Study On The Effect Of Pretreatment On Promoting Acid Production Fermentation Of Waste Activited Sludge In Refinery

As an industrial sludge that is difficult to handle,the waste activated sludge in a refinery is a companion product produced by a biochemical treatment process of a refinery wastewater treatment plant in the treatment of oily wastewater.Sludge contains a large number of dead microbial cells,microbial metabolites,including polysaccharides,proteins,lipids and other substances.It is an organic resource.The recovery and utilization of organic resources in the remaining activated sludge of refineries through scientific and effective treatment technologies will inevitably generate environmental and economic benefits that cannot be ignored.Compared with H₂ and CH₄,volatile acids are more widely used and can be used to make degradable plastics and other substances with better added value.Based on this,in this dissertation,acid production process was used to convert the organic matter in the remaining activated sludge of the refinery into volatile short-chain fatty acids,and five pretreatment methods were investigated for the problem of poor solvability of the remaining activated sludge.The conditions for the fermentation acid production of the remaining activated sludge in the refinery are optimized to provide a new theoretical and technological basis for the resource utilization of the remaining activated sludge in the refinery.In this study,a pretreatment method for improving the lysis efficiency of the remaining activated sludge in the refinery was studied.The results showed that,at the initial temperature of 30°C and the energy density of 2 W/mL under ultrasonic irradiation for 45 min,the soluble chemical oxygen demand?SCOD?in the sludge increased nearly 4 times.Under the condition of pH=3,the dosage of Fe²⁺was 1.0g/L,the amount of H₂O₂ was 8.0 g/L,and the SCOD in the sludge increased by nearly 1 time after oxidation treatment for 2 h.The amount of K₂S₂O₈ added to the sludge was 0.3 g/gSS,and oxidation treatment at 80°C for 90 min resulted in 1 time increase in SCOD in the sludge.The amount of sodium sulfite added to the sludge was 0.8 g/L.Treatment at 4°C for 24 h increased the SCOD in the sludge by nearly 2 times.Alkaline treatment at pH=13 for 24 h,then the highest total volatile fatty acid?VFAs?was produced at pH=11.This topic explores the optimization conditions of anaerobic fermentation of residual activated sludge in refineries and the accelerating effect of pretreatment on anaerobic fermentation of residual activated sludge in refineries.The results showed that the optimal anaerobic fermentation of sludge was performed under the condition of pH=7,temperature of 35°C,shaking speed of 120 r/min.The effects of the five pretreatment methods on the production of acid from the fermentation of sludge were analyzed by examining changes in VFAs,SCOD,soluble proteins and sugars.The results showed that the amount of VFAs fermented by sludge after ultrasonic treatment was increased by nearly 3 times compared with the blank group.The amount of VFAs fermented by Fenton oxidation increased by nearly 5 times.After the potassium persulfate oxidation pretreatment,the amount of VFAs fermented by sludge increased nearly one time.The amount of fermentation VFAs in the sludge after pretreatment with sodium sulfite increased by nearly 5 times.Alkali pretreatment increased the amount of fermentation VFAs by nearly 7 times.The experimental results show that the amount of acid produced by pretreatment of the remaining activated sludge in the refinery is:alkali>sodium sulfite>Fenton oxidation>ultrasound>potassium persulfate.