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VATIS Update Waste Management . May-Jun 2006

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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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VATIS Update Waste Management Oct-Dec 2016
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Ozone Layer
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Contents

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IN THE NEWS

Hazardous waste remediation market over US$11 billion

According to a new technical market research report, The Global Market for Hazardous Waste Remediation from BCC Research, the worldwide market for hazardous waste remediation technologies was worth about US$10.7 billion in 2005. It is tipped to rise to US$11.4 billion in 2006 and US$16.6 billion by 2011 at an average annual growth rate (AAGR) of 7.8 per cent.


Hazardous waste containment technologies were the largest segment of the global hazardous waste remediation market in 2005, with over 25 per cent of the market, followed by separation (19 per cent), chemical treatment (18 per cent), and recycling (15 per cent). However, recycling is the fastest-growing market segment, with AAGR projected at 19 per cent and reaching almost US$4.5 billion, approximately 27 per cent of the market, by 2011. With almost 30 patents in as many years and many remediation processes resulting in recyclable material, the substantial growth rate for reuse technology is highly probable.


Hazardous waste remediation is not only an ecological issue but an economic one as well. The equipment design and the distribution of goods and services represent an industry worth billions of dollars, generating profit for investors, shareholders, and employees with personal interest.


Website: www.solidwaste.com 

China sets green standard for electronic imports

Chinas Ministry of Information Industry (MII) has issued a regulation that prescribes a green standard for imported electronic products. The regulation, which will take effect from 1 March 2007, bans the import of e-products that do not conform to Chinas national standards on the amount of poisonous and harmful materials, which include mercury, lead, cadmium and chromium(VI).


Experts estimate that around 80 per cent of the worlds highly polluting e-products are imported to Asia, of which 90 per cent enter China, making the country a major victim of e-garbage. The regulation is meant to control pollution brought about by deserted e-products and to encourage manufacture of products with low pollution, said an MII spokesman. E-products that come under the new law include mobile phones, computers and home appliances.


Website: www.ban.org 

POP Convention comes into force in India

India deposited its instrument of ratification of the POP Convention on 13 January 2006. The Convention comes into force for India on the 90th day after the date of deposit of its instrument of ratification. Mr. Namo Narain Meena, Minister of State for Environment and Forests,have this information in a written reply to a question in the Lok Sabha.


Persistent organic pollutants (POPs) are chemicals that persist in the environment for long periods, become widely distributed geographically, accumulate in the fatty tissues of living organisms and are toxic to humans and wildlife. The Stockholm Convention on Persistent Organic Pollutants covers 12 POPs eight pesticides (aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, mirex and toxaphene); two industrial chemicals (polychlorinated biphenyls or PCBs and hexachlorobenzene) and two unintended by-products (dioxins and furans). The Convention was adopted in May 2001 and came into force on 17 May 2004.
Five new chemicals namely pentabromodiphenyl ether, chlordecone, perfluorooctane sulphonate, hexabromobiphenyl as well as lindane are being considered for inclusion by the POPs Review Committee of the Stockholm Convention. The proposed chemicals are suspected to exhibit POP characteristics.


Website: www.pib.nic.in 

Measures in China for safe disposal of medical waste

An environmentally friendly large-scale project for the safe disposal of medical waste will be carried out in China by the State Environmental Protection Administration (SEPA), the countrys environmental watchdog, with cooperation from the international community. The project will cost around US$45 million, nearly half of which will come from Global Environment Facility. The four-year project aims to reduce the production of persistent organic pollutants (POPs) during the disposal of medical waste by improving the current treatment facilities and setting up new advanced services.


According to SEPA, China now produces 1,500 t of medical waste a day and this is likely to rise in the future. Experts say if SEPA does not consider reduction of POPs, it may lead to a serious pollution risk, especially in levels of dioxin. Currently, Chinas treatment facilities mainly use combustion methods. However, most of the countrys 171 incinerators for medical waste do not reach the correct standards for pollution control, according to Mr. Wu Shunze of the Chinese Academy for Environmental Planning.


For solving the pollution problem, the State Council entrusted SEPA and the National Development and Reform Commission with the compilation of the Hazardous Waste and Medical Waste Treatment Facility Construction Plan. Although we now have regulations on how to treat medical waste, there are still many difficulties since the plan is not very practical or complete, opined Mr. Wu Yinghong from the Ministry of Health.


Website: www.english.people.com.cn

Philippines heightens war against garbage

Mr. Michael Defensor, Environment and Natural Resources Secretary of the Philippines and the Chairman of the National Solid Waste Management Commission (NSWMC), is pushing to reduce and properly manage the amount of garbage in the country. The NSWMC recently issued new guidelines on the:
 
  • Proper closure and rehabilitation of open and controlled dump sites;
     
  • Promotion and development of alternative technologies to process residual wastes;
     
  • Categorization based on waste generation of engineered or sanitary landfills; and
     
  • Establishment of an ecological solid waste management (ESWM) system.
     

Mr. Defensor directed the conduct of command conferences of all the Regional, Provincial and Community Officers of DENR and its Bureaus all over the country to brief them on the latest initiatives and practical approaches to solid waste management. At the same time, several con-sultative meetings have been held with a host of government and non-government organizations, donor agencies, the recycling industry, technology providers and consultants for formulating more responsive solid waste management strategies.


Website: www.gov.ph


Law on anvil in Pakistan to protect rivers from pollution

Several mega development projects in the agricultural water sector, especially those dealing with salinity and water logging management, that have been approved by the Ministry of Finance and the Planning and Development Division, would be put to test once again after the enforcement of a planned legislation on protection of rivers from pollution, according to a senior government official. The proposed legislation would also force the local industry and the agriculture sector not to let persistent organic pollutants into the rivers.


According to the official, there are several projects, which stand approved from the planning bodies, that have been implemented without con- sidering the environmental hazards they are to bring about. Discharging untreated sewage and industries chemical wastes directly into drains, lakes and rivers has become a habit. Water bodies can no longer cope with the increasing pollution load, said an official from the Worldwide Fund for Nature (WWF). WWFs findings suggest that 34,000 million litres of wastewater having 20,000 tonnes of pollutant chemicals are daily discharged into water bodies from the industrial sector.


Website: www.dailytimes.com.pk

Indian pollution boards to keep tab on soft drink effluent

Following the occurrence of considerable cadmium concentration in soft drink plants in the country, the Indian government has asked state pollution control boards to monitor the sludge generated by the effluent treatment units of soft drink plants. After surveying 16 soft drink plants in India, the Central Pollution Control Board (CPCB) found cadmium concentration of more than 50 mg/kg in eight plants, according to Mr. Namo Narain Meena, the Minister of State for Environment and Forests.


Other heavy metals in varying concentrations were also observed in the samples, Mr. Meena said. Consequently, the state pollution control boards have been asked to check various parameters against the limits notified in Schedule-2 of the Hazardous Waste (Management and Handling) Rules, 1989.


Website: www.newkerala.com

Low interest on waste management among Bangla industries

The Bangladesh Bureau of Statistics (BBS) in a survey report has revealed that the countrys industries last year spent for waste management only 0.11 per cent of their production expenses. An official from the Department of Environment (DoE) said the existing law has no clear-cut indication of the amount of money an industrial unit needs to spend for waste management. It just asks the industries to take care of their wastes and there is a provision for filing case for non-compliance of the law.


