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VATIS Update Waste Management . May-Jun 2007

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Waste Management May-Jun 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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Contents

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IN THE NEWS

Basel Convention push to address e-waste problem

Parties to the United Nations Basel Convention have reached accord on new initiatives to address mounting volumes of electronic waste. At the recent eighth conference of the parties (COP-8) held in Nairobi, Kenya, there was an agreement to: promote clean technology and phase out hazardous substances; collaborate in combating the illegal waste trade; and to develop pilot take-back systems. A Basel Convention working group will prepare a plan on environmentally sustainable management of electronic waste for consideration in the autumn of 2008.


It was anticipated in some quarters that the COP-8 meeting would usher in a ban on exports of hazardous waste to developing countries, but the matter was shelved until the next conference in the autumn of 2008.


At the same meeting, the parties to the Basel Convention reaffirmed that the global ship recycling law being developed by the International Maritime Organization (IMO) should impose levels of control equivalent to those of the Basel Convention. They added that clear responsibilities should also be outlined for all stakeholders.


Website: www.recyclinginternational.com

E-waste recycling centres are hot spots for POPs

Discarded electrical and electronic equipment is becoming a major environmental concern, particularly in developing countries. Researchers from Hong Kong Baptist University have found elevated levels of polybrominated diphenyl ether (PBDE) flame retardants as well as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in surface soil samples and combustion residues in Guiyu in Southeast China, a region notorious for its intensive e-waste recycling centres.


Ms. Anna Leung, the papers first author, says: Crude e-waste recycling activities, including the open burning of e-waste, are a hot spot for PBDEs and PCDD/Fs. The researchers found that PBDE levels in combustion residues from open burning were some of the highest found in any environmental medium, more than 16,000 times higher than those found in soil samples used as control. Soil with high PBDEs levels was also found at an acid-leaching site, where workers use an acid mixture to recover precious metals from shredded printed circuit boards, and from a printer-roller dump site. Levels of PCDD/Fs at an acid-leaching site were higher than those in the combustion residues.


The United Nations Environment Programme estimates that each year 20-50 million tonnes of e-waste are produced worldwide; this number is increasing rapidly. As an alternative to over-packing landfills or recycling domestically, some industrialized countries have found it cheaper and more convenient to export e-waste to developing countries, where labour costs are low, and occupational and environmental laws are lax or not well implemented.


Website: www.pubs.acs.org

India yet to finalize norms for e-waste disposal

A conservative estimate of electronic wastes generated in India puts the figure at 150,000 tonnes every year. As the countrys Central Pol-lution Control Board is yet to finalize guidelines for disposal of e-waste, the current unregulated handling practices suffer from use of crude methods for dismantling and storage, minimal capital input and zero health or environmental safeguards.
Almost all e-waste finds its way into the informal sector.


With the volume of waste generated now increasing manifold, studies by experts have shown that both Delhi and Mumbai are burdened with waste that is too dangerous to be handled in such congested areas. A new study on Mumbai: choking on e-waste, says that Mumbai is not just the leading e-waste generator; the rate at which the city is throwing away electronic goods is far higher than previously believed. Meanwhile, Delhi has been tipped as the largest e-waste recycler and receives a substantial part of Mumbais electronic discards.
Releasing the study, Toxics Link Director Mr. Ravi Agarwal pointed out that extended producers responsibility approach, which broadly implies that producers be responsible for their product even after the consumer has bought and used it, is emerging as a popular e-waste management alternative in various countries of the world. He said that India too needs to take steps in that direction.


Website: www.ban.org

China to tighten screws on polluters

China will draft and amend a series of laws to further protect the environment from fast economic growth. The draft circular economy laws promote sustainable development through a tighter legal framework. In August, it would be submitted to the Standing Committee of NPC for review. The law is expected to pass at the end of this year, before the 10th NPC ends its five-year tenure in early 2008.


The draft law encourages the efficient use of resources and energy, while minimizing waste, through the 3-R principle: reduce, reuse, and recycle. Mr. Mao Rubai, Chairman of the Environmental and Resources Protection Committee of NPC, said the draft law includes provisions on basic management requirements to reduce resources, and reuse them where possible. Some mandatory systems with details are written into the draft, which provide the law with a high feasibility, Mr. Mao said.


For example, there is an article instructing industry to be responsible for collecting and recycling packing materials of its own products. It calls for the recycling of waste products such as electronic waste, discarded automobiles and ships, and other mechanical products. Organizations that take an active role in Chinas Circular Economy growth through sustainable development would be offered incentives such as preferential tax policies, while there are penalties for non-compliance which would be heavier and continue till the problem is rectified.


Website: www.english.sepa.gov.cn

Thailand promotes recycling of plastic garbage

The Ministry of Energy of Thailand is promoting the recycling of plastic garbage as substitute energy. It hopes that energy from plastic garbage would reduce the import of oil by 80 billion baht (US$2.44 billion) per year. Energy Minister Mr. Piyasawasdi Amranand stated that the Ministry recently initiated the recycling of plastic garbage in view of the readily available supplies of millions of tonnes of plastic garbage that can be transformed into substitute energy.


One local administration organization will be selected to participate in a pilot project on the recycling of plastic garbage. The Ministry has imported a technology for garbage recycling from Poland to use in the pilot project.


It will launch a campaign for garbage segregation and to create awareness on energy conservation in the general public. The Minister said that if local administration organizations nationwide were to cooperate in the garbage recycling project, a significant portion of the total plastic garbage could be successfully transformed into crude oil. He revealed that the testing of this crude oil shown that it has a better quality than the Dubai-grade crude oil and has only a small amount of sulphur.


Website: www.thaisnews.com

World Bank aid for Viet Nams environment revamp

The World Bank has approved a credit totalling US$125 million for major environmental projects in three coastal Vietnamese cities of Dong Hoi, Quy Nhon and Nha Trang. The credit is part of the Development Credit Agreement that the World Bank inked recently with the State Bank of Viet Nam.


The credit will be earmarked for upgrading and building new drainage and wastewater treatment systems in the three aforesaid cities. Work on expanding and constructing garbage dumps will also be funded by the credit. The Bank also pledged another non-refundable credit worth US$4.6 million, focusing on training human resources for environmental projects in those cities.


Website: www.thanhniennews.com

Pakistan to award green industrialists

In Pakistan, a sub-committee of the Senate Standing Committee on Defence has recommended that the government institute a civil award to honour industrialists contributing towards environment conservation. The sub-committee was formed to prepare a report on how to check environmental pollution caused by industrial and domestic waste, which is damaging vital defence assets of the Navy and Air Force in Karachi.
 

The sub-committee has directed the Environment Ministry to launch a sustained public awareness campaign for a cleaner environment in collaboration with the Information Ministry after taking stakeholders on board. Mr. Nisar Memon, head of the sub-committee, stressed the need to adopt a holistic approach to combat the issue of pollution. He recommended that National Environmental Quality Standards be adhered to in letter and spirit, and that civil society organisations be involved for achieving the desired results.


