| With the accelerating process of the construction of municipal services facilities in China, the production of sludge also significantly increased as the increasement of sewage production. Surplus sludge has high moisture content and organic matter content. It contains a great quantity of pollutants and leads to high levels of environmental risks. How to properly deal with the large number of excess sludge, making it quantitative reduction, stabilization, harmless and resourceful is the urgent problem of our country and the world.In this study, laboratory experiments were carried out to investigate the potential of hot acid hydrolysis as a combined sludge pretreatment, which could not only improve excess sludge dewaterability but also solubilize sludge solids. The effect of hydrolysis temperature, pH value, and reaction time on dewatering performance and solubilization of cellular effects were discussed. And from the point of the bound water, EPS content analyzed the mechanism of hot acid hydrolysis improve sludge dewatering performance. And from the point of variation of SCOD, TCOD, ammonia nitrogen and total nitrogen content discussed the mechanism of the effect of hot acid treatment on sludge disintegration.To decrease the production of surplus sludge is as important as improving its performance in dehydration. Hot acid hydrolysis, as the pretreatment methods for the sludge’s mechanical dewatering, can effectively solve this problem. Bound water is the upper limit of the sludge’s mchanical dewatering, its core problem is how to get rid of the bound water as much as possible. The study found that extracellular polymer substance have fallen off from the surface of cell and the bound water wrapped by the extracellular polymers is released. In the while,microbial cells expand, rupture and collapse when is heated,the bound water inside of the cell is released.In the environment of acidity,groups such as carboxyl, its hydrophobicity have been enhanced and reduced the adsorption ability for water molecules. The distribution of water in sludge has changed. Based on the above three reasons, the content of bound water in sludge greatly reduced.This paper studys the impact of hot acid pretreatment sludge dewatering performance. The research results showed that the sludge’s degree of dehydration has increased with the increasing of hydrolysis temperature. Bound water content in the original mud up to11.21g/g ds, On the condition of170℃reaction temperature, pH value of2and60min reaction time, the content of bound water h dropped to7.07g/g ds, its content was reduced by36.93%. After centrifugal dehydration, the content of water in sludge has dropped to55.65%and reduced30.45%compared with the datum before heat hydrolysis.This experiment has researched the influence of hot acid hydrolysis conditions on the effect of excess activated sludge. The content of SCOD can characterization the effect of the hot acid hydrolysis on excess sludge. The results showd that the hot acid hydrolysis is effective on sludge crack. Adding acid has weakened the resistance of microbial cell wall to high temperature. The degree of cell disruption has deepened, the release of organic matter and hydrolysis in the cell of surplus sludge aggravated. The consistence of SCOD is rising.Through the orthogonal test, this experiment analysised the influence degree of hot acid hydrolysis conditions parameters to sludge hydrolysis and the result is: hydrolysis temperature, pH, reaction time.besides,this research has established the hot acid hydrolysis dynamic model by9group date gotten from the orthogonal test. |
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