According to the BBS survey, the production cost of the industrial units was about US$1,365 million last year while the amount spent for environment protection activities was only about US$1.63 million. Of this, 45 per cent was spent for protection of ambient air and 31 per cent for wastewater and sewerage, and just 0.5 per cent on solid wastes.


Website: www.thedailystar.net

PLASTIC WASTES

Technology to convert polystyrene waste

Although polystyrene foam commonly known as Styrofoam has many excellent qualities that make it ideal for disposable coffee cups and convenience food packaging, it has always been difficult to recycle. As a result, most polystyrene waste ends up in landfills where it breaks down very slowly. A group of scientists has developed a microbial technology to transform the waste into a useful biodegradable plastic.


The technology was jointly developed by a group of microbiologists from the School of Biomolecular & Biomedical Sciences, University College Dublin, Republic of Ireland and pyrolysis experts from the Institute for Technical and Macromolecular Chemistry, University of Hamburg, Germany who found a way to transform materials by heating them in the absence of oxygen. The scientists carried out the pyrolysis of polystyrene in a fluidized bed reactor to produce an oil composed of 83 per cent styrene. Next, they used a special strain of a common soil bacterium, Pseudomonas putida, that could synthesize the biodegradable plastics known as polyhydroxyalkanoates (PHA). The scientists were surprised to learn that the bacteria thrived on the dirty pyrolysis oil. The strategy developed for recycling polystyrene into PHA might also work for other plastics or even batches of mixed plastics, says Dr. Kevin OConnor of University College Dublin.


Pyrolysis is an energy-demanding process and can generate hazardous wastes, which would make the process less green. However, Dr. Walter Kaminsky, with the Institute for Technical and Macromolecular Chemistry, says that one way to fuel the system would be by redistilling the crude pyrolysis oil. This cleaner styrene oil can be consumed by the bacteria, while the remaining material can be burned to produce energy for the process.


Website: www.pubs.acs.org 

Diesel from plastic waste

Envosmart Technologies B.V., the Netherlands, is planning to build 15 plants that will produce diesel fuel from plastic waste in 14 European Union countries. The first plant, to be located in Germany, will produce 38 million litres of diesel per year by processing 42,000 tonnes of plastic waste.


The technology to transform plastic waste into diesel was developed by the Australian company Ozmotech. It involves liquefaction, pyrolysis and the catalytic breakdown of plastics. The major advantage of the process is that it can handle different plastics. This facilitates the processing of mixed and contaminated plastics waste streams. The production process captures most of the polluting gases and liquids, making the diesel environmentally clean. The fuel can be used in any standard diesel engines of trucks, buses, trains, boats, heavy equipment and generators.


Website: www.planetark.com

Composites from post-consumer plastic waste

A new plastics recycling technology is set to come on stream in August in the German state of Thuringia in a plant with capacity of 3,000 tpa. The four-stage wet recycling process is similar to that used for recycling waste paper but has been adapted by CVP GmbH, Germany, to handle post-consumer plastics waste. The CVP process consists of grinding (homogenization) and washing of the plastic waste with water, grinding in a refiner to eliminate coarser particles, dewatering by centrifuge and drying to around 0.3 per cent residual moisture content.


The Grain Blend material produced in the process is expected to have a market price of around 250 per tonne ex-works. CVP expects to find applications for compounding with wood into wood plastic composites (WPC), as well as other plastic compounding applications, said managing director Mr. Michael Hofmann.


Website: www.prw.com

New plastics from old

Making the most of waste plastics is the focus of the European project Sustainable Polymers to Olefins Recycling Technology (SPORT). The fundamental approach of SPORT, led by BP plc. of the United Kingdom, is to break down waste plastics into their basic building blocks so that these can be used again.


Plastics are much more than solid oil a great deal of processing has gone into converting the oil into plastics, through refining, cracking and polymerization. By partially reversing the process through SPORTs polymer cracking technology, valuable petrochemicals could be manufactured from waste plastics more cheaply and using less energy than manufacturing them from virgin oil, while at the same time conserving valuable resources. Over the past two years, a series of technological innovations has transformed BPs polymer cracking technology into a highly energy-efficient process. However, this alone is not enough. Of equal importance is the supply chain, said Mr. Graham Rice, project leader for sustainable polymers.


SPORT is a rational green project in that its distinctive environmental, social and marketing value is built on sound economic foundations of long-term, low-cost feedstock. The aim is to decouple a portion of current polymer feedstock from the oil price, and meet the growing market demand for high-quality recycled plastics. SPORT employs closed loop recycling technology by which waste plastics are broken down, or cracked, to create virgin feedstock. The small molecules produced, such as benzene, ethylene and propylene, are easily purified to create a low-cost feedstock identical to the virgin feedstock used for the manufacture of polyethylene, polypropylene and polystyrene.


Website: www.bp.com

Automotive recycling to include plastics

A mechanical recycling technology developed at the Argonne National Laboratory (ANL), the United States, could bring some of the junked automotive material back into the marketplace. With a design capacity of up to 2 t/h on the mechanical separation system and a 450 kg/h capacity on the froth flotation system, ANLs pilot plant is the largest such facility anywhere for investigating shredder residue recovery.


At ANLs pilot plant, a bulk separation process sorts the shredder residue into four main categories. The mixed-plastics concentrate includes polypropylene, polyethylene, acrylonitrile-butadiene-styrene, poly- vinyl chloride, nylon, polyester and other plastics. The second category, polyurethane foams, includes materials that are mixed into these foams, like polybrominated diphenyl ether flame retardants. The other categories are residual metals and fines the mixture of particles smaller than 0.25 inches in diameter including iron and other metal oxides, fibres, glass and dirt. The sorted plastics-rich stream becomes the feed for a six-stage froth flotation process during which individual plastic types are extracted. The materials in the plastic polymer concentrate are mixed with a patented solution that has a combination of specific gravity, surface tension and pH that allows air bubbles to stick to one type of targeted plastic but not the others. The plastics that catch the air bubbles float, while the others sink and are moved on to the next separation tank.


So far, the process has proved successful in extracting polyethylene and polypropylene, which are the predominant plastic formulations in todays junked cars. Subsequent tests have shown that the recovered materials are of sufficient quality to be moulded into new car parts.


Website: www.pubs.acs.org

New process to recycle scrap tyres

An innovation by a British scientist may spark a renewed interest in the environment-friendly but little-used recycling process of pyrolysis and help reduce the growing mountains of scrap tyres awaiting disposal in most parts the world. Pyrolysis uses heat to break down the tyre rubber into an oil and gas, leaving a residual carbon and the steel casing of the tyre. All these are recyclable. The oil produced during pyrolysis has valuable chemical compounds such as benzene, toluene, xylene and limonene, which are widely used in the chemical industry particularly in the manufacture of rubber, insecticides, pharmaceuticals and explosives. However, the quantity of the chemicals produced by the process has not been sufficient to offset the cost of the treatment.


Dr. Paul Williams of the Department of Fuel and Energy at the University of Leeds, the United Kingdom, has produced significant increases in high-value chemical yields from the derived oil, which may add as much as 1 per tyre to the commercial value of the pyrolysis process. Dr. Williams process involves passing the gases evolved from pyrolysed tyres through a secondary catalytic reactor. This reduces the amount of oil obtained, but increases the concentration of certain chemical compounds within it by as much as 40 times in some cases.


