Study On Nitrogen Removal Mechanism Of Dyeing Wastewater Treatment Process

Printing and dyeing industry is one of the largest industries which generate industrialwastewater,its wastewater has following features: poor biodegradability, high color, lowercarbon-nitrogen ratio, large organic content, complex composition and great changes of watertemperature,water quality, water quantity and other characteristics. According to these characteristics,currently we dealt with printing and dyeing wastewater by the combination of biochemical andphysicochemical process and achieved good treatment effect.. But in the wastewater treatment process,due to the higher nitrogen content, it is becoming more difficult to treat dyeing wastewater treatment,and this leads to a corresponding increase in the cost of printing and dyeing wastewater treatment.Thepurpose of this paper is to seek the nitrogen removal mechanism in dyeing wastewater biologicaltreatment process,and combine with pilot experimental data and existing theoretical to study.In this paper, we apply "UASB hydrolytic acidification+A, B two aerobic+C segment contactoxidation+coagulation sedimentation" process to deal with the actual dyeing wastewater,to stady onthe transformation and removal of TN, NH+4-N, NO-2-N and NO-3-N in every biochemical reactionspool.The results showed that:(1) It is beneficial to keep CODCrand TN stable with low-load and high hydraulic retention time(HRT=30h) to start pilot testing device.In15days,each reaction sludge basin change significantly,andin25days,complete the sludge domestication.At this time,the hydrolysis acidification effect is obviousin UASB reactor.The results showed that: CODCrremoval rate in each reaction cell can reach40%,51.5%,67%,respectively, and remained stable. CODCr, TN of the entire process total removal efficiencycan reach90%,75%.(2)when the HRT is shortened,removal rate fluctuations of each reaction cell is very mall,Thisindicates that the treatment process has a good impact resistance.(3)In UASB reaction,there mainly exists ammoniated Org-N, sulfates anaerobic ammoniumoxidation,Sulfur nitrogen oxide, denitrification and other processes, so the overall presentation of thisreactor: Org-Nâ†'NH4+-Nâ†'N2; S2-, SO42-â†'S, there brings the following result: Org-N reduces, N2overflows, TN reduces, S2-, SO2-4content decrease, and S accumulation.(4) In A, B two hypoxia segments, there is a common effect of anaerobic ammonia oxidation,anaerobic denitrification, shortcut nitrification and denitrification and other shorts.Its transformationlikes following mainly: NH+-4-Nâ†'NO2-Nâ†'N2.The TN removal rate can reach nearly50%, whilethe form transformation of sulfur don’t change significantly.(5) In the C segment contact oxidation pond,Obvious morphological transformation is following: S â†'SO2--4, NH+4-Nâ†'NO3-N, but its TN removal efficiency is low.If we can further train aerobicdenitrifying bacteria, its NO-3-N removal rate will be optimize, and the total TN removal of thisequipment will be better.(6)In summary, COD, color, TN, NH4+-N, S2-of this pilot testing device removal rate can reach90.7%,87.3%,85.6%,76.3%,100%,respectively.