Process for preparing active carbon by co-decomposition of city sludge and agricultural wastes

Abstract

A process for preparing activated carbon by co-pyrolysis of municipal sludge and agricultural waste comprises the steps of mixing the agricultural waste and the municipal sludge in a certain proportion to obtain a mixture; heating the mixture at a certain temperature under the condition of air isolation, keeping the temperature for a period of time, collecting a solid product, and cooling; and pulverizing the solid product to obtain the activated carbon product. In order to obtain an activated carbon with higher absorptive capacity, a certain amount of nitrate can be added into the mixture. Because the agricultural waste can make up the low heat value shortcoming of the sludge, while the municipal sludge can solve the problems with the agricultural waste that the pyrolysis solid product is easy to flow away and difficult to store, the inventive process can not only solve the high energy consumption and high cost problems of the prior sludge incineration, pyrolysis and other heat treatment methods, but also can be used for environmental treatment to save energy and reduce emission.

Description

technical field [0001] The invention relates to the preparation of activated carbon, in particular to the co-pyrolysis of municipal sludge and agricultural waste to prepare activated carbon. Background technique [0002] Municipal sludge is the sediment produced in the process of municipal sewage treatment. By 2006, a total of 791 sewage treatment plants had been built in 661 cities with municipalities in my country, and the annual sludge output (dry weight) was about 1.73 million tons, and it was increasing at a rate of about 10% every year. It is generally believed that the amount of sludge usually accounts for about 0.5% to 0.7% (volume) of the amount of sewage, or about 1% to 2% (mass) of the amount of sewage treatment. If the depth of sewage treatment increases, the amount of sludge will sometimes increase by 0.5 to 1 times. [0003] Municipal sludge is the sludge discharged from urban sewage treatment plants, and it can also be the sludge containing organic matter di...

AI Technical Summary

Problems solved by technology

Sludge incineration was once very popular. However, sludge incineration has limited its use due to large one-time investment, high investment in equipment, high operating costs, the production of highly toxic substances such as dioxin, and the need for reprocessing of incineration ash.

Due to the complexity of the incineration equipment, the construction and operation costs are much higher than the general sludge treatment method, and the incineration cost is 2 to 4 times that of other processes (the comprehensive treatment cost of a ton of dry sludge is about 700 to 1,000 yuan), which is difficult to support economically. Therefore, in practice, it cannot be promoted and applied