Sludge treatment process
Release time：2021-7-16 18:0
The typical sludge treatment process includes four treatment or disposal stages. The first stage is sludge thickening, the main purpose of which is to reduce the initial volume of sludge and the volume of subsequent treatment structures or equipment; The second stage is sludge digestion to decompose organic matter in sludge; The third stage is sludge dewatering to further reduce sludge volume; The fourth stage is sludge disposal, in which the final sludge is absorbed in some way. The clear liquid or filtrate produced in the above stages still contains a lot of pollutants, so it should be sent back to the sewage treatment system for treatment. The above typical sludge treatment process can realize "four modernizations" after sludge treatment
(1) Reduction: due to the high water content, large volume and fluidity of sludge. After the above process, the volume of sludge is reduced to one tenth of the original, and the sludge is transformed from liquid to solid, which is convenient for transportation and consumption.
(2) Stabilization: the content of organic matter in sludge is very high, and it is easy to corrupt and produce stench. After the treatment in the digestion stage of the above process, some organic matter that is easy to corrupt is decomposed and transformed, which is not easy to corrupt, and the odor is greatly reduced, which is convenient for transportation and disposal.
(3) Harmless: sludge, especially primary sludge, contains a large number of pathogenic bacteria, parasite eggs and viruses, which is easy to cause large-scale spread of infectious diseases. After the digestion stage in the above process, most of the eggs, pathogens and viruses can be killed, and the sanitary index of sludge can be greatly improved.
(4) Resource utilization: sludge is a kind of resource, which contains a lot of heat. Its calorific value is between 10000-15000kj / kg (dry sludge), higher than coal and coke. In addition, the sludge is also rich in nitrogen, phosphorus and potassium, which is an organic fertilizer with high fertilizer efficiency. Through the digestion stage of the above process, the organic matter can be converted into biogas, so that the heat can be used, and the fertilizer efficiency can be further improved. The processes of sludge thickening are gravity thickening, centrifugal thickening and air flotation thickening. Sludge digestion can be divided into anaerobic digestion and aerobic digestion. Sludge dewatering can be divided into natural drying and mechanical dewatering. The commonly used mechanical dehydration processes include plate and frame filter pressing dehydration, belt filter pressing dehydration, centrifugal dehydration, etc. There are many ways of sludge disposal, including agricultural and forestry use, sanitary landfill, incineration and production of building materials.
