Study On Extracting Protein From The Residual Activated Sludge After The Biological Treatment Of Waste Water From Papermaking

It produces a lot of waste water in paper manufacturing industry. There is lots of residual activated sludge after the biological treatment of waste water, which can cause serious environment pollution, and is also a significant financial burden to Paper enterprises. So it is necessary to find a good way in resource utilization of residual sludge.In the paper, the acid and alkaline hydrolysis of residual activated sludge had been studied. Protein solution had been concentrated by ultrafiltration membrane.Firstly, when HC1and CaO are used as an addition agent, the effect of pH, water ratio, temperature and time on the extracting of protein from sludge and the foaming ability of protein were investigated through the orthogonal experiment. When HC1is the medicament, pH is1.5, temperature is121℃, time is5h, water ratio is92%, the average extracting ratio of protein is41.19%, the value of the protein foam is27.33ml with the half time11.80h. When CaO is the medicament, pH is12.5, temperature is125℃, time is4h, water ratio is92%, the average extracting ratio of protein is41.85%, the value of the protein foam is28.33ml with the half time10.77h.Second, the effect of concentration pressure and different ways to the ultrafiltration membrane concentration process were investigated. The better conditions of concentrated protein were determined. The2%protein was concentrated by three stages, one is from2%to4%, another one is from4%to8%, the last stage is from8%to14%.At last, the effect of cleaning agent concentration, cleaning pressure and cleaning methods on the recovery rate of ultrafiltration membrane flux were investigated. When the pressure is0.05MPa, the membrane was cleaned by0.1%HC1firstly, then by the mixture of0.3%NaOH and0.1%NaCIO, the recovery rate of ultrafiltration membrane flux is90.4%.The results demonstrated that it was feasible that the residual activated sludge from the paper mill were hydrolyzed.by acid and alkaline to extract protein, and it provides a lot of raw material for protein foaming agent.