Green waste is biodegradable waste, usually from gardens and parks, and includes grass, hedge trimmings, leaves and tree trunks. It can be used to produce energy in biomass power stations and receives a renewable energy subsidy in Germany. It can also be recycled as compost, which reduces the extraction of peat – an important sink for CO2. However, composting does not receive financial support in Germany. The EU is currently developing policy to encourage composting and develop standards for composting across the EU1.

The research compared the environmental benefits of energy recovery from green waste and of recycling green waste using 81 samples. It analysed the CO2 balance of each system by estimating the release and savings of CO2 at the different stages of the process chain. For energy recovery this included the transport, shredding, incineration and the CO2 saved from the renewable energy produced. For recycling this included stages such as transport, composting and CO2 saved by replacing peat. Four different types of green waste were considered that differed in their amount of wood, herbaceous/grassy material and soil.

The results demonstrated that waste with a high percentage of wood produced the most CO2 savings for both composting and energy recovery whilst those with only herbaceous and soil components produced the least savings. The CO2 savings from energy recovery varied from 126 to 1040kg of CO2 saved per tonne of green waste, depending on the type of waste and its composition. The CO2 savings from recycling varied from 259 to 1193kg of CO2 per tonne of green waste, again depending on the type of waste. This indicates that the environmental gains, in terms of CO2 savings, were similar for both energy recovery and recycling of green waste.

Notably, green waste with a high percentage of herbaceous/grassy content and soil content had twice the CO2 savings from recycling as from energy recovery. This is probably because this type of waste has low heating values, due to high water and ash content, and is therefore better for composting purposes.

The researchers suggested that energy recovery and recycling of green waste should be judged as complementary systems. It is unlikely that one method on its own will achieve the desired reduction in CO2 levels and a combination is more likely to lead to a significant decrease in greenhouse gas emissions. As such they recommend that recycling of green waste be awarded equivalent financial support as the use of green waste to produce renewable energy.

These wastes have a renewable energy potential and a   potential of reutilization in an Environment friendly way. Some estimates are as follows:
Distillery-350 MW
Sugar-285MW
Paper and Pulp-58MW
Dairy-58MW
Poultry-44MW
Starch-40MW
Slaughter Houses-100MW

To utilize these wastes gainfully, farmers, rural cottage agro industries and their associations, local governments and Municipal organizations, NGO’s and self help groups  can be mobilized . This would give a decentralized energy generation source, improve the working and living conditions and gives a cleaner local and global environment.

Many Industries in India have started using Biomethanation Technologies. The gas produced serves as a useful source of energy while the slurry has a good fertilizer potential. The savings in fossil fuel has resulted in reducing costs and thereby increasing profits.

At a biomethanation plant installed in Sakthi Sugars, Maharashtra the Internal Rate of Return has been reported as high as 32% and the Biogas substituted for almost 87% of the consumption of Furnace oil. A biogas based power plant of 1 MW capacity was installed at the K.M.Sugar mills in Uttar Pradesh with financial assistance from the Ministry of Non Conventional Energy Sources, Govt. of India. It utilizes 12000 cubic meters of biogas produced from 400 KL of spent wash per day. Kanoria Chemicals Ankleshwar has installed a 2 MW power plant based on biogas.

Many Sugar mills have also started using press mud, earlier considered as waste, for the production of biogas. Press mud has 75% organic matter and 29% total solid content out of which 65% is volatile. Four biogas plants each having a capacity of 85 cubic meters were set up at the Pravarnagar, Sugar Factory at Maharashtra with financial assistance from the MNES, Govt. of India .A biogas yield of 165 liters of Biogas per Kg. press mud (having 60% methane) with a processing time of 35 days was observed during monitoring of the stabilized biogas plant. The biogas from the plant was piped to 196 households within factory premises for 4 hours daily to meet cooking needs.

The Pradeshik Investment Corporation of U.P. (PICUP) had estimated that a 60000 TPA biofertiliser unit based on spent wash and press mud would require an investment of Rs. 209 lakhs( Land,116;Building,6.00;Plant machinery59.90 plus others). PICUP envisages a debt equity ratio of 1.49:1. Manpower required is 10 and the total power requirement is 400KVA.The cost of production works to Rs. 400 per ton, the selling price Rs. 1000 per ton and a repayment of 5 to 6 years.