Website: www.chemicalhouse.com

Granulators process variety of plastic parts and films

Suited for injection, extrusion and blow moulding operations, custom-built IMS Sharxx LineTM granulators enable users to reclaim and reuse plastic scrap. IMS Company Inc., the United States, offers the granulators in 10 models and 25 sizes that include beside-the-press and central models with light-, medium- and heavy-duty capacities for processing a variety of plastics: parts, film, pipe, web scraps, purging etc.


Every IMS Sharxx Line plastic granulator is custom-built to individual specifications. Customers choose from a variety of options to create a grinder to best suit each operation. IMS evaluates each customers needs with a free test run on excess plastic material supplied by the customer to recommend the size and type of granulator best suited to the operation. IMS also distributes auxiliary equipment and supplies for the plastics industry.


Contact: IMS Company Inc., 10373 Stafford Road, Chagrin Falls, Ohio 44023, the United States. Tel: +1 (800) 537 5375; Fax: +1 (888) 288 6900


E-mail: sales@imscompany.com


Website: www.news.thomasnet.com 

Recycling rubber into a multi-functional adhesive

Researchers from Universiti Sains Malaysia have developed a novel recycling process that produces a multi-functional adhesive from waste rubber. The process employs two roll mills used in conventional rubber processing and is carried out at room temperature. The low-cost process, which employs a patented chemical called DeCrossCHEM, can recycle various types of rubber wastes into a multi-functional adhesive. The adhesive is a strong contact adhesive specially formulated for bonding wood, PVC pipe, laminates, leather, cork, foam, polyurethane, rubber, etc. It is easy to apply, fast to dry, highly water resistant and can be made in different colours.


Contact: Prof. Hanafi Ismail, Universiti Sains Malaysia, 11800 Minden, P. Pinang, Malaysia.


E-mail: hanafi@eng.usm.my


Website: www.researchsea.com

Recycling abandoned plastics

Every year, the agriculture industry throws away almost as much plastic as the amount of curbside recyclable wastes. Agri-Plas Inc., the United States, is the only agricultural plastic recycling centre in the nation that collects all types of plastic types that other recyclers will not touch, like HDPE pots, pesticide bottles and polystyrene trays.


At Agri-Plas, plastics are fed into machines such as the granulator, aspirator and extruder, where they are chipped and cleaned with high-pressure air. This process prevents the wastewater discharge problematic to other recycling facilities. Agri-Plas then sells the clean plastic pellets to manufacturers who melt them into new products. Polypropylene from old nursery pots is melted and blended to make new plant containers, reducing the need for virgin material by 10-20 per cent. Baling twine formerly used to hold hay is refashioned into auto parts, while the plastic film used to cover greenis turned into plastic lumber.


Contact: Agri-Plas Systems 2000 Inc., 52 Matwood Drive, Stratford, PE, CA, C1B 1K6, United States of America. Tel: +1 (902) 569 1965; Fax: +1 (902) 569 1952


E-mail: info@agriplas.ca


Website: www.epa.gov

Rubber-plastic mix for composites

Mr. Buzz Sanderson and Prof. Alan Crosky from the University of New South Wales in Australia say that with a bit of clever processing it is possible to produce a tyre-based composite suitable for impact barriers, earth retainers and curb blisters. Not only does the composite absorb energy better than traditional materials used in these products (such as timber or concrete), but it also makes use of two under-utilized waste streams.


Tyres and plastic milk bottles are both polymers but each has quite different properties when it comes to recycling. Plastic milk bottle is high-density polyethylene (HDPE), which is a thermoplastic polymer, meaning that it can repeatedly be heated and formed. Car tyres are made from rubber, a mix of various thermoset polymers that are heated during their forming process causing their molecules to cross link, forming three-dimensional networks. As these molecules are set, they cannot be re-heated and re-formed.


The most common treatment to reuse the tyre rubber is to grind it down into crumbs, which are then used in a range of products. The crumb is often used in sports and playing surfaces, brake linings, landscaping mulch, carpet underlay, shoe soles, and as absorbents for wastes. Tyre crumb can also be recycled for use in road asphalt. The addition of rubber to thermoplastics is used to produce thermoplastic elastomers and toughened engineering polymers. However, waste car tyre is not suitable for this because the crumb size is around a tenth of a millimetre about 100-fold the diameter of the rubber particles used in toughened engineering polymers.


The process we are investigating is called Reactive Injection Moulding, says Mr. Sanderson. Basically the rubber tyre crumb is the filler and the bottle plastic is the matrix that binds the crumb together. These two materials are introduced concurrently into a moulders screw, forming a simple mix varying anywhere between 10 per cent and 65 per cent tyre crumb by weight. Dimethylol phenolic resin is added to the mix to initiate a process that would generate bonds between the crumb and plastic. Then dicumyl peroxide is added and the whole mix is heated. The resulting material is then injected into test moulds to form a range of shapes, which undergo materials characterisation in which they are examined for tension and compression, as well as to determine how good the plastic-rubber bonding is.


Website: www.future.org.au

ELECTRONIC WASTE

Gold separation and recovery from electronic waste

The Polytechnic of Milan, Italy, has developed a stable alternative approach to the established laborious and cumbersome process for recovering precious metals from several types of scraps. In the new process, the firing step for the removal of the organic fraction is substituted by a pyrolysis treatment, and gold re- covery from the leaching solution is performed by solvent extraction.


Pyrolysis leaves a residue of inorganic materials (unmodified metals, glass, mineral fillers, etc.) mixed with carbon residue (pyrolytic carbon). As leaching of gold in presence of carbon is not an easy process, it is necessary to oxidize the carbon at about 500C. At this low operating temperature, neither the metals nor the glass and inert materials melt. Thus they can be easily recovered at the end of the treatment process.


Solvent extraction of gold is based on the repartition equilibrium of metal cations between an aqueous phase and an organic one containing a quaternary ammonium salt. Gold is extracted with very high efficiency by the quaternary ammonium salt. On the other hand, stripping gold from the organic phase may be problematic due to the very high affinity of gold for the ammonium salt.


Another process step was devised, consisting in the separation of the gold carrying organic phase in two phases, one of them having a very high content of gold (about 100 g/l). The formation of the second organic phase is an event highly reproducible in the presence of some aromatic diluents. The gold-rich phase can be finally leached by the standard method.


Website: www.europeanleadfree.net

Recycling of waste from PC board assemblies

Two inventors, Mr. Ralf Jakob and Ms. Michele Melchiorre, from Daimler-Benz AG, Germany, have devised a method for recycling electronics waste in the form of disassembled printed circuit boards (PCBs) with components still in place.


After removing batteries, mercury switches and capacitors, the PCBs are mechanically pre-comminuted, and the particles are made brittle cryogenically with liquid nitrogen and comminuted in a hammer mill. The ground material, divided into a fine fraction, emerges from a sieve at the bottom of the grinding chamber. The coarser metallic fraction, from which iron particles can subsequently be magnetically removed, is discharged batchwise. The fine fraction is sorted into several narrow-band size classes with a particle size of about 1:1.6 per size class. Each individual size class of particles can be separated with corona-roller separators into residue material particles and metal particles. The latter can then be divided into different metal classes.


Website: www.freepatentsonline.com

Recycling waste printed circuit boards

Researchers from the Department of Precision Instrumentation, Tsinghua University, Beijing, China, have developed a physical process for recycling waste printed circuit boards (PCBs) as well as a process for reusing the epoxy resin recovered from PCBs. They also developed a special crusher with extra extruding, impacting and shearing forces to crush PCBs to proper granularity, as well as a cooling spray technology to reduce toxic gases and dust.


