Phy-chemical Properties And Deep Dewatering Of Municipal Sludge In Large City

Sludge is the product of wastewater in city. Beijing as the national capital and a big city, the amount of sludge generated every day is great and need to overall planning.Advanced sludge dewatering is a main technology for adapting Chinese conditions to suit for the rapid development technology, it will replace the traditional centrifugal or belt type equipment. The main influence factors of sludge dewatering include sludge age, Extracellular Polymeric Substances, sludge particle size, surface charge and cation, etc. In order to improve the sludge dewatering ability, the related research mainly includes as following:chemical?physical?biological and combined tempering. Chemical conditioning is most widely used, So medicament selection not only needs to be combined with the local situation and the original sludge properties, but also considered by way of follow-up. Now Beijing focus on the application in the forest, landscaping and sandy land improvement.This paper analyzes the character and the factors influenced dewatering of four different wastewater treatment plant (WWTP) of Beijing, the results showed that the ability of sludge dewatering have the relevant with dissolved Extracellular Polymeric Substances (EPS) and protein content. The mucus layer of biological polymers is not conducive to cell adhesion caused sludge flocculation capacity variation, the result causes poor biological flocculation, more cell corrosion and poor slurry separation performance; the same period, the sludge composition of different WWTP is similar to EPS and the same trend; LB-EPS layer of organic matter concentration is lowest, Slime layer of organic matter concentration is higher; from the whole dehydration, each WWTP sludge dewatering performance are best in the summer, with the decrease of temperature in winter, dehydration of sludge gradually deteriorated, which is mainly due to the content of dissolved EPS sludge system increased gradually; the organic and the joint effect of inorganic coagulant sludge conditioning of sludge dewatering performance obtained after improved obviously, and the first dosage of inorganic and organic coagulant dosage dehydration effect is better than the first adding organic and inorganic coagulant for sludge dewatering performance is significantly improved, along with the decrease in EPS protein content, increase the number of sugar and Deoxyribonucleic Acid (DNA) content. After thermal hydrolysis treatment the dewatering performance of sludge improved significantly.According to the laboratory experiment data, we have the production experiment of sludge deep dehydration in Beijing WWTP, respectively by chemical conditioning plus high frame and electro-osmosis process, contrast mud effect and investment operating cost, the results show that two methods can make water content below 60%,reduction effect reaches above 50%; but from the economy of the overall consideration, or chemical conditioning combined frame dehydration more economic, more suitable for the needs of Beijing.In 2014 Beijing reformulate the sludge treatment engineering technical route, by thermal hydrolysis + frame depth dehydration + compost + dominated land use planning, the completion of five sewage sludge disposal center, and priority in Gaobeidian WWTP construction sludge dewatering project of 1358 tons / day. The project will be built in early 2015,.Biosolid water ratio is stable under 60% adding the thermal hydrolysis operation.