Cane leaves left in the fields after harvesting of sugarcane form a thick mat on the fields and are generally burnt in the open fields without extracting any form of energy causing widespread pollution. An NGO called the Appropriate Technology Institute (ARTI) has developed an oven and retort kiln technology to char leafy waste. The plant can be operated by three persons and generate 100Kg. per day of char which can be turned into briquettes by using an extruder. In a period of 25 weeks during the sugarcane harvesting period, a family can generate about 15 tonnes of Briquettes which would earn an income of Rs. 75000. Under the Ashden Award a project using this technology aims to manage 4.5 million tones of sugar cane wastes generated in Maharashtra. Ten Sugarcane demonstration plants will be set up in Maharashtra. These briquettes are being used as a source of fuel and in innovative applications like keeping food warm in Tiffin boxes for long periods.

Leafy wastes can be a rich source of biogas. The biogas potential of leafy wastes is almost twice that of cow dung. The total annual production of leafy biomass in India is of the order of 1130 million tones. Even if 10% of this be mobilized for biogas production about 2/3rd of the rural families estimated at 100million rural households could be provided with biogas for cooking. ASTRA, IISc., has successfully developed and demonstrated several “plug flow” biogas plants in the field using leafy biomass as feed material in the southern states of Kerala.

Paper production is energy intensive. Energy costs account for more than 30% of the cost of paper production. Chemical recovery in agro based paper mills is a major constraint with most of the industries discharging untreated or partially treated black liquor which accounts for more than 80% pollution from such mills. Biomethanation plants for pulp and paper mill effluents have been installed at a few places in India and the gas is being flared to the boiler and cofired with rice husk.

Slaughter houses generate considerable solid and liquid wastes Al Kabeer Exports Pvt. Ltd, Medak, Andhra Pradesh has installed an indigenously developed two stage digestion process which handles 60MT of slaughter house wastes per day. The second stage uses modified UASB Technology. The 3000-4000 cubic meters of gas produced per day reduced the furnace oil consumption by over Rs. 40 lakhs per annum. The dried sludge almost 20 TPD is used  as  manure.

Poultry wastes can also be used to produce energy. Western Hatcheries Has installed a demonstration biogas  plant based on UASB technology to treat about 600 Kg. of poultry waste. The biogas produced is collected in gas balloons, pressurized and piped for use in canteen Kitchens. The sludge is used as a fertilizer. The plant is producing 60 cubic meter of gas per day which is equivalent to 24 Kg. of LPG. A 1.2 MW power project for 200 TPD of poultry waste has been set up at Namakhal. The total cost of the project was 14 crores with a capital subsidy of Rs. 3.5 crores.

Pine needles are a difficult forest waste. They cannot serve as fodder. They do not decay as other biomass and piled up pine needles are a major source of forest fires. They are however a good source of biomass fuel. Briquettes made up of charred pine needles are being used in the hill regions of Kumaon and Garhwal. Cities like Gurgaon are using briquettes from local biomass like bagasse and vegetable market wastes.

The organic fractions of municipal wastes can be gainfully utilized to produce biogas. The Technology Informatics Design endeavor (TIDE) in collaboration with the Centre for Sustainable Technologies, IISc., has implemented a project for the conversion of the organic fraction of Municipal wastes into energy and resources in Singupa town, Bellary District. A plug flow biogas reactor has been designed. Data collected shows that 1 Kg. waste gives between 50 to 60 liters of biogas. The C/N ratio of compost was found to be 11.4. Segregation and transportation are limitations that need redressal.

Coffee pulping wastes are a rich source of biogas too. The Indo Norwegian Environment project and the Coffee Board in the Ministry of Commerce have supported a project for biogas generation from coffee pulping wastes. High B.O.D. effluents can be treated in bioreactors to give biogas. The B.O.D. of the treated effluents has been reported to be below the standards prescribed. About 80 cubic meters of biogas is produced for every ton of coffee parchment. 1 cubic meter gas substitutes 0.5 Kg. LPG in cooking operations and 0.25 liters of diesel in dual fuel mode of operation in the generation of 1KWH of power. The technology has been demonstrated in 13 locations and is working satisfactorily. In the off season the bioreactor may be fed with other waste biomass like coffee husk, leaves, grass etc. to produce gas.

