The Study Of Dephosphorization Of A/O One-piece BAF

With the rapid development of our economy, the continued growth of the sewage and water environment pollution is more serious. In order to effectively control the increasingly serious of nitrogen, phosphorus pollution and eutrophication, caused by China in July 1,2003 implementation of the urban sewage treatment plants standards for pollutants discharge "(2002), GB18918 to towns sewage effluent of nitrogen, phosphorus index put forward stricter requirements. This standard, when sewage effluent introducing dilution ability of smaller lakes as urban landscape water and general back water such use, or out of the basin water drainage to focus when the executive level standard, are A standard, namely NH3-N< 5mg/L, TP< 0.5 mg/L. At present our country urban wastewater treatment out of the water to TP secondary standard, we need A achieve A level of depth processing auxiliary chemical follow-up phosphorus.Taiyuan economic development zone sewage treatment plant construction started in 2007, with the first 20000m3/d design dimensions for acceptance of taiyuan city, the economic and technological development zones and industrial wastewater and sewage, industrial wastewater 70% of biological wastewater for 30%. Design effluent is executive level A standard. USES it was introduced from abroad A/O (anoxia-good oxygen) integral BAF (biological aerated filters) process.The author June 2009 to 2010 during August of sewage treatment plant, the main during phaseⅠproject running water quality indexes were monitored and analyzed, in order to fill BOD5, pH value, DO, the nitrate, gas backflow liquid water hydraulic loading for influence such as ratio of biological phosphorus removal, study the main factors of biological phosphorus removal influence, satisfying the nitrogen under the premise of demand, seeking the best operation parameters. Process And the A/O integral BAF water chemical auxiliary phosphorus beakers test and productive experiment, to allow the effluent meet design requirements of effluent water. Test results are as follows:1.The average water 306mg/L for COD and the effluent 37mg/L for COD average COD removal rate, the average for 86.7%; Water 116mg/L for average BOD5, effluent BOD5 average for 9.1 mg/L, average BOD5 removal rate for 91.8%; Fill NH3-N average for 21.5 mg/L, effluent NH3-N average 3.73 mg/L, for the average NH3-N removal rate for 81.6%; Fill TN average 6.39 mg/L for, effluent TN average 1.27 mg/L, for around for 61% average TN removal rate; For 251mg/water SS average and the effluent SS L mean 14.4 mg/L, average SS removal rate for complex; Fill TP average 7.10 mg/L, for water for 3.61 mg/L average TP average, for 48.3% removal TP. In addition to SS and TP outside, the second pond water quality indexes of other water can achieve the urban sewage treatment plants standards for pollutants discharge GB18918-2002 level A emission standard.2. The mean water BOD5/TP month for 8～30, monitoring period average of 18.3, reflow liquid concentration of nitrate for 6mg/L or so, anoxia pool 0.6 mg/L DO mean about, BOD5/TP lower, nitrate density high, DO higher oxygen is the main factor of affect the pool of biological phosphorus removal process. The best reservoir mud pool stay time should be less than 4h.3.The day for 2.5-40mg/L water TP concentration, change tremendously; Water 116mg/L for average BOD5, BOD5 load is lower; The sole use of A/O integral BAF process is difficult to achieve the urban sewage treatment plants standards for pollutants discharge (GB 18918-2002) the level A emissions standards, so must be supplemented by chemical phosphorus.4.Chemical auxiliary phosphorus beakers test results show that, in A/O integral BAF out water clear liquid concentration of TP 1.39 mg/L for when 60mg/L alone dosing of PAC can make the effluent TP< 0.5 mg/L, increases the vote no obvious help coagulation PAM role. Productive experiment results show that the water quality stable, biological treatment unit and stable operation, A/O integral BAF out water clear liquid TP concentration 1.05～1.39 mg/L for turnover, PAC in about 65mg/L, can assure effluent TP< 0.5 mg/L, achieve the urban sewage treatment plant standards for pollutants discharge (GB 18918-2002) level of A emission standard. Good hydrodynamic conditions is to reduce turnover and ensure outlet TP PAC standards premise parts, chemical phosphorus cost about 0.20-0.25 yuan/m3, accounting for sewage treatment plant operation costs 30%.