Upgrading And Analysis On The Obarl Oxidation Ditch Process Of A Wastewater Treatment Plant In Xi’an

The design water quality of the current operation of the wastewater treatment plantin xi an, the guanzhong coast of weihe, is on the basis of the first class B nationstandard-"city wastewater treatment plant pollutant discharge standard"(GB18918-2002). Shaanxi province proposed three years action plan of Weihe, whichdemand to realize Weihe "three years become clean". In order to achieve this plan assoon as possible, the governments of Shaanxi province and Xi’an City asked that thecity wastewater treatment plant of Weihe coast should dispose the index up to the firstclass A standard. Based on the above background, aiming at the Orbal oxidation ditchprocess of a wastewater treatment plant in Xi’an couldnot meet the the first class Aemission standard, changes of the water quality of processing unit were investigated andanalyzed. The results showed that the Orbal oxidation ditch process of wastewatertreatment plant influent water quality have high organic matter, N and P, so it wasoverload operation, far higher than the design influent water quality standards of thewastewater treatment plant.According to the analysis of the Orbal oxidation ditch process of the wastewatertreatment plant, the study of the migration regularity of different pollutants in oxidationditch, and the comparison and analysis of changes along the pollutants the oxidationditch which has and hasnot the primary settling tank system, results showed that theprimary settling tank could remove most of the suspended solids (SS) and some organicmatter (COD), TN, TP in wastewater, to reduce the pollution load of oxidation ditch inthe biochemical pool and ensure the biochemical oxidation ditch system in the scope of normal operation. In addition, DO concentration in the primary settling tank system washigher than the none, biological activity was better than the latter. These reasons leadthe organic effluent effect of the primary settling tank oxidation ditch system better thanthe latte. The oxidation ditch brush aeration lead to serious stratification of dissolvedoxygen and aerobic zone,which was the main reason of poor NH3-N removal effect.For the problem of the dissolved oxygen distribution imbalance in biologicaltreatment system in wastewater treatment plant, with the goal of energy saving, basedon oxidation ditch system partition oxygen theory and micropore aerationvariable-speed oxidation ditch, it put forward modification plan: the inner ditch turnedinto bottom aeration，increased nitrified liquid inner recirculation system. At the sametime through adding fillers in the oxidation ditch, in order to increase microbial contentto improve the load of wastewater treatment, and the addition of cloth filter to achieveenhanced treatment effect of SS.Monitoring and analysis of the implementation effect of upgrading the wastewatertreatment plant, the various effluent water indexes were up to the first class A nationstandard. The upgrade results have practical guidance value for the similar Obarloxidation ditch wastewater treatment plant in China.