A bioreactor for canteen wastes has been installed at the Transport House, KSRTC,Bangalore. This reactor is an immobilized cell bioreactor- a high rate biomethanation plant  using spent biomass as support for the methanogenic bacteria. The biomass would range from rice straw, bagasse, paper shreds, garden cuttings, lawn mowing, vegetable peels, uneaten rice, plate and dish washings, fruit and vegetable rejects etc. On the basis of raw material fed to the reactor every Kg. of feed produces 50 to 80 liters of Biogas. The KSRTC plant can handle 25 Kg. of canteen rejects per day along with the leaf litter. About 1.5 cubic meter of gas is produced every day. At present the gas is being used to keep the food warm.

TERI initiated a project in 1996 for the development of a high rate reactor for biomethanation of fibrous and semisolid organic wastes. Consequently the TERI enhanced acidification and methanation process was developed and patents applied. A 50 Kg. per day green leafy vegetable waste treatment plant is operational at TERI’s Gurgaon campus at Gual Pahari. This has now been converted into a canteen waste treatment plant. Good quality biogas and manure is being generated. The TEAM (TERI Enhanced Acidification and Methanation) is a two stage process. The first phase consists of extracting a high concentration leachate (C.O.D. 15000-20000 Mg. / liter) from the solid waste in the acidification reactor. In the second phase the leachate is treated in the UASB reactor with retention of 16 hours to give methane and more than 60% C.O.D. is discharged. The acidification process residue is good quality manure after drying. The biogas consists of 70 to 75% methane, Carbon dioxide, traces of Hydrogen Sulphide and moisture. The biogas production rate is 0.45 cubic meter per Kg. of C.O.D. removed. The TERI process shows a useful way to turn wastes from food and fruit processing industries, hotels, pilgrim houses, hostels, housing colonies, community kitchens, vegetable markets etc. into wealth. Vegetable markets can produce 20 cubic meters biogas / ton of waste, fruit and vegetable processing 20 cubic meter /ton, press mud 9 cubic meter/ton, food wastes 54 cubic meter/ ton and coffee pulp 10 cubic meter/ton. The manure is richer in N.P.K. than any other natural manure.

The Ministry of Non conventional Energy Sources, India is publishing a news letter named Bioenergy News.

References
www.iges.or.jp/APEIS/RISPO/SPO/Pdf
www.picupindia.com
www.wmc.nic.in/case-studies.asp
www.teriin.org
www.tide-india.org
www.ficci.com
www.mnes.nic.in
www.cgpl.iisc.ernet.in

Carbon Activation
Activated carbon is made from any substance with a high carbon content, and activation refers to the development of the property of adsorption. Activated carbon is important in purification processes, in which molecules of various contaminants are concentrated on and adhere to the solid surface of the carbon. Activated carbon is generally nonpolar, and because of this it adsorbs other nonpolar, mainly organic, substances. Extensive porosity (pore volume) and large available internal surface area of the pores are responsible for adsorption.

Any inexpensive material with a high carbon content and a low inorganic content can be used as potential
raw material in producing activated carbons. The most often used raw materials for manufacturing activated carbons include wood, peat, bituminous coal, lignite, coconut shell, nutshells, lignin, and others.
Activated carbons can be manufactured by either a physical or a chemical activation process. The physical activation process generally is used to manufacture activated carbon in a two-step activation process—the carbonization of raw materials in the absence of O2 followed by the activation of carbonized products. Steam and carbon dioxide (CO2) are the activating reagents most commonly used in physical activation, significantly influencing the porosity of the activated carbons.  The chemical activation process is used to manufacture activated carbons usually in a single step, using zinc chloride, phosphoric acid, and potassium hydroxide as the activating reagents.The carbonaceous materials are converted into activated carbons depending upon the nature of the raw materials, the nature of the activating reagent, and the conditions of the activation process.Furthermore, activated carbon can be impregnated with sulfur (S), chloride, or iodine to increase its adsorptive capacity, making the impregnated activated carbon much more effective than un-impregnated activated carbon for removing gaseous mercury (Hg) from flue gases at low temperatures.

