A method and device for low-temperature drying of residual activated sludge in sewage treatment

Abstract

The invention discloses a low-temperature drying method and device for residual activated sludge in sewage treatment. The device includes sludge freezing equipment, a sludge curing room, a sludge thawing and preliminary dehydration device, sludge dehydration equipment and sludge Air-drying device: The residual activated sludge after preliminary dehydration treatment in the sewage treatment plant is sequentially processed by the above-mentioned device to obtain low-temperature dried sludge. The present invention cooperates with the sludge thawing device, the sludge dehydration device and the sludge air-drying device to continuously dehydrate and air-dry the sludge, shorten the sludge drying period, and have an obvious drying effect. All drying processes are carried out at normal temperature and below, which reduces the volatile gas produced by the secondary fermentation of microorganisms in the sludge, thereby reducing pollution. The invention directly freezes the sludge without adding other chemical agents, reduces the drying cost, keeps the biological characteristics of the sludge unchanged, and lays a foundation for the resource utilization of the sludge.

Description

technical field [0001] The invention belongs to the technical field of sludge treatment, and in particular relates to a low-temperature drying method and device for residual activated sludge in sewage treatment. Background technique [0002] A large amount of excess activated sludge is produced in the process of sewage treatment, and the investment and operation costs of excess activated sludge are relatively high, which brings a heavy burden to sewage treatment. The forms of the existing sewage treatment residual activated sludge drying process: mechanical dehydration, sludge drying or mechanical dehydration + sludge drying; the main technical measures adopted are: (1) Mechanical dehydration stage: the remaining activated sludge needs to be dehydrated first Quenching and tempering, mainly by adding PAC, PAM, lime and other measures to improve the dehydration performance of the sludge, and then using mechanical dehydration equipment for dehydration, the disadvantage is that ...

AI Technical Summary

Problems solved by technology

The forms of the existing sewage treatment residual activated sludge drying process: mechanical dehydration, sludge drying or mechanical dehydration + sludge drying; the main technical measures adopted are: (1) Mechanical dehydration stage: the remaining activated sludge needs to be dehydrated first Quenching and tempering, mainly by adding PAC, PAM, lime and other measures to improve the dehydration performance of the sludge, and then using mechanical dehydration equipment for dehydration, the disadvantage is that the moisture content of the sludge can only be reduced to about 60%, and at the same time, adding lime Finally, the pH value of the mud cake is strongly alkaline; (2) sludge drying stage: the existing technology uses artificial heat sources to make the remaining activated sludge dry and dehydrate by directly or indirectly heating up and evaporating the water in it. The temperature is above 100°C, and its disadvantages are: high energy consumption, changing the biological characteristics of sludge, and producing a large amount of toxic and harmful gases in the process

[0003] CN105461182A discloses a biological sludge reduction method, which integrates aeration, ultrasonic treatment, hydrolysis, anaerobic fermentation, conditioning, concentration, refrigeration treatment, thawing, and vacuuming technologies, and can reduce sludge Chemical treatment, but this technology has the disadvantages of long reduction period, high cost, inconvenient operation, need to add additional chemicals, and high pH of sludge after reduction

CN102815848A and CN102815848B disclose a high-efficiency drying process for excess sludge. This method integrates anaerobic fermentation, vacuum preloading and freeze-drying technologies, and can effectively dry sludge. However, this technology has a drying cycle Disadvantages of length, high cost, need to add additional chemicals, inconvenient operation, and ineffective drying effect

CN105330111A discloses a method for drying surplus sludge, which improves the existing surplus sludge treatment, but this method has the disadvantages of long drying period, high cost and inconspicuous drying effect

Images