Website: www.dailytimes.com.pk


PLASTIC WASTES

Bioplastic that breaks down into biodiesel after use

In an effort to develop a new source of sustainable energy, researchers at the Polytechnic University of New York, the United States, have bioengineered a fuel-latent plastic that can be converted into biodiesel after use. The new plastic is made from plant oils and has remarkable properties, such as being tougher and more durable than the petroleum-based polyethylenes. It can be put in a simple container where it can be safely broken down to liquid fuel, ready for use in cars. The concept thus shortcuts a costly waste management process and simplifies fuel logistics.


Professor Richard Gross, director of Polytechnic Universitys National Science Foundation (NSF) Centre for Biocatalysis and Bioprocessing of Macromolecules (CBBM) developed the bioplastic using vegetable oils. He also partnered with DNA 2.0, a biotech company, to develop enzymes that can both synthesize and break the fuel-latent plastic down into biodiesel after its use. The next phase of the research will involve developing a more efficient low-cost process for both manufacturing the bioplastic and converting it into biodiesel. This would be a key step in developing green technologies and reducing waste.


Website: www.biopact.com

New nano-composite material to combat white pollution

Polystyrene (PS), also known under its trademark name Styrofoam, is found in many shapes and forms in homes, offices, grocery shops, fast-food outlets and cafeteria. It is a white pollutant material that takes hundreds of years to break down and is not recovered in recycling. To address this problem of white pollution, a research team in China has developed a nano-composite super-absorbent material that utilizes waste PS foam. If commercially successful, this and similar methods could go along way in reducing the white pollution worldwide.


Super-absorbents are lightly cross-linked functional polymers that can absorb, swell and retain aqueous solutions up to a thousand times of their own weight in relatively short period of time. They are used in a wide range of personal care and industrial products. Researchers at the Jiangsu Engineering Research Centre for Biomedical Functional Materials at Nanjing Normal University and Jiangsu Technological Research Centre for Interfacial Chemistry and Chemical Engineering at Nanjing University devised a nano-structured super-absorbent composite with water absorbency of about 1,200 times its weight.


The introduction of PS chain into the nano-composite not only reduces the production cost of the super-absorbent, but also improves the water absorbency rate, explained Dr. Jian Shen, Director of Jiangsu Engineering Research Centre for Biomedical Functional Materials. He and colleagues focused on cross-linked poly(acrylic acid), one of the most effective super-absorbents. The researchers used partially neutralized acrylic acid, montmorillonite a low-cost layered aluminium silicate and waste PS foam to create the novel super-absorbent. In their experiments, the percentage range of waste PS foam used in the nano-composite material was between 7.7 per cent and 20 per cent. According to Dr. Shen, this could reduce the production cost of these super-absorbent materials by approx. 2.9 per cent to 8.7 per cent.


Website: www.nanowerk.com

Method of recycling plastic from printer cartridges

Canon Kabushiki Kaisha, Japan, has obtained a United States patent for an invention to efficiently recycle a plastic resin material used in printer cartridges. The method separates a specific plastic material from other plastics, and moulds it into a cartridge again.


To achieve this, the used cartridge is first crushed and particles such as toner are collected by suction. These particles and foreign matter are separated in a screening step and later in an air selection step, a secondary crushing step, a peeling step, and a dry gravity separation step. Metallic components are separated using magnetic and eddy current separation steps. Plastic material having a specific density and a reflection density of 1.00 or more is then separated in a colour separation step.


Website: www.freepatentsonline.com

Liquid coatings from scrap PET

EvCo Research LLC of the United States has formulated a range of liquids with recycled PET plastic as a key ingredient to serve as recycling-friendly coatings on a variety of boxes and paper packaging products. These products can be used for coatings employing conventional coating methods (such as rods or air knives) at the wet end of the paper machine or at the size press. The most noteworthy product is a substitute for the waxes that are not recycling-friendly those that coat cardboard boxes used by produce and meatpacking companies.


The process we have here is to chemically modify the PET so that we can disperse it in hot water so it can be applied as a coating, says Mr. John Kokoszka, EvCos Vice President of Operations. Heat is the key processing method for EvCo; it is a high-energy process that gets the PET up to about 205 to 230C. We break the PET down to an oligomer and then add different chemicals as we build it back up to a polymer, says Mr. Kokoszka.


The company has developed many different water-dispersible products using scrap PET as a key ingredient, including products that either repel or absorb water. The majority of its products are geared for the paper industry and offer protection from moisture, including the EvCote PWR Series, marketed as a substitute for wax coatings on corrugated boxes. Other products can substitute for UV coatings as a top-gloss coat on boxboard, serve as a base coat for ink-jet paper or as a barrier coating on paper bags or a partial substitute for wet-strength chemicals used in paper bags.


Website: www.findarticles.com

Plastic that degrades in seawater

A new type of environment-friendly plastic that degrades in seawater may make it safe and practical to toss plastic waste overboard, thus freeing-up valuable storage space, say scientists at the University of Southern Mississippi (USM) in the United States. The biodegradable plastics could replace conventional plastics that are used to produce stretch wrap for large cargo items, food containers, eating utensils and other plastics used at sea, the USM researchers say.


The new plastics are capable of degrading in as few as 20 days and result in natural by-products that are non-toxic, reveals study leader Dr. Robson F. Storey. They are made of polyurethane, which is modified by incorporating poly(D,L-lactide-co-glycolide), a degradable polymer used in surgical sutures and controlled drug-delivery applications. By varying the chemical composition of the plastic, the researchers achieved a wide array of mechanical properties ranging from soft, rubber-like plastics to hard, rigid structures depending on their intended use.


Exposure to seawater makes the plastics degrade via hydrolysis into non-toxic products, according to the scientists. Depending on the composition of the plastics, these compounds may include water, carbon dioxide, lactic acid, glycolic acid, succinic acid, caproic acid and L-lysine, all of which can be found in nature. Because the new plastics are denser than saltwater, they have a tendency to sink instead of float, a feature that could prevent them from washing up on shore and polluting beaches.


Website: www.sciencedaily.com

Method for recycling expanded polymers

Xerox Corporation of the United States has been awarded a patent on a process for recovering thermoplastic polymer particles from an expanded thermoplastic polymer material. The process provide cost-effective mechanical compacting of expanded polymers, particularly expanded polystyrene, and eliminates the use of solvents in compaction and the problems associated with such solvents.


The process includes grinding the expanded thermoplastic polymer in a grinding chamber under elevated temperature in the presence of hot air and ionized air. The polymer of is recovered in particle form, and is suitable for reuse in manufacturing recycled products.


The invention uses only mechanical procedures for recovering the polymer material, and thus avoiding the use of solvents associated with chemical procedures, which give rise to other environmental problems.