After the powdering and separation processes, more than 95 per cent of metals could be separated from non-metals. The toxic heavy metals content found in the non-metals powder was far below the allowable limit according to the national criteria. The entire recycling process is designed as a closed-loop, environmentally sound system. At present, the research on reusing recovered resin powder focuses mainly on its use as fillers for paint, construction materials, etc.


Website: www.ieeexplore.ieee.org

Recovery of silver from computer circuit board scrap

Researchers at the Department of Chemical and Materials Engineering, University of Alberta, Canada, have patented a process for recovery of silver from scrap printed circuit boards used in computers.


Silver and base metals in the scrap are dissolved in a leaching solution containing 1:2 concentrated nitric acid and water at 70C for one hour. After solid-liquid separation, the chips, intermixed with some solid flakes and oxide precipitates, are mechanically crushed to liberate the base and precious metals encased within protective plastic or ceramic coatings. The silver and base metals are dissolved by further leaching with the nitric acid solution.


The metal nitrate filtrate from the above two leach stages is treated with NaCl to precipitate an impure silver chloride, which is dissolved in an NaOH solution, and then reprecipitated as silver chloride by pH adjustment with nitric acid. Silver chloride is converted to silver oxide by selective precipitation with KOH, and silver oxide into metallic silver by a peroxygen process.


Website: www.widener.edu 

BIOREMEDIATION

Bioremediating pentachlorophenol

In New Zealand, a team of scientists studied white-rot bioremediation of aged PCP-contaminated soil, from a former timber treatment site, in engineered soil cells to develop proof-of-concept biopiles. The study examined the ability of a white-rot fungus isolate, Trametes versicolor, on PCP degradation, and the effect of fungal inoculum concentration on PCP degradation and reproducibility of the experiments. The soil cells were constructed to allow for forced aeration, irrigation, leachate accrual, and temperature and soil humidity monitoring. The need for irrigation did not arise and there was no proof of leachate. PCP degradation and fungal survival were monitored at regular intervals for 2.5 years. PCP levels decreased from a range of 800-1,000 mg/kg to 0-9.4 mg/kg according to first-order kinetics.


Website: www.clu-in.org

Acid mine drainage treatment system

Linden AMD Bioremediation project is an experimental passive treatment alternative with potential for low
maintenance, high metals reduction and the generation of alkalinity. The system comprises a big limestone-filled bed that has been inoculated with micro-organisms cultured using the Pyrolusite process developed by Allegheny Mineral Abatement Co. (AMA), the United States. This patented process employs highly selected groups of aerobic micro-organisms that grow on limestone while oxidizing iron and manganese into insoluble metal oxides.


The bioremediation process consists of several separate but interrelated systems. Mine drainage passes sequentially through a flow control system, a wetland to lower metals concentrations and provide microbial nutrients and finally through an inoculated limestone treatment bed and/or attendant discharge fixtures and diversion ditches, before being discharged to a receiving stream.


Website: www.osmre.gov

Treating polluted soil/sediment

Adventus Remediation Technologies Inc., Canada, is offering a patented bioremediation technology that uses matrix-specific solid-phase organic amendments to beneficially alter the soil or sediment structure, nutrient profile and water-holding capacity. Following homogenous distribution through the soil or sediment, DaramendTM particles become hydrated and function as aquatic microsites where native micro-organisms can grow, contact contaminants and degrade them. This allows the soil or sediment to be bioremediated more rapidly and thoroughly than would otherwise be possible.


Daramend is designed to enable rapid bioremediation of sediments or soils with high concentrations of creosote, pentachlorophenol (PCP), polycyclic aromatic hydrocarbons (PAHs), heavy oils and petroleum hydrocarbons. Daramend products are matrix-particular solid phase organic particles that are produced from natural botanical materials. Prior to field-scale treatment, the technology is optimized in the lab. Parameters that are optimized are the size, shape, nutrient content, nutrient-release kinetics as well as application rate of the


Daramend particles, running and maintenance conditions like soil water content and aeration status.
Daramend products allow for the treatment of soils with very high PCP concentrations (e.g. 2,000 mg/kg). Large quantities (>10,000 t) of soil or dewatered sediment can be treated at less than US$100/t, which compares favourably with costs of up to US$1,500/t for some alternate methods. Results have shown that after the application of Daramend, degradation of the contaminants carries on even after stoppage of active care.


Contact: Adventus Remediation Technologies Inc., 1345 Fewster Drive, Mississauga, Ontario, L4W 2A5, Canada. Tel: +1 (905) 2735 374; Fax: +1 (905) 2734 367


E-mail: info@adventustech.com


Website: www.adventusremediation.com


Website: www.oceta.on.ca

On-site treatment of sediment

National Water Research Institute, Canada, offers an on-site process for the remediation of contaminated aquatic and marine sediments. Limnofix in situ sediment treatment (LIST) utilizes specially designed equipment for injecting chemicals directly into polluted sediments, thereby enhancing bacterial activity and hence contaminant degradation. The process involves three stages:
 
  • An investigation to determine the type and concentration of chemicals essential to treat the site pollutants. This is done through bench-scale and pilot-scale tests;
     
  • A material handling system to prepare the chemical mixtures and deliver them to the injection site; and
     
  • Patented injection equipment to directly inject treatment chemicals into surface sediments.
     

Contact: Mr. Tom Murphy, National Water Research Institute (NWRI), 867 Lakeshore Road, P.O. Box 5050, Burlington, ON L7R 4A6, Canada. Tel/Fax: +1 (905) 3196 900/3368 901


Website: www.nwri.ca


Website: www.oceta.on.ca


PERSISTENT ORGANIC POLLUTANTS

Decomposition of PFOS using sub-critical water

The National Institute for Advanced Industrial Science and Technology (AIST), Japan, has succeeded in the development of an efficient method to decompose bio-accumulative and environmentally persistent and perfluorooctane sulphonate (PFOS) and related compounds to fluoride ions. PFOS shows a very high chemical and thermal stability it cannot be decomposed even if it is boiled in sulphuric acid and its long-term toxicity is a health hazard. There have been no effective methods for decomposing PFOS, except for incineration at high temperature.


AIST has achieved highly efficient decomposition of PFOS into fluoride ions by adding iron powder to water containing PFOS and taking the mixture to sub-critical water state at 250-350C. The fluoride ions produced may be recycled as a source of fluorine using an established processing method for fluoride ions. This method was successfully applied to decompose other related fluorochemicals and to decompose PFOS contained in a coating agent used in electronic industry.


Website: www.azom.com

Gamma ray induced degradation of PCBs

Lockheed Martin Idaho Technologies Company, the United States, has developed a radiation process for on-site breaking down of polychlorinated biphenyls or PCBs in transformer oils and transformers. These compounds are broken down selectively by irradiation of the object or mixture using spent nuclear fuel or any isotopic source of high energy gamma radiation. The level of applied dose needed to decompose 400 ppm of PCB in transformer oil to less than 50 ppm is 500 kilogray. Destruction of PCBs to levels of less than 50 ppm renders the transformer oil or transformer contamination-free under current regulations.


