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| A study on transformation of main pollutants along the wastewater flow in biological aerated filter. |
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Abstract The performances of biological aerated filter (BAF) with hollow bamboo balls as filter media for wastewater treatment in marine aquaculture was investigated. The wastewater was conditioned at pH ranging from 7.8~8.0, DO ranging from 2.8~5.8mg/L, air-to-water ratio at 3, hydraulic load of 0.58m3/(m3×h), TAN load of 0.35~0.46g/(m3×h), and organic load of 1.58g/(m3×h). Transformation of organic substances and ammonia nitrogen along the water flow were evaluated to determine the spatial distribution characteristics of pollutants. Results showed that most CODMn was removed between 0~10cm height, with 49.12% CODMn removed and 34.88% soluble CODMn removed in this range, meanwhile most TAN removed between 0~30cm height, with 18% TAN removed at 10cm and 55% removed at 30cm. The biomass and microbial activity decreased from the bottom of the filter to the top. In conclusion, pollutants were mainly removed between the height of 0~30cm, and the left section of the filter always acted as a buffer to remove pollutants remained in the wastewater, in case of sudden waste load or hydraulic impact.
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Received: 25 February 2011
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