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

The activated sludge process for solid-liquid separation domestic wastewater. This parts: laboratory-scale and coupled with hollow fiber was applied to treat the low thesis work can be divided pilot-scale experiment. In laboratory-scale experiment, two operating conditions were investigated: non-aerated and aerated system. Each of these cases were investigated at different initial hydraulic retention time (HRT) of 1,3 and 6 h which corresponding to the permeate flux of 0.1, 0.0333 and 0.0167 m3/m2 .d. Hollow fiber membrane module with a pore size of 0.1 ~m. and a surface area of 0.3 m2 was immersed in the reactor which have the same working volume of 1.25 1. AIT domestic wastewater, used as a substrate, was fed to the reactors which have the same working volume of 1.25 1. AIT domestic wastewater, used as a substrate, was fed to the reactors by gravity. Treated water was collected as permeate through the membrane by roller pump. Non-aerated condition takes an advantage over aerated condition at initial HRT of 3 and 6 h since lower energy consumption was required while giving similar effluent quality and process stability. At high permeate flux rate, clogging in aerated condition was less than in non-aerated condition since the aeration played an important role in detaching the attached solids on the membrane surface. Since low strength wastewater was used in this study, clogging was observed even at the organic loading less than 2 kgCOD/m3.d. In pilot-scale experiment, 2 modules of o. 03 um , pore size wi th 9 m2 surface area each were immersed in the reactor which has a maximum working volume of 1.5 m3{u2022} Treated water was collect as permeate through the membrane by a centrifugal pump. AIT domestic wastewater which was controlled by a floating valve was supplied to the reactor by gravity. Even when sewage was fed at varying rate following diurnal variation to the bioreactor, a good stability of the process was achieved which was shown by the consistency in treated water quality. The effect of jet aeration arrangement was studied in view of reducing the clogging of the membrane. The effect of jet aeration pattern was not clearly seen whereas the effect of jet aeration period was noticed. The jet aeration could be used to prolong the operational life of the membrane in the bioreactor but clogging was an unavoidable factor in long term operation.