| Chinese President Xi Jinping in the National Ecological Environmental Protection Conference in 2018 pointed out that the construction of ecological civilization is a fundamental plan for the sustainable development of the Chinese nation.Ecology is prosperous,and ecological decline is civilized.Therefore,solving environmental problems and improving environmental governance is not only a major political issue that affects the party's mission,but also a major social issue that affects people's livelihood.Acetate fiber has been widely used in the production of cigarette filter tow,and its production wastewater has the characteristics of high organic concentration,high phosphorus content and complex phosphorus form.The discharge into the water body will bring huge pollution to the water body.At present,research on such wastewater treatment is still relatively rare.UASB-chemical phosphorus removal-SBR combination treatment process was proposed for the wastewater generated from the production of acetate in a chemical plant in Ningbo by analyzing and comparing the research status of related wastewater at home and abroad.The unit conducts research on the treatment effect and influencing factors.Experimental results show:(1)UASB treatment of acetic acid fiber production wastewater,after the reactor is started and stabilized,the influent pH is adjusted to 6 and the hydraulic retention time is 24h.When the volumetric load is 7.5kgCOD/(m~3·d),the effluent COD is about 710mg/L,the COD removal rate is over 90%.At this time,the average gas production rate per unit volume of UASB is about 2.3L/(L·d),the average gas production rate per unit of organic matter is about340ml/gCOD,and the methane content in biogas is about 70%,which can produce better economic and energy benefits.(2)Study on the phosphorus removal of UASB effluent by chemical method.By comparing the treatment effects of three typical phosphorus removal agents,such as calcium chloride,polyaluminum chloride(PAC)and polyferric sulfate(PFS),PFS was found to be the best phosphorus removal agent to treat the wastewater.By controlling the effects of pH value,dosage and stirring time on the effect of phosphorus removal,it was found that the optimal phosphorus removal condition of PFS was pH=7,the dosage was 4g/L,and the stirring time was 6min.At this time,the chemical phosphorus removal effluent TP=18.5mg/L,and the TP removal rate can reach 92%.(3)SBR further treats chemical phosphorus removal effluent,because the COD of chemical phosphorus removal effluent is about 200 mg/L.To ensure the effect of biochemical phosphorus removal,sodium acetate is added to the wastewater as carbon source.Through the effects of influent COD concentration,sludge age(SRT),operation mode and temperature on the dephosphorization effect of SBR,the optimal operating conditions were obtained.Adjust the influent COD=500mg/L into the SBR reactor.When the water temperature is 20°C,the running conditions of 0.5 h of influent,anaerobic 2 h,aeration for 5 h,precipitation for 0.5 h,and SRT=15 d are used.At this time,the SBR reactor can stably operate with an effluent COD of about 70 mg/L and a TP of about 3.5 mg/L.The treatment of cellulose acetate production wastewater by the combined process of UASB-chemical phosphorus removal-SBR can effectively treat the wastewater with high organic matter concentration,high phosphorus content and complex phosphorus form.The raw water COD of wastewater is 7500mg/L,the TP is 230 mg/L,the final effluent COD is70mg/L,TP is 3.5 mg/L,which meets the standard COD of the plant sewage treatment system provided by the plant,COD?100mg/L,TP?5mg/L.The research of this subject provides guidance for practical engineering and has reference value for the treatment of this type of wastewater. |
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