Influence Of Carbon Source Type On The Denitrifying Sulfide Removal Process In UASB Reactor And Screening Analysis Of The Functional Bacteria

Sulfide and nitrate with producing secondary pollution often be produced afteranaerobic biological treatment of organic wastewater containing sulfate and ammonianitrogen, denitrifying sulfide removal process is a new wastewater treatment technologywhich cost valid and operation easily to treat the wastewater with nitrate and sulfide at thesame time. Nowadays much research works have already been launched on the design andoperation of DSR process. However, there are still many works should be examined beforethe process could put on the practical engineering application. This paper was focus onseveral subjects of the quick start-up and operation of denitrifying sulfide removalprocess. In addition, enriched and isolated two strains which could remove nitrate andsulfide simultaneously(named H3and H7temporarily), the analysis of its16S rDNA,growth and denitrification characterizations were studied. The conclusions were as follows:(1) Quick start-up of UASB mixotrophic desulfurization-denitrification technique usingexcessive nitrate, the seed sludge was general anaerobic granular sludge, the removal ofeach pollutant can reach a high level in10days, the influent concentration of sulfide was300mg/L, the ratio of carbon, nitrogen to sulfur1:1:1,HRT12h, pH7.5, the relevantremoval efficiencies of S2--S、NO3--N�'�AC--Cwere91.4%、89.4%and87.3%respectively.The volumetric removal rates of sulfide and nitrate were0.5502kg/m3d and0.236kg/m3dwhich had reached the reported level in liteaturd;(2) The condition of the ratio of carbon, nitrogen to sulfur1:1:1was benefical for theproduction of sulfur, the yield of sulfur was83.1%which explained mixotrophicdesulfurization-denitrification technique can rest on the elemental sulfur recovery,while steady run the dominant reaction of autotrophic denitrification occurred togetherwith the heterotrophic denitrification whose percent was29.2%;(3) Removal of nitrate using different carbon source was sodium acetate＞acetic acid＞ethanol＞glucose, Removal of sulfide using different carbon source wasacetate＞ethanol＞acetic acid＞glucose, and the yield of sulfur was acetate＞acetic acid＞ethanol＞glucose, the results showed that glucose can inhibits autotrophic denitrifyingmicrobial growth when using it as carbon source, the nitrite generation rate was high andthe yield of sulfur was low when using ethanol as carbon source, they are not the suitablecarbon source for mixotrophic desulfurization-denitrification technique;(4) The relevant removal efficiencies of S2--S、NO3--N and AC--C were75.1%、81.2% and85.4%, theoretical yield of elemental sulfur was75.8%when using sodium acetate ascarbon source, sodium acetate was the most suitable carbon source for mixotrophicdesulfurization-denitrification technique;(5) It was discovered that the granular sludge in UASB reactor with mixotrophicdesulfurization-denitrification technique showed good settlability, whose diameters,settling velocities and density were1.25~1.66mm(Occupied50.96%of the total sludge),43.5~82.5m/h and1.038g/mL;(6) Seven strains were enriched and isolated, which could remove nitrate and sulfidesimultaneously. The strongest removal capability of nitrogen and sulfur were two strains(named H3and H7temporarily), According to the16S rDNA sequence, the morphologic,physiobiochemical characteristics, the strain was identified as Pseudomonas stutzeri andnon-halophilic strain;(7) Studies showed that the optimal conditions for denitrification of H3and H7werepH6.77,31.4℃and6.56,31.2℃respectively, while the optimal growth conditions of H3and H7were pH6.94,30.4℃and6.88,30.6℃respectively.