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Method for enhancing anaerobic digestion of excess sludge by utilizing freezing and free nitrous acid combined pretreatment

A technology for excess sludge and anaerobic digestion, applied in chemical instruments and methods, sludge treatment, biological sludge treatment, etc., can solve problems such as low methane efficiency, achieve good results, consume less chemicals, and avoid mechanical dehydration Effects of Energy Consumption Problems

Inactive Publication Date: 2020-02-21
HUNAN UNIV
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Problems solved by technology

This method is mainly based on the joint treatment technology of freezing and free nitrous acid, and finally anaerobic digestion is carried out to produce methane, so as to solve the current situation of low efficiency of anaerobic digestion of excess sludge for methane production

Method used

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Embodiment 1

[0019] A method for strengthening the anaerobic digestion of excess sludge by combined pretreatment with freezing and free nitrous acid, which is carried out as follows: the excess sludge discharged from the secondary settling tank is precipitated and concentrated for 2 days to a total solid content of 25 ± 1 g / L ; Transfer to the pretreatment reactor afterwards, add 500 mg / L sodium nitrite; Stir immediately after adding, while adjusting the initial pH in the reaction tank to 6.0 ± 0.2, the stirring rate is at 150 rpm; ℃ for 4 hours; then put the frozen excess sludge at 40 ℃ for 6 hours to thaw, add industrial alkali and adjust the pretreatment sludge to 7.0±0.2 under the polyethylene leaf type turbine agitator at 120 rpm. The final nitrogen stripping was carried out for 3 minutes; after that, the remaining sludge mixture after conditioning was transferred to an anaerobic digestion tank. During the digestion process, the temperature was controlled at 35°C, the stirring intensit...

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Abstract

The invention provides a method for enhancing anaerobic digestion of excess sludge by utilizing freezing and free nitrous acid combined pretreatment, and belongs to the field of resourceful treatmentand disposal of solid waste excess sludge. According to the invention, a freezing and free nitrous acid combined treatment technology is mainly adopted; finally, anaerobic digestion is performed to produce methane, so that rupture of extracellular polymeric substances and cells of the excess sludge is promoted, release of organic matters and biodegradability of soluble organic matters are improved, and the yield of the methane in the anaerobic digestion process of the excess sludge is greatly increased in a short time period. Compared with conventional heat treatment and alkali treatment, themethod has the advantages of lower energy consumption, lower consumption of chemical agents, better methane production effect of residual sludge and better sludge dewatering performance after anaerobic digestion.

Description

technical field [0001] The invention relates to the field of resource treatment and disposal of excess sludge of solid waste, and specifically refers to a method for strengthening anaerobic digestion of excess sludge by combined pretreatment of freezing and free nitrous acid. Background technique [0002] In the past few decades, with the improvement of my country's urbanization development level, people's material living standards and the enhancement of environmental protection awareness, my country's total sewage discharge has increased significantly, and more and more new sewage treatment facilities have been built. According to statistics, the main process of more than 85% of sewage treatment plants in my country is the activated sludge process, and excess sludge is produced as a by-product of this process in large quantities. As of the end of December 2017, my country's excess sludge production reached 40 million tons . The treatment and disposal of a large amount of ex...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C02F11/04C02F11/20C02F11/00
CPCC02F11/00C02F11/04C02F11/20Y02E50/30
Inventor 刘旭冉王冬波
Owner HUNAN UNIV
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