Study On Sewage Treatment And Recycle Technology Of University By Biological Contact Oxidation Process Combined With Fenton

Water reuse system as a kind of effective method to ease the water shortages for city, are receiving more and more attention. In view of the particularity of university bath wastewater , one side ,the quantity of water during the summer and winter vacation is too little to maintain the system; on the other side,the waste water to wash is mainly bath wastewater among which a lot of surface active agent （LAS） that can inhibit microorganism activity and reduce the biochemical of bath wastewater; So biological contact oxidation treatment phase is different to consider in water reuse system to avoid affecting the normal processing effects of the system.Test bath wastewater is taking from university bath center outlet, COD is between 80-120 mg/L , NH₄⁺-N is between 25-35 mg/L , LAS is between8-10 mg/L in the wastewater. The mainly purpose is to study on the removal of surfactant exist in bath wastewater and improvement the biodegradability of raw water combined with operation commissioning work of a college bath wastewater reuse system.The raw water is pretreated by Fenton reagent prior to contact oxidation pretreatment,so the LAS in it can be oxidated and its biodegradability can be improved.The test is divided into three phases, the first stage is to cultivate biological membrane for contact oxidation system , raw water is taking from college dorms, COD is between 138-480 mg/L , NH₄⁺-N is between 30-40 mg/L , the COD and NH₄⁺-N in influent and effluent are detected every day during the first stage,when the value of COD and NH₄⁺-N can be both stable at 75% and a layer of mousy activated sludge on biofilm packing,the biological membrane is cultivated successfully and the test can be started.At the second stage,the first work is to confirm the best dosing quantity of Fenton reagent that remove the LAS of bath wastewater,by comparing the test data,we can concludes that when Fenton reagent dosing quantity is 1 mg/L,the removal rate of LAS can be up to 85% and the removal rate of COD and NH₄⁺-N can be respectively up to 20% and 18%.Then observe the toxicity of LAS to microorganisms through microscopic,by comparing can be conclude that microbial lose breeding activity when the LAS is 15 mg/L in the waste water and massive microbes death when the LAS is 30 mg/L in the waste water .The third stage is continuous operation stage, first,detected the removal of COD and NH₄⁺-N of bath wastewater directly into contact oxidation system,when DO value is at 1.5 mg/L, HRT is at 2.5h, value of C/N is at 6, the removal rate of COD and NH₄⁺-N can respectively at 60% and 75% ,the effluent can meet the reuse standards. Then detected the removal of COD and NH₄⁺-N after pretreatment by Fenton reagent of contact oxidation. when DO value is at 0.8 mg/L, HRT is at 1.5 h, C/N value is at 3.5, the removal of COD and NH₄⁺-N can respectively at 63% and 77% .It illustrates that the raw water after pretreatment by Fenton reagent can meet standard in low DO,HRT and C/N. Finally,the research take comparison of economical and technological, through comparing, we can conclude that the application of Fenton reagent to strengthen contact oxidation process in university water reuse system can reduce investment of reconstruction and extension of project, although increased devotion of medicament of, save operating costs, from considerations of a technical and economical cost, this process is feasibility and have high value of application.