Website: www.freepatentsonline.com

ELECTRONIC WASTES

Metal separators for e-scrap recycling

O.S. Walker, the United States, supplies magnetic and eddy current separators for use in recycling e-scrap. The Walker R Series permanent rare earth magnetic separators have an extremely powerful magnet, light weight and low cost. Magnets are available for use over 24, 30, 36 and 48 wide conveyor belts. These permanent magnet units provide field intensities that are equal or superior to conventional electro-magnetic separators with reduced energy costs.


The Walker 16 Series high-power eddy current separator is designed for the removal of smaller conductive metals from e-scrap after it has been processed. The unit provides the field intensity and frequencies to effectively remove the difficult smaller particles. It is a complete integrated system with frame, belt, and variable speed drives to provide total non-ferrous metallic recovery. The unit comes in various widths for small to large capacity facilities.


Contact: O.S. Walker, Rockdale Street, Worcester, MA 01606, United States of America. Tel: +1 (508) 853 3232; Fax: +1 (508) 852 8649


E-mail: sales@walkermagnet.com


Website: www.walkermagnet.com

Winning gold by recycling PCBs

A new process of recovering metals from printed circuit boards (PCBs), developed by Professor Derek Fray from the Department of Materials Science & Metallurgy at Cambridge, the United Kingdom, is simple and more environmentally friendly than existing techniques.


The process involves dissolving the solder with fluoroboric acid (HBF4), shredding the bared boards, leaching out the copper and then burning the residue in such a manner as to catch all the bromine. The copper, tin, lead and precious metals are recovered by electro-winning. The whole process has progressed to pilot scale and has been shown to be safe to operate in a clean environment, although HBF4 is a very harsh chemical.


Website: www.eurekamagazine.co.uk

Method of recycling printed circuit board

Denso Corp. of Japan has patented a method and apparatus for recycling printed circuit boards (PCBs) to retrieve metallic component and insulating material. The method employs hot filtration equipment and resin-metal separation equipment. The waste PCB is heated and force-filtered so that only the insulating material passes through the filter. Then, the insulating material and the metallic material are separated and retrieved.


If the resin comprising the insulating material in the PCB is thermoplastic resin or its mixture with an inorganic loading material, the insulating material is recyclable using this method. In the separating and retrieving process, the multi-layer PCB is heated to a temperature that is nearly the process temperature for forming the stacked multi-layer PCBs. Therefore, the elastic modulus of thermoplastic resin would be sufficiently reduced to perform the separation and retrieval operations such as filtering.


The recycling apparatus has means for heating and exerting pressure on the PCB, and a filtering mechanism. The pressurizing means includes a drive shaft, a drive unit and a holder unit. The drive shaft has a helical rotating body, which generates a centrifugal force and a feed force to force-filter the resin. The filter is made of sintered metal and has meandering mesh holes, not a straight through hole, which would catch even long and thin needle-like metallic material.


Website: www.freepatentsonline.com

New e-waste recycling technology

Scientists in China have reported the development of a much-needed new recycling and recovery technology for a troublesome component of e-waste printed circuit boards (PCBs). In a report in ACS journal Environmental Science & Technology, Mr. Zhenming Xu and his colleagues point out that PCBs are an ideal target for recycling and reuse. PCBs are self-contained modules of interconnected electronic components deposited on the surface of an insulating board. They contain materials potentially toxic if discharged to the environment. However, PCBs also are a source of valuable metals and other materials that could be recovered.


The researchers describe tests of their process on almost a half-tonne of scrap PCBs, which showed that it is efficient and environmentally friendly. The technology involves special crushing of scrap PCBs, followed by separation of the non-metallic and metallic materials with an electric field. The technique has advantages over other processes proposed for recycling PCBs, the researchers claim.


Website: www.sciencedaily.com

PERSISTENT ORGANIC POLLUTANTS

Bacteria that degrade PCBs

In the United States, researchers have identified a group of bacteria that can detoxify a common type of polychlorinated biphenyls (PCBs). The discovery forms a first step towards a bioremediation strategy that would naturally detoxify the chemicals without risky removal of the sediments in which they persist.


A PCB expert at Rensselaer Polytechnic Institute (RPI) collaborated with microbiologists at the Georgia Institute of Technology to research microbial degradation in a common, highly chlorinated PCB mixture Aroclor 1260. Prof. Donna Bedard of RPI collected samples of PCB-contaminated sediment from the Housatonic River, Massachusetts, and found that Aroclor 1260 was indeed being degraded by native sediment microbes. She developed sediment-free enrichment cultures, and collaborated with Georgia Tech researchers to further characterize these cultures. The team was able to determine that Dehalococcoides (Dhc) bacteria were responsible for the dechlorination of Aroclor 1260. These bacteria replace the chlorine atoms in Aroclor 1260 with hydrogen, which fuels their growth and starts the PCB degradation process.


The study indicates that the Dhc bacteria active in the enrichment cultures also contribute to in situ PCB dechlorination. Once Dhc bacteria dechlorinate Aroclor 1260 to a certain level, other microbes will degrade it further and fully detoxify PCBs. Instead of taking decades, the microbes might be able to degrade the PCBs in a few years. The scientists are optimistic as they had earlier identified microbes that degrade the common solvents tetrachloroethene and trichloroethene.


Website: www.physorg.com

Removal of dioxin from municipal waste incineration fly-ash

Toxic heavy metals from fly-ash from municipal waste incineration (MWI) plants are effectively cleaned by acid wash process. However, the fly-ash would still contain dioxin and it is desirable to remove it before the fly-ash is dumped at waste sites. The Institute for Environmental and Process Engineering (UMTEC), Switzerland, has shown that dioxin from fly-ash may be removed by an innovative method called exDIOX. The product is a filter cake, largely free of mobile heavy metals as well as dioxin and other organic pollutants.


The core of the exDIOX method lies in flotation of the fly-ash. The dioxin-containing soot particles in the fly ash are separated and concentrated. This concentrate is recycled back into the incinerator, wherein the dioxin is finally destroyed. The residue is a mineral fraction that is depleted in dioxin and heavy metals. A pilot trial achieved the depletion of more than two-thirds of dioxin. A supplementary trial series further showed that dioxin concentrate is fully destroyed in the MWI.


Contact: Institute for Environmental and Process Engineering UMTEC, Oberseestrasse 10, 8640 Rapperswil, Switzerland. Tel: +41 (55) 222 48 60; Fax: +41 (55) 222 4861


E-mail: umtec@hsr.ch


Website: www.umtec.ch

Dehalogenation of pollutants

Dr. Stuart Harrad and co-workers at the University of Birmingham, the United Kingdom, have developed a new system for treating persistent organic pollutants. The researchers treated polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) with a biomass-supported palladium catalyst, and successfully removed the halogen atoms and considerably reduced their toxic effects. The work exploits the catalysed reducing power of biomass materials for dehalogenation, a less problematic system than the common zero-valent metal catalysts which produce harmful metal ions.


