MUNICIPAL SLUDGE WASTES BIOGAS PRODUCTION

AN INVESTMENT THAT PAYS BY ITSELF.

When organic waste has to be processed efficiently and cheaply, then we have Biogas Plants for municipalities, industry...in commercial use since 1990.

                  

WABIO is an efficient recycling plant.

WABIO is a highly developed process for the treatment and refinement of organic waste and sludge. The Wabio Process is based on the Anaerobic. It is one stage, medium concentration anaerobic digestion process operating in the mesophilic temperature range.

WABIO is an investment that pays for itself in many ways. Compared to conventional methods it is more efficient, uses space more effectively, recycles wastes better, and reduces the need for landfill dumping, all part of a good investment.

What is more, the WABIO plant generates electricity and heating energy for sale and yields valuable, high-quality humus.

The WABIO plant conserves land, it requires less landfill space, leaving extra land for other uses by local residents.

Another major plus is higher amenabity value for local residents.  WABIO plants are an IDEAL SOLUTION for municipalities, industries... and saves you from many environmental problems, enhancing the image of your municipality or company. WABIO means caring. The entire system is closed, which minimizes odours problems. If necessary, the plants can be placed right next to residential areas. Unlike composting, the WABIO plant requires no purchases of electricity. In fact, it generates an electricity surplus for sale. In the WABIO process, bio waste or sludge is refined into useful products, electricity and humus. No more landfills for bio waste; When you factor in the profits from the sale of products and the savings on landfill charges, a WABIO plant is a profitable investment.

So, The WABIO process has a wide field of applications:

1. It solves municipal problems of bio waste and sludge.

2. It is suited for processing food-industry waste.

3. It is also suitable for processing slaughterhouse wastes.

4. It solves tricky problems of agricultural waste and slurry.

In Europe a lot of works are being done on Anaerobic Digestion (AD) process for treating MSW (Municipal sludge wastes) with or without sewage, agricultural wastes, piggery wastes etc. There are variations in this process for MSW treatment, such as high solid, medium solid or low solid concentration. Also, the method can be carried under mesophilic or thermophilic conditions.

Based on the operating experience, it is found that anaerobic digestion process under mesophilic conditions having solid concentration of 10-20% is preferable. Wabio is one such process of anaerobic digestion developed by our partners in Finland.

Our WABIO Biogas; PROCESS Production consists of :

1. Reception and sorting. (is the pre-treatment stage where the garbage is received and is followed by hand picking belt conveyor and an electro magnet)
2. Mechanical conditioning.( After segregation, the material is shredded to smaller pieces i.e. 25-50 mm size. The shredded material is screened.)
3. Anaerobic digestion/methanisation. (consists of feed preparation tanks which receive the screened material and a slurry of 15% solid concentration is made. The slurry is then pumped to Bioreactors where the process of digestion takes place. The products from Bio-reactors are methane rich gas from the top and sludge/slurry from the bottom. The supernatant liquid, near the top, is sent for recirculation to make the slurry. Gas is stored in the Gas holder. Part of this gas is used for mixing the contents in the Bioreactors.)
4. Power generation.( From the gasholder the gas is sent to Gas engines to produce electricity)
5. Dewatering of slurry to produce organic fertilizer. Sludge/slurry from the bottom of the bioreactors is sent to Filter press for dewatering. After dewatering, the filtrate is sent back to the feed preparation tanks. The remaining dewatered cake is the organic fertilizer having nitrogen, phosphorus and potassium)

THE SALIENT FEATURES OF THE WABIO PROCESS ARE AS FOLLOWS :

