Separating Organic Matters And Follow-up Purifing By Biological Filter Bed For Benzoic Acid Production Wastewater

Being as an important organic chemical raw material,benzoic acid is widely used in medicine,food and chemical industry etc.However,a large amount of benzoic acid wastewater with strong toxicity and heavy acid corrosion would be emerged during the production process of benzoic acid;moreover,the environment would be polluted by this high-concentration organic wastewater if discharged directlly.Therefore,according to the characteristics of this kind of wastewater,the extraction-follow up biological filter bed process was proposed in this thesis;and this combination technique was efficiently utilized for benzoic acid wastewater treatment.First of all,high concentration of benzoic acid wastewater was extracted.In the extraction experiments used raw materials of the production toluene as extracting agent of benzoic acid extraction experiments.Experiment changed the volume ratio of toluene and benzoic acid wastewater as the experiment conditions,therein,the toluene and benzoic acid wastewater volume ratio of 1:1,1:4 and 1:9,extracted benzoic acid wastewater under the same proportion for three times,the quantitative analysis is operated in extraction raffinate of benzoic acid,benzyl alcohol and benzene formaldehyde after the extraction.At the room temperature,toluene and benzoic acid was volumed ratio of 1:1 and uniform mixed 5 min,when water phase and organic phase stratified,taken extraction raffinate doing the high performance liquid chromatography(HPLC)analysis,experimental results show that benzoic acid,benzyl alcohol and benzene formaldehyde concentrations were respectively 19.64 mg/L,23.07 mg/L and 0 mg/L in the extraction raffinate after three times of extraction,as the same time,the extraction rate were respectively 70.21%,62.97%and 100%,showing the toluene extraction of benzoic acid wastewater treatment effect is obviously.In addition,compared with three extraction raffinate,three kinds of material concentrations were respectively 65.92,62.31 and 0 mg/L in secondary extraction raffinate also has the very good extraction effect.In order to reduce the usage of extraction agent and do experiment of subsequent processing of biological filter bed,toluene and benzoic acid wastewater volume is selected as 1:1,at the same time,the concentration of benzoic acid,benzyl alcohol and benzaldehyde in secondary extraction raffinate are selected as experimental conditions of biological filter bed.Anaerobic-aerobic biological filter bed experiments analysis:each material concentration in secondary extraction raffinate as experiment condition,benzoic acid and benzyl alcohol concentration is respectively 100 mg/L in configuration of benzoic acid wastewater.Experiment used the method of biological filter bed by self-made biological purification tank for dye wastewater treatment after mixing.In benzoic acid waste water set domestic sewage and benzoic acid waste water volume ratio of 1:4,2:3,1:1,3:2 and 4:1.Study on acid waste water treatment in anaerobic and two stage aerobic conditions.The aeration rate of primary aerobic zone and the secondary aerobic zone were 2.4 L/min and 1.2 L/min in experiment,into the water for 30 L/d,recidence time for 24 hours.Continuous running 4 to 5 days later are measured,the experimental results show that when toluene and benzoic acid waste water volume ratio is 3:2,the effluent concentration of COD,BOD5,NH4+-N,benzoic acid and benzyl alcohol is respectively 33 mg/L,13 mg/L,30 mg/L,1.3 mg/L and 0.8 mg/L,all can meet the national discharge level standard.It proves that benzoic acid wastewater has very good removal efficiency by biological filter bed.Complete aerobic biological filter bed experiments analysis:At three levels of aerobic aeration condition,the concentration of dissolved oxygen is controlled in 3.510.2 mg/L,other conditions are the same as the anaerobic-aerobic.Experimental results show that when toluene and benzoic acid waste water volume ratio is 3:2,various effluent indexes meet the national level of emission standards,one out of the water the concentration of COD,BOD5,NH4+-N,benzoic acid and benzyl alcohol is respectively 44.8 mg/L,18 mg/L,3.0 mg/L,0.8 mg/L and 1.2 mg/L.