The Study On Wastewater Individual Treatment And Reuse

The paper chooses the small equipment that purified the domestic wastewater individually as the object. Anaerobic- aerobic aerated technique is introduced in order to reduce operation cost. The main aim makes the final effluent satisfy the standards of the irrigation water or domestic water. Meanwhile, the research of removing nitrogen is considered.Individual treatment and reuse of domestic wastewater was especially adapted to communities, schools and small towns etc. The advantages included that the cost of constructing underground pipelines is reduced and the rate of repeating use is enhanced.Two-step Anaerobic Baffled Reactor is applied to anaerobic phase. Anaerobic process need not the power consumption and made the removal rate of COD_Cr reach 40-60%. Adsorption-renew technique is applied to aerobic aeration so as to prevent the active sludge from bulking.The experiment contains two parts. In the first part, the device introduces anaerobic-aerobic techniques being combined with the method of adding bacteria into it so as to make the effluent meet the standard of the water for irrigation or domestic use. The result revealed that with HRT being 4h, the average removal rate of COD_Cr, BOD₅, and turbidity were respectively 78.6%, 85.6%, 54.3%, 86.6% and the effluent meets the standards of water for irrigation;when HRT was more than 7h, the result shows that the average removal rate of COD_Cr, BOD5, NH₃-N and turbidity are respectively 92.3%, 96.4%, 69.7%, 97.5% and the effluent meets the standards of water for domestic use.In the second part, in order to remove nitrogen, the integrative device made use of anaerobic-aerobic techniques with refluxing process. The results still showed that when HRT was 7h, the average removal rate of TN was 76.5%, if the reflux ratio was 2:1 and the DO was within 2.5-3mg/L. The concentrations of pollutant criteria COD₍Cr_, BOD₅, NH3-N,and TN all comply to the first standard, according to the newest 8975-1996 discharge standard.The applied technique spends much less HRT on aerobic aeration than that of the single active sludge treatment, so it can economize more than 50% of the energy consumed by single aerobic aeration. ABR and adsorption-renew technique all have the powerful capacity of bearing shock load. Adding nitrification and heterotrophic bacteria to the active sludge enhanced the removal rate of NH₃-N. This kind of bacteria has the outstanding merits that it can remove COD_Cr and NH₃-N simultaneity. The emphasis of subsequent research consists in maintaining its dominance in the system and prolonging the period of adding bacteria.