Utility of Activated Carbon
Waste Treatment
Activated carbon may be used to treat a number of contaminants in liquid wastes including Non-biodegradable organic compounds (COD), Adsorbable Organic Halogens (AOX), Toxicity ,Colour compounds and dyestuffs ,Inhibitory compounds for biological treatment systems ,Aromatic compound including phenol and bis-phenol A (BPA),Chlorinated/halogenated organic compounds ,Pesticides and a host of toxic substances.

Air Pollution Control
In the context of air pollution control, Volatile Organic Compounds (VOCs) from air and other gases can be removed to below the detection limit.Noxious compounds such as hydrogen sulphide and mercaptans are readily trapped through adsorption and help to prevent odours. Incinerators dealing with Municipal Solid Waste (MSW), hazardous industrial waste, medical waste, sewerage sludge and crematoria results in the formation of a flue gas containing a range of pollutants. Dioxins and heavy metals such as mercury and cadmium are not normally removed to low enough concentrations by conventional treatment.
A range of industrial inorganic compounds and materials can be removed from gas streams, before venting to the atmosphere, using specialised impregnated or catalytic (Centaur) carbons.

In the Food and Beverage Industry
Activated carbons can be used in the Food and Beverage industry to decolourise,dechlorinate,deozonate,decaffeinate,debitter,deodorise a number of food products.

In the Pharmaceutical Industry
In the Pharmaceutical industry activated carbons are used to provide superior removal of colour compounds, odour compounds, proteins and other contaminants that could be present in the raw materials or that form during production.

As a Catalyst
With its large surface area, purity and relative hardness, activated carbon is an ideal carrier for catalytic metals or  a catalyst by itself.Activated carbons  have been successfully used as a catalyst in the manufacture of dry cell batteries, production of biodegradable herbicides like cyanuric chloride glyphosate, mercaptan removal in petroleum distillates and in the production and destruction of phosgene.

In the production of natural gas
Activated carbons have also been used for removal of mercury from natural gas for the production of L.N.G. , the removal of mercury from liquid hydrocarbons and  the removal of mercaptans/thiols , hydrogen sulphide and amine solutions  from natural gas and natural gas scrubbing.

In the brewing industry
Industrial uses of activated carbon also include its use for the purification of  hydrocarbon contaminated Carbon Dioxide generated from the conversion of sugars to alcohol and its reuse for carbonation in the brewing Industry  thereby eliminating the need from purchasing Carbon Dioxide from outside sources.

For the storage of gases
It can also be used to remove trace lubrication oils from waste streams and in fruit storage for gas storage(under pressurised condition the extensively developed carbon porosity provides for greatly enhanced volume storage of either a pure gas, such as carbon dioxide or nitrogen, or a gas mixture such as air) and delivery and also in applications that provide alternatives to greenhouse gas emissions.

In the Caustic soda Industry
Caustic Soda is used extensively in, and is also a by-product from, the chloralkali industry. Mercury cells are used for production of chlorine, hydrogen, and sodium (in a few plants potassium) hydroxides by electrolysis of a brine solution, and this can cause contamination.  Steam activated and impregnated carbons  are proven for this application.

For the purification of Electroplating Chemicals
Electroplating chemicals that become contaminated with organics and metal finishing residues can be purified by the use of steam activated carbon and the chemicals can be recycled for reuse.Chromium can be recovered from electroplating solutions.

In Gold recovery applications
Coconut shell based granular activated carbons are used in gold recovery applications employing the Carbon in Leach (CIL) or Carbon in Pulp (CIP) processes.

In Process Water treatment
In process water treatment, activated carbons are used to remove tastes and odors ,disinfection byproducts like chloramines, free and combined chlorine,trihalomethanes and halocarbons, for pH and alkalinity control,condensate recovery and treatment systems in steam generating operations,personal and collective protective masks against toxic gases includind Industrial and military respirators.

Other Applications
Other applications include within air filtration systems in archives and museums,ozone management in ponds and aquaria,treatment of swimming pool water for removal of organic matter, chloroform ,ozone,chloramine and other bonded chlorine and in cigarette filters,filters for treating cabin air in automobiles.

