Use of biogas effluent for the cultivation of photosynthetic bacteria
1987
Marasri Reungjitchachawaly
Use of biogas effluent to cultivate photosynthesic bacteria was aimed at producing microbial biomass as animal feed supplement and COD removal. Growth of mixed culture of Rhodopseudomonas spp. and Rhodospirillum spp. previously isolated from anaerobic digester was studied in the effluent drawn from digester fed with pineapple peel. The study showed the increase in biomass, however, the yield was unsatisfactory. The addition of carbon and nitrogen source into effluent having organic content (COD) approximately 3,000 mg/l stimulated the productivity of microbial cell. The utilizable substrates were 0.15 % (v/v) acetic acid, 0.15 % (v/v) propionic acid and 0.15 % butyric acid with butyric acid was the most. The nitrogen source was 0.1 % ammonium sulfate. The addition of acetic acid and ammonium sulfate into diluted effluent did not increase the biomass. It is suggested that the effluent may provide not only carbon and nitrogen source but also growth stimulating substances. Though the organic content of effluent was necessary for the growth of Rhodopseudomonas and Rhodospirillum but high turbidity would limit the penetration of light. On the dry weight basis the biomass yield was 2.89+-0.23 g/l and the protein content was 34.86+-2.85 % COD reduction was 80.84+-4.35 %.
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