Study On Characters Of BIO-Filter BED In A Small-Scale Household Sewage Purifying-Tank

In the last thirty years, more and more household sewage has been discharged to the environment with the living standard becoming better and better especially the tap water engineering carried out in the vast rural areas, and most of the new urban and rural areas have flush toilets with water, especially, about70%of the rural household wastewater is unpurified. However, the municipal wastewater plants cannot be operated in the suburbs, villages and towns, and scenic spots because of the expensive sewage pipe system and the lack of government finance. Therefore, it’s very important for "decentralized sanitation and reuse" to improve our condition of water pollution. It is necessary to promote decentralized sewage treatment plant technology in China’s urban and rural areas, which will improve the new rural construction, urban waste water recycling.Decentralized sewage treatment system can overcome many disadvantages of the centralized sewage treatment, this approach does not depend on a complex infrastructure such as large-scale power and water supply systems, influence self-construction, and convenient to operation and maintenance, less unpredictable damage, can be applied to a variety of occasions,the treated effluent is easy to reuse. Especially fit for us developing country, and strive to save and recycling of resources to protect the environment, the use of decentralized wastewater treatment system can lower costs to achieve the required purpose.Actual sewage is used in the experiment of investigating a small small-scale purifying-tank.These devices are a complementation for household sewage system in the town, constructing a complete system for household sewage in China.A compact purifying-tank process was developed being suit for treatment of the domestic sewage. The influence of domestic sewage treatment in the different zones of the domestic sewage purifying tank is investigated by putting bio-filter bed into each zone step by step. Stable effluent quality and good resistance to shock-loading are showed from the purifying tank as the bio-filter beds are added in the aerobic zone and two anaerobic zones successively, which achieves better effect of treatment. While all three zones are added in bio-filter bed and the tank runs steadily, attending the mean values of CODcr, of the effluent is lower than37.8mg/L, mean values of BOD5of the effluent is lower than12.4mg/L, which is better than the national primary standard. Compared with no bio-filter bed, the removal efficiency of CODCr, NH3-N,turbidity and BOD5rises from73%,32.4%,70.8%,74.7%to90.4%,76.2%,95.3%,95.1%, respectively, which showed that the bio-filter bed is a key technology, which plays an important role as solid-liquid separation, bio-sorption and bio-degradation, to raise the effluent quality in the purifying tank.