Website: www.rsc.org

Minimizing dioxin emissions from MSW thermal treatment

The combustion of wastes has very significant benefits in reducing the volume of waste materials and producing energy. However, combustion processes produce emissions, and these must be below the Best Practical Means (BPM) specified legislative limits. Researchers at the Department of Chemical Engineering, Hong Kong University of Science and Technology, have developed a method that integrates combustion of municipal solid waste (MSW) for cement production with minimized emissions.


Several wastes, such as tyres and meat meal, have been successfully combusted in cement kilns, up to 20 per cent w/w, while maintaining emission standards below the BPM limits. The introduction of large quantities of MSW into cement kilns is not practical because the additional kiln volume required is too great, the large amounts of ash generated will affect the cement clinker quality, and it would be difficult to sustain the needed very high clinkering temperature of 1,500C with large quantities of low calorific value MSW. A novel process the Co-Co process developed by the researchers integrates MSW combustion with the cement production in a synergistic fashion.


This process combines the cement front-end calcination reaction with a high-temperature (1,200C) combustion process, providing a giant acid gas scrubber. A pilot plant was designed, constructed, and operated to demonstrate the benefits of the Co-Co process. The pilot plant achieved emissions minimization: dioxins were typically 0.5-1 per cent of the European BPM limits, HCl, SOx, NOx, and particulates were 15, 10, 20, and 25 per cent of BPM limits, respectively. Heavy metals were typically below 25 per cent of BPM limit values.


Website: www.pubs.acs.org

Decomposition and removal of dioxins from sludge

Kubota Corporation of Japan has received a United States patent on a process for decomposing and removing dioxins from sludge. In the process, the sludge to be treated is first slurried and ultrasonic radiation is applied to the slurry. The reaction field developed by the ultrasonic radiation decomposes dioxins in the sludge and transfers pollutants from a solid phase to a liquid phase of the slurry. This is then followed by separation of the slurry into liquid phase containing the pollutants and solid phase free from dioxins.


The sludges that can be treated by this process include raw sludge, thick sludge, dewatered sludge and mixtures thereof. The sludge is imparted with a proper fluidity by the slurrying. The ultrasonic radiation creates, disperses, expands and crushes cavitation bubbles in the slurry, thereby developing a reaction field at very high temperature and a pressure. The reaction field decomposes dioxins contained in the sludge.


In the reaction field, hydrogen, oxygen, nitrogen and hydroxyl radicals are generated, besides oxidizing compounds such as hydrogen peroxide, nitrous acid and nitric acid. These radicals and oxidizing compounds decompose dioxins and pollutants contained in the sludge. The solid-liquid separation of the treated slurry provides for sludge free from dioxins and other pollutants. A more effective treatment can be obtained by blowing an oxygen-containing gas into the slurry when the ultrasonic radiation is applied.


Website: www.freepatentsonline.com

Elimination of harmful PCBs

A team of researchers led by Dr. Lee Myun-joo at the Korea Atomic Energy Research Institute (KAERI), the Republic of Korea, has developed a new technique to process large quantities of insulating oils containing environmentally hazardous polychlorinated biphenyls (PCBs). The KAERI team used a high-density electron beam to expel chlorine ions from PCBs and change the properties of the compound. This allows the material to be recycled for further use or be incinerated without concern of environmental pollution. The methods developed by the research team are conducted under a high-heat and high-pressure environment, and can process large quantities of the insulating oil in a relatively short period of time.


Website: www.english.yonhapnews.co.kr

Process for treating dioxin-containing exhaust gas

Toda Kogyo Corporation of Japan has secured a United States patent on a process that treats a dioxin-containing exhaust gas from incineration facilities and inhibits, using a composite catalyst, the generation of dioxin downstream. The catalyst consists of an iron compound (iron oxide or iron oxide-hydroxide particles), an acid gas neutralizing agent and optionally, an activated carbon.


The amount of iron compound catalyst added is 0.01 to 2.5 per cent by weight based on the weight of dry wastes incinerated per hour. The iron oxide or iron oxide-hydroxide particles have an average particle size of 0.01-2.0 m, a phosphorus content of not more than 0.02 per cent by weight based on the weight of the particles, a maximum sulphur content of 0.6 per cent by weight based on the weight of the particles and a sodium content of not more than 0.5 per cent by weight based on the weight of the particles.


Website: www.freepatentsonline.com

INDUSTRIAL WASTEWATER

Common effluent treatment plant

The Ranipet Common Effluent Treatment Plant (CETP) at Ranipet, a town about 120 km from Chennai, is a successful facility catering to the needs of 76 tanneries in the area. The effluent from these tanneries is transported to the treatment plant through a system of pumping stations, pressure and gravity mains. The CETP has a designed capacity of about 4,000 cum/day of effluent, making it one of the largest such plant for tannery wastewater in the country.


The tannery effluent flows through a mechanized bar rake screen to the receiving sump, from where it is transferred to the pre-settler units, for removal of coarse solids. The overflow from this unit is passed through a rotary fine screen before discharge into the equalization tank. The effluent from the equalization tank is chemically treated with lime (calcium oxide) and alum (aluminium potassium sulphate) in a flash mixer and polyelectrolyte is added in the baffle channel to facilitate coagulation and flocculation of solids. A pH of 8.5 to 9.0 is maintained in the primary clarifier to precipitate chromium (Cr3+) as its hydroxide. The primary treatment removes 65-70 per cent of suspended solids and 40-45 per cent of BOD, besides precipitating most of the chromium.


The overflow from the clarifier is further treated using an extended aeration-type activated sludge process with diffused aeration system. The outflow from the clarifiers has a BOD of around 30 mg/l. To further improve the effluent characteristics and colour, the effluent is passed through pressure sand filters and activated carbon filters after the addition of alum and polyelectrolyte in the flash mixer and flocculation in the flocculator. The treated water will be recycled back to the member tanneries as process water. The sludge from the clarifiers is discharged to the sludge drying beds or to the mechanical centrifuge for dewatering. The backwash effluent from the filters is discharged back into the receiving sump. The dried sludge is disposed of in landfill.


Contact: Mr. I. Sajid Hussain, Plant Manager, Ranipet Tannery Effluent Treatment Co. Ltd., Common Effluent Treatment Plant, V.C. Mottur, Vannivedu, Walajah, Vellore, Tamil Nadu 632513, India. Tel: +91 (4172) 570529; Fax: +91 (4172) 274812


E-mail: isajidh@rediffmail.com


Website: www.waterandwastewater.com

Photocatalyst for decolourization of textile dye effluent

In textile dyeing process some auxiliary compounds, such as organic acids, fixing agents, surfactants, defoamers, oxidising/reducing agents and diluents, are added in the dyeing solution, which results in dye effluent with complex composition. Scientists from Victoria University and Deakin University in Australia studied nano-structured titanium dioxide (TiO2) as a photocatalyst for effectively degrading aqueous dye compounds by photocatalytic oxidation (PCO) in the presence of ultraviolet (UV) rays. The photocatatlytic decolourization of highly concentrated dye effluent was investigated using TiO2 as a photocatalyst in the presence UV-B. The researchers found that the process can achieve the optimum rate of decolouration in test conditions.


