Study On Comprehensive Utilization Technology Of Municipal Sludge Sintering Brick Making In Meizhou City

With the increase of solid waste in China,the utilization of solid waste resources has become a trend of urban management,and the concept of"no-waste city"is being promoted.One of the problems currently plaguing solid waste management in Meizhou is the disposal of municipal sludge.In order to solve the problem of disposal of domestic sludge in Meizhou,to ensure environmental safety and to realize resource utilization,this paper studies the sludge disposal technology at home and abroad on the basis of analyzing the present situation of sludge in Meizhou,the two processes of co-combustion in sludge-cement Kiln and brick-making by sludge sintering were selected as the comparison schemes.After the comparison of technical and economic indicators,the final selection of sintered brick as a comprehensive utilization process.Due to the problems of high water content and bad odor of the unpretreated sludge,several sludge pretreatment technologies at home and abroad are studied in this paper.Compared with several drying technologies commonly used in China,it is found that the high temperature drying technology needs a lot of energy,and it is easy to produce dust under the high temperature condition,so there is a certain risk.The advantages of low-temperature drying technology are as follows:1.Low thermal energy requirement,flexible and convenient heating mode;2.The whole process is closed to reduce the release of odorous gas.3.The drying process is safe and controllable,and the hidden danger such as explosion can be reduced.This technology can reduce the water content of sludge from 80%to 10%without adding modifier and regulator,and the heat value of dried sludge is high.After the technical scheme of pretreatment and comprehensive utilization was selected,the experiment of brick-making by sludge sintering was carried out in this paper.The content of Si O₂and Al₂O₃ in Meizhou City sludge was high.After drying and mixing with fly ash and clay,the sludge could be used as silica substitute for clay to prepare sintered brick.Two pretreatment methods of tunnel kiln drying and low temperature drying were used to carry out proportioning test,the brick-making experiment of sludge with different ratio of sludge was designed,and the brick-making experiment of low temperature dried sludge with clay,fly ash and other raw materials was conducted,the changes of compressive strength,dry density and plasticity index of brick under different parameters were obtained.The results show that:（1）Except for the high water content of the sludge,the other properties of the sludge basically meet the requirements of the brick-making standard;（2）With the increase of the sludge content,the compressive strength of the brick decreases obviously;（3）The natural state,dry and dried-roasted sludge produce bricks of similar quality to ordinary sintered bricks,but with cracks or uneven surface;（4）When the addition of low-temperature dried sludge is less than 15%,the strength of the sludge fired brick is more than 10MPa,and the indexes basically meet the requirements of the national standard of fired brick.The scheme also relies on the existing brick factories in Meizhou to carry out the industrial test of making bricks from sludge.The technological process is basically as follows:After the sludge is pretreated by drying at low temperature,it is mixed with clay and fly ash,crushed and stirred again after aging and extruded,then it is sent to the tunnel kiln for drying at 110～150°C.The brick was then fired and sintered at a temperature between 1000°C and 1050°C.It is concluded that the mixing amount of sludge（moisture content≤40%）for each brick is about 5%-15%.The quality of sintered brick is stable when the proportion of sludge is about 10-15%.During the test period,the main pollutants in the flue gas were monitored in order to know the situation of pollutant emission.It is expected that the technical scheme proposed in this paper can solve the problem of sludge disposal in Meizhou while maximizing the use of resources and achieving certain environmental and social economic benefits.