Study On Treatment Of Municipal Wastewater With Biochemistry Process

With the development of economy,the contents of phosphate in the nature water keepson increasing, eutrophication question of nature water has beeome more and more obvious.The Pollutants Emission Standard of Urban Wastewater Treatment Firm(GB18918-2002) waslaid down in our country, which stipulate that total of the class A standard shouldless than 0.5 mg/L. But most of urban wastewater treatment firm can't meet the standard. So,the study of using chemical treatment to remove phosphorus is imperative. Treatment ofmunicipal wastewater with biological/ chemical process is studied in the paper. Theexperiment selects four different chemical agents, respectively chlorides, polyferricsulfate, aluminium sulfate and polyaluninum sulfate.To determine effect of phosphorusremoval using different coagulants cooperate with organisms and explore the best operatingconditions of various coagulants in biological/chemical process. Assessing the effect ofcoagulants on denitrification and organics removal.besides,using molecular biologytechniques to research the change of microbial number in the reactor. In the later part of theexperiment, The continuous flow bioreactor was used to conduct adding experiment. Theresults indicate that:(1) For iron chlorides, aluminium sulfate and polyaluninum sulfate, there are cooperativeeffect with organisms; for polyferric sulfate, there is no cooperative effect.(2) Iron chlorides, aluminium sulfate and polyaluninum sulfate give an impetus tobiological nitrogen removal, but polyferric sulphate cann't. Each of the four coagulants canpromote organic matter removal in the biochemical reactor.(3) Comparising the value of SVI in different reactors,the results indicate that:polyaluninum sulfate< polyferric sulphate<Iron chlorides<aluminium sulfate< bioreactor. Thesludge in the bioreactor adding polyaluninum sulfate has the best sludge flocculation andsettling performance.(4) The sludge yield from the bioreactor adding polyferric sulphate is 3~4.5 timescompared with conventional aeration,and the yield of the rest three methods likeconventional aeration.(5) The nitrogen and phosphorus removal effects within biochemical reactor hassignificant correlation with pH and temperature.(6) After adding PAS in the continuous flow bioreactor, the removal rate of totalphosphorus raises noticeably and meets the class A standard. The removal of total nitrogen are improved after adding coagulants .Besides,the coagulant is help to remove organic matter.(7) Through the analysis of DGGE, the numbers of microbial population in the reactors which adding coagulant and the biological reactors is different and there are all less than seed sludge. The reactors which adding coagulant and the biological reactor cultivate different microorganisms and form their own dominant species.