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, 1981

This study was aimed at evaluating the performance of an integrated system of septic tank and anaerobic upflow filter called the 'septic tank- AUF' as an onsite domestic waste treatment alternative and to investigate the effectiveness of the AUF in providing further treatment of the septic tank effluent. Two full-scale units employed in this study yielded more than 90% removal efficiencies of TCaD, TSS, VSS and more than 75% scaD reduction with respect to mean septic tank influent concentrations of about 1,600 mg/l TCaD, 1,250 mg/l TSS, 775 mg/l VSS and 340 mg/l SCaD, respectively, at the system detention time (6SYS) of 4.5 days and a mean influent organic loading of 0.5 kg CaD/m3/d. The AUFs yielded more than 60%, 40%, 70% and 65% reductions in TCaD, SCaD, TSS and VSS, respectively, for the correspon- ding mean septic tank effluent concentrations of about 310 mg/l, 180 mg/l, 170 mg/l and 110 mg/l respectively. It was found that a 1 day 6AUF corres- ponding to a hydraulic loading of 0.43 m3/m2/d was optimal for the AUF. Mathematical relationships between J/A and So were established for the AUF in terms of TcaD and scaD. Engineering application of this relationship in terms of SCaD was presented in a graphical form as a guideline for· the design of AUF.