A clean production method for improving the energy recovery rate of surplus activated sludge resources

Abstract

A cleaner production method for improving residual activated sludge resource energy recovery rate is disclosed, and the method comprises the following steps: (1) sludge is pressed until the sludge has a moisture content of 75-80%; (2) the pressed sludge is remixed and soaked with water according to the ratio of 1g to 3-5ml for 2h; (3) the above mixture is stirred and aerated, after 12-72h, the stirred and aerated mixture is naturally sedimented; (4) supernatant in the step (3) is discharged into a MAP precipitation reactor, magnesium salt and phosphate salt solutions are added for adjusting the molar ratio of P to Mg to N being 1 to 1.2 to 1, 5MNaOH is used for adjusting the pH of the reaction solution to 8.9 + / -0 .1, the supernatant after precipitation is discharged into an anaerobic regulation pool, precipitate is discharged into a separation recovery device for recovering the precipitate; and (5) supernatant after MAP precipitation in the step (4) and precipitated bottom sediment after natural sedimentation in the step (3) are respectively discharged into the anaerobic regulation pool for further fermentation to produce methane to recover energy. The method is easy to operate and simple, no new chemical substance is introduced, and the running cost is low.

Description

technical field [0001] The invention relates to a clean production method for improving the energy recovery rate of excess activated sludge resources, and realizes the goal of efficiently recovering resources and energy from excess activated sludge in sewage treatment plants, belonging to the technical field of excess activated sludge treatment and resource utilization, and is a A new technology for cleaner production. Background technique [0002] About 86.2% of the sewage treatment plants in the country adopt the activated sludge method, and the volume ratio of the remaining activated sludge generated during the treatment process accounts for about 0.3% to 0.5% of the total sewage treatment, and the treatment and disposal costs usually account for 10% of the sewage treatment operation cost. 40%-60% or more. The treatment methods generally adopted at this stage are landfill disposal in garbage dumps or anaerobic digestion treatment in sewage plants. The landfill disposal ...

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Problems solved by technology

Currently reported sludge pretreatment methods include microwave method, ultrasonic method, heating method, freeze-thaw method, high-pressure homogenization method, bead milling method, ozone oxidation method, wet oxidation method, acid method and biological cracking method (enzyme method, etc.) , the cracking effect on sludge has its own characteristics, but the practical application requires high equipment, complex operation and safety hazards, and many technologies are difficult to implement engineering applications

Chinese invention patent "two-stage alkaline hydrolysis and acidification recovery method for sludge carbon source" (CN101708932B), Chinese invention patent "alkaline hydrolysis pretreatment - ammonium magnesium phosphate method to recover phosphorus and nitrogen - anaerobic digestion methane production integrated process to treat excess sludge Method” (201310708860.6) Utilize alkaline hydrolysis pretreatment to recycle remaining activated sludge. The color of the treated sludge is very heavy. For example, the supernatant after treating the sludge with 5% NaOH is dark brown, and the alkali treatment contains a large amount of Na + , OH - The high salinity and high alkalinity of the supernatant will increase the chroma and salinity of the subsequent treatment water, which is not conducive to the discharge of wastewater up to the standard, especially the high pH value of the treatment solution, which is not conducive to the subsequent anaerobic digestion treatment and cannot be realized Comprehensive sludge treatment, disposal and resource utilization