Research On Sludge Conditioning And Mechanical Dewatering

Sludge is the solid waste produced in the process of sewage water treatment,it's an important way that sludge is conditioned for improving the performance of sludge dewatering and decreasing the content of sludge moisture,which has significance for realizing sludge reduction and recycling.The main factors influencing sludge conditioning for mechanical dewatering were explored in this paper,and the conclusions are as follows:The factors influencing sludge conditioning by the addition of semi-coke for mechanical dewatering were explored using the vacuum dehydration experiments.The mechanism behind sludge conditioning and mechanical dewatering based on semi-coke was revealed by a set of analytical techniques,including the specific resistance of sludge(SRF)test,Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM)and Zeta potential test analysis.The results show that when the particle size of semi-coke derived from the pyrolysis of Yunnan brown coal under 500 centigrade was from 75-200 ?m and 1.5g semi-coke·(100mL)-1 sludge(water content is 98.49 %)was added,the water content decreased from76.02 % to 61.14 %,the dehydration time decreased from 124 s to,75 s.These findings proved that semi-coke has a significant effect on sludge conditioning for mechanical dewatering.There is a apparent correlation between the water content of mechanical dewatering sludge and the quality parameters of semi-coke(O/C,H/C,specific surface area and pore volume).The mechanism could be explained by the improved dewatering performance and reduced the absolute value of zeta potential and the weakened hydrophilic properties of sludge conditioned by semi-coke and the adsorption of sludge on the semi-coke.Sludge conditioning by the addition chemical conditioners for mechanical dewatering was researched using the vacuum dehydration experiment.The PAFC and PAC can greatly improve the performance of activated sludge dewatering,which lead to less content of activated sludge moisture after mechanical dewatering.When adding 0.03 g PAFC combined with 1mL CPAM in 100 mL activated sludge(water content is 97%)for conditioning,the moisture content of activated sludge cake from its mechanical dewatering was the lowest,when adding 0.06 g PAC combined with 3mL CPAM in 100 mL activated sludge(water content is 97 %)for conditioning,the activated sludge have less SRF and the minimum dehydration time.But for the digested sludge,the Fe Cl3 can greatly improve the performanceof sludge dewatering,which lead to less content of digested sludge moisture after mechanical dewatering.When adding 1.2g Fe Cl3 combined with 5m L CPAM in 100 mL digested sludge(water content is 90.5%)for conditioning,the moisture content of digested sludge cake from its mechanical dewatering was the lowest,when adding 1.5g FeCl3 combined with 15 mL CPAM in 100 mL digested sludge(water content is 90.5%)for conditioning,the sludge have less SRF and the minimum dehydration time.Effect of the pyrolysis products of sludge——sewage sludge biochar(SSBC)on sludge conditioning for mechenical dewatering was investigated by the vacuum dehydration experiment method.Results show that,the sludge-sewage sludge biochar can not only improve the dewatering performance,also can enhance the calorific value of sludge;when the particle size of SSBC was under 75 ?m and 2.0 g·(100 mL)-1 sludge(water content is 98.49 %)was added,effect of the sludge conditioning for mechanical dewatering is good.Comparative tests showed that SSBC is a kind of good sludge conditioner for the sludge conditioning and mechanical dewatering.The effects of pH and temperature on sludge conditioning for mechanical dewatering were explored by regulate and control pH and temperature of the sludge.The results show that the effect of sludge conditioning and mechanical dewatering was better when the sludge is weak acid,and dewatering performance was poorer with the increase of sludge alkalinity.The effect of FeCl3 on sludge conditioning and mechanical dewatering is less related with pH(when the pH between 6.5 and 8.5)of the sludge.For SC500 and FeCl3,higher of the temperature,more better of the effect of sludge conditioning and mechanical dewatering,for PFS,when the sludge temperature was 40 ?,the effect of sludge conditioning and mechanical dewatering is better.