Treatment of Bio-genic Wastewater by Multi-Soil-Layering MethodEffect of Various Positions of Aeration Using Small Model Systems

The effects of various positions of aeration in Multi-Soil-Layering (MSL) method of bio-genic waste water treatment were investigated. Porous aeration pipes were installed in upper, middle, and lower positions in model MSL systems. Each model MSL packed in 10X50X60cm sized acrylic box. Air was supplied at the rate of 48000 l.m super(-3).d super(-1) through the porous pipes installed at various positions. Loading rate of waste water was 288 l.m super(- 2).d super(-1). In the upper position of aeration, clogging was prevented and nitrogen removal was efficient. But efficiency of aeration was low for high level of removal of COD.BOD and T-P, because air leaked from surface of the system. In the middle position of aeration, the efficiency of T-P removal and decomposition of organic matter were high because of the efficient aeration to create relatively large aerobic parts in the MSL. But nitrogen removal was low. Because of nitrate was leaching. It was thought that anaerobic parts were too small to efficient denitrification. In the lower position of aeration, clogging was happened at the early stages of treatments. Fe(II) and Mn(II) were oxidized efficiently to prevent the solubilization. COD.BOD of final effluent water was also low. Based on this study, if only one aeration position has to be selected, the appropriate aeration position was considered to be the position between the first and second of soil layers of MSL. This aeration position may prevent clogging effectively. Large aerobic condition may contribute to efficient phosphorus and organic matter removals. Nitrogen removal may also be enhanced because of nitrification of the upper position and denitrification of the lower position.However, since each upper, middle, and lower position showed different efficiency characteristics on treatments, the positioning of aeration and the operational condition should be selected depending on the given target of the treatment, including the combinations of the two positions, upper/lower, upper/middle, and middle/lower.