Method for extracting protein from excess sludge

Abstract

The invention discloses a method for extracting protein from excess sludge, and belongs to the field of sludge recycling. The method provided by the invention comprises the following steps: (1) adding water into the residual sludge for adjustment to obtain a sludge solution with the sludge concentration of 100-200g / L; (2) mixing the sludge solution with a compound enzyme preparation, and performing enzymolysis to obtain a mixed solution after enzymolysis; wherein the compound enzyme preparation is a compound enzyme composed of glycosidase and lipase in a mass ratio of (1-5): 1, and the glycosidase is alpha-amylase and beta-amylase in a mass ratio of (1-5): 1; (3) pressurizing the mixed solution after enzymolysis, adjusting the pH value to 10-13, and hydrolyzing to obtain a mixed solution after hydrolysis; and (4) filtering and concentrating the hydrolyzed mixed solution to obtain a protein solution. The method provided by the invention can effectively degrade polysaccharide and fat in the sludge, and improve the protein concentration, the protein quality and the sludge dewatering performance.

Description

technical field [0001] The invention relates to a method for extracting protein from excess sludge, which belongs to the field of sludge resource utilization. Background technique [0002] Surplus sludge is an inevitable by-product of sewage treatment. Since 2008, China's surplus sludge production has grown by an average of 10% per year, and increased to 58 million tons (with a moisture content of about 80%) in 2019. Excess sludge not only has high moisture content, is perishable, and has an unpleasant smell, but also contains a large amount of organic matter, pathogenic microorganisms, and heavy metals. If it is piled up randomly without treatment, it will cause secondary pollution to water and soil. The excess sludge contains a large amount of organic matter, mainly protein, polysaccharide, humic acid, etc., among which the protein content accounts for about 30-60%. The protein extracted from excess sludge can not only effectively solve the problem of sludge treatment, b...

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Problems solved by technology

For example: the patent of invention with the publication number CN111116705A discloses a method for extracting protein from sludge by using ozone treatment. In this method, the sludge is placed in a reactor and fed with ozone for ozone oxidation, and then the modified cationic guar is added. Glue, coagulation and precipitation, the final product protein concentration is 5000 ~ 8000mg / L; the invention patent with the publication number CN102702306A discloses a method for recovering protein by ultrasonic gradient hydrolysis, which uses ultrasonic gradient hydrolysis sludge, through the isoelectric point Precipitation and recovery of protein precipitation; the invention patent with the publication number of CN108658411A discloses a method for recovering protein from sludge. The method uses wet oxidation to recover protein from organic sludge. The time is 90min, the rotating speed is 500rpm / min, and the pressure is 40bar. After hydrolysis, ammonium sulfate is added to centrifuge, and the final protein extraction rate is 19-50%. The invention patent with the publication number of CN1868929A discloses the use of quicklime to hydrolyze active sewage. A production process and equipment for preparing hydrolyzed protein from mud. In this method, after adding excess sludge: water: quicklime at a ratio of 1:1:0.06, hydrolyze at 135-150°C for 1-3 hours, filter and obtain protein by spray drying; the above The method can extract the protein in the sludge to a certain extent, but it only increases the hydrolysis degree of the sludge by increasing the process intensity, and does not pay attention to the influence of the organic components (polysaccharides and fats) in the sludge on the protein in the extracted sludge

Polysaccharides and fats in sludge will not only affect the concentration and efficiency of protein extraction from sludge, but will also affect the quality of the final product

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