Research On The Coalescence And Separation Of Oily Sludge And Regeneration And Utilization Of Aluminum In Oily Sludge From Coal Chemical Wastewater

Coal chemical wastewater is a typical wastewater with high treatment difficulty,showing multi-component water quality characteristics such as high suspended matter,oil,phenols and ammonia nitrogen.The content of oil and SS had been stable from1700～2000 mg/L and 1500～2000 mg/L,respectively.Among them,if the high concentration of oil and sludge were not effectively separated and recovered,its not only cause the waste of resources;but also presence in the wastewater stably,making it difficult to settle the solids and separate,and hinder the normal operation of the subsequent process.Therefore,the effective removal of oil and oily sludge are a practical problem that needs to be solved in the pretreatment of coal chemical wastewater.Based on the above issues,an inorganic and organic composite material was prepared in this study,and the effect of the composite material on the removal of oil and sludge from wastewater and the removal characteristics of organic matter from wastewater were investigated.Based on this,the physicochemical characteristics of the separated oil sludge were analyzed,and the resourceful disposal of aluminum resources in oily sludge was realized by pyrolysis activation method.In order to find a high efficiency,low cost and stable treatment effect of oily sludge in coal chemical wastewater pretreatment and sludge resource disposal method.The main results are as follows:（1）The experiment prepared a variety of inorganic materials with high charge and low polymerization and organic materials with low charge and high polymerization by screening and compounding different types of aluminum salts,iron salts,calcium salts and polymers.Analysis and comparison of the effect of various composite materials on the aggregation and separation of oily sludge in wastewater.The optimal inorganic and organic composite material was selected.When the dosage of inorganic composite material was 10 g/L and the dosage of organic composite material was 15 mg/L,the sludge removal effect was the best,in which the oil and SS removal rate was stable at about 48%～50%and 95%～98%,respectively.（2）The composite material was applied to the field pilot test.The results showed that after 10 rounds of intermittent operation,the oil content in the effluent remained at900 mg/L～1100 mg/L,and the oil removal rate was stable at 45%～50%.The SS content in effluent remains between 25 mg/L and 250 mg/L,and the removal rate of SS was stable at about 95%.It can be seen that the composite material shows good stability for sludge removal.（3）The analysis of PAHs,benzenes and phenols in the wastewater before and after sludge removal showed that 13 PAHs,7 benzenes and 20 phenols were detected.The total removal rate of PAHs was 82.85%,the total removal rate of benzene was 41.9%,and the total removal rate of phenols was 37.56%.The comprehensive analysis shows that the oil sludge removal process has a better effect on the removal of PAHs substances.（4）In order to realize the resource recovery and harmless disposal and utilization of oil sludge,the physical and chemical characteristics of oil sludge were analyzed.The results of XRF analysis showed that there were abundant aluminum resources in the oil sludge,which could be recycled.Based on this,pyrolysis activation method and acid-base combined method were used to treat the oil sludge.The optimal regeneration conditions of aluminum resources were determined by single factor method,including pyrolysis temperature 750℃,pyrolysis time 2h,activation agent Na₂CO₃.Under the condition that the ratio of sludge to activator material is 1:1,the leaching time is 1.5h,the leaching concentration is 12%,and the leaching temperature is 65℃,the maximum extraction rate of aluminum from sludge can reach 82%.（5）The adsorption performance of aluminium-based adsorbent on fluoride was investigated,and the results showed that aluminium-based adsorbent had good adsorption performance and fast adsorption rate;The adsorption process was fitted with the adsorption model,which showed that the adsorption process belonged to chemical adsorption,and the maximum saturated adsorption capacity was 11.67 mg/g.Through the analysis of fluoride removal effect under different p H conditions,p H has an important effect on the adsorption of F^-,but the optimum p H range is narrow.When the influence of coexisting anion concentration on fluoride adsorption was investigated,the results showed that the order of influence of anion concentration on fluoride adsorption was PO₄^3->Cl^->SO₄^2->NO₃^->HCO₃^-.After 8 times of elution and regeneration,the removal rate can still remain above 90%.It is found that the adsorbent has a large specific surface area and pore size structure,and its adsorption process is affected by electrostatic attraction and ion exchange.