Cel The project aims to demonstrate a full scale plant for the biological treatment of wastewater originating from a potato-processing factory, including an anaerobic stationary fixed film methane digester and a finition aerobic treatment system.Innovative is the energy saving through the recycling of waste energy of the potato-processing factory to heat the wastewater to be treated, the full-scale stationary fixed-film process and the biogas recovered from it, and, hence, the lower energy consumption by the aerobic treatment.The wastewater treatment plant will be installed in the Company Convent, Knaber Gebaeck, GmbH and Co, Frankenthal.The expected energy production is 170 TOE per year. The simple payback period is estimated at 2 years by comparison with an alternative conventional solution.The fixed-film methane reactor has proved a success. Since reaching the operating temperature there has been no instabilities. The highest possible anaerobic degradation is achieved. The load cannot be increased as there is no higher concentrated waste water available.Particularly noticeable is the fact that a stable sludge blanket could be cultivated underneath the swimming support media. The sludge has high SS-concentrations of more than 80 g/l with very good settling velocities.The flexibility of the activated sludge blanket has proved good. A definite advantage is the fact that each tank can be bypassed and used for nitrification and denitrification.The circulating pumps in the buffer tanks of the fat containing waste water were a failure as they required regular repair. Eventually they were removed. The open effluent shaft of the methane reactor has also proved a failure due to bad odour and corrosion problems around the shaft. This shaft was closed between the 23.08 and the 06.09.1990. Small changes to the pipes on the roof of the methane reactor had to be made because the flame trap filled with condensate. This resulted in biogas from the methane reactor passing the over-pressure protection ventilator.Despite these minor problems, the project can be considered a technical success.The methane digester, central place of the potato-processing wastewater treatment system is a stationary fixed film reactor of 1400 m3 capacity containing 1000 m3 of plastic material as carrier with a specific surface of 150 m2 per m3. The running conditions are the following : mean hydraulic residence time 2 to 2.5 days, loading rate from 1.5 to 3 kg COD per m3 of digester working volume and per day, temperature of the mixed liquor between 35 and 37 deg.C. The expected performances are the following : 85% conversion in the anaerobic step on a COD basis, a yield of 0.8 m3 biogas per m3 wastewater treated, excess sludge production amounting to 7% of the excess sludge produced in a similar aerobic system, a biogas production rate of 1440 m3 per day.Upstream of the methane digester, 700 m3 wastewater per day, with a COD of 6 g/l, are sieved through trommel-type sieve, heated from 25 deg.C to 40 deg.C in a heat exchanger, and led to step l of the system : a buffering tank of 1000 m3where acidogenesis and acidification take place.Downstream of the methane digester, the wastewater being treated is led to an aerobic fixed film trickling filter of 200 m3 capacity filled with plastic carrier, at a loading rate of 2 kg BOD per m3 reactor per day, at a superficial velocity of 2 m/h, a temperature of 30 deg.C. The conversion is expected at 15% of the initial COD content. The effluent is filtered on a filter and the collected sludge recycled upstream. The liquid is led to a 1000 m3 aerobic tank at a low loading rate of 0.2 kg BOD per m3 reactor per day, a long mean residence time and a food to microorganism ratio of 0.06 kg BOD per kg suspended matter per day. The effluent passes through a conventional decanter before being disposed off. The sedimented sludge is recycled upstream.The demonstration project relies on a 3 year preliminary study conducted by the University of Hannover using pilot plants of 1 m3 and 13 m3 one year each.The monitoring will be effected by the University of Hannover and consists of a follow-up to the start-up. During an 18 months operation period, the following analyses will be performed : energy, mass and flow balances, pH, temperatures, balances and fate of P and N, volatile fatty acid content as well as performances : biogas production, COD and BOD conversions. These data will be scrutinized.The energy production is expected at 0.65 TOE per day, and 170 TOE/y on a 250 working days a year basis. Comparatively to an anaerobic treatment only, the expected savings amount to 2.31 DM per ton potato processed, half as biogas produced, and half as electricity saved. Program(-y) ENG-ENALT 2C - Programme (EEC) of demonstration projects relating to the exploitation of alternative energy sources and to energy saving and the substitution of hydrocarbons, 1983-1985 Temat(-y) 1.3 - PRODUCTION AND USE OF BIOGAS Zaproszenie do składania wniosków Data not available System finansowania DEM - Demonstration contracts Koordynator CONVENT KNABBER-GEBAECK GMBH AND CO KG. Wkład UE Brak danych Adres LINNICHERSTRASSE 48 POSTFACH 45 09 07 41 Köln Niemcy Zobacz na mapie Koszt całkowity Brak danych
