Malong, Corazon E. creator Chongrak Polprasert Chairperson Hanaki, K. Examination Committee Shin, Hang-Sik Examination Committee DAAD , Federal Republic of Germany Scholarship Donor text series technical report th Bangkok Asian Institute of Technology 1987 continuing eng 64 p. Bench scale experiments were conducted to determine the biodegradability of the tapioca starch and the vegetable oil wastewaters. Two batch digesters and three semi-continuous digesters were operated for each run. The batch digesters were filled with influent mixtures of digested sludge: wastewater at 70:30 and 50: 5 0 ratio. The first run of the semi-continuous digesters was fed with tapioca starch wastewater at organic loadings of 0.4, 1 and 2 kg COD/m3 -d , corresponding to hydraulic retention times (6) of 21.6, 8.7 and 4.3 days, respectively. The vegetable oil wastewater was used during the second run at organic loadings of 0.2, 0 .5 and 1.0 kg COD/m3 -d corresponding to a of 7, 2.8 and 1.4 days, respectively. Gas production was shown to increase with retention time and with increasing influent concentration. The maximum CH4 production a nd COD reduction recorded were 0.09 m3 /m3 -d a nd 88 %, respectively, at a loading of 0.4 kg COD/m3 -d for tapioca wastewater a nd similarly for vegetable oil wastewater, CH4 production was 0.04 m3 /m3 -d and COD reduction was 80% at 0.2 kg COD/m3 -d. The results indicated that only the tapioca starch wastewater was satisfactorily applicable for kinetic analysis. In both batch and semi-continuous systems, the results indicated that the degradation of tapioca starch wastewater was better than the vegetable oil wastewater in relation to gas production and COD removal efficiency. A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Environment, Resources and Development Thesis (M.Eng.) - Asian Institute of Technology, 1987 Sewage Purification Biological treatment Factory and trade waste Asian Institute of Technology. http://203.159.5.9/ait-thesis/detail.php?q=B19252 http://203.159.5.9/ait-thesis/detail.php?q=B19252 011298 20260817162224.0