona-induced chemical scrubber) are below the detection limit of the chemiluminescent NOx analyser. At least two dielectric materials, such as barium titanate and glass, can be used in the non-thermal plasma discharge unit for decomposing NOx. The dielectric materials are packed into the annular space of the plasma reactor to form a dielectric barrier.


Catalyst for NOx reduction

Nitrogen oxides (NOx) discharged from various combustion systems and metal etching plants are major air-polluting substances. For NOx reduction, the selective catalytic reduction (SCR), using ammonia as a reducing agent has been widely used. The de-NOx catalysts used for this process are key to the SCR process. Nippon Shokubai, Japan, supplies de-NOx catalysts for use in de-NOx systems for various exhaust gas sources such as boilers and power stations.

The main features of the de-NOx catalysts are:
  • Wide selection to suit various exhaust gas sources;
  • High NOx-reduction rates in a wide temperature range of 160C to 600C;
  • Durable catalysts with high de-NOx activity for a long period;
  • Low formation of ammonium sulphates owing to low SO2 oxidation rate; and
  • Sieve opening of catalyst can be adjusted to make it applicable to any exhaust gas from coal-fired boilers with a high dust abrasion resistance.

Contact: Nippon Shokubai Co. Ltd., Kogin Building, 4-1-1 Koraibashi, Chuo-ku, Osaka 541-0043, Japan.


NOx reduction in diesel engine emissions

Researchers from Pacific Northwest National Laboratory (PNNL) have developed a new cost-effective and energy-efficient method for reducing oxides of nitrogen (NOx) in diesel engine emissions. Called the reformer assisted catalysis, the process is three-fold syngas production, reductant synthesis and catalytic reduction of NOx in emissions.

PNNL researchers began to work on this problem more than 10 years ago, when they developed a plasma-facilitated catalyst. They realized that a more energy- and cost-efficient system could be built, leading to the development of the reformer-assisted catalysis. The process includes treating hydrocarbon in a reformer before being introduced into the exhaust. Diesel is then extracted from the fuel tank and reformed into syngas, a mixture of hydrogen and carbon monoxide. Next, syngas is chemically converted to dimethyl ether, which has proved to be highly selective for NOx reduction, from the syngas stream. In the final step, catalysis, an ether mixture is injected into the exhaust, enhancing the performance of certain catalysts that allow for significant NOx reduction.



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