Anaerobic digestion of slaughterhouse waste with UF-membrane separation and recycling of permeate after free ammonia stripping.
Anaerobic digestion can adapt to free ammonia to a certain extent. During the anaerobic digestion of slaughterhouse waste, however, an ammonia concentration of up to 15 g Nl(-1) can be reached in the sludge liquid and this will even inhibit adapted sludge. To lower this concentration, a fraction of the digester liquid must therefore be continuously separated from the digested sludge and the free ammonia stripped before the liquid is recycled to the digester. A mesophilic laboratory digester was successfully operated with an ammonium concentration of 4-5g l(-1) and a pH of 8.0-8.4. After free ammonia stripping, the excess liquid was treated in a laboratory SBR for nitrogen and phosphorus removal before being added to the receiving water. The effluent had no toxic effect on daphnia and algae.
Siegrist
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EAWAG, Swiss Federal Institute for Environmental Science and Technology, Dübendorf, Switzerland.
Hunziker
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W
Hofer
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D000003:Abattoirs; D000641:Ammonia / Q000378:metabolism; D001421:Bacteria, Anaerobic / Q000378:metabolism; D019149:Bioreactors; D005232:Fatty Acids, Volatile / Q000378:metabolism; D007220:Industrial Waste; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D012037:Refuse Disposal / Q000379:methods*; D012722:Sewage; D014462:Ultrafiltration; D014865:Waste Disposal, Fluid / Q000379:methods*
D005232:Fatty Acids, Volatile; D007220:Industrial Waste; D000644:Quaternary Ammonium Compounds; D012722:Sewage; D000641:Ammonia