Application On The Treatment Process Of Organosilicon Silicone Product Wastewater

According to the important environmental indicators in the Environmental Protection Law,continuous water pollution problems with increasing contaminants caused by the organosilicon industry.Taking the example of a materials company in Jiangxi Province,the production of silicone materials brings organic wastewater pollutants.To fulfill the requirement of green emission,the plant urgently needs to establish supporting water treatment facilities.In accordance with the relevant requirements of the Environmental Protection Law,the project has designed a set of wastewater treatment solutions that are both economically efficient and effective in terms of the characteristics of high concentration of COD(Chemical Oxygen Demand),salinity,ammonia nitrogen(NH3-N)and silicone oil in wastewater.The laboratory studies and the actual commissioning of the plant have resulted in the completion of the wastewater treatment to standard.Based on literature research and laboratory wastewater studies,this project adopts the pretreatment process of "coagulation air flotation + multi-effect evaporation +Fenton oxidation + coagulation precipitation" to improve the biochemical properties of the wastewater,and then the combined process of "UASB + A/O + BIOFOR aeration biofilters" used for comprehensive treatment.Based on the experimental studies and commissioning data,the following conclusions are drawn.(1)Based on the screening experiments of different coagulants,it was determined that the most suitable coagulant for the wastewater treatment of this project was PAC(Poly Aluminium Chloride).According to the results of the coagulation and sedimentation of single factor and orthogonal tests,and combined with the economic efficiency of the project,the best reaction conditions for the coagulation test were determined such as PAC 200 mg/L,PAM(cpolyacrylamids)2 mg/L,reaction time 15 min,and p H=8.The removal rate of COD in the wastewater was 24.1% with these conditions.(2)According to the Fenton oxidation single factor and orthogonal tests,the optimum conditions for the Fenton oxidation test were determined: reaction time 2h,p H=4,ferrous sulphate dosage 4.0g/L and hydrogen peroxide dosage 8ml/L.Under these conditions,the removal rate of COD in the wastewater was 30.2%.(3)Based on the above wastewater study in the laboratory,the pretreated wastewater at the plant was then treated by anaerobic digestion and the UASB anaerobic tank reached a steady state of operation and could steadily degrade 81% of the influent COD with a wastewater COD effluent concentration of 800-900 mg/L and NH3-N concentration of 57.1 mg/L.(4)With the A/O tank in stable operation,the wastewater COD removal rate is around80% and the ammonia nitrogen removal efficiency reaches between 70% and 80%.the COD effluent concentration in the A/O tank is around 200 mg/L and the ammonia nitrogen concentration is below 22 mg/L.(5)After 2 months of operation and commissioning,the biofilter operated stably and the effluent concentration met the design requirements.The solution achieved a removal rate of about 65% of COD in the wastewater,with a stable effluent concentration between 50 mg/L and 70 mg/L.The removal rate of ammonia nitrogen in the wastewater reached 60% and the effluent ammonia nitrogen concentration was below 10 mg/L.In order not to affect the biofilter treatment efficiency,the biofilter should be backwashed regularly.Combining site experience and data from the ledger records,the backwashing cycle was determined to be 10-15 days,with the flushing process being gas flushing-gas-water flushing-water flushing.(6)In this project,through the determination of COD,the content of organic matter that needs to be oxidized in the produced wastewater is in the range of48000mg/L～53000mg/L.After the treatment of air flotation and coagulation,multieffect evaporation,Fenton oxidation and coagulation and sedimentation,the salt and SS(suspended substance)in the wastewater can be removed,and the removal rate of COD is 67.4%.In the biochemical system,the COD removal rate of the wastewater was 98.8%.In addition,the NH3-N in the wastewater is mainly diluted by the domestic wastewater and the biofilter backwater,which then enters the biochemical system at a concentration of 53.1 mg/L.The combined system of A/O tank and BIOFOR aeration biofilter can remove 85.4% of NH3-N with an effluent concentration of less than10mg/L.The system operates stably and the final discharge effluent quality is better than the primary discharge standard in the "Comprehensive Sewage Discharge Standard(GB 8978-1996)".(7)When the wastewater station is in stable operation,the wastewater COD and NH3-N emissions can be reduced by 1,674t/a and 6.57t/a respectively.The cost per ton of wastewater treatment is RMB 106.2/t.It has good environmental benefits and has high reference value for the same type of wastewater treatment.