1. In the heart of the process is the bioreactor in which organic matter is broken down by bacterial action into biogas and humus. Because the process takes place in closed vessels, thereby avoiding odours nuisance or leakage of biogas into the atmosphere. Further it attracts no birds or vermin such as rats, mice etc. Carbon dioxide emissions are minimal from the Wabio process
2. The humus drops to the bottom of the reactor, from which it is removed at regular intervals.
3. The biogas is collected in a separate tank and is used to generate energy.
4. One ton of biological waste matter generates roughly 150 - 200 cubic meters of gas, and about half of the quantity of waste ends up as humus.
5. Biogas is 60 - 65% methane and it can be used unmodified in gas-powered engines to generate electricity. Power produced by the generators will be used preferentially to supply the power requirements of the plant. Surplus power can be delivered into the grid or sold to a third party. The gas engines are water cooled and the heat removed by the cooling water system provides a source of low grade heat. This shall be available either as hot water at about 80^O C or hot air at 60^O C. If no commercial outlet is available for this heat, the same will be dissipated.
6. After the biogas is extracted, the reject water formed by the mechanical drying of the humus sludge is used to dilute fresh input waste. This stabilizes its solid content and warms it in preparation for the next stage.

THERE ARE THREE PLANTS IN OPERATION.

The first one at Vaasa in Finland has been in operation since 1991. The plant treats sewage sludge and MSW. In this plant, the non-biodegradable portion is separated from the organic fraction and is incinerated. Combustion takes place in two phases in a bubbling fluidized bed boiler with a post combustion section. The organic fraction is combined with the sewage sludge and treated in the Wabio AD plant. The electricity is fed to the grid and heat is used for domestic heating.

The second one in the city of Forssa, in Finland.

The third one in Germany. (The Bottrop plant)

The German city of Bottrop, which has approximately 1,200,000 inhabitants, took on the target of reducing the amount of waste delivered to the municipal waste power plant at Karnap. In 1993, Bottrop, in cooperation with ROeG Umwelttechnologie GmbH, decided to order a Wabio plant for the digestion of 6500 tonnes per annum of source-separated household waste from Deutsche Babcock Anlagenb GmbH (DBA), a German licensee. Our Finish partner supplied the engineering and the core equipment of the digestion process.

The special requirements for this plant included reliable operation : compact construction on site at the municipal landfill area of Donnerberg : high-quality end-product (humus) ; and optimal connection to the existing infrastructures. Wabio technology was found to fulfil these requirements.

One special feature of the project is the large proportion of population living in apartment blocks, and an expected high concentration of contaminants in the source-separated household waste. Wabio provides separation of unwanted particles in several unit operations in the process. New features in comparison to the earlier Wabio plant in Finland are hygienization and humus post-treatment. The Bottrop plant started up in spring of 1995.

Proposed 4th Plant at Kalyan (India)

Kalyan Dombivli Municipal Corporation (KDMC) has signed an agreement with Future Fuels eng. (India) Pvt. Ltd. (now known as Nestler EcoTec Pvt. Ltd. _ NPL). NPL will set up a 150 TPD MSW treatment plant on BOOT basis. The treatment plant consists of steps as described earlier and produces Electricity and Organic fertilizer.

RESUME OF WABIO PROCESS

Environmental impact: The whole Wabio process takes place in closed vessels, and consequently there is no odours nuisance or leakage of biogas into the atmosphere. Thanks to its closed characteristics, the Wabio process attracts no birds or vermin such as rats, mice, etc. It becomes an asset specially important to neighbours of the plants.

energy: The high quality biogas of the Wabio process is converted into electricity in a power plant through gas engine generators. Thus the Wabio plant produces excess power for sale.

Compost Quality: The quality of Wabio humus is very high. In the Wabio process all disease-producing micro-organisms are eliminated. The maturity is grade IV or better according to the German classification. The organic matter content is 30 - 40%. Humus does not contain easily mineralizable carbon or pathogenic bacteria.

Land area: The land area required for a Wabio plant is only 20% of that required for an aerobic composting installation.

Treatment time: Anaerobic digestion by the Wabio process requires only 15-20 days as compared to a minimum of 6 months required for aerobic methods.

Co-digestion of sludge: In the Wabio process, sewage sludge can be conveniently and economically co-digested with solid municipal waste. In aerobic composting, sludge treatment is not practical, therefore, separate treatment is required for sludge.

Economy: Given the above comparison and considering the investment and operating costs, the conclusion is clear : a Wabio plant represents an economical investment in the best available technology.