Study On The Preparation And Properties Of Environment-friendly Fired Permeable Brick Based On Sludge And Alternanthera Philoxeroides

With the acceleration of urbanization in China,the yield of municipal sludge increases rapidly with the increase of the number of sewage treatment plants,and the problem of how to dispose of sludge efficiently and reasonably is becoming more and more obvious.In addition,urbanization also leads to more and more ground covered by impervious materials,which makes urban waterlogging occur frequently.As a highly permeable pavement material,permeable brick can effectively alleviate the above problems.In this paper,sludge and A.philoxeroides were used as pore-forming agent,and then mixed with clay,the environment-friendly fired permeable brick was made by high temperature sintering,then tested for purifying the polluted water.The conclusions are as follows:(1)Through the analysis of the basic physical and chemical properties of sludge,A.philoxeroides and clay,it can be concluded that the chemical composition of sludge is similar to that of clay,so it could be used to prepare permeable brick.Sludge and A.philoxeroides have a high content of organic matter and burn out at high temperature,so they can be used as pore-forming agents for fired permeable bricks,which can significantly increase the permeability coefficient,but the maximum addition should not exceed 40%and 12%,respectively.(2)The preparation process of fired permeable brick was optimized by the response surface method.When the addition amount of sludge is 39.50%,the amount of A.philoxeroides is 11.90%,the sintering temperature is 1045℃and the sintering time is 75 min,the water permeability of the fired permeable brick is(1.21±0.03)×10-2 cm/s,the compressive strength is 10.9 MPa,the water absorption is 38.33%,the porosity is 43.12%,and the water retention is 0.71 g/cm2,which meets the requirements of JC/T 945-2005 and GB 51012003;the leaching concentration of heavy metals conforms to the relevant national standards.(3)The fired permeable brick could remove COD effectively,and the removal rate is 74.20%after 24 h.The removal capacity of NH4+-N is lower,with a removal rate of 56.33%after 24 h.When TP is treated by sintered permeable brick,because the phosphorus dissolution rate in the brick is greater than the removal rate,the TP concentration increases at first,then decreases,and finally in dynamic equilibrium.When the fired permeable brick is used to treat sewage,the phosphorus of brick will be dissolved,resulting in the acidity of the water and affecting its ability to remove pollutants.