Subcritical hydrothermal treatment-based efficient recycling treatment process for sludge

Abstract

The invention relates to a subcritical hydrothermal treatment-based efficient recycling treatment process for sludge. According to the treatment process, sludge with the solid content of 10 to 25 percent of a sewage treatment plant is placed into a hydrothermal reaction kettle for 5 to 30 minutes at the subcritical high temperature of 200 to 300 DEG C and under the high pressure of 1.6 to 8.6 MPa, so that intracellular substances in sludge are fully dissolved, solid organic matters are fully dissolved and hydrolyzed and are partially decomposed; the release of bound water and surface water in the sludge facilitates improvement on the dehydration performance of the sludge. The sludge which is subjected to hydrothermal modification is dehydrated to enable the solid content of the dehydrated sludge to be not higher than 60 percent, and then aerobic composting stabilizing treatment is performed. The filtrate which is rich in dissolved organic matters and is obtained by dehydrating the sludge enters a high-speed anaerobic digestion system for fully recovering methane. According to the technology, the hygienization, the recycling and the stabilization of the sludge are realized effectively; the subcritical / supercritical reaction speed is high, the subsequent efficient anaerobic digestion hydraulic retention time is short, and the solid residues generated after hydrothermal modification dehydration are few, so that large-scale urban sludge treatment capacity can be realized by adopting small-capacity reactors in a hydrothermal link, an anaerobic link and an aerobic link of the treatment process.

Description

technical field [0001] The invention belongs to the field of solid waste recycling, and relates to a high-efficiency sludge recycling process based on subcritical hydrothermal treatment. Background technique [0002] The amount of dewatered sludge produced by urban sewage treatment plants due to the purification of domestic sewage is huge. At present, the annual collection capacity is about 30 million tons. Traditional sludge treatment methods, such as landfill, open-air stacking and foreign transportation Unable to adapt to the increasingly stringent sludge treatment and disposal standards. In recent years, the global energy structure is undergoing a transformation from fossil energy-based to the coexistence of multiple energy sources. Issues such as food security and environmental degradation have become increasingly prominent. Anaerobic fermentation technology has been adopted Recycling of non-food biomass energy in sludge—biogas has gradually gained attention. [0003] ...

AI Technical Summary

Problems solved by technology

However, municipal sludge is rich in microbial residues and has a high proportion of solid organic pollutants, which leads to the following problems in the process of using anaerobic digestion technology for sludge recycling and harmlessness: First, the organic matter in sludge Most of them exist in solid form and are mixed with anaerobic microorganisms, and the residence time of anaerobic microorganisms and pollutants cannot be controlled separately, so the traditional high-speed anaerobic digestion process has not been applied in the field of sludge anaerobic digestion; second, Compared with the dissolved organic matter in sewage, the solid organic matter in the sludge needs to add a "dissolution" process in the anaerobic digestion process. In addition, the organic matter in the sludge is mostly microbial residues, which are relatively complex, and the dissolution and hydrolysis rates are low. , both characteristics reduce the efficiency of sludge anaerobic digestion

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