The Study On Utilization Of The Urban Sewage Sludge In The Process Of Production Of Building Material

This thesis is focused on how to carry out dehydration and recycling of the sewage sludge. Some industrial solid wastes (such as fly ash and powered lime) have been used as the additives, which can improve the effect of dehydration. At the same time, the mixture after dehydration process can be made into building materials. Thus, this recycling process of sewage sludge is combined with conventional dehydration process, which has a lot of advantages, such as lower cost, waste co-reutilization process, and so on.Considering the utilization of the remain sludge, we study the basic characteristic of remain concentrated sludge which was immediately retaken from sewage plant, including the moisture content of water, dewatering performance(specific resistance), composition of volatilization, loss of ignition, composition of the inorganic chemistry, crystalloid composition of the mineral, composition and content of heavy metals, carloric value and so on.Aiming at the key difficult problem in the process of sewage sludge treatment, we pay much attention to the experimention on how to improve the dewatering performance of the sludge, the effect of the dosage of fly ash and powered lime on sludge dewatering is analyzed. Experiment result shows that dewatering performance of sludge could be improved by adding fly ash or powered lime, and it could be improved by adding powered lime better than by adding fly ash. With the experiment on combined use, we found out the best coagulant for sludge treatment, and further more, the best proportion for this two additives were found through the experiment. The result shows that the specific resistance of sludge could be reduced from 10~9s~2/g to 10~6s~2/g and the moisture content of the could be decrease from 83.14% to about 50% in mixture cake by adding fly ash and powered lime, and sequentially freezing and thawing on pilot plant scale. The cost of this treatment is much lower than that of using macromolecule organic flocculation. After dehydration process, sludge cake could be used in the process of production of building materials, for example, autoclaved brick and fired brick technics, by adding other building materials. With comprehensive and orthogonal experimention, performance of the building materials were compared, experiment shows that the compressive strength could attain to 12.2Mpa, flexural strength could attain to 2.5 Mpa, live up to the performance of steamed lime-sand bricks the requirement of GB11945-1999"Autoclaved lime-sand brick", when sludge cake dehydrated in the discussed above, was mixed with stone, powered lime, fly ash and cement in proportion, controlling the moisture content of the mixture properly. The cost of a standard brick is below the price of 0.18 yuan.