Study On The Test Of Biological Purification For Urban Polluted River Water

In recent years, because of the rapid development of economy and city expansion, pollution emergencies of medium and small rivers happened frequently, leading to serious deterioration of river ecosystem. Therefore, how to prevent river from getting worse, maintain the safety of water resources, and carry out the strategy of sustainable development become the main targets pursued by human being. The Center Park section of Futian River in the city of Shenzhen was considered as the investigation object, and the latest research results in further purification technologies of polluted water reported home and abroad was summarized, a self-designed device system was performed in this research to simulate rivers in specific conditions based on the situation that rivers are polluted heavily and the economy of our country is still increasing. Aeration styles, membrane materials and specific-effective bacteria was studied and chosen in this system. Meanwhile, in-situ experiments were carried out by emplacing fillings and introducing specific-effective bacteria.First of all, the packing was dynamically cultivated with the polluted water, after 30 days the removal efficiency of COD_Cr and NH₄⁺ -N was stabilized at about 35% and 25% respectively. The appearance of the biofilm on the packing experienced the process of being colorless and transparent to light green, yellowish green, brownish green, then to dark brown sequentially. At the same time, the living things on the packing changed from nothing which could be observed under microscope to several kinds of algae, zoogloea, miniature animals coexisted which symbolized the successful dynamical membrane hanging on media-filling in the device.Secondly, compound biological purification technology (aeration + fillings + specific-effective bacteria) was studied after the mature of biofilm. During the experiment, the average removal of BOD₅,CODcr,TN,TP,NH₄⁺-N and SS were 53.34%,45.44%,28.64%,22.61%,28.51% and 74.51% respectively in no adding specific bacteria device,and the removal efficiencies were 76.38%,69.58%,44.39%,30.00%,57.95% and 85.17% in adding specific bacteria device, which was more effective than no adding device.Meanwhile MPN counting experiments were carried out, the results showed that the nitrifying bacteria, nitrite bacteria and denitrifying bacteria increased by 2-3 orders of magnitude in adding bacteria devices, and refractory and poly-phosphate bacteria enhanced by 1-2 orders of magnitude, which is consistent with the removal rate. That means the added specific bacteria promoted the removal of pollutants in the system. According to the DGGE results of biofilm, the biological diversity and total biomass of biofilm increased gradually after adding the specific-bacteria. It is showed that the compound biological purification technology is more effective than a single technology or a single combination of purification technologies.