Study of mathematical model for wastewater treatment by plastic media trickling filter process
1997
Vichai Chamnannarongsak
This research is indicated the study for the performance of a plastic media trickling filter in pilot scale. The trickling filters were packed with cross-flow PVC plastic media with a depth of 2.9 m and its typical specific surface area of 243 and 102 square m/cubic m (PAs-243 and PAs-102). They were operated with the synthetic wastewater with mixture of dairy waste and tap water. The wastewater characteristics were prepared based on average 620 and 330 mg/L of COD and BOD respectively. For this research the hydraulic loading (HLR) 3.39-16.60 cubic m/square m-d, organic loading (L) 0.82-2.73 kg COD/cubic m-d and recirculation ratio (R) 0 to 4 were applied. When increasing HLR and L without recirculation, the process efficiency will decrease. When L was 0.82 kg COD/cubic m-d and HLR was 3.39 cubic m/square m-d, the total COD removal was 84.9 and 78.9 percent for PAs-243 and PAs-102 respectively. The units with recirculation (R=4 and HLR=16.60 cubic m/square m-d) gave COD removal efficiency of 89.5 ad 87.5 percent for PAs-243 and PAs-102 respectively. The data and result from this research were applied to the mathematical models of other researchers in order to obtain the kinetic coefficients. The most suitable mathematical model was of Eckenfelder (1961), which could be applied in both types of plastic media in general form of :- Se/Si = exp (-k As H*[m)/HLR*[n)). Without recirculation (R=0): For PAs-243, the k, m and n are 0.00067, 1 and 0.4902 respectively and for PAs-102, they are 0.00138, 1 and 0.4791 respectively. With recirculation (R=1-4): For PAs-243, the k, m and n are 0.00339, 1 and -0.1063 respectively and for PAs-102, they are 0.00818, 1 and -0.1582 respectively. The studies were also carried out on the modified mathematical models, using HLRAT and HLRAs instead of HLR. All these modified models were valuable in designing wastewater treatment plants, especially when the simple models had their limitations.
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