GEWINNUNG MIKROBIELLER BIOMASSE ALS NEBENPRODUKT DER ABWASSERBEHANDLUNG IN ALGENGRÄBEN

Abstract

In the course of an Israeli-German Project concerning photosynthetic treatment of domestic sewage the "Intensive Algal Wastewater Treatment System (IAWIS)" was developed from existing high-rate pond technology. An IAWIS demonstration plant near Haifa was operated for several years, rendering effluent of high quality. Several tons of algae-bacteria biomass were recovered as a byproduct containing about 50 % of crude protein. Extended feeding tests and toxicological studies in animals proved the microbial biomass to be a suitable feed ingredient. Experiments with high-rate sewage oxidation ponds in the Federal Republic of Germany concerned the treatment of the liquid phase of piggery waste. The removal of BOD, , N and P was efficient, proceeding, however, at lower rate in winter, especially with respect to P removal rate. In order to conserve energy, concentrated liquid wastes should rather be treated by anaerobic/aerobic multistage processes in which high-rate oxidation ponds may be used as the aerobic step. Excess quantities of liquid manure are suggested as target substrates. Improved removal of COD is one of the aims of ongoing studies.