Recycling of spent activated carbon
Once granular carbon is saturated or the treatment objective is reached, it can be recycled, by thermal reactivation, for reuse. Reactivation involves treating the spent carbon in a high temperature reactivation furnace to over 800°C. During this treatment process, the undesirable organics on the carbon are thermally destroyed. Recycling by thermal reactivation is a highly skilled process, to ensure that spent carbon is returned to a reusable quality.  Recycling activated carbon by thermal reactivation meets the environmental need to minimise waste, reducing CO2 emissions and limiting the use of the world’s resources.

The students of National Model School in Peelamedu, G.R. Damodaran School on Avanashi Road and Elgi Matriculation Higher Secondary School in Vellalore have set up bio-compost pits on the school premises to decompose wastes into organic manure. Two baskets are kept at various points inside the campus – one for non-biodegradable wastes such as chocolate wrappers, pen caps and plastic bags and another for biodegradable wastes that include food leftovers, waste papers, dry leaves, dry flowers and twigs.

Coordinator of Siruthuli A.C. Prabhu says the process is simple. “With the help of students, a six ft length, four ft breadth and one ft deep pit is dug out and waste from trees inside the school campus and vegetable wastes are dumped into it and covered by a layer of soil. Water and diluted Effective Microbes (EM) solution are added and the contents are allowed to decay. After 45 days, the waste is decomposed into manure and used for the afforestation programme of the school,” he adds.

The students visit neighbouring areas to spread awareness on the need to have bio-compost pits. They  give a demonstration on the method to be followed beginning with segregation of waste at source.

The amount of soil available in potted plants is sufficient for a bio-compost pit. A litre of EM solution concentrate comes at Rs. 240 and is available at outlets selling agro-based products. It can be diluted with 100 litres of water and sprayed on the contents on alternate days.

From Walnut shells
Walnut shells serve as an alternative source of  Activated Carbon. Adsorption capacity increased with increase in activation temperature but beyond 400 degrees celsius resulted in thermal decomposition. Activation longer than one hour at 375 degrees celcius resulted in a destruction of the micropore size.Activation with ZnCl2 was better than that with CaCl2 and increased with increasing concentrations upto a certain limit beyond which increasing concentrations inhibited activation.Applicability of the activated carbon from walnut shells, as adsorbent  for synthetic copper wastewater, was better for Copper Ions as compared to  carbon from coconut shell.

From Rosa canina seeds
“An activated carbon has been developed from Rosa canina sp. seeds, characterized and used for the removal of methylene blue (basic dye) from aqueous solutions.”

From Corn Cobs
A new absorbent material  made from the remains of corn cob is being used to store natural gas. A nanaporous carbon material is produced from the waste corn which is referred to as the “sponge for natural gas”,where the methane uptake is 120v/v or more. Other materials used to make this adsorbent material , olive pits and coconut shell, are more expensive to produce.Flat low pressure high capacity natural gas tanks for vehicles holding no greater than 500psi of methane have been developed.This  reduced the effects in the event of an explosion because of lower pressure of the storage tank and allowed for more trunk space in cars.

Corn cob dried and crushed is mixed with phosphoric acid (H3PO4),where it serves as an activating agent.Excess phosphoric acid is removed and the mixture is carbonized at 450-650oC in a reactor, after which it is evaporated at 160oC for 3 hours.It is washed with hot water to bring the pH to a neutral point.The washed activated carbon is dried at 110oC and grinded and sieved to a particle size of 40 mesh.Using a hydraulic press and a die the powder and a small quantity of binding agent is pressed into monoliths or briquettes to obtain the highest density .These briquettes are used for storage of natural gas at a targetted capacity of 150v/v .The applications include use in gas based vehicles,transportation of natural gas and adsorption of gas from land fills.

From Oil Palm wastes,cork powder and other agricultural wastes
Adsorption of Sulfur Dioxide on Activated Carbon from Oil-Palm Waste and use of cork powder as source of activated carbon has also been studied.Agricultural wastes could be considered as suitable raw materials for the production of activated carbon.activated carbon was produced by chemical activation with phosphoric acid of agricultural wastes such as bagasse, hard shells of apricot stones, almond, walnut and hazelnut shells,activated carbon from the hard shells of apricot stones have the best adsorption properties and the highest surface  area. This activated carbon could be used in the separation of metal ions from wastewaters.