Website: www.patentstorm.us

Activated coke fixed bed system

The activated coke fixed bed system (ACFB), from Takuma of Japan, employs optimum control technology for removing of dioxins, other organic trace substances and heavy metals from flue gas. Takuma-ACFB is filled to a thickness of 800 mm with activated coke as an absorption medium. Flue gas with pollutants goes perpendicularly through the layer and get absorbed. Takuma-ACFB assures removal of dioxins to the level or below 0.1 TEQ-ng/m3N. The pollutant-laden coke is incinerated at an incinerator located upstream.
With treated gas temperature below 180C, the results observed are the following:
 
  • Dioxins removal rate of better than 99.9 per cent, or emission concentration of 0.1TEQ-ng/m3N or less (below 0.01TEQ-ng/m3N under certain conditions).
     
  • HCl emission concentration of 1ppm or less.
     
  • SOx emission concentration of 1ppm or less.
     
  • Mercury removal rate of 90-97 per cent, or emission concentration of 0.05 mg/m3N or less
     

Contact: Takuma Co. Ltd., 2-2-33, Kinrakuji-cho, Amagasaki, Hyogo 660-0806, Japan. Tel: +81 (6) 6483 2615; Fax: +81 (6) 6483 2757


Web-site: www.takuma.co.jp


Website: www.gec.jp


Halogenated aromatic compound removal and destruction

PCB Sandpiper Inc. in the United States has patented a process for removing halogenated aromatic compound, such as polychlorinated biphenyl (PCB), from a liquid carrier, such as transformer oil, and for dehalogenating the PCB. The process comprises mixing the contaminated carrier with a solvent for extracting the halogenated aromatic compound from the carrier into the solvent and then separating the contaminated solvent from the cleansed carrier. The contaminated solvent is electrolytically dechlorinated.


In the electrolytic cell, the preferred cathode is mercury and the preferred anode is titanium coated with ruthenium dioxide. The cell also contains an electrolyte soluble in the solvent and a source of hydrogen ions (such as hydrochloric acid). The preferred solvent is a cyclic ester like propylene carbonate. Advantages of the system include its ability to treat liquid carriers having high concentrations of PCBs, the lack of any residue that is difficult to dispose of and the ability to reclaim a cleansed liquid carrier from the process. Another advantage is that the process can be adapted for removing and destroying PCB contaminant in oil in electrical transformers and other electrical devices on site.


Website: www.freepatentsonline.com

Biological removal of PCDDs from incinerator fly ash

Researchers at the School of Environmental Science and Engineering, Pohang University of Science and Technology, Republic of Korea have studied the ability of the bacterial strain Sphingomonas wittichii RW1 to remove polychlorinated dibenzo-p-dioxins (PCDDs) from fly ash. All experiments were carried out in a slurry-phase system. Preliminary studies with resting cells of RW1 strain in a model fly ash system indicated the complete removal of dibenzofuran (DF) and 81 per cent of PCDDs. Incubation of real fly ash collected from municipal waste incinerators with strain RW1 for 15 days resulted in a 75.5 per cent reduction in toxic PCDDs. When the same experiment was carried out using dead strain RW1 cells a 20.2 per cent reduction in toxic PCDDs was observed, indicating that adsorption onto biomass was an important factor in dioxin elimination.


Further analyses revealed that live strain RW1 cells removed 83.8 per cent of the 2,3,7,8-substituted congeners from the fly ash, while dead cells removed 32.1 per cent of the same congeners. The effects of adding surfactant, repeated inoculation and pre-adaptation of cultures were studied to enhance the removal effi- ciency of toxic PCDDs. The removal of toxic PCDDs was enhanced by up to 10.3 per cent upon repeated inoculation of the strain RW1, but was not much affected by the addition of surfactant. These results suggest that S. wittichii strain RW1 is a potential candidate for the industrial removal of PCDDs from incinerator fly ash.


Website: www.ncbi.nlm.nih.gov

Activated coke moving bed filter for flue gas

Sanki Engineering Co. Ltd., Japan, has developed an activated coke moving bed filter for the removal of dioxins and other pollutants from the flue gas exhaust from municipal solid waste or industrial waste incinerators. The system can be adjusted to higher pollutants loading and/or fluctuating operation. Besides activated coke, the filter can take in other adsorbents such as activated carbon or special Aktinert adsorbent (inert material covered by powdered activated coke).


As the moving bed layers are separated as three independent sections, dust removal is efficient. Thus adsorbent consumption can be minimized and stable operation realized without clogging or pressure loss increase. Waste adsorbent can be recycled to the incinerator to destruct dioxins to avoid generation of the dioxins contaminated waste. As the operating temperature can be designed up to 200C to meet the temperature of downstream bag filter or ESP, no special cooling or heating device will be required.


The pollution removal efficiency of the moving bed filter is as follows:
 
  • Dioxins emission at outlet less than 0.05 ng-TEQ/m3N (at maximum inlet loading of up to 100 ng-TEQ/m3N.
     
  • Mercury emission at outlet less that 0.05 mg/m3N.
     
  • Heavy metals emission at outlet less than 0.5 mg/m3N.
     

Contact: Sanki Engineering Co. Ltd., 1-4-1 Yurakucho, Chiyoda-ku, Tokyo 100-8484, Japan. Tel: +81 (3) 3502 7849; Fax: +81 (3) 3506 8546


Web- site: www.sanki.co.jp


Website: www.gec.jp


PCB mobile processing unit

Kinectrics PCB mobile processing unit (MPU) eliminates the need to transport toxic waste. Kinectrics self-contained MPU is designed and built to selectively destroy polychlorinated biphenyls (PCBs) and other organo-chlorinated toxic material contained in transformer oil.
This powerful process based on the low-temperature, atmospheric-pressure reaction between a chlorinated contaminant and finely dispersed metallic sodium is equally efficient in treating low-level PCB contaminated oils and destroying high-level PCB wastes. The toxic contaminant is converted to NaCl, NaOH and a petroleum-based by-product (polyphenyl).


Contact: Mr. Luciano Gonzalez, Kinectrics Inc., 800 Kipling Avenue, Toronto, Ontario M8Z 6C4, Canada. Tel: +1 (416) 207 6000


E-mail: luciano.gonzalez@kinectrics.com


Website: www.kinectrics.com

Chemical oxidation of PCBs

Researchers at Tampere University of Technology, Finland, modified Fentons reaction to chemically
oxidize polychlorinated biphenyls (PCBs) in polluted lake sediment. For the study, the team employed a central composite rotatable experimental design to study the effects of H2O2 and Fe2+ concentration on PCB decomposition. Experiments were conducted using unstabilized and stabilized H2O2, with KH2PO4 as stabilizer. The effect of using HCl or H2SO4 for pH adjustment was also studied.


Results have shown that up to 87 per cent of PCBs were removed in experiments when unstabilized H2O2 was used with H2SO4 for pH adjustment. Only 54 per cent PCBs were removed when H2SO4 was replaced with HCl. The use of stabilized H2O2 instead of unstabilized H2O2 did not improve reaction efficiency.


Contact: Mr. Tuomo Aunola, The Tampere University of Technology, Environmental Engineering and Biotechnology, P.O. Box 541, FIN 33101 Tampere, Finland. Tel: +358 (3) 3115 3517; Fax: +358 (3) 3115
2869


E-mail: tuomo.aunola@tut.fi


Website: www.joensuu.fi

Process for sediment decontamination

Aleph Group, the United States, has developed an advanced chemical treatment technology called GeoremediationTM. The patented method has been successfully tested for the decontamination of soil, sediments and other wastes with pollutants such as TPHC, PAH, PCBs, heavy metals and dioxins. It employs off-the-shelf equipment and does not produce excess contaminated water and/or air emissions. The end result is environmentally benign, appears and behaves like soil, and can be used as structural or non-structural fill material in transportation and infrastructure construction, land re-habilitation and landfill applications.