The experimental results indicated that eight dyeing wastes added with different auxiliaries could be de-graded at different efficiencies. The decolourization degree of wool dyeing wastes would depend on both types of dyes and auxiliaries in the solutions. Study on the influence of two common auxiliary compounds Cibaflow Cir and Albegal B in the PCO degradation of dyeing solutions indicated that colour removal for Lanasol Blue CE with Cibaflow Cir can reach 78.0 per cent compared with 28.9 per cent removal for Lanasol Blue CE with Albegal B after 3 hours of PCO degradation. This result could help design PCO process for degradations of dyeing effluent.


Website: www.apnf.org

Novel catalyst for wet oxidation of industry wastewater

Wastewater from chemical, paper, dyeing, pharmaceutical and petrochemical industries contains non-degradable chemical compounds, which makes it difficult to treat the wastewater using a traditional process. Wet oxidation is a technique that oxidizes organic matter using oxygen in atmospheric phenomena as an oxidizing agent under high temperature (125-320C) and pressure (0.5-20 MPa). However, the use of a catalyst could ease the requirement for such a high temperature and pressure. Researchers at the Korea Advanced Institute of Science and Technology (KAIST), Republic of Korea, studied catalyst-assisted wet oxidation with a solid Ceria-Zirconia composition, which has excellent oxygen storing ability, as the catalyst carrier.
 

Phenol, which is very toxic and is a middle product in oxidation reaction of carbon compounds, was used as a model reactant to calculate the catalysts reaction activity. The 45 minutes of catalysing reaction fully eliminated phenol, confirming the high reactivity of the catalyst (such as manganese) on Ceria-Zirconia carrier. The KAIST team also found that this catalyst formulation takes less time to complete the phenol oxidization reaction than traditional formulation that use alumina or titania carrier.


Contact: Korea Advanced Institute of Science and Technology, 335 Gwahangno, Yuseong-gu, Daejeon 305-701, The Republic of Korea. Tel: +82 (42) 869 3915; Fax: +82 (42) 869 2114


E-mail: skihm@kaist.ac.kr


Website: www.apec-vc.or.kr


Denitrification plant for pharmaceutical wastewater

The Industrial Solutions & Services Group (I&S) of Siemens, Germany, has supplied the design and equipment to Degussa (China) Co. for a denitrification plant for treating the wastewater from L-methionine amino acid production. L-methionine production generates various types of wastewater containing carbon and nitrogen compounds. The I&S denitrification plant can treat 300,000 cubic metres of wastewater per year to the officially required discharge standards.


The expanded denitrification plants concept is based on a flexible two lane, cascaded bioreactor that can be connected in parallel or series, and can be run with variable gassing zones. The secondary clarification, to separate the biomass from the purified wastewater, has been implemented in the form of vertical flow round separators, and there is also a special facility for aerating the wastewater with fine bubbles.


The excess sludge produced by the biological purification is homogenized, concentrated and physico-chemically conditioned to enhance the dewatering characteristics of the sludge suspension. This is then mechanically dewatered using a chamber filter press. The dewatered sewage sludge is alkalinized with caustic lime to prevent further biological activity, and made ready in the storage area to be taken away for disposal.


Website: www.pennnet.com

Decolourization of dye industry effluent by mildew

Researchers at the Key Laboratory of Industrial Biotechnology, China, evaluated the ability of Aspergillus fumigatus XC6 strain, isolated from mildewing rice straw, to decolourize a dye industry effluent. The strain was capable of decolourizing the effluent over a pH range of 3.0 to 8.0, with the dyes as sole carbon and nitrogen sources. The optimum pH was found to be 3.0; however, supplemented with either appropriate sources of nitrogen (0.2 per cent NH4Cl or NH42SO4) and carbon (1.0 per cent sucrose or potato starch), the strain decolourized the effluent completely at the original pH of the dyes effluent. A. fumigatus XC6 is, therefore, an efficient strain for decolourizing effluents with reactive textile dyes, and it might be a practical alternative in the treatment of dyeing wastewater.


Contact: The Key Laboratory of Industrial Biotechnology, Ministry of Education, Southern Yangtze University, Wuxi 214 036, China.


E-mail: xchjin@yahoo.com.cn


Website: www.ncbi.nlm.nih.gov

Degradation of ionic liquids

Ionic liquids are widely regarded as a greener alternative to many commonly used solvents. Nonetheless, concerns about their toxicity have raised questions about their use in large-scale industrial applications, particularly those that involve the creation of large amounts of waste. Researchers from the South China University of Technology, China, and University of Reading, the United Kingdom, studied ultrasound irradiations effect on solutions of hydrogen peroxide, acetic acid as well as dialkylimidazolium-based ionic liquids. Dialkylimidazolium groups broke down to the non-toxic biurea and acetoxyacetic acid. We have studied many degradation processes, explained team member Mr. Xuehui Li, and so far, this is the most efficient. However, we think that this can be improved by using a catalyst, and we are now investigating possible catalysts that may enhance the degradation process.


Website: www.rsc.org

Low-cost technology for industrial effluent treatment

A joint Bangladesh-Canada project the Bangladesh Environmental Management Project (BEMP) has invented a sustainable technology for the treatment of industrial waste discharges, particularly from the textile and dyeing industries. The method, which employs minimum machinery to separate dyeing sediments and liquid wastes from the fabrics dyeing mills, is also proved to be environment-friendly apart from being a cheaper-than-hi-tech technology of waste treatment. According to BEMP Director Mr. Syed M. Iqbal Ali, the main features of the technology include:
 
  • Demonstration of good housekeeping practices;
     
  • Waste minimization through reuse of dyes and chemicals;
     
  • Process modification, pre-treatment of effluent and settling;
     
  • Treatment of pre-treated effluent through a reed bed; and
     
  • Management of sludge in environmentally sound manner.
     

In this process, liquid textile waste is filtered through several layers to achieve separation of a large portion of dyeing chemicals. BEMP sources report that 75 per cent of the fresh dye solution used in dyeing could be recovered for potential reuse. Then the flow of wastes is pressed to enter into a reed bed, a constructed wetland of several layers consisting of brick chips, sand, tiny stones and soil, on top of which selected vegetation is cultivated. It was found that some typical wetland vegetation in Bangladesh like Phragmites, Murta and bamboo are highly suitable for absorbing soluble contaminants from the reed bed with at least three feet deep cluster roots. Later, the reed bed drains clean water in the opposite direction to that of the incoming polluted water. The filtered sediment is burnt carefully to make sludge, which can be used in making bricks after mixing with mud or cement.


