The Effect Of Biochemistry Joint Condition On Paper Mill Sludge Dewatering

With the development of our country's economy,the papermaking industry has been developing rapidly,along with a large number of papermaking sludge generated.The papermaking sludge has a huge amount,high water content,complex composition,difficult to dewatering,perishable characteristics,so it need to be disposed properly.Sludge dewatering is the main way to realize sludge reduction,and sludge conditioning is the key technology of sludge dewatering.In this paper,we aimed at strengthening the dewatering performance of papermaking sludge,using biological enzyme and chemical flocculant(coagulant aids)as conditioning agent,to explore the biochemical conditioning on dewatering performance of papermaking sludge,and to analyze dewatering mechanism.First,the basic properties of the test sludge were tested.The results showed that the water content of the papermaking sludge was 99.00%,the content of organic matter was about 52.00%,the SRF(specific resistance)was more than 1.0×1013m / kg,and the dewatering was more difficult.Sludge particle size was 22.3?m,the specific surface area was about 810m2 / kg;there was more adhesion between the sludge floc,and the Sludge skeleton was obvious.The papermaking sludge conditioning of PAM conditions were optimized by the SRF,CST(capillary suction time),TTF(time to filtration)and the moisture content of the mud cake after pumping.The results showed that SRF decreased 89.8%,CST decreased by 32.7%,TTF decreased 78.3% and water content decreased by 29.5%,when the PAM(polyacrylamide)molecular weight was 8 million,the dosage was 2.0mg / g DS and pH = 7.0.When the addition of 20% CaCl2 plus 2.0mg / g DS PAM,the conditioning effect was better.PAM can increase the average particle size of sludge significantly,reduce the specific surface area and supernatant COD(chemical oxygen demand),improve the sludge dewatering performance greatly.When the PAM dosing excessive,the sludge dewatering performance deteriorated.It was investigatede the effects of cellulase,protease and lipase on the dewatering performance of papermaking sludge,including SRF,CST,TTF and moisture content of the mud cake.The results showed that the effect of cellulase was better than that of protease,both of them were better than that of lipase.When cellulase was combined with protease,it can further enhance the effect of sludge conditioning.When the dosage of cellulase was 20 mg / L and the dosage of protease was 10 mg / L,the effect of sludge conditioning was the best,while the SRF dropped to 2.94×1012m/kg and the moisture content dropped to 71.5%,compared with the original sludge reduced 72.0% and 27.5% respectively.The addition of biological enzymes would increase the particle size dispersion of sludge and supernatant COD.Compared with the original sludge,the maximum reductions of SRF,CST and water content were 74.9%,35.0% and 32.7%,respectively,when the biological enzyme was combined with 8 million molecular weight CPAM(cationic polyacrylamide)to further enhance the sludge dewatering performance.In the combined conditioning,the CPAM and the biological enzyme were synergistic,and the COD of the supernatant was reduced by the action of adsorptive bridging.The combined conditioning reduced the specific surface area of the sludge,decreased the particle size and the dispersion.The sludge floc structure was tight,but there were still some gaps,which were conducive to water outflow.