Georemediation has been shown to decontaminate soil, sediments and other wastes by mineralizing all types of organic contaminants or converting them into environmentally benign and inert compounds like calcium carbonate and water. The process immobilizes inorganic contaminants through pozzolanic reactions and by incorporation into new insoluble crystalline structures. The proprietary Georemediation reagent has a blend of dispersants, clay pillaring agents, oxidative reagents, metal salt catalysts as well as pozzolans.


Contact: Mr. Ajay Kathuria/Ms. Anita OConnor, BEM Systems Inc., 100 Passaic Ave., Chatham, NJ, the United States. Tel: +1 (908) 5982 600; Fax: +1 (908) 5982 622


E-mail: akathuria@bemsys.com

E-mail: aoconnor@bemsys.com


Steam stripping TBT and PAH from soil

A steam stripping process has been developed by researchers at the GKSS Research Centre GmbH,
Germany, as an efficient way to treat dredged sediments contaminated by PAH, residues of mineral oils and organotin-compounds (TBT-tributyltin). The steam stripping process is based on spontaneous vaporization caused by changes in temperature and pressure. Alteration of the physical-chemical conditions within the process results in deagglomeration of the aggregates, desorption of the contaminants and vaporization of the contaminants and water. Afterwards, the steam phase contains the contaminants and the clean solid component is separated using a cyclone unit.


This technique has proved capable of decontaminating different types of materials, almost 100 per cent. Drilling muds tainted with mineral oils were cleaned with an efficiency of up to 100 per cent. Decontamination of mercury and PAH from soil washing residues also produced similar results.


Contact: Mr. A. Eschenbach, GKSS National Research Centre GmbH, Max-Planck-Strae, 21502 Geesthacht, Germany.


Website: www.containment.fsu.edu

INDUSTRIAL WASTEWATER

Wastewater reuse in zinc plating

A wastewater recycling system installed by Protectakote Pty. Ltd. a small metal plating and powder coating operation in Victoria, Australia at its facility is saving the company approximately US$14,500 per year. The main operation of the company is cyanide-zinc plating of a range of metal components, processed in a barrel plating line or using racks and finished with either a blue or gold chromate. Zinc die-cast components are also cleaned in a separate barrel line using an acid-based cleaner followed by a phosphate treatment.


Effluent from the two plating lines used to be discharged through floor drains to a central pit, where the pH was adjusted to a target value of 10. The effluent was then pumped to a series of holding tanks where it was held for approximately 24 hours to allow settling of the precipitated metals. The resultant sludge phase was then drained off through a manifold system fitted with a number of filter bags. The filtrate was discharged to sewer. The sludge filled filter bags were allowed to dry prior to disposal. The clarified effluent was also discharged to sewer.


The cleaner production initiative implemented by Protectakote involves reuse of treated effluent in a number of the rinsing processes. In Stage 1 of the project, the clarified effluent from the settling tanks is gravity-fed to a recycle tank and returned to the plating process. In Stage 2, a filter press used allows the filtrate to be collected and returned to the process. The recycled effluent is not used in any of the final rinse stages because of concerns about the impact on final product quality. Therefore, the amount of recycle effluent generated is greater than demand and the excess is discharged to sewer. The development of the recycle system has seen the mains water consumption reduce from an average of 18.1 kl/day (KL) to 8.0 kl/day for comparable production levels.


Contact: Mr. Neil Hornsey, Protectakote Pty. Ltd., 21 Lambert Avenue, Newtown, Victoria 3220, Australia. Tel: +61 (3) 5221 6438; Fax: +61 (3) 5222 2692.


Website: www.deh.gov.au

Filtration system designed for oily wastes

Inducor and Inducor R-G tubular modules offered by Koch Membrane Systems in the United States can be employed for the ultrafiltration of industrial process streams as well as wastewater. They are especially useful for treating oily wastes before they leave the plant. The modules have higher packing density and require less power than traditional tubular membranes, resulting in systems with a smaller footprint and reduced capital cost and operating cost, according to Koch.


The Inducor modules are configured with one-half inch diameter tubules. The Inducor-G modules have one-inch diameter tubules. Their open- channel configurations are tolerant of high-solids streams, including food waste and the activated sludge from membrane bioreactors. The membrane is compatible with most industrial waste water streams. The modules employ industry-standard threaded and Victaulic fittings. The membranes, owing to their tubular configuration, handle system upsets well and can be cleaned mechanically using spongeballs. The Inducor modules can be used for systems with flowrates of 37,800 litres per day and higher.


Contact: Koch Membrane Systems, 850-T Main Street, Wilmington, Massachusetts, MA 01887, United States of America. Fax: +1 (978) 6575 208


E-mail: info@kochmembrane.com


Website: www.kochmembrane.com


Website: www.foodproductiondaily.com

On-site treatment of high-strength alcohol distillery wastewater

In Japan, a team of researchers from Nagaoka University of Technology, Kagoshima National College of Technology and Ebara Corporation have developed a pilot-scale multi-staged UASB (MS-UASB) reactor with a working volume of 2.5 m3 for thermophilic (55C) treatment of alcohol distillery wastewater (ADWW) for a period of over 600 days. The reactor steadily achieved a super-high rate COD removal (60 kgCOD/m3/d) with over 80 per cent COD removal.


However, when higher organic loading rates (above 90 kgCOD/m3/d) were further imposed upon the reactor for barley-based ADWW and above 100 kgCOD/m3/d for sweet potato-based ADWW, the reactor performance somewhat deteriorated to 60 per cent and 70 per cent COD removal, respectively. Methanogenic activity (MA) of the retained sludge in the thermophilic reactor was assessed along the time course of continuous run by serum-vial test using different substrates as a vial sole substrate. With the elapsed time of continuous run, hydrogen-utilizing MA, acetate-utilizing MA and propionate-fed MA increased at maximum of 13.2, 1.95 and 0.263 kgCOD/VSS/d, respectively, indicating that propionate-fed MA attained only 1/50 of hydrogen-utilizing MA and 1/7 of acetate-utilizing MA.


Since the ADWW tested was a typical seasonal campaign wastewater, the influence of shutdown upon the decline in sludge MA was also investigated. Hydrogen-utilizing MA and acetate-utilizing MA decreased slightly by 3/4, during a month of non-feeding period, whereas propionate-fed MA decreased significantly by 1/5th. The relatively low values of propionate-fed MA and its vulnerability to adverse conditions suggest that the propionate degradation step is the most critical bottleneck in the anaerobic degradation of organic materials in thermophilic condition.


Website: www.iwaponline.com

Decolourization of industrial dyeing process wastewater

In Portugal, a team of researchers from the University of Minho and the National Institute for Industrial, Engineering and Technology has developed an enzymatic cocktail for the decolourization of process wastewater, containing mainly three reactive azo dyes, from a textile dyeing and printing company. The enzyme mix could decolourize to different extents water sampled from different processing streams and combinations. The decolourization was most for C.I. Reactive Black 5, followed by C.I. Reactive Red 158, whereas C.I. Reactive Yellow 27 was the least decolourized.


As wastewater from the printing process was inhibitory, a stirred tank reactor type prototype was installed near the outlet before the discharge of wastewater from the printing process. Temperature and pH control systems were installed to ensure optimal enzymatic decolourization about 45C and 6.4, respectively. The average temperature observed at the reactor was 42.1C, which indicated the need for improved temperature control. Laboratory-scale tests were done to assess the reusability of the bio-treated wastewater for the washing of dyed cotton fabrics.


