Using waste generating energy. Bassum dry fermentation plant and composting plant. Composting and fermenting. Generating value from biowaste.

Transcription

1 Using waste generating energy. Bassum dry fermentation plant and composting plant Composting and fermenting. Generating value from biowaste.

2 Biowaste The dry fermentation plant Using available raw materials The initial material household biowaste and green waste is collected in the organic waste bin. All households throughout the rural district of Diepholz can dispose of their organic waste in these 120- or 240-litre bins. The waste is collected every fortnight. In addition, AWG also operates a large number of green waste collection facilities, where private householders can bring tree and shrub trimmings. These materials, however, do not play any role in biomass fermentation. Once it has arrived at the waste treatment centre, some of the biowaste is treated in the dry fermentation plant and some of it is sent directly to the composting plant with the shredded green waste and (aerated) digestate from the biogas production process. Raw materials for the organic waste bin: Fruit and vegetable waste Stale bread Coffee grounds and coffee filters, tea bags, tea leaves Egg shells, nut shells Hair and feathers and of course green waste from the garden Easily decomposable biowaste is particularly suitable for fermentation. Therefore, only the material from the organic waste bin is used in the dry fermentation plant. Environmentally friendly bioenergy is generated from these raw materials. Unloaded biowaste is mixed with an equal amount of previously fermented material in the mixing hall using a wheel loader. The digestate is used to»inoculate«the new material with bioactive microorganisms. Filling the fermenters. The composting plant The purpose of a very different biological process, the composting of waste, is to produce a high-quality soil conditioner BassHum Qualitätskompost. The treatment begins in the delivery hall of the composting plant. Biowaste and (aerated) digestate from the fermentation process are mixed and shredded in a screw mill. To improve the structure, shredded tree and shrub trimmings are also added. A magnet removes any metal that is present, a drum screen filters out all other foreign substances. The material is then transported on conveyor belts to the composting hall. Adding the biowaste to the macerator.

3 Fermentation the production process The dry fermentation plant centre contains six enclosed fermentation boxes filled with biowaste enriched with previously fermented material. These units are operated in stages, ensuring a continuous supply of gas. The fermenters are heated and equipped with a sprayer. The fermenting mixture is sprayed several times a day with a percolate a bioactive leachate which is collected in the fermenter. The fermentation process takes around four weeks and takes place in a mesophillic temperature range of 37 to 39 degrees, guaranteeing an optimum balance between yield and fermentation time. At the end of the process, half of the material is aerated in two aeration tunnels if required and then processed further in the composting hall. The other half is added to the new input material for»inoculation«. Biogas is converted to electrical energy The biogas that is produced, which has a methane content of between 50 and 60 percent, is transported via a collection pipe to the treatment area. Here it is dried and cleaned using activated carbon. It is then forwarded to an AWG combined heat and power plant where the energy that is recovered drives a gas turbine to generate electricity. Each year, approximately 3,700 megawatt hours of power are produced and fed into the public grid using this method. The fermentation process takes place in hermetically sealed fermenter boxes. Electricity is generated in the gas engine. Composting hall is key The composting hall is 178 m long, 35 m wide and hermetically sealed. Here, the biowaste is piled up into a stack and constantly aerated through the perforated floor panels under optimum climatic conditions (suction and forced aeration). Once a week, a fully automatic turning machine, the»wendelin«turns the stack and restacks it. The resulting outlet gas is cleaned using a biofilter. This prevents odour emissions from dispersing outside the system. It takes eight weeks for the high-quality compost to mature each year 50,000 tons of bio and green waste are processed in this way. It is a completely biological process: microorganisms decompose the organic substances and create new biochemical compounds. At the beginning of the composting process, temperatures in the stack rise as high as 70 degrees. This ensures that the end product does not contain any pathogens or germinable seeds. Foreign substances are screened out before the material is loaded into the composting hall. Composting hall with»wendelin«turning machine.