From pyrolysis of sewage sludges
Activated carbons can also be produced by the chemical activation and pyrolisis of sewage. The adsorbents produced from sewage sludges were able to adsorb dyes from coloured waste waters like saffranine and methylene blue.Methylene blue absorption was faster than that for Saffranine.

From Waste newsprint
Waste paper activated carbon has been  prepared from waste newsprint paper and its adsorption capacities were almost the same as ordinary activated carbon on the market.

From Waste Tyres
Technology is available to burn tires in order to seperate and recover carbides.Some parts of the carbides are active and can be used as active carbon. Water (steam) is added to the system for activation.Steel and generated steam can be recovered seperately.

Methods for treating waste tires include retreading,stockpiling, landfilling, recycling, pulverization, fueling, incineration,and pyrolysis. The simplest means of treating waste tires are landfilling and stockpiling. However,wastetires are not easily biodegradable in landfills and, when stockpiled, the accumulation of water in waste tires provides an ideal breeding ground for disease-carrying mosquitoes and rodents. Moreover, uncontrolled fires have broken out in piles of waste tires, and the emission of gaseous air pollutants during open burning has threatened human health and the safety of nearby communities.Waste tires contain more than 90% organic materialsand have a heat value of 32.6 mJ/kg (14,000 Btu/lb),compared with that for coal of 18.6–27.9 mJ/kg (8000–12,000 Btu/lb). Several attempts have been made to convert waste tires to auxiliary fuel. Among them, pyrolysis is a favorable choice for treating waste tires from environmentaland economic perspectives. Pyrolysis is a typical thermal treatment process in the absence of oxygen (O2),which decomposes waste tires into carbon black, combustible gas, and pyrolysis oil.The combustible gas can be recovered as an auxiliary fuel, while the pyrolysis oil, with a composition similar to that of diesel, can be further distilled as supplemental fuel. Furthermore, waste tires or carbon black could be activated into powdered or granular activated carbon for air pollution control and wastewater treatment.

Rubber separated from waste tires was first carbonized at 500 °C in N2 atmosphere. Next, the obtained chars were activated with steam at 850 °C. As a result, fairly mesoporous activated carbons  were obtained. To further improve the porous properties of the activated carbons, the char was treated with I M HCl at room temperature for 1 day prior to steam activation. This treatment increased mesopore volumes , Furthermore, adsorption characteristics of phenol and a dye, Black 5, on the activated carbon prepared via acid treatment were compared with those of a commercial activated carbon in the liquid phase. Although the prepared carbon had a larger micropore volume than the commercial carbon, it showed a slightly lower phenol adsorption capacity. On the other hand, the prepared carbon showed an obviously larger dye adsorption capacity than the commercial carbon, because of its larger mesopore volume.

From Waste Wood
Activated carbons have been produced from waste wood and have the added advantage of  better utilization of resources and reduction of carbon dioxide generation from waste incineration.Specific surface area and adsorption performance of activated carbons from waste wood were found to be nearly equal to those of commercial activated carbons which could be used for humidity-control in houses and leachate treatment in landfill. Waste wood activated carbon also demonstrated equivalent or superior performance to commercial activated carbons.

From Waste Tea
Activated carbons were prepared by phosphoric acid activation with and without microwave treatment and carbonisation of  waste tea under nitrogen atmosphere at various temperatures and different phosphoric acid/precursor impregnation ratios.

From spent activated carbon from water filters
Spent activated carbon from water purifier (Aqua Guard, India) for the removal of atrazine (2 chloro-4 ethylamino-6-isopropylamino-1, 3, 5 triazine) from wastewaters has also been tried successfully.

From Beer Lees
Activated carbon was successfully produced from beer lees which are the main waste material from a beer-production process, when KOH and CO2 were used as oxidizing agents in activation process.

From combustion ash from low Nox boilers
Coal fired plants now use low NOX boilers to reduce emissions. These burners reduce the NOX but increase the unburnt carbon left after combustion and power plants are left with fly ash and unburnt carbon.This impacts the recycle and reuse of fly ash.One use of combustion waste is as activated carbon.While both anthracite and unburned carbon can produce acceptable activated carbon, unburned carbon is probably less expensive and better for the environment. Unburned carbon, separated from fly ash, does not need cleaning or crushing, nor does it need heating to remove volatile components. Also, while anthracite sells for about $50 a ton, the waste from power plants can be separated for $10 to $15 per ton, and the fly ash could be sold to cement manufacturers.

