Preparation Of High-efficiency Sludge Dewatering Conditioner From Municipal Sludge And Its Application In Sludge Press Filter Dewatering

A large amount of municipal sludge will be generated during urban sewage treatment.The more significant the amount of urban sewage treated,the more sludge will be produced.It is estimated that the annual domestic production of sludge will exceed 90 million tons in 2025.There is a serious"heavy water and light mud"phenomenon in China,so sludge reduction and resource utilization are imminent.The deep dewatering of sludge is a technical problem that needs to be solved first in the field of sludge resource utilization.At present,the more realistic and feasible way of deep sludge dewatering is"sludge conditioning+mechanical dewatering".In this paper,municipal sludge is used as the main raw material,and sludge charcoal and high-efficiency sludge dewatering conditioner are prepared by the pyrolysis method.Sludge dewatering conditioner improves the dewatering effect of municipal sludge,its influencing factors,and its mechanism,The application of high-efficiency sludge dewatering conditioner in sludge press dewatering is studied.Conclusion as below:The sludge charcoal was prepared by the method of municipal sludge pyrolysis.The results showed that the yield of sludge charcoal（received base）at higher temperature was lower than that of low-temperature sludge charcoal;if the pyrolysis temperature was the same,the sludge pyrolysis.The longer the time,the lower the yield of sludge charcoal;the volatile content(V_ad)of sludge charcoal decreases with the increase of pyrolysis temperature and pyrolysis time,while the ash content(A_ad)is fixed.The changing trend of carbon content(C_ad)is the opposite;in the process of urban sludge pyrolysis,the hydrophilicity of sludge char is weakened,and the aromaticity is enhanced.The calorific value of sludge charcoal increased first and then decreased with the increase of pyrolysis temperature.The p H value of sludge charcoal increased with the increase of pyrolysis temperature,all of which were alkaline;the specific surface area of sludge charcoal showed a trend of first increasing and then decreasing with the increase of temperature.The effects of sludge conditioning and vacuum filtration dehydration were studied by using sludge charcoal under different pyrolysis conditions as a sludge dewatering conditioner.The results show that:SC400（pyrolysis condition is 400℃,30 min,particle size is 75～180μm）is a good sludge conditioner with a good conditioning effect;and when the addition amount of SC400 is 4 g/When 100 m L of sludge（water content 98%）was used,the water content,sludge specific resistance and dehydration time of the filter cake after vacuum filtration and dehydration decreased from 73.6%,1.561×10¹³ m/kg,and 510 s of the original sludge,respectively.55.87%,9.54×10¹¹ m/kg,82 s after conditioning and dehydration.However,the absolute value of the Zeta potential of sludge was only reduced by 4.2 m V,and the degree of reduction was limited.Considering that the physical conditioning agent alone may not be able to achieve the optimal conditioning effect,a method of using chemical conditioning agents in combination is sought to achieve the best dewatering performance of the sludge.A high-efficiency sludge dewatering conditioner RO-Ⅲwas prepared by the mixed pyrolysis of municipal sludge and metal compound M⁺to reduce the Zeta potential of sludge significantly.Studies have shown that when the particle size of RO-Ⅲis 75～180 um,and the addition amount is 2 g/100 m L of sludge（water content 98%）,it has a significant effect on the conditioning and vacuum filtration dehydration of urban sludge.The filter cake’s moisture content,sludge-specific resistance,and dehydration time after vacuum filtration and dehydration were 59.28%,7.21×10¹¹ m/kg,and 50 s,respectively;the absolute value of Zeta potential decreased by 8.01 m V.Using RO-Ⅲto quench and temper urban sludge and dewater by mechanical filtration,the results show that:under the conditions of RO-Ⅲaddition of 4 g/100 m L of sludge（water content 95%）and filtration pressure of 0.78 MPa,the water content of the cement cake removed by mechanical pressure filtration of municipal sludge decreased from 65.81%before conditioning to 34.8%after conditioning;and the calorific value of the pressure filter cake increased from 3.98 MJ/kg before treatment to 3.98 MJ/kg after treatment.9.54 MJ/kg,which can be directly incinerated for power generation,and at the same time realize efficient resource utilization of urban sludge.