POLYCHAETE ASSISTED SAND FILTER IN TREATING SYNTHETIC WASTEWATER

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Date
2014-09
Authors
HAJI BAHARUDIN, NURUL SYUHADA
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Abstract
This study is about polychaete assisted sand filter in treating synthetic wastewater. To test the application of this concept, polychaete assisted sand filters were experimentally tested for their ability to treat synthetic wastewater. The main objective in this study was to examine the feasibility of polychaete assisted sand filter for synthetic wastewater filtration. The comparison between beach and construction sand in terms of percolation rate and water quality in polychaete assisted sand filtration of synthetic wastewater was also investigated. Besides that, the growth and survival of the polychaete at three different polychaete stocked density (500, 100 and 1500/m2) after 7 weeks. Scale up (1:5) of the sand filter was also studied to investigate the application of sand filter in larger scale. The results of this study provided information on the study of polychaete assisted sand filter performance in relation to percolation rate, water quality of wastewater and also growth and survival of polychaete. Juvenile polychaete (Perinereis nuntia) was used in sand filter and stocked at a control density of 1000 polychaete/m2. Synthetic wastewater was prepared for the filtration by mixing ground dried fish pellets and sea water. Synthetic wastewater percolating through polychaete assisted sand filter beds were reliably treated where total suspended solids (TSS) levels were consistently reduced by more than 70% by the process. pH, dissolved oxygen (DO) and biochemical oxygen demand (BOD) levels were also lowered significantly by the filtration process of polychaete assisted sand filter. However, for sand filter without xvi polychaete, the total suspended solid (TSS) was removed only 60% from the filtration process. This comparative study clearly indicated that the sand filtration stocked with polychaete has higher potential to treat wastewater than the sand filter without polychaete. Both beach and construction sand filters showed similar performance in terms of percolation rate and also water qualities of filtrate wastewater as there was no significant difference (P≥0.05) between both sand. The percolation rate effluent wastewater for sand filter using beach and construction sand had the same trend, where sand filter using construction sand gave slightly higher percolation rate value (0.26 L/m2s) than sand filter using beach (0.24 L/m2s). Thus, beach and construction sands can be used as medium bed for sand filter. In this study, it was proved that polychaete stocking density did affect percolation rate, water quality of wastewater and polychaetes growth and survival. This was due to the presence and quantity of polychaetes. Higher polychaete stocking density has lower DO and TSS concentration which were around 4.25 mg/L and 182.04 mg/L, meanwhile lower polychaete stocking density produced higher polychaete growth and survival compared to higher polychaete stocking density. The survival rate of polychaete after 7 weeks was lower at high polychaete stocking density, CH (71.85 %) in comparison to medium polychaete stocking density, CM (81.11 %) and low polychaete stocking density, CL (100 %). The percentage of survival of polychaete decreased as stocking density increased. From this work, scale up sand filter (1:5) was comparable with small (control) sand filter as there was no significant difference (P≥0.05) between small and larger sand filters in terms of pH, DO, TSS concentration and also polychaetes growth and survival. For the conclusion, polychaete assisted sand filters can be used to treat synthetic wastewater in filtration process.
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POLYCHAETE ASSISTED SAND FILTER
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