Website: www.news.xinhuanet.com


Pharmaceutical wastewater treatment

Zenon Environmental Inc., Canada, offers ZeeWeed membrane bioreactors (MBRs) for effective and reliable treatment of pharmaceutical wastewater (PWW). PWW can be very high in mixed liquor suspended solids (MLSS: 10,000-20,000 mg/litre) and chemical oxygen demand (COD: 2,000-4,000 mg/litre). It can also have high ammoniacal nitrogen loads, with up to 1,000 mg/litre total Kjeldahl nitrogen (TKN). Normally, conventional physical, biological and chemical treatment methods are used to process PWW prior to discharge into sewer or directly to the environment. Depending upon location-specific consent, the effluent will normally have to be reduced to a COD of 100-1,000 mg/litre and less than 10 mg/litre ammonia. ZeeWeed MBR technology provides a cost-effective PWW treatment solution with proven effectiveness, with a consistently high-quality effluent that can reliably meet demanding discharge consents.


ZeeWeed MBR eliminates multiple process steps of conventional activated sludge (CAS) treatment systems by combining clarification, aeration and filtration into a single process step. Durable reinforced hollow fibre membranes are specifically designed to operate in a high-solids environment, and to produce near-drinking water quality effluent in a fraction of the space and time of CAS systems. This highly automated and versatile technology can be retrofitted into existing plants to upgrade capacity and performance or completely replace a system in a new plant.


Contact: Zenon Environmental Inc., 3239 Dundas Street West, Oakville, Ontario L6M 4B2, Canada. Tel: +1 (905) 465 3030.


Website: www.processingtalk.com

Decolourization of triphenylmethane dye-bath effluent

The Department of Civil Engineering, Guru Nanak Dev Engineering College, India, has investigated the decolourization of a simulated dye waste containing three different triphenylmethane dyes magenta, malachite green and crystal violet in a laboratory scale, two-stage, anaerobic reactor. The effect of various parameters (dye concentration, hydraulic and co-substrate loading rates) on colour and COD removal efficiency of the reactor was studied.


It was shown that the dye concentration had little effect on overall COD and colour removal efficiency. Higher than 99 per cent colour removal and 96 per cent COD removal efficiency were maintained even at a dye concentration of 500 mg/litre and a dye loading rate of 1,000 mg/litre/day.


A minimum level of glucose as supplementary carbon source is, however, required to maintain the maximum colour removal efficiency, which drops appreciably when no glucose is added to the influent. The study also showed that the acidogenic phase of the reaction plays an important role in decolourization of triphenylmethane dyes. In addition, the two-stage anaerobic reactor was observed to have distinct advantages over the single-stage system, as the drop in colour and COD removal efficiencies of Stage 1 was adequately compensated by Stage 2 of the reactor.


Website: www.ncbi.nlm.nih.gov

BIOREMEDIATION

Biodegradation of cyanide and complex cyanides

Industries like paint, polymer, electroplating, pharmaceuticals, steel, chemicals and mining tend to produce wastes and wastewaters with high cyanide content. Oxidation with hypochloride is the most common treatment for cyanide-containing wastes and wastewaters. However, this generates significant amounts of chlorinated organic compounds as by-products. Other methods like oxidation with hydrogen peroxide monopersulphate or ozone, precipitation, UV-oxidation and electrolysis are inefficient and expensive.


Biodegradation is a possible alternative: transform cyanide by assimilating or oxidizing it. But cyanide assimilation generates thiocyanate, amino acid derivatives and nitriles, while cyanide oxidizing systems are dependent on molecular oxygen and co-enzymes like NAD(P)H. Scientists at Fraunhofer IGB, Germany, have isolated a new bacterium, with a cyanide hydrolysing enzyme, from an abandoned coal gasification site under oxygen and nitrogen limited conditions.


Bacterium KS-7D is highly tolerant of cyanide up to concentrations of 1.4 g/litre. No toxic effect is visible up to a concentration of 6.5 mg/litre. Cyanide at concentrations higher than 6.5 mg/litre is degraded by KS-7D without bacterial growth, until the cyanide concentration falls below 6.5 mg/litre and bacterial growth begins. Exponential growth needs an additional source of carbon and energy like fructose, several organic acids, phenols and other aromatic compounds. The highest turnover rate for cyanide was observed at pH 7.5-8.5 and temperature 30-40C. Furthermore, KS-7D is able to degrade complex cyanides like ferrocyanide, ferricyanide and even prussian blue, one of the most stable metal complex compounds.


KS-7D can be cultivated easily in mass culture and the cyanide hydrolase activity may be induced in the stationary growth phase. As it is a microaerophilic organism and no oxygen is required for the cyanide degradation, it may be applied to water treatment systems without any aeration. KS-7D is easily immobilized and readily forms biofilms at solid surfaces. Therefore, it is well suited for applications in bio-filters, bio-washers or bio-trickling-filter systems.


Contact: Fraunhofer Institute for Interfacial Engineering and Bio-technology - IGB, Nobelstrasse 12, 70569 Stuttgart, Germany. Fax: +49 (711) 9704 200


E-mail: info@igb.fraunhofer.de


Website: www.igb.fraunhofer.de

Bioremediation process utilizing in situ soil washing

University of Tennessee Research Corporation, the United States, has patented a treatment process for the on site purification of soils contaminated with polychlorinated biphenyls (PCBs). New strains of micro-organisms, which have the capabilities for growth on surfactants and degradation of PCBs, are employed in combination with soil washing for soil bioremediation. Soil to be treated is washed with a surfactant to solubilize the hydrophobic contaminants. The surfactant solution is then treated in a bioreactor with the micro-organisms. As the surfactant is degraded, the residual desolubilized contaminants are adsorbed onto an inert substrate, which is removed from the effluent and can be recycled to the bioreactor.


Website: www.freepatentsonline.com

Novel perchlorate remediation methods

Locus Technologies Inc., the United States, is one of the leading firms in the application of advanced solutions to address perchlorate contamination issues. A project includes several phases carefully planned to ensure a high level of data quality to differentiate between natural and anthropogenic sources. The groundwater study includes a determination of historical groundwater gradient directions to identify potential background areas and selected aquifer depths not affected by human activities. This is followed by well sampling and data interpretation. Statistical data analysis and chemical forensic evaluation form part of project implementation.


In an innovative remedial application, Locus treated soil from a contaminated site using a closed-loop bioreactor (CLB) air circulation system that induces an on site closed loop system with a continual circulation of nutrient-rich vapour through the affected media. The CLB combines technologies to promote and maintain an engineered biodegradation environment. At the start of the process, the technology uses a surface bioreactor to initiate the formation of degrading bacteria at the surface operation location. This small bioreactor enhances moisture, nutrients and associated co-metabolites to accelerate the growth of indigenous bacteria, which are then capable of destroying perchlorate constituents.


The process employs a system of blended humic, fulvic and acetic organic nutrients to accelerate the growth and degradation characteristics of indigenous bacteria. As delivery of the nutrient train is via moist vapour in the closed vapour loop and not liquid, the potential for vertical leaching of perchlorate is greatly reduced. The project demonstrated a >99 per cent removal of perchlorate from the soil.