Contact: Ms. Maria Costa-Ferreira, Bio-engineering and Bioprocessing Unit, Department of Biotechnology, National Institute for Industrial, Engineering & Technology, Portugal. Tel: +351 (2) 1716 5141; Fax: +351 (2) 1716 3636


E-mail: maria.fereira@ineti.pt

Textile Research Journal, Vol. 76, No. 1

Bacterial recovery of metal from electroplating wastewater

Several valuable metallic ions such as iron, nickel and zinc are contained in the wastewater from electroplating plants. In general, neutralization followed by sedimentation is used for the treatment of electroplating wastewater because of low treatment cost and high stability of treated water quality. However, this method results in the production of large amounts of heavy metal sludge that cause secondary pollution and additional cost. Furthermore, the recovery of valuable metallic contents from the sludge was not technically feasible. A joint research team from Pohang University of Science & Technology and the Research Institute of Industrial Science & Technology in the Republic of Korea and Nippon Steel Corporation in Japan have developed a pilot-scale biological process for recovering metals from electroplating wastewater.


Electroplating wastewater contains iron, in the form of ferrous ion, and other metal ions. To add economic value to the sludge, iron should be separated from other metals, such as nickel and zinc, in the wastewater. The iron could be separated from the mixture of metal ions by using biological oxidation of ferrous ion into ferric ion followed by stepwise chemical precipitation with hydroxide ion since ferric ion begins to precipitate around pH 4 while ferrous ion precipitates around pH 7, similar to the other metal ions nickel and zinc. The feasibility test conducted by the research team employed acidophilic iron-oxidizing bacteria. To improve the biological oxidation, an immobilized bioreactor using polyurethane foam as support media was developed. The bioreactor system showed a very good performance and worked stably over a long period of time.


Website: www.pubs.acs.org 

Electrochemical treatment of electroplating wastewater

In a joint research effort, metallurgists from the Universidad Autnoma de San Luis Potos in Mexico and the University of Science and Technology Beijing in China have devised an electro-chemical treatment for wastewater from the electroplating industry. The researchers employed a twin-technique for the treatment of an electroplating wastewater with a high chromium concentration.


Chemical precipitation or electrodialysis alone cannot produce water with quality adequate to be recycled as rinsing water for electroplating lines. Therefore, in a novel process, the researchers combined chemical precipitation and electrodialysis (CP-ED) for the treatment. The experimental results have shown that the CP-ED process substantially eliminated (95 per cent removal) hexavalent chromium Cr (VI) from the wastewater. Cr(VI) in the treated water assayed just 0.18 mg/l . The CP-ED process also removed other ions such as sodium and chlorine in the wastewater because of the addition of precipitants in the chemical precipitation step. Compared with chemical precipitation treatment, the CP-ED process allowed a large saving in reagent and operation costs, and posed less environmental concerns.


Contact: Mr. C. Peng, Department of Environmental Engineering, University of Science and Technology Beijing, Beijing 100 083, China.


Website: www.ejmpep.com

Catalytic wet air oxidation of effluents

Lenntech, the Netherlands, offer a catalytic wet air oxidation (CWAO) process capable of converting all organic contaminants to carbon dioxide and water. The process can also remove oxidizable inorganic components such as cyanides and ammonia. The process uses air as the oxidant, which is mixed with the effluent and passed over a catalyst at high temperatures and pressures.
CWAO is particularly cost-effective for effluents that are highly concentrated (COD ranging from 10,000 to over 100,000 mg/l), or contain components that are not readily biodegradable or are toxic to biological treatment systems. CWAO process plants also offer the advantage that they can be highly automated for unattended operation, have relatively small plant footprints, and are able to deal with varied effluent flow rates and compositions.


Organic and some inorganic contaminants are oxidized in the liquid phase by contacting the liquid with high pressure air at temperatures, which are typically between 120C and 310C. In the CWAO process, the liquid phase and high pressure air are passed concurrently over a stationary bed catalyst. The operating pressure is kept well above the saturation pressure of water at the reaction temperatures usually 15-60 bar so that the reaction takes place in the liquid phase. This enables the oxidation processes to proceed at temperatures lower than those required for incineration. Residence times are from 30 minutes to 90 minutes, and the chemical oxygen demand removal may typically be about 75-99 per cent. The effect of the catalyst is to provide a higher degree of COD removal than is obtained by WAO at comparable conditions (over 99 per cent removal can be achieved), or to reduce the residence time.


Organic compounds may be converted to carbon dioxide and water at the higher temperatures; nitrogen and sulphur hetero-atoms are converted to molecular nitrogen and sulphates. The process becomes autogenic at COD levels of about 10,000 mg/l, at which the system will require external energy only at start-up.


Contact: Lenntech Water Treatment & Air Purification Holding B.V., Rotterdamseweg 402 M, 2629 HH Delft, The Netherlands. Tel: +31 (15) 2610900; Fax: +31 (15) 2616 289


E-mail: info@lenntech.com


Website: www.lenntech.com

One-step process to remove chromium from wastewater

In China, a research team led by Prof. Anhuai Lu of the Peking University has devised a simple and potentially inexpensive approach to removing toxic chromium(VI) from wastewater. The technology uses naturally occurring clino-pyrrhotite, a common iron sulphide mineral.
While working on gold mineralization, Prof. Lu realized that natural gold always appears on the surface or in the crannies of iron sulphide minerals, as iron sulphide adsorbs and reduces gold ions into solid gold. This prompted him to use iron sulphide for disposal of chromium(VI) in wastewater because chromium behaves similarly to gold when in contact with iron sulphide.


Prof. Lu and his colleagues tested the idea by adding fine grains of clino-pyrrhotite directly into chromium-tainted wastewater obtained from electroplating plants. In an hour, the mineral reduced the chromium(VI) levels by more than 98 per cent to below maximum allowable levels (0.5 mg/l and 1.5 mg/l for chromium(VI) and total chromium, respectively). The treatment left two distinct liquid phases with all the chromium in the yellowish lower layer, which can be removed and the residues of unreacted clino-pyrrhotite then regenerated and reused. Prof. Lu says that other metals such as divalent species of copper, lead, zinc, cadmium and mercury can also be treated by this method.


Website: www.pubs.acs.org

AIR POLLUTION CONTROL

Exhaust gas treatment equipment

The DC-21 system, from Dust Collector Co., Japan, is an exhaust gas treatment system, which very efficiently removes soot, dust and harmful gases (hydrogen chloride, sulphur oxides, etc.). In addition, it uses a quenching tower to remove dioxin contained in exhaust gas discharged from waste incinerators, urban refuse incinerators, metal melting furnaces, boilers of various kinds, etc.


Its performance (removal rate) data are as follows:
 
  • Soot and dust: 99.9 per cent or more, discharge concentration: 0.05 g/m3 or less
     
  • Harmful gases: min. 95 per cent
     
  • Heavy metals: min. 95 per cent
     
  • Dioxins: 90 per cent or more,
    discharge concentration: control standard or below.
     

The DC-21 system can be used as peripheral equipment with: activated charcoal adsorption tower, catalytic reaction tower, device for rendering ashes inert, and measuring equipment (CO-O2 analyser and HCl analyser). It can be retrofitted to most existing furnaces.


