Experimental Study On Pulp Papermaking Wastewater By Combined Process Of Acid Precipitation/Micro-electrolysis/MBR

The paper industry is one of the more polluting industry and papermaking wastewater treatment has been one of the difficulties in the field of water treatment,because of its wastewater COD,high color,poor biodegradability.Currently the number of small and medium enterprises account for most of the paper industry.They are difficult to be outlawed because the huge demand for paper products market.By the economic and management level restrictions,wastewater treatment technology,equipment used by some large paper companies is difficult to apply to small and medium paper companies.So it is still very necessary to explore suitable for pulp and paper and paper wastewater treatment for small and medium enterprises in the next period of time.In this paper,based on the applicability of small and medium paper industry,designing a combined process of Acid precipitation/Micro-electrolysis/MBR,pulp papermaking wastewater which brought back from Jing County of Xuancheng is processed to carry out experimental research,analysis and removal efficiency of organic pollutants and chroma by combined process.The results provide guidance for the process into research and application.The main findings are as follows.（1）Papermaking wastewater for acid precipitation method,it can extract lignin from the pulp and paper black liquor but also effectively reduce wastewater pollution indicators.The process of COD and color removal was 27.1% 49.1%,75.7% 85.8%.（2）Papermaking wastewater treatment by Micro-electrolysis,Continuous flow test results show that the processes average removal of COD and chroma reached 54.9% and 57.6%.BOD₅/TOC to study biodegradability improvement,the results show that after the treated wastewater BOD₅ /TOC up to 2.9 times.The results show that when the influent COD concentration of less than 3000mg/L,the effluent water of micro-electrolysis process don’t produce significant microbial toxicity.The GC-MS mensuration showed that the role of the micro-electrolysis can damage the structure of certain organics,make it into small organic molecules,thus contributing to the improvement biodegradability in wastewater.（3）The optimum reaction time is 25 h,average removal of COD and chroma respectively 68.4% and 34.3%;SRT is 50 d,the average COD removal efficiency was 68.4%;in order to ensure efficient organic removal efficiency of MBR,the DO should be greater than 1mg/L.Through the Lawrence-Mc Carty Models,obtained yield coefficient Y is dirty 0.794gVSS/gBOD₅,Endogenous metabolic coefficient Kd is0.029d^-1,the maximum ratio of substrate utilization rate is 0.18gCOD/（gVSS*d）,the sludge-saturation constant r_max Ks is 232.9gBOD₅/m³.The results can provide a reference for MBR processes depth treatment of papermaking wastewater design and operation.The results showed that membrane fouling in membrane pore clogging the main.The GC/MS detection test results show that MBR can effectively remove the organic matter in the pulp and paper waste,organic species reduced to 44 from the 88 kinds of species,of which a total reduction of 65 kinds of organic compounds,the addition of 21 kinds of organic pollutants.The removal of the material showed MBR process can effectively remove the alcohol,lipids,ketones and other small organic molecules,but limited removal to recalcitrant phenols,aromatic,heterocyclic,chlorinated hydrocarbons and other refractory organics.（4）Pulp papermaking wastewater treated by combined process of Acid precipitation/Micro-electrolysis/MBR,COD and chroma average decreased to 260 mg/L and 33 times.The total removal of COD and color of pulp papermaking wastewater can be up to 90% by combined process.But the water still contains some of the refractory organics,it is necessary to increase the subsequent processing unit to further enhance the COD removal efficiency.