A thesis submitted in partial fulfillment of the requirement for the degree of Master of science

Thesis (M.Sc.) - Asian Institute of Technology, 1992

Laboratory scal e experiments were carried out to study the feasibility of employing UASB reactors to treat mungbean starch wastewater. Four 2.9 1 (in effective volume) UASB reactors, each with a 60 mm inner diameter and 1 m h e ight, were used in this study which was conducted in a room where the temperature was controlled at about 31°C . Four reactors were started with origi nal wastewater from mungbean starch and were studied for possible effec t of SS on anaerobic treatment. Different con centration of Suspended solids (O; 0.5; 1 . 0; 1.5 g SS/l) were added to four reactors. Suspended solids solution was extracted from the origi n al wastewater by centrifuging. Although t here was no s ignificant effect of SS in the ef flu e nt CODr of the reactors and the specific activity of sludge, it s howed a n effect of SS in wastewater on the daily gas production. During period- 1, the organic loading was increased to 5.0 kg COD/(m3 .d ) within 50 days after start- up. The HRT was reduced from an initi a l value of 12 days to 0 . 7 days. However, in period- 2, the start-up was done at an organic loading of 0.3 kg COD/(m3 .d) corresponding to a HRT of 7 days. The organic loading was increased to 3 kg COD/(m3 . d) within about 50 days. The HRT was decreased to 0.75 days within this period. The experimental results obtained indicate a good technical feasibility of employing anaerobic reactors to treat mungb ean starch wastewater.