Contact: Locus Technologies, 299 Fairchild Drive, Mountain View, CA 94043, United States of America. Tel: +1 (650) 960 1640; Fax: +1 (650) 960 0739


E-mail: Info@locustec.com


Website: www.locustec.com

Advanced and rapid soil remediation

Hydrocarbons such as fuels, oils, grease, solvents, coolants and lubricants are the common types of contaminants in industrial applications. Typically, standard bioremediation of soils contaminated with hydrocarbon takes approximately 18 months. Virotec International, Australia, employs ViroSoil technology to speed up soil remediation. ViroSoil technology makes use of rapid sequestro-degradation (RSD), an advanced form of bioremediation, which typically reduces the time taken to destroy hydrocarbons in soil by up to 50 per cent.
Unlike standard methods, including the more costly thermal desorption methods, RSD permanently binds heavy metals while eliminating hy-drocarbons in soil. To assist and enhance the natural processes and significantly increase the rate of degradation of the contaminant, an inoculum of natural petrophilic bacteria is required to rapidly proliferate. Piles of soil are aerated using an excavator and irrigated regularly to provide the optimal growth conditions to enzymes and microbes.
ViroSoil Technology absorbs hydrocarbons between 6-10 times its own weight, and bioremediates it using a naturally derived product from a totally renewable source. It leaves surfaces dry and residue-free, does not release hydrocarbons on compaction, does not leach, decreases the amount and hazardous nature of waste, and offers multiple treatment and safe disposal options.


Website: www.ferret.com.au

Anaerobic bioremediation technology

Bercan Environmental Resources Inc., Canada, develops anaerobic/aerobic facultative bio-remediation technologies. The firm also manufactures, using such technology, bioremediation formulas, biosonic filters.


Bercans Biocat is the only known broad-spectrum anaerobic facultative product on the market today. This is a naturally occurring dehydrated blend forming a biosynthesis based on individual combinations of aerobic and anaerobic bacteria, broad range enzymes, and a rich nutrient base acting symbiotically with the ecosystem to rapidly digest organic wastes. Biocat provides only half of the reactive process, the other half coming from the existing micro-organisms in the organic waste. In combination, these control the anaerobic digestion and reduce or eliminate the hydrogen sulphide odour.


Contact: Bercan Environmental Resources Inc., No. 6645 Elm Road, Lantzville, British Columbia, V0R 2H0 Canada. Tel: +1 (250) 390 3113; Fax: +1 (250) 390 2312


E-mail: candlshb@cadvision.com


Website: www.strategis.ic.gc.ca

Phase transfer remediation technology

Ivey-sol technology, from Canadas Ivey International Inc., eliminates petroleum hydrocarbons (such as petrol, diesel and fuel oil) and polycyclic aromatic hydrocarbon (PAH) contaminants from groundwater, soil and bedrock. Ivey-sol technology is a phase transfer process that works at the molecular level, separating petroleum hydrocarbons and PAHs. Proprietary biodegradable mixtures are used to increase the solubility of the contaminants, making them easier to liberate, recover and treat on-site.


Ivey-sol technology incorporates designed phase transfer mixtures that interact with a specific class or type of organic contaminants. The contaminants are liberated and encapsulated, allowing for their rapid recovery at an on-site pumping well. The encapsulated hydrocarbons called micelles vary in size and composition and make the contaminants water-soluble.


Ivey-sol guarantees an increase in the rate of contaminant recovery. The clean-up times are shortened and project costs are dramatically reduced. More of the contaminated material can be recovered easily. This reduces the need for costly and extensive soil excavation.


Contact: Ivey International Inc., P.O. Box 706, Campbell River, British Columbia, V9W 6J3 Canada. Tel: +1 (250) 923 6326; Fax: +1 (250) 923 0718


E-mail: canada@iveyinternational.com


Website: www.strategis.ic.gc.ca

AIR POLLUTION CONTROL

New catalyst for denitrification of diesel engines fumes

A novel catalyst could assist auto makers to eliminate 95 per cent of nitrogen oxides (NOx) from diesel engine exhausts, at the same time saving energy. The catalyst, developed by the United States Department of Energys Argonne National Laboratory (ANL), is one of a family of related catalysts that also shows promise for reducing emissions of NOx from industrial sources, such as coal-fired power plants and furnaces at chemical plants.


According to Dr. Chris Marshall of ANLs Chemical Engineering Division, Our most promising catalyst for diesel engines is Cu-ZSM-5 with an external coating of cerium oxide. Cu-ZSM-5 is a zeolite a common catalyst used in petroleum refining doped with copper.


Those working previously with Cu-ZSM-5 and similar catalysts, he said, had found that they performed poorly at removing NOx from diesel exhaust. They need temperatures higher than normal exhaust temperatures and dont work well when water vapour is present, which is almost always the case in engine exhausts.
Our new cerium oxide additive, Dr. Marshall said, is the breakthrough that makes it work. When it is combined with Cu-ZSM-5, the resulting catalyst works at normal exhaust temperatures and is actually more effective with water vapour than without it. With a lean fuel-air mixture, it removes as much as 95-100 per cent of NOx emissions. ANLs new catalysts also avoid the problems associated with ammonia that competing catalysts generate.


Contact: Dr. Christopher Marshall, Chemical Engineering Division, Argonne National Laboratory, #9700 S. Cass Avenue, Building 205, Argonne, Illinois, IL 60439-4837, United States of America. Tel: +1 (630) 252 4310


E-mail: marshall@cmt.anl.gov


Website: www.cmt.anl.gov

Adsorption type hybrid recovery unit to reduce VOCs

A non-discharge technology developed by Segye Chemical Co., the Republic of Korea, employs an adsorption type hybrid recovery unit to reduce the total amount of volatile organic compounds (VOCs) in exhausts at low cost and high efficiency. The technology is suitable for middle- and small-sized emission sources, and it uses the selective adsorption method to remove moisture flowing in along with the VOCs (such as toluene) from air before treating them. While VOCs are being adsorbed and removed, the clean air is exhausted. A small quantity of high-density VOCs generated in the desorption process is compressed, condensed and collected.


An experiment found that the proportion of toluene content in the entire amount of desorbed compounds converted and collected in the adsorbing tower is 99.7-99.9 per cent, and the total recovery rate is about 99.5 per cent. The conversion and collection of acetone is 99.0-99.8 per cent when using the equipment. The new adsorber can collect anhydrous VOCs in their liquid state. The equipment, when commercially produced, is expected to cost about US$100,000 (capacity 1,000 m3/h), while comparable systems made in Japan cost about 45 times more.


Contact: Segye Chemical Co., Ltd., Kyungnam 626110, Republic of Korea. Tel: +82 (55) 385 4211; Fax: +82 (55) 384 4128


E-Mail: goodsale@newchem.co.kr


Website: www.apec-vc.or.kr

Using microalgae to eliminate CO2 emissions

Scientists led by Mr. Gabriel Acin at the University of Almeria, Spain, are carrying out a research project to develop new systems that use microalgaes photosynthetic activity to eliminate carbon dioxide (CO2) emissions. On the pilot plant developed at the experimental station of Las Palmerillas, Almeria scientists are trying to prove the validity of this new technique for eliminating CO2 emissions.


