The Performance Of AAFEB On Treating Domestic Wastewater In Low Temperature Region And Research Of Effluent On Irrigation

With the development of economics, the level of urbanization in our country has improved a lot, as well as the great pressure of environment. Water pollution and shortage is becoming a key factor in limiting China’s economic development.The problem is urgent. Based on this, psychrophilic treatment of domestic wastewater by the anaerobic attached film expanded bed sludge (AAFEB) is studied in this paper.The feasibility of effluent for agricultural irrigation is discussed to solve the pollution problem and make the best use of the water and nutrients in it.The results show that, AAFEB reactor start-up can be completed in26d, around20oC.COD removal effiency could reach60%or above by adjusting the parameters of the reactor at above10oC, and the average concentration of COD in effluent is57.72mg/L.In addition, the anaerobic process play an important role in the removal of heavy metals, fecal coliform and other pollutants,but do nothing with the removal of nutrients in the wastewater, such as different forms of nitrogen and phosphorus.Thus, nutrients could be retained after anaerobic treatment, the concentration of pollutant could meet the requirement of “standards for irrigation water quality”.Although differs in the concentrations of nutrients used for irrigation, the concentration of chlorophyll in cabbage leaf is similar. However, rate of emergence, root length, stem length, fresh weight, dry weight and area of leaves are far greater than the diluted results. It indicates that,the nutrients in the effluent could satisfy the need of crops with no inhibition on it.On the other hand, rate of emergence after irrigation of actual wastewater is only60%, due to the increase of salinity and C/N as well as high concentration of Hg, which couldn’t meet the requirement of national “Environmental quality standards for soils”.The active ingredient in nutrients will increase after the irrigation of anaerobic effluent,while no significant change occurs in soil pH.What’s more, the concentration of Cd, Cr, Cu, As, Zn, Hg, Pb and other heavy metals is very low which can meet national standards.Compared to diluted results, leaf area, fresh weight and grass height of the cabbage and lettuce will increase more after irrigation with effluent, due to more nutrients accumulated in the soil and crops; The change of pH in the soil is not obvious and no harm occurs after a short-term irrigation with different kinds of water, though sality of soil is slightly increased. Concentration of heavy metals in crops and soil could meet “Safety qualification for agricultural product-Safety requirements for non-environmental pollution vegetable” and “Environmental quality standards for soils” respectively. Although both of the two water quality do no harm to the crops and soil, irrigation with anaerobic effluent will be more favourable from the point of crop growth.