Treatment Of Dyeing-Life Mixed Wastewater By PVA Biological Process

At present,dyeing wastewater is one of the main industrial wastewater which is difficult to treat in our country.It has the characteristics of high concentration of organic pollutants,deep chroma,large fluctuation of water quality and so on.As well as the increasing demand for high-level printing and dyeing products,the biodegradability of dyeing wastewater is obviously reduced,and the processing difficulty increases,resulting in outstanding environmental problems.In the face of the crucial period of printing and dyeing industry entering the transition and upgrading period,In particular,dyeing wastewater treatment,environmental protection situation has been urgent.At present,aerobic biological treatment is widely used to treat dyeing wastewater in China.Compared with adsorption,electrochemical and chemical oxidation,the traditional aerobic biological treatment process has unique advantages,However,there are some problems which can not be solved by themselves,such as low operating load,poor resistance to load and high excess sludge.A large number of previous experiments show that the biological treatment process of PVA has the advantages of high volumetric load,strong impact resistance,low surplus sludge yield and stable treatment effect.Therefore,in this paper,PVA biological treatment process is applied to the treatment of dyeing wastewater.At the same time,the mixing of a certain proportion of domestic wastewater in the same conditions was investigated to optimize the influent conditions.The PVA biological treatment process was used to treat dyeing-life mixed wastewater,and the treatment effect was explored.Finally,the microorganism adhesion on the surface and inside of PVA-gel pellet was researched.The main research contents and conclusions were as follows:?1?The bioreactor was operated for 12 days under the conditions of DO from 3.0 to5.0 mg/L,the temperature is 30?,pH value from 6.7 to 7.0 and the initial volumetric load is 0.5 kg[COD_Cr]/?m³·d?of dyeing wastewater treated by PVA biological treatment process.From the 7^thh to 12^thh day the removal rate of NH₃-N and COD_Crr was stable above 90%and the removal rate of BOD₅ remained stable at more than 94%,which successfully completed the start-up of the reactor.Then,the reactor went through 102 days of operation,including 62 days of volume load increase stage and 40 days of continuous operation stage.The volume load of PVA technology increased to 4.5 kg[COD_Cr]/?m³·d?,and the continuous operation stage,the average removal rates of COD_Crr and NH₃-N and chromaticity were 87.8%and 92.6%and 84.7%,respectively.The final effluent of COD_Crr was reduced to 200 mg/L and NH₃-N was reduced to 2.63 mg/L as well as chromaticity less than 55 times.?2?The biodegradability of dyeing wastewater was improved by mixing the actual dyeing wastewater with the actual domestic wastewater.According to the volume ratio of dyeing wastewater to domestic wastewater of 1:5,the influent condition was optimized,and the mixed wastewater entered PVA bioreactor.After 70 days of operation,the volumetric load was up to 5.5 kg[COD_Cr]/?m³·d?.It runs 25 days of continuous operation,the average removal rate of COD_Cr,BOD₅ and NH₃-N was 96.2%,95.5%and 95%as well as the average chromaticity removal rate was 94.5%.The final effluent of COD_Crr and BOD₅ was reduced to 14²9.9 mg/L and 11.4¹9.13 mg/L,NH₃-N was reduced to 0.7⁰.9mg/L as well as chromaticity was reduced to 12²0 times.?3?From the appearance and microcosmic changed of PVA-gel carrier,obtains the PVA biological process for treatment of high efficiency is due in the PVA biological treatment system,PVA-gel beads and internal surface enrichment of a large number of microorganisms,mainly bacillus,filamentous bacteria,Staphylococcus aureus,ect.This microorganism play a major role in the process of sewage treatment.In addition,PVA-gel beads surface and internal microbial inhibition sludge production by self oxidation is the root cause of this process has a good effect of sludge reduction.