Effects Of Chemical And Biological Conditioning On The Dewatering Performance Of Municipal Sludge

With the vigorous development of the economy and the continuous advancement of modernization,the discharge of sewage in the country has increased year by year,and the task of sewage sludge treatment and disposal has been increasing year by year.Municipal sludge has the characteristics of large processing capacity,high water content,pungent odor,poisonous and harmful,etc.It needs to be reduced,harmless and resource-based treatment,and sludge dewatering is the key link of sludge reduction.It has a direct impact on storage,transportation and subsequent processing and disposal.Traditional dehydration methods can only reduce the water content to more than 80%.In recent years,many conditioning methods have been developed at home and abroad to condition the sludge in order to achieve a better dehydration effect.However,there is a lack of research on the mechanism of conditioning agents affecting dehydration performance.This article takes municipal sludge as the object to study the mechanism and ways of chemical and biological conditioning to improve sludge dewatering performance.Firstly,the thesis studies the influence of chemical and biological conditioning on water distribution.Select chemical conditioning agents such as inorganic flocculant FeCl₃,polymer inorganic flocculant PAC,polymer organic flocculant CPAM for individual and compound conditioning,and biological enzyme conditioning agents such as neutral protease and?-amylase for individual and compound conditioning,Use the water content of centrifugal de-cement cake and CST as indicators to evaluate the conditioning effect and determine the optimal concentration of conditioning agent.The low-field nuclear magnetic resonance method was used to test the moisture distribution of sludge before and after conditioning,and through various moisture content and fluidity changes,the path of the conditioning agent to improve the sludge dewatering performance was analyzed.Secondly,a comparative analysis of various conditioner formulations from three aspects:the improvement effect of dehydration performance,the impact on subsequent disposal and the economy,found that:chemical flocculants and biological enzymes can change the moisture distribution of sludge and improve the dewatering ability,And the effect of compound conditioner is better than single conditioner.60 mg/g PAC+1.5mg/g CPAM has the best conditioning effect,which can reduce the water content of the filter cake to 60.77%;80mg/g FeCl₃+1.0 mg/g CPAM is the second,which reduces the water content of the filter cake to 61.21%;1.0 mg/g amylase+1.0 mg/g protease can also reduce the water content to 63.02%.From the perspective of the impact on the subsequent treatment and disposal of sludge,the addition of FeCl₃ will significantly increase the acidity of the sludge after conditioning,which will easily cause corrosion of subsequent treatment equipment and increase the difficulty of subsequent treatment;and the addition of biological enzymes will increase the increase of organic pollutants.From the economic point of view,the dosage of flocculant is large,and the conditioning cost is high;the cost of biological enzyme conditioning is low,but the equipment cost is increased due to the temperature requirements of the enzyme.On the whole,the flocculant conditioning and the biological enzyme conditioning have their own advantages and disadvantages.The PAC+CPAM compound conditioning has the best effect and simple operation.It is a commonly used flocculation formula.However,due to the large dosage of PAC and high conditioning costs,the idea of using biological enzymes and flocculants for compound conditioning is proposed.The introduction of biological enzymes reduces the amount of flocculants and the addition of flocculants makes up for the lack of actual dehydration effect in order to obtain better conditioning effects at a lower cost.