4 Heating using waste heat Even the thermal energy generated in the production of electricity, i.e. the waste heat, is utilised. It is used to heat water in a heat exchanger which is subsequently transported over a 3.2 km district heating pipe to Bassum hospital s heating system. The generation of electricity combined with a useful heat source is one of the most important benefits of this process, as it is only in this way that the maximum energy yield can be obtained. Integrated and environmentally friendly energy system This form of alternative energy generation represents an important step in reducing CO2 emissions in the atmosphere. No waste is incurred as the digestate is composted. Despite the innovative technology, the dry fermentation plant has an extremely robust structure and faults are very unlikely. For AWG, this dry fermentation plant represents an addition to the efficient and environmentally friendly energy supply sector, complementing its Blumenthal CHP plant, wood-chip heating system, combined heat and power plant and photovoltaic installations. The heat energy is delivered via a heat exchanger to the district heating pipe. The waste heat that is generated is used to heat the hospital in Bassum. Compost with the seal of quality The end result is a high-quality compost plus a variety of potting composts which are ideal for use in the garden and for horticulture and landscape gardening purposes. Customers can purchase the compost, known as BassHum, loose or in bags. Constant monitoring ensures a consistently high quality. BassHum has been awarded the coveted compost seal of approval from the Bundesgütegemeinschaft Kompost (the German Compost Quality Assurance Organisation). Stockists Order BassHum products directly from Humus Vermarktungs GmbH in the Bassum waste treatment centre or from specialist stores in the rural district of Diepholz. Call +49 (4241) for a list of stockists. Compost is also used in the agricultural sector.

5 Generating value from biowaste Using resources in an efficient and sustainable way is not only an imperative today, it also makes economic and environmental sense. Waste is an important and often underestimated raw material. This applies in particular to green and biowaste, which AWG makes full use of in its composting plant and in its dry fermentation plant, which it set up in The company has created a perfect valueadded chain consisting of disposal, composting, heat and energy generation. The dry fermentation plant is part of AWG s composting plant which became operational in the Bassum waste treatment centre in In the composting plant, valuable compost and potting compost, which is returned to the ecological cycle as a soil conditioner, are produced from the contents of the organic waste bin and from green waste. AWG has achieved great success with a variety of high-quality products in this segment. State-of-the-art environmental technology in the dry fermentation plant This new dry fermentation plant operates in a way that is technically and economically innovative. Energy electricity and heat is generated virtually as a by-product of the composting process using alternative methods. The result is a meaningful reduction in the consumption of primary energy sources such as oil, gas and coal. The process is also extremely efficient from an economic point of view. This process has become known above all in recent years in the biogas plants that have been built in rural areas, which are fed mainly by agricultural products, e.g. corn. As AWG already has access to the required raw materials in its composting plant (biomass), it was an obvious step for it to adopt and use this advanced and environmentally friendly process. Dry fermentation plant Delivery / treatment Compost storage Fine processing CHP room Aeration tunnels Fermenters Composting hall Wendelin Biofilter Composting plant Dry fermentation plant Biogas Biowaste from the organic waste bin Mixed with previously fermented material Fermenter boxes are filled Fermentation process Output / separation 50% Aeration tunnels Output 50% Green waste from tree and shrub trimmings Shredders Trimalin macerator Screening foreign substances Composting Output and fine processing Storage / sale Composting plant Compost

6 Advantages of the process Reduced CO 2 through the use of the biogenic energy in biowaste Continuous production of gas through staged fermenter operation Waste-free process digestate is processed directly (composted) Robust technology that is less prone to faults (simple, enclosed concrete tunnels) Combining the generation of electricity and heat means the process is very efficient from an economic point of view Technical data for the dry fermentation plant Process: Dry fermentation in a batch operation using 6 BEKON fermenters Input: Approx. 18,000 t/a Output: Digestate (fed to the composting plant) Biogas (used in the CHP plant) Power generated in CHP plant: 625 KW electrical energy, 680 KW thermal energy Energy yield: Electrical energy approx. 3,700 MWh/a Thermal energy approx. 4,000 MWh/a KH heat usage approx. 2,800 MWh/a Energy usage: Electrical energy is fed into the public grid (remuneration as per EEG (Renewable Energy Act)) Bassum hospital is heated via a 3.2 km district heating pipe Technical data for the composting plant Process: Static dynamic shifting stack system Input: Approx. 50,000 t/a of bio and green waste Output: 16,000-18,000 t/a high-quality compost Pre-treatment: Trimalin screw mill Screening: 80 mm perforated screen Dimensions of composting hall: 178 x 35 m, fully enclosed Composting period: 8 weeks Stack temperature: C AbfallWirtschaftsGesellschaft mbh Entsorgungszentrum Bassum Klövenhausen 20 D Bassum Telefon +49 (4241) Fax +49 (4241) info@awg-bassum.de Stand rossberg-gestaltung DRY FERMENTATION Generating biogas from biowaste Maximum gas yield, high-quality gas Low energy consumption in the process Compact design, modular expandability Low-maintenance, robust technology Minimum expense for technical equipment Less susceptible to impurities Few moving parts, less wear Filled using existing machine (wheel loader) BEKON Energy Technologies GmbH & Co. KG Feringastraße 9 D Unterföhring Telefon + 49 (89) contact@bekon.eu