Contact: Dust Collector Co. Limited, 2-6-8, Shingashi, Itabashi-ku, Tokyo 175-0081, Japan. Tel: +81 (3) 3938 3711; Fax: +81 (3) 3938 3716


Website: www.ducoll.co.jp


Website: www.gec.jp


Algae a breath mint for smokestacks?

Faced with a multibillion-dollar push into other clean-coal technologies, a handful of tiny companies are racing to create an even cleaner, greener process using the same slimy stuff that thrives in the worlds oceans. Dr. Isaac Berzin, a rocket scientist at Massachusetts Institute of Technology (MIT) in the United States, came up with the idea of using algae to clean up power-plant exhaust. Bolted onto the exhaust stacks of a brick-and-glass 20 MW power plant behind MITs campus are rows of thick, clear tubes with green algae soup simmering inside.


One key is selecting algae with a high oil density about 50 per cent of its weight. Because this kind of algae also grows so fast, it can produce about 57,000 litres of biodiesel per acre. Just 230 litres are produced from soybeans, a major biodiesel crop today.


Fed a generous helping of CO2-laden emissions from the power plants exhaust stack, the algae grow quickly. The cleansed exhaust bubbles skywards, but with 40 per cent less CO2 (a larger cut than the Kyoto treaty mandates) and another bonus 86 per cent less of nitrous oxide. The algae are harvested daily after they soak up the CO2 like sponge. From that harvest, a combustible vegetable oil is squeezed out for use as biodiesel for automobiles. Even the remnant algae can be further reprocessed to create ethanol, also used for transportation.


GreenFuel Technologies, founded by Dr. Berzin, has already garnered US$11 million in venture capital funding and is conducting a field trial at a 1,000 MW power plant owned by a major power company. Greenshift Corporation, a technology incubator company in the United States, licensed CO2-gobbling algae technology that uses a screen-like algal filter. A prototype built is capable of handling 140 cubic metres of flue gas per minute, an amount equal to the exhaust from 50 cars or a 3 MW power plant.


Website: www.csmonitor.com

Hazardous gas treatment system

The hazardous gas treatment system from Japans Shinko Plantech Co. removes hazardous acid gases, dioxins, heavy metal particles and particulates generated by urban refuse incinerators, industrial waste incinerators and melting furnaces. It consists mainly of a total vaporization cooling tower that quenches hot gas by means of a water spray, a chemical injection system and a bag filter. Plants that release the hazardous gases into atmosphere can be economically upgraded using a combination of the total vaporization cooling tower and the chemical injection system.


Examples of the SPC hazardous gas treatment system include: urban refuse incinerator flue gas treatment (design capacities 14,000 m3/h and 20,000 m3/h); and industrial waste refuse incinerator flue gas treatment system (design capacity 10,000 m3/h).


Contact: Shinko Plantech Co. Limited, 27-5, Shin-Isogocho, Isogo-ku, Yokohama, Kanagawa 235-00 17, Japan. Tel: +81 (45) 758 1956; Fax: +81 (45) 758 1974;


Website: www.s-plantech.co.jp


Website: www.gec.jp

Hydrogen sulphide scrubber

The THIOPAQ Scrubber technology, from USFilter Inc., the United States, is used to remove hydrogen sulphide (H2S) from biogas and landfill gas. In the THIOPAQ Scrubber process, gas gets treated in a wet scrubber in order to absorb H2S. The H2S-laden scrubber liquid is fed to a bioreactor where the sulphide is converted into elemental sulphur by a biological process, regenerating the scrubber liquid in the process and enabling the bioreactor effluent to be recycled to the scrubber.
THIOPAQ Scrubber used in industrial applications is claimed to offer benefits such as: high reliability, low operational costs, minimum operator attention and no spent caustic bleed.


Contact: USFilter Inc., 2000 Marconi Drive, Warrendale, Pennsylvania, PA 15086, United States of America. Tel: +1 (866) 926 8420


E-mail: information.water@siemens.com


Website: www.usfilter.com

Advanced scrubber unit

Research scientists from TRIUMF, Canada, has licensed a novel cryogenic method of cleaning flue gas emissions to CDS Research Inc., who has further developed the process, making an advanced scrubber unit. The CDS scrubber technology consists of multiple treatment modules designed to perform specific mitigation duties.


The advantage of this process is its simplicity, flexibility and ability to adapt to a large variety of emissions.
The scrubber unit is connected to the vent stack of the boiler, and its controls are fully integrated with the boilers controls. Whenever the boiler is in operation, the flue gas is directed to the scrubber for clean up. The CDS scrubber is meant to filter particulate emissions and reduce NOx and SOx, but can also selectively trap other contaminants, such as mercury and arsenic. Besides, the process eliminates the strong odours that are generally associated with burning sulphur-bearing coal. The collected particulate matter, including trace elements, could be disposed of periodically as per the local waste disposal guidelines.


The scrubber introduces an innovative method of advanced clean-up technology that moves away from the conventional method of converting one form of waste from flue gas into another form of waste. Instead, potentially harmful effluents can be recovered as recyclable materials and introduced as feedstock into secondary industries. This allows for the use of significant coal energy still available today without the associated environmental penalties, due to the effectiveness of the integrated recovery and cleaning systems. The CDS technology involved may additionally be refined and used in other combustion industries.


Contact: CDS Research Limited, Suite 1088, P.O. Box 11611, #650 West Georgia Street, Vancouver, British Columbia, Canada V6B 4N9. Tel: +1 (604) 669 4450; Fax: +1 (604) 669 4458


E-mail: info@cdsresearch.com


Website: www.triumf.info 

SCR NOx removal system

SCR NOx removal systems, from CTCI in Taiwan, comprise a number of sub-systems, designed and integrated to accomplish customers specific requirements. These sub-systems include SCR reactors with associated flue work, and equipment for ammonia mixing and injection, and ammonia storage and delivery.


Flue gas exiting the economizer outlet enters the ammonia injection grid zone in the reactor inlet flue. Ammonia injection grid (AIG) feeds in ammonia from the ammonia flow control unit (AFCU). The ammonia-laden flue gas then flows through the catalyst bed where NOx reacts with ammonia and is converted into N2 and H2O. The flue gas exiting the reactor passes to the air pre-heater.


Economizer bypass, as required, is used to supply flue gas to reactors at the desired temperature when flue gas temperatures are low, such as during low-load operation.
Anhydrous ammonia storage tank, operated at around ambient temperatures and the pressure range of 4 to 12 kg/cm2, is supplied to serve the ammonia demand from SCR systems. Liquid anhydrous ammonia from the storage tank is fed directly to a vaporizer. The vapour generated then returns to the storage tank.


Ammonia vapour from the storage tank is directed to AFCU. A modulating valve controls ammonia flow based on demand indicated by SCR dedicated control system. An automatic shut-off valve is provided as part of this flow control unit.


At AFCU, ammonia is injected into a mixer where air is used to dilute it. This dilution helps simplify the issue of distributing the relatively small quantity of ammonia across a large area of flue work. Dilution air blower is used to supply the dilution air.


After existing AFCU, ammonia/air mixture is fed to AIG and then distributed into flue gas for optimizing the mix.


Contact: CTCI Air Pollution Control Project Group, 20th Floor, 77 Sec. 2, Tun Hua South Road, Taipei 106, Taiwan. Tel: +886 (2) 27 009659 Ext. 2031 or 2032; Fax: +886 (2) 2707 4007


E-mail: power@ctci.com.tw


Website: www.ctci.com.tw 



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