Pretreatment Of High Nitrate Industrial Wastewater And Anaerobic Denitrification Treatment Of EGSB Reactor

Industrial wastewater not only contains higher nitrate,but also contains high COD,ammonia nitrogen,sulfate and some toxic substances such as heavy metal ions?copper,nickel,etc.?.Due to the complexity of the composition of microbial proliferation will have a negative effect,resulting in increased biological method to remove the difficulty of nitrate in industrial wastewater.This article through reasonable pretreatment means to control the inhibitory factor in the microbial within acceptable limits.The denitrification treatment was carried out using an expanded granular sludge bed?EGSB?reactor biological treatment system.At the same time,the system may be running during the suspension of the situation,the study of the running performance in the re-start process.The microbial community and evolution process were analyzed by molecular biology techniques such as PCR-DGGE and high-throughput sequencing in restart process.The major conclusions are described as follows:1.The removal rate of the blowing method is about 80%⁹0%.From the engineering point of view,it is most appropriate to use pH=12 and the reaction time is 3 h.First remove the copper,nickel effect by Na₂S than the first to remove the ammonia after the removal of ammonia removal of copper,nickel effect is poor.Removal rates were reduced by 45%and 23%.Pretreatment process must first ammonia nitrogen stripping treatment to remove copper and nickel.Cation exchange method to remove copper,nickel effect is good,the second exchange of copper and water for the 0.6 mg·L^-1,the remaining nickel 3.0 mg·L^-1.Through the single factor experiment,it was found that there was sufficient adsorption point,the contact reaction was about 30 min to meet the requirement.The removal rate of sulfate in 0-120 min gradually increased with time,and then the removal rate became stable.From the feasibility point of view of the reaction is more suitable for 30min.2.EGSB denitrification system with HRT 22 h,water bath temperature stability of 33±1?,the internal reflux ratio R is 180%start,and to increase the current load by20%each time?On the 74th day,the influent of EGSB reactor was 1.1×10³ mg·L^-1,and the nitrate removal rate was 99%and no accumulation of nitrite.The system on the 49th day is more than 2.0%salt into the high salt state,the final salt is 3.5%.COD removal rate of the average removal rate of 60.7%,of which the highest removal rate of 84.8%,the lowest removal rate of 23.4%.PH changes range from 7.8 to 8.7,and the value of ORP varies from-450 mV to-300 mV.3.The EGSB system is stopped after one month of operation,the average NO₃^--N removal was 99%during the 23 days re-startup period with influent NO₃^--N concentration of 710.7 mg·L^-1.The specific denitrification rate(R^-_NO3)increased from49.4 mg·?g·h?^-1 to 170.7 mg·?g·h?^-1?based on VSS?.Through the study of diversity and similarity of microorganisms,the Ace and Chao indices show that the abundance of bacteria in the initial sludge is relatively large and the load is reduced.PCA analysis showed that the difference was greater in the first principal component than the denitrification rate of 157.5 mg·?g·h?^-1?based on VSS?.The OTU Rank curve showed that the OTU span was reduced after the system was restored.The high-throughput DNA sequencing technology showed that Halomonas,Pseudomonas,and Alcaligeneswere the dominant species of denitrifying bacteria,and their relative abundance after re-startup were increased by 35%,31%and 14%,respectively.The relative abundance was positively correlated with the specific denitrification rate.The double value of R^-_NO3 was relative to 6.7%increase of the abundance of the dominant species.