Nittaya Muangphan creator Umita, Teruyuki Chairperson Fujii, Shigeo Examination Committee Chongrak Polprasert Examination Committee Samorn Muttamara Examination Committee The Government of Denmark (DANIDA) Scholarship Donor text series technical report th Bangkok Asian Institute of Technology 1994 continuing eng 87 leaves In this study two pilot-scale rock bed filters were conducted to determine the effects of design parameters and operating conditions namely; type and arrangement of filter media, location of aerator and HRT on RBF's petformance. Influent used was a mixture of AIT domestic wastewater and tap water in a ratio of 1:1. The long term behavior of sediment and biofilm was also studied. For filter media effect, two types of filter media, broken bricks (diameter of 10 cm) and rocks (diameter of 20-15-10-5 cm), were installed in the reactors under the same HRT of 4 hours (OLR of 30 gBOD/m2 .d) and aerator location. The arrangement of rocks, which was from big ones to small ones in the reactor direction, may be recommended for better filter media installation. Since the rock media showed higher removal efficiencies of SS and VSS than the brick media. In case of different aerator location, three patterns (pattern 1-3) of aerator location on RBF's petformance were studied at 4 hour HRT (OLRs of 20-30 gBOD/m2 .d) by keeping the similar type of filter media. Aerator were installed at 0.5-1.5 m for pattern 1, 0.5-2.0 m for pattern 2 and 1.5-2.0 m for pattern 3. In pattern 2, the highest removal efficiencies of 78.4%, 74.0%, 60.9% and 60.9% for SS, VSS, BOD and COD, respectively were obtained. This was followed by pattern 3 and 1. However, there was only a small difference between pattern 2 and 3. The effect of HRT was examined in three cases; namely 2, 4 and 8 hours HR.Ts. These OLRs were 68, 20 and 17 gBOD/m2 .d respectively. The highest RBF's performance was obtained at the longest HRT of 8 hours or the lowest OLR of 17 gBOD/m2 .d.The removal efficiencies of pollutants seem to be directly proportional to the hydraulic retention time. The overall removal efficiencies of SS, VSS, COD, BOD and NH4-N were 84.7, 86.5, 77.1, 76.4 and 50.3%, respectively. To study long term behavior of sediment at the bottom and biofilm on the media, the accumulation of these were considered at the first-half portion of the reactors during four months operation. A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science. School of Environment, Resources & Development Thesis (M.Sc.) - Asian Institute of Technology, 1994 Filters and filtration Asian Institute of Technology. http://203.159.5.9/ait-thesis/detail.php?q=B15774 http://203.159.5.9/ait-thesis/detail.php?q=B15774 230399 20260818090413.0