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Method for improving anaerobic digestion performance of sludge by utilizing microwave alkaline thermal hydrolysis

A technology of anaerobic digestion and thermal hydrolysis, applied in biological sludge treatment, solid waste removal, etc., can solve the problems of low organic matter load and biogas yield, long solid residence time, etc., to improve the conversion efficiency of organic matter, realize Pollution control, energy saving and emission reduction effect

Inactive Publication Date: 2009-09-09
TSINGHUA UNIV
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  • Summary
  • Abstract
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AI Technical Summary

Problems solved by technology

However, the conventional anaerobic digestion of sludge is to directly digest the concentrated sludge. Due to the characteristics that a large amount of organic matter in the sludge is wrapped by the cell wall, the anaerobic digestion of sludge generally has long solid residence time, organic matter load and biogas production. Low rate and other deficiencies

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] The thickened sludge from the urban sewage treatment plant will further increase the solid concentration to 8% through the integrated thickening and dewatering machine. Add NaOH solution with a molar concentration of 1mo / L to the sludge, adjust the pH value to 13, and stir and mix for 5 minutes. Put the alkalized sludge in a microwave field of 2450MHz and heat it to 150°C, keep the temperature and continue heating for 5 minutes before ending. During the microwave heating process, the sludge hydrolysis reaction occurs, 55% of the volatile suspended solids dissolve into the liquid phase, and 40% of the suspended solids dissolve into the liquid phase. The chemical oxygen demand (COD) of the liquid phase in the sludge accounts for 40% of the total COD, the pH value of the sludge was reduced to 10.5 after thermal hydrolysis. The sludge treated above is subjected to anaerobic digestion at a temperature of 35° C., and the removal rate of organic matter in the sludge reaches 5...

Embodiment 2

[0020] For the dewatered cake with a water content of 80% in the urban sewage treatment plant, it is firstly diluted to make the sludge solid concentration reach 10%. Add KOH solution with a molar concentration of 1mo / L to the sludge until the pH is 12, and stir and mix for 10min. Put the sludge added with lye into a 2450MHz microwave field to heat the sludge to 170°C, keep the temperature and continue heating for 10 minutes, then stop the heating. During the microwave heating process, the sludge hydrolysis reaction occurs, 60% of the volatile suspended solids dissolve into the liquid phase, 45% of the suspended solids dissolve into the liquid phase, and the chemical oxygen demand (COD) of the liquid phase in the sludge accounts for the total COD 50%, the pH value of the treated sludge was reduced to 10.8. The sludge after the above treatment is anaerobically digested at a medium temperature of 37° C., and the organic matter removal rate reaches 60%.

Embodiment 3

[0022] For the dewatered cake with a water content of 80% in the urban sewage treatment plant, it is firstly diluted to make the sludge solid concentration reach 10%. Adding mass percent concentration to the sludge is 5% Ca(OH) 2 The solution was brought to pH 10 and stirred for 10 min. Put the sludge added with lye into a 2450MHz microwave field to heat the sludge to 160°C, keep the temperature and continue heating for 10 minutes before ending. During the microwave heating process, the sludge hydrolysis reaction occurs, 50% of the volatile suspended solids dissolve into the liquid phase, and 35% of the suspended solids dissolve into the liquid phase. The COD in the liquid phase in the sludge accounts for 40% of the total COD. After the thermal hydrolysis, the pH value of the sludge is reduced to 9.0, and the treated sludge is anaerobically digested at a medium temperature of 37° C., and the organic matter removal rate reaches 53%.

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Abstract

The invention relates to a method for improving anaerobic digestion performance of sludge by utilizing microwave alkaline thermal hydrolysis, and the method belongs to the technical field of solid waste treatment. Alkaline solution is firstly added in the sludge with the solid concentration of 7 percent-10 percent for controlling the pH value of the sludge, the mixing is carried out after adding the alkaline solution, the alkalified sludge is placed in a pressure-bearing reactor, the heating is carried out in a microwave field with the frequency of 2450MHz, the sludge heated by microwave is cooled to the room temperature, and the anaerobic digestion treatment is carried out on the sludge after the cooling. More than 60 percent of organic matters in the sludge which is treated by the method are converted to liquid phase; during anaerobic digestion, the conversion efficiency of the organic matters of the sludge is improved, thereby being an effective means for realizing the whole process pollution control, the energy conservation and the emission reduction of sewage treatment.

Description

technical field [0001] The invention relates to a method for improving the anaerobic digestion performance of sludge by using microwave alkaline thermal hydrolysis, and belongs to the technical field of solid waste treatment. Background technique [0002] With the acceleration of urbanization and the rapid development of social economy in our country, the amount of urban sewage has increased rapidly. At the same time, the country's increased investment in environmental governance has also greatly promoted the development of the sewage treatment industry. The sewage treatment process produces a large amount of surplus sludge. According to statistics, the annual dewatered sludge with a moisture content of 80% in the country has exceeded 10 million tons. Sludge contains a variety of harmful substances, such as heavy metals, refractory organic matter, persistent organic matter, and pathogenic microorganisms. Its treatment and disposal has always been an important content of urb...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B09B3/00C02F11/04
Inventor 王伟乔玮高兴保郑蕾罗玉翔
Owner TSINGHUA UNIV
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