Effect Of Carbon Materials On Sludge Electro-Osmotic Dewatering And Its Performance

In this paper,the municipal sludge were treated by four kinds of carbon materials?AC-0,AC-1,AC-2 and graphite?,the effect of carbon materials on electro-dewatering and properties of sludge was studied.The effects of carbon materials on the physical and chemical properties of municipal sludge,the content of extracellular polymeric substances?EPS?and the efficiency of electro-dewatering were analyzed with emphasis.On the basis of this,the fuel utilization of sludge cake was discussed,which was of great significance to the utilization of sludge in the later stage.The sludge dewatering performance were tested by capillary suction time?CST?,Ma Erwen laser particle size and viscometer.The effects EPS conditioned by carbon materials were investigated with three-dimensional fluorescence spectroscopy?3D-EEM?and high performance size exclusion chromatography?HPSEC?.The microstructure and thermal properties of sludge cake were studied by BET,SEM,laser scanning confocal microscopy?LSCM?,TG-DTG.The results showed that the carbon materials promote the performance of sludge electro-dewatering,and the dewatering performance of sludge was improved better by carbon material?AC-2?with high adsorption capacity.The CST_n of raw sludge was 2.6s·L·g^-1 and the particle size of floc was 40.862?m.When the dosage of AC-2 was 20%g/gTSS,the CST_n was 1.54 s·L·g^-11 and the particle size of floc was 39.346?m.The removal order of S-EPS was AC-2>AC-1>AC-0>graphite,and the removal effect of carbon materials on macromolecular components in soluble EPS?S-EPS?was limited.The electro-osmotic dewatering experiment showed that the carbon material can effectively improve the sludge dewatering rate,the current increased with the addition of carbon material,and the maximum current increased 0.43 A when the dosage of graphite was increased to 14%g/gTSS.The analysis of the content and composition of the filtrate showed that the carbon material can effectively adsorb DOM,in the filtrate and lead to the decrease of DOM content.Fluorescence analysis showed that the fluorescent substance of protein in sludge decreased obviously.The molecular weight distribution of cathode and anode filtrate was different,and the molecular weight component of cathode was richer than that of anode.The pore volume of the cathode and anode sludge were 0.1219 cm³·g^-1,0.0837 cm³·g^-1,respectively with the addition of AC-2.The difference of pore volume between cathode and anode sludge cake reached the maximum.The analysis of sludge cake showed that the moisture content decreased to less than 50%,and the energy consumption required to separate from each mass of water decreased with the addition of carbon materials.The calorific value of sludge cake was increased by the treatment of sludge with carbon materials,the calorific value increased from 14.52 MJ·kg^-1 to 15.74MJ·kg^-1 with the addition of 20%g/gTSS AC-2,and the sustainable combustion time also increased.The protein and polysaccharide in cathode sludge cake were decomposed.