The mechanism is easily explained. Water tanks at gas emission points retain the pollutant gases resulting from an industrial process. This polluted water would go through bioreactors that have microalgae culture where the CO2 emissions would get transformed into vegetal matter and oxygen through photosynthesis process. This system also offers the added value of the resulting materials, in addition to purified air the organic matter obtained could be reused as fuel for biomass plants, transforming it into biofuel through fermentation, or as manure.


Website: www.sciencedaily.com

Hydrogen chloride removal system

The Kawasaki Lime Moving Bed hydrogen chloride removal system (KALM system), devised by Kawasaki Heavy Industries Ltd., Japan, is completely dry type cross-flow moving bed system that removes acid gas constituents effectively from the combustion exhaust gas. The quick lime (calcium oxide) filled in the moving layer removes hydrogen chloride and sulphur oxides as per the following reaction formula.
CaO+2HCl CaCl2+H2O
CaO+SOx CaSOx


As this technology does not use water, white smoke is not generated and calcium ion accumulation does not occur. When it is installed downstream of the dust collecting device, reaction products can be separated from fly-ash, ensuring remarkable utilization. The technology is suitable when the exhaust gas temperature is 200 to 300C, and the required hydrogen chloride removal is less than 50 ppm and sulphur oxide less than 10 ppm (in case of municipal solid waste incineration plant).


Website: www.gec.jp

Semi-dry type system for acid gas removal

Takuma Co., Japan, fabricates and erects semi-dry type systems for removing hydrogen chloride (HCl) and sulphur dioxide (SO2) from exhaust streams. In Takumas system, hydrated lime (calcium hydroxide) slurry is injected into a quenching reactor to reduce the gas temperature and to neutralize the acidic gases contained in the exhaust. Hydrated lime powder is injected into a dry Venturi to enhance pollutant removal. The bag-house (fabric filter) is designed to allow the formation of a thick dust cake layer on its surface. As the exhaust gas passes through the bag-house, the unreacted hydrated lime contained in the cake layer contacts and reacts with the acid gas in the exhaust, thereby improving removal effect.
The chemical reaction formulae are as follows:
2HCl + Ca(OH)2 CaCl2 + 2H2O
SO2 + Ca(OH)2 CaSO3 + H2O
CaSO3 + (l/2)O2 CaSO4


The treatment removes 90-98 per cent of HCl and 80-95 per cent of SO2. Mercury elimination efficiency is 50-70 per cent. The removal performance of the equipment is largely dependent on the gas temperature at the bag-house the temperature has to be controlled very precisely by spraying hydrated lime slurry in the quenching reactor. At lower gas temperatures, higher amounts of HCl and SO2 are removed. The system can be built to any capacity.


Website: www.gec.jp

Adsorbent for nitrogen oxides

Calixarenes are bowl-shaped macrocyclic organic molecules that can trap guest molecules within their cavity. These molecules can adsorb nitrogen oxides (NOx), making it potentially useful for both storage and sensing applications. In the United States, researchers at the Pacific Northwest National Laboratory and the University of Missouri-Columbia are working to develop gas storage, separation and sensing materials based on calixarenes.


The scientists made a low-density form of p-tert-butylcalix[4]arene that can adsorb gases such as carbon dioxide and methane, and showed that NOx can be trapped inside this calixarene. When the calixarene crystals are exposed to NOx, they change colour because of a charge transfer complex formed. This implies that the calixarene might also be useful for detecting NOx in the presence of other gases. Development of improved NOx sensors will enable better control of the combustion process in power plants and even automobiles to help minimize NOx emissions.


Website: www.rsc.org

Removal of harmful gases by fibrous ion-exchangers

Encoco Co., the Republic of Korea, has developed a technology that uses the physical and chemical properties of fibrous ion-exchangers to adsorb acidic or alkaline substances to remove odour and harmful gases. Radiation (g-ray) is applied to form radicals on polypropylene non-woven cloth. Then graft polymerization is executed through fibrous adsorbing agents manufactured to exchange and adsorb acidic and alkaline.


Odorous and harmful gases collected from sources are transmitted into ion exchange scrubbers. The contaminants are removed while the gases pass through many cartridges of fibrous ion-exchangers, which are positively and negatively charged, according to the type of contaminant. Results of ammonia analysis revealed that the technology features a removal efficiency of 99.4~99.8 per cent for a positive ion exchanging scrubber in which the maximum inflow concentration is 200~248 ppm.


Contact: Encoco Co. Ltd., Republic of Korea. Tel: 82 (31) 659 0751


E-mail: dwkim@encoco.co.kr


Website: www.apec-vc.or.kr

PUBLICATIONS

Southeast Asian Solid Waste Recycling Markets

This Frost and Sullivan research report provides an overview of the forecasts of the solid waste recycling markets, along with a complete analysis of drivers, restraints, and market trends that are influencing the revenues of these markets. In this report, expert analysts present a thorough examination of the following markets: electronic (e-waste) recycling, industrial waste recycling, commercial waste recycling, and domestic waste recycling.


Contact: MindBranch, Inc., 131 Ashland Street, Suite 200 North Adams, Massachusetts, MA 01247, United States of America. Tel: +1 (413) 662 3700; Fax: +1 (413) 664 9791


E-mail: support@mindbranch.com

EPR: Sustainable Solution to Electronic Wastes

Extended producer responsibility (EPR) is an emerging principle for a new generation of pollution prevention policies. It imposes accountability over the entire life-cycle of products and packaging introduced in the market. This document discusses in details the policy instruments that embody the EPR principle. It essays the initiation of EPR and then talks on EPR programmes around the world with special emphasis on the EPR for electronic waste.


Contact: Toxics Link, H2 (Ground Floor), Jungpura Extension, New Delhi 110 014, India. Tel: +91 (11) 2432 8006; Fax: +91 (11) 2432 1747


E-mail: tidelhi@toxicslink.org

Feedstock Recycling and Pyrolysis of Waste Plastics

This publication provides an overview of the science and technology of pyrolysis of waste plastics. This book describes the types of plastics that are suitable for pyrolysis recycling, the mechanism of pyrolytic degradation of various plastics, characterization of the pyrolysis products and details of commercially mature pyrolysis technologies. The book also covers co-pyrolysis technology, including: waste plastic/waste oil, waste plastics/coal, and waste plastics/rubber.


Contact: Customer Service Department, John Wiley & Sons (Asia) Ltd., 2, Clementi Loop #02-01, Logis Hub@Clementi, Singapore 129809. Tel: +65 6463 2400; Fax: +65 64634604


E-mail: csd_ord@wiley.com.sg


ASIAN AND PACIFIC CENTRE FOR TRANSFER OF TECHNOLOGY

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