Treatment and utilitzation of tapioca starch waste with photosynthetic bacteria and heterotrophic bacteria
1989
Jaruwan Hawahsuwan
Nutrient supplementation in the proportion of (g/l) of starch: diammonium hydrogen phosphate: potassium dihydrogen phosphate: dipotassium hydrogen phosphate as 2:1:1:1 was optimal. The cultivation yielded maximum dry cell mass of 5.7 g/l after 8 days with COD reducing efficiency of 99.02 % and starch utilization of 99 % whereas the addition of three vitamins:- nicotinic acid, biotin and thiamine showed no effect on growth. Various volatile fatty acids were produced and some were gradually consumed by the photosynthetic bacteria during cultivation; acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid and isovaleric acid. Among these, acetic acid and propionic acid were the most respective volatile fatty acids produced. Cultivations of photosynthetic bacteria yielded 5 g. dry matter/l after thirteen days culture with 94.4 % of COD reduction and 98.65 % of starch utilization. Increase of inoculum size to 50 % was able to increase the maximum cell mass to 6.2 g/l after 12 day-cultivation with a slight-increase in COD removal efficiency to 98.95 %. The final cell mass contained 0.96 mg/g dry matter of carotenoid and 10.02 mg/g dry matter of bacteriochlorophyll. Analysis of the nutritional values of bacterial cell mass harvested from Rhoux bottle culture; crude protein content of 57.65 % whereas outdoor culture-cell mass was 53.58 % with considerable amounts of various vitamins such as:- biotin, vitamin B12 and niacin of 35.9, 16.6 and 253.7 mg/kg dry matter respectively.
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