From Chicken Waste
Preparation of low cost activated carbon from chicken waste is a promising way to produce a useful adsorbent for Hg removal. The activated carbon from chicken waste has the same mercury  capacity as commercial activated carbon.

From Broiler Excreta
Ammonia (NH3) pollution from broiler excreta is a primary concern for broiler industry viability.Activated carbon made from broiler litter is effective for NH3 adsorption originating from litterand provides  an opportunity to not only reuse the manure, but also treat the emissions from or within broiler houses.
The BAC is a much cheaper alternative than commercially produced activated carbons and can be applied directly tohe litter if health of birds are the concern or via a filtration system if air pollution concerns demand compliance to standards.

From Urban Waste
The organic fraction of urban waste is converted to active carbon via an improved pyrolytic process. The active carbon produced has a low ash content, high pore volume and hardnessand the active carbon of the present invention possesses superior characteristics. The urban waste referred to herein includes various types of waste produced in the urban environment. For the purpose of this invention urban waste is defined as waste which includes domestic waste and commercial waste but does not include industrial waste. In this context, domestic waste includes waste produced in an average normal household which comprises food waste, paper products and packaging, plastic products, wood, glass and metal. Commercial waste is the waste produced by the commercial sector. Much of the commercial waste is generated by food establishments, markets, grocery stores and the like.

In the initial stage the waste is sorted for the removal of foreign materials. The waste is then shredded to particle size of about 2cm x 2cm x 2cm, and then dried at a temperature of about 110°C. The dried particulate waste is then transferred to the pyrolysis vessel wherein the pyrolysis is a two stage process conducted at a temperature, preferably, in the range of 1400C to 500°C, in which primary pyrolysis takes place at about 160°C and in the second stage the temperature reaches 3900C. The pyrolysis stage takes about 2 hours. Optionally, matter made of polymeric materials, typically, plastics and rubbers, are removed prior to and/or subsequent to any one of the pyrolysis stages. The charcoal produced in the pyrolysis is crushed to a mean particle size up to about 0.01mm. This charcoal produced in the pyrolysis stage has an ash content of 9-20%. This charcoal is granulated in an extruder with a charcoal: water: oil ratio of about 1: 0.7: 0.15. The subsequent carbonization is carried out at a temperature, preferably, in the range of 110oC to 600°C. The granulated carbon is then carbonized at about 180°C under anaerobic conditions. The subsequent activation is carried out at about 790OC in the presence of steam and combustion gases. The combustion gases used in this stage are mixed with gases from the drying process.

The final purifying of the activated carbon is done by rinsing with an aqueous acidic solution, preferably, 5%-20% HCl solution, until the ash content is 2%-5% followed by washing in water until the water extracts have a pH of 3.5-5. The rinsed activated carbon is finally dried at about 100oC to a final water content in the range of 4%-8%.

The activated carbon obtained by the process of the present invention has an ash content of 2%-5%, a mean pore volume in the range of 0.95-1.2 ml/g  and a hardness in the range 85-95.

From Chlorella Vulgaris and Rice Husk
Chlorella vulgaris and rice husk were selected from microorganisms and agricultural waste, respectively, to create new gold-eluteable adsorbents for adsorption of gold-thiourea complex, and compared with activated carbon.  Although heated-immobilised C. vulgaris had the highest eluteability, it adsorbed less gold. Therefore, heated rice husk could be used as an alternative adsorbent for gold-thiourea pre-concentration.

Activated carbon (AC) of high quality has been produced from rice husk. The production involves two (2) main steps: (1) carbonization of raw material at temperature below 800oC in the absence of air using fixed bed reactor (furnace); (2) activation of resulting char with an alkali. The high-quality activated carbons produced have surface areas of 2,896-3,287 m2/g, methylene blue values of 999-1,050 mg/g and benzene gas adsorption of 167-212%.
References

1.Jin-Wha Kima, Myoung-Hoi Sohna, Dong-Su Kim, Seung-Man Sohnb and Young-Shik Kwonc ,Production of granular activated carbon from waste walnut shell and its adsorption characteristics for Cu2+ ion, Journal of Hazardous Materials,Volume 85, Issue 3, 17 August 2001, Pages 301-315

