Application On The Treatment Process Of The Wastewater From The DMBA Production

A chemical plant will produce waste water when it produces a water-borne anionic chain extender DMBA(2,2-dimethylolbutanoic acid).A set of wastewater treatment facilities needs to be built in the plant area so that the wastewater can be discharged up to the standard.This topic is based on the high concentration of COD and formaldehyde in the wastewater to Looking for an Efficient and Economically Efficient DMBA(2,2-Dimethylolbutanoic Acid)Production Wastewater Treatment Project.It was finally determined that the combined treatment of"Formose formaldehyde polymerization+iron-carbon micro-electrolysis+Fenton oxidation+coagulation precipitation+UASB anaerobic+BIOFOR biological filter"was used for comprehensive treatment of wastewater.DMBA production wastewater mainly comes from two process links,one is the high concentration of formaldehyde wastewater generated during the aldol condensation of formaldehyde with n-butyraldehyde to produce DMB(2,2-dimethylolbutyraldehyde),and the second is the oxidation of condensed wastewater generated during the oxidation of DMB to DMBA.For the waste water produced by the aldol condensation process,because the formaldehyde concentration is as high as 18000 mg/L,it has a great biological toxicity,and corresponding pretreatment measures must be taken to reduce the formaldehyde concentration in the waste water.Formose formaldehyde polymerization after the experiment to get the best conditions:calcium hydroxide dosage 8g/L,the reaction temperature 70°C,the reaction time 60min,under the conditions of formaldehyde concentration reduced to50mg/L or less.Then,the oxidized condensing wastewater was subjected to combined experiments of iron-carbon microelectrolysis and Fenton oxidation.After the experiment,the optimal reaction conditions for iron-carbon micro-electrolysis were as follows:iron powder dosage 10 g/L,carbon powder dosage 10 g/L,reaction pH 3,reaction time 3 h,and effluent COD under this condition Concentration21462mg/L,COD removal rate 26%.The iron-carbon micro-electrolysis effluent followed by Fenton oxidation experiments,the experimental optimum reaction conditions were as follows:30%hydrogen peroxide water dosage 20 ml/L,reaction pH 3,reaction time 2 h,under this condition effluent COD concentration 15600 mg/L,COD removal rate was 25.7%.The optimal reaction conditions for coagulation and sedimentation of comprehensive wastewater were as follows:PAC dosage 300mg/L,PAM dosage 20 mg/L,coagulation sedimentation time 25 min.Under this condition,the effluent COD concentration was 9492 mg/L and the removal rate was20.9%.After the above pretreatment process,the integrated wastewater enters the biochemical treatment stage.Through the design,start-up commissioning and operation data of this project,research indicates:(1)After a stable operation,the UASB anaerobic tank volume load can be maintained within the range of 3 to 5 kg COD/(m~3·d).The COD removal efficiency is between 80%and 90%,and the effluent COD is less than or equal to 1000 mg/L.(2)The bio-filter backwash cycle was determined once a week by running data.The backwashing process is:air wash for 10minutes(air volume 25L/(s·m~2))→air water flush for 10 minutes(water volume8L/(s·m~2))→water wash for 5 minutes.The COD removal rate is between 50%and60%,the effluent COD is less than or equal to 500mg/L,and 30%of the water is returned to the anaerobic tank for water inflow.The COD removal rate of the engineering system is stable between 98%and99%,the COD value of the effluent is kept below 500mg/L,the formaldehyde removal rate is stable at 99.9%,and the effluent formaldehyde concentration is≤0.5mg/L,which can meet the industrial park wastewater Treatment plant takeover standard.After the stable operation of the sewage treatment station,the treatment cost is11.7 yuan/ton water except artificial and equipment breakage fees.The cost of treatment within a reasonable range is economically beneficial and provides a reference for similar industries.