Experimental Study On Removal Of Nitrate From Groundwater By Heterotrophic-sulfur Autotrophic Integration Denitrification

Due to the fertilization of crops,the discharges and discharges of sewage and nitrogen-containing wastewater,and the massive recharge of sewage,nitrate contamination of groundwater has evolved into a growing problem.Nitrogenous nitrogen was reduced to nitrogenous nitrogen after a series of reactions.Because the hemoglobin in blood and its reaction lost the ability to transport oxygen,human breath difficult,serious harming to life safety.Traditional heterotrophic biological denitrification technology can easily cause secondary pollution at the same time as the cost of external carbon sources increases.It also has high requirements for the stable operation and maintenance of the system.Through the coupling of heterotrophism and sulfur autotrophy,the addition of carbon source can be reduced and the rate of denitrification can be accelerated.Meanwhile,the proportion of the three can be controlled to realize synchronous nitrogen,sulfur,carbon and energy saving.Based on the latest research results of heterotrophic denitrification and autotrophic denitrification of sulphur ions,this topic proposes a heterotrophic and autotrophic coupled denitrification system for denitrification treatment in upflow anaerobic sludge reactor(UASB).The experiment analyzed system startup process,heterotrophic system load and the study of carbon nitrogen ratio,autotrophic and heterotrophic sulfur collection system startup process,sulfur,nitrogen,earbon ratio on collection system,and discussed the temperature,substrate concentration,ratio of carbon and nitrogen and sulfur nitrogen ratio process operation the key influence factors.On this basis to determine the optimal processing load and conditions of this process.The results showed that:1.In lower temperature under the condition of cultivation of heterotrophic denitrifying bacteria.The removal rate of total nitrogen and COD was 98%and 86%,and the total nitrogen of effluent was about 2mg/L,indicating the success of cold denitrification strain culture.2.Under the action of heterotrophic denitrification bacteria,the water nitrogen concentration in and out of the reactor was 300 mg/L and 6 mg/L,respectively.At this point,the maximum removal load of the reactor was 2.3 kg/(m3·d),and the removal rate was about 97%.When the carbon nitrogen ratio was 3.25 and 3.76,the removal rate of nitrogen was about 96%,but when it was reduced to 2.69,the removal rate was reduced to 85%,so the optimal carbon nitrogen ratio was 3.25.3.In the stage of integrated denitrification,the concentration of sulfide was increased to 300 mg/L,the removal rate of COD was reduced to 70%,and the conversion rate of sulfur was 80%.Reducing the concentration of sodium acetate to 600 mg/L,the removal rate of sulfide is close to 100%.and the formation rate of sulfur is stable.However,when the concentration of organics drops to 300 mg/L,the sulfide will be partially converted to sulfate.The removal rate of sulfide and organics was close to 100%when the concentration of nitrate nitrogen was increased to 400 mg/L,but the proportion of sulphur elemental and sulfate in the effluent was about 3:7.4.The operation efficiency of the integrated denitrification process was significantly affected by the ratio of sulphur,nitrogen and carbon.The synchronous removal rate of the three was about 90%.A synchronous denitrification,sulfur,and carbon ratio was obtained through experimental study,and S:N:C was approximately(0.625?1.25):1:(1.17?1.75).5.This experiment utilizes an up:flow anaerobic sludge reactor(UASB)for integrated denitrification of heterotrophic and sulphur autotrophic.Compared with various parameters of heterotrophic denitrification alone.The removal load of nitrate nitrogen is increased by 0.7 kg/(m3 · d).The removal rate is maintained at 98%.46%of the organic carbon source is saved.The average rate of denitrification is increased by 20?30 mg/(L·h).