2.Abe Ikuo,Maruyama Jun,   Fukuhara Tomoko,Iwasaki Satoshi ,Production of Activated Carbon from Waste Wood by Air-Based Activation Method. Science and Industry VOL.74;NO.9;PAGE.442-447,2000

3.F. Rozadaa, L. F. Calvoa, A. I. Garcíaa, J. Martín-Villacortab and M. Otero,Dye adsorption by sewage sludge-based activated carbons in batch and fixed-bed systems  , Bioresource Technology ,Volume 87, Issue 3, May 2003, Pages 221-230

4.A. Gürsesa,  Ç. Dogarb, S. Karacac, M. Açikyildiza and R. Bayraka ,Production of granular activated carbon from waste Rosa canina sp. seeds and its adsorption characteristics for dye ,Journal of Hazardous Materials, Volume 131, Issues 1-3, 17 April 2006, Pages 254-259.

5.The Properties of Activated Carbon Made from Waste Newsprint Paper ,Journal of Porous Materials, Volume 6, Number 3 , May, 1999 ,Pages 191-196

6.Emine Yagmura, Meryem Ozmaka and Zeki Aktas,A novel method for production of activated carbon from waste tea by chemical activation with microwave energy, Fuel, Volume 87, Issues 15-16, November 2008, Pages 3278-3285

7.Emine Yagmura, Meryem Ozmaka and Zeki Aktas,A novel method for production of activated carbon from waste tea by chemical activation with microwave energy ,Fuel,Volume 87, Issues 15-16, November 2008, Pages 3278-3285

8.Pranab Kumar Ghosh and Ligy Philip, Performance Evaluation of Waste Activated Carbon on Atrazine Removal from Contaminated Water,Journal of Environmental Science and Health, Part B, Volume 40, Issue 3 May 2005 , pages 425 – 441

9.Hyoung-Ho LEE, Yuki HIRANO, Norihiro MURAYAMA, Shigeno MATSUMOTO and Junji SHIBATA, Adsorption Properties of Activated Carbon Prepared from Waste Beer Lees by KOH Activation and CO2 Activation, Department of Chemical Engineering, Kansai University and Asada Iron Works Co. Ltd.  February 1, 2007

10.Aik Chong Lua,  and Jia Guo, Journal of Environmental Engineering, Vol. 127, No. 10, October 2001, pp. 895-901,

11.Beatriz Cardoso, Ana S. Mestre, Ana P. Carvalho,* and Joa~o Pires,Activated Carbon Derived from Cork Powder Waste by KOH Activation: Preparation, Characterization, and VOCs Adsorption,Ind. Eng. Chem. Res., 47 (16), 5841–5846, 2008.

12.Masahiro Shimada1, Takahiko Iida1, Kensuke Kawarada1, Yoshifumi Chiba, Toshihiro Mamoto and Takayuki Okayama
Porous structure of activated carbon prepared from waste newspaper ,Journal of Material Cycles and Waste Management
Volume 2, Number 2 ,October, 2000,Pages 100-108

13.Chung-Shin Yuan, Hsun-Yu Lin, Chun-Hsin Wu, and Ming-Han Liu,Preparation of Sulfurized Powdered Activated Carbon from Waste Tires Using an Innovative Compositive Impregnation Process,Journal of the Air & Waste Management Association, Volume 54, July 2004, 862-870

14.Yaji Huang, Baosheng Jin, Zhaoping Zhong, Wenqi Zhong, Rui Xiao ,Characteristic and mercury adsorption of activated carbon produced by CO2 of chicken waste.J Environ Sci (China). 2008 ;20 (3):291-6

15.Fitzmorris, K.B., Miles, D.M., Lima, I.M. 2007. Efffacy of activated carbon from broiler litter in the removal of litter generated ammonia. Proceedings International Symposium on Air Quality and Waste Management for Agriculture Research,September 16, 2007,701P0907 CD-ROM.

16.Dr. R.B. Lartey, & Dr. Francis Acquah, K.S. Nketia,  CSIR Developing National Capability For Manufacture Of
Activated  Carbon From Agricultural Wastes ,The Ghana Engineer, May 1999.