Study On Process Conditions And Product Characteristics Of Bioflocculant Prepared From Surplus Sludge

The sludge is used as the product of the urban sewage treatment plant and contains a plurality of harmful substances,there are great environmental risks,and the sludge also contains proteins and other macromolecular organic substances.Direct discharge will cause waste of resources.Microorganisms can produce proteins,polysaccharides and other metabolites in the process of growth,which have certain flocculation ability and can be used as bioflocculants,and bioflocculant is obtained by treating sludge,and the industrialization conditions of preparing bioflocculant from sludge are explored,which can provide data support for practical application.In this paper,the thermo-alkali treatment technology of sludge was used to compare treatment conditions and treatment effects under static experiment and dynamic experiment,and the application performance of hydrolysate as bioflocculant was analyzed.Firstly,the effects of different treatment conditions on sludge treatment by thermo-alkali process were explored under static experiment.The COD dissolution rate,the concentration of protein and polysaccharide were taken as analysis indexes.It was found that the optimum conditions under static experiment were pH = 13,hydrolysis temperature of 30 C and reaction time was 10 h.Under the single factor experiment,the three products reached the maximum at pH = 13.At low temperature,the temperature had little effect on the cracking effect.The best effect was obtained when the reaction time was 10 h,and then changed little with the extension of time.Secondly,referring to the static experiment,the treatment conditions and effects in the dynamic experiment were investigated.It was found that the optimum treatment time was 10 h,and the content of the product in the dynamic experiment was significantly higher than that in the static experiment.At this time,the COD dissolution rate increased by 14.24%,the protein concentration increased by 262.96 mg/L,and the polysaccharide concentration increased by 174.49 mg/L.It showed that the static experiment had a good guiding effect on the dynamic experiment.High flocculation rate can still be obtained after high temperature treatment,which shows that the thermal stability of the product is good.According to the analysis of the content and properties of the product after drying,it is speculated that the main substance that plays a role is polysaccharide.Finally,the flocculation effect of the decomposition product was analyzed.The conditions of kaolin suspension solution,Congo red simulated dye wastewater,Wande actual dye wastewater and water-borne paint wastewater were explored and evaluated.The results showed that the product was effective as a bioflocculant for wastewater treatment.The order of the treatment effect of the four kinds of wastewater is as follows: water-based paint wastewater > kaolin suspension solution > Congo red simulated dye wastewater > Wande actual dye wastewater.Under the optimum conditions,the flocculation rate is 95.92%,93.86%,86.43% and 69.19%,which all have good treatment effect.