Bioremediation Of Organic Matter Accumulation In Artificial Soil Rapid Infiltration Bed

Artificial soil rapid infiltration (ASRI) is a kind of newly advanced technology using artificial soil instead of natural soil as porous filter media in the rapid infiltration system. It has a better sewage treatment effect, local available and a lesser land areas requirement than that of traditional land treatment. However, given high organic matter concentration or heavy inlet flow, hydraulic loading rate of the system, oxygen transfer and biodegradation capability will be reduced due to the accumulation of organic matter in the system. And then the filter media will be clogged. There are two methods to resolve this problem presently: one is to prolong the drying period; the other is to scrape off the surface bio-film and infill with new filter media. But the former could reduce the treatment capability of the system and waste time, the later could affect the microbe constitute and lead to outflow reduction.ASRI is a friendly way for sewage treatment, but organic matter accumulation and its clogging are one of the most important problems of ASRI. In order to find a way to improve removal efficiency of the system and to solve the problem above, bioremediation technology such as phyto-remediation, micro-remediation and animal remediation were applied in this research. Vegetables, microbes and earthworm that have high sewage purification capability were used separately in columns. In order to find out the effect of these methods on effluent quality and the distribution of nutrient, the effluent quality, the organic matter, nitrogen and phosphorous in soil columns have been investigated. The results show as follows:(1) Water hyacinth and chysanthemum have high capability to purify sewage than that of other tested plants. In this study 22 strains were separated from the soil columns, and 10 strains were screened out to besuperior strains. The rate of sand to soil was 9:9 when earthworms were brood in soil columns.(2) To plant vegetable or to inoculate superior bacterium could improve the effluent quality. The average removal rates of BOD5, COD, NH4+-N, and TP were 80%, 80%, 80%, and 50%, respectively. But the removal rate of TN was at low level due to nitrogen leaching. The removal rate of NH4+-N was above 90% after earthworms being brood in soil columns.(3) With the depth of soil layer increasing, the content of organic matter, nitrogen, and phosphorous declined. But the organic matter, nitrate, and phosphorous will be leached more or less by coinage. The content of organic matter increased gradually as the process of irrigating, especially at the soil surface.(4)Planted vegetables or inoculated microbes or brood earthworm could decline the content of organic matter in soil column correspondingly, and postpone the organic matter accumulating in the system.(5) Planted vegetable in the system has advantages on nitrification and phosphorous adsorption. Microbes remediation could accelerate nitrification process, but had no obvious affect on phosphorous adsorption. Earthworms had no evident effect on nitrite and phosphorous removal.(6) 1:5 w/d and 2 days operation regime was more economic and met with the need of social for sewage treatment, despite of high organic matter accumulating rate. Whereas, 1:8 w/d and 3 days operation regime was reasonable when earthworms were brood in the system.