Study On Enhanced Sludge Dewaterability Using Iron Powder-Peroxymonosulfate Combined With Straw

With the development of sewage treatment systems,the output of sludge has increased significantly,and activated sludge has a high moisture content as the residue of wastewater treatment.In order to maintain the continuous operation of the sewage treatment plant and further reduce the environmental burden,an effective sludge dewatering method is urgently needed.Persulfate advanced oxidation process has attracted more and more scholars'attention due to its high performance.In this study,stable and recyclable zero-valent iron?Fe⁰?was selected as an activator to activate peroxymonosulfate?PMS?,which in turn produced a sulfate free radical?SO₄^?·?with strong oxidative capacity to destroy extracellular polymerization substances?EPS?and release intracellular material.However,in the high-pressure dehydration process,the pores of the sludge filter cake were easily closed,which would reduce the sludge filterability.Therefore,the waste straw?WS?was used as a filter aid to improve the compression performance of the sludge.The combination of chemical conditioners and physical methods was used to adjust the sludge deep dewatering.The specific resistance to filterability?SRF?and water content?Wc?were used to characterize the dewatering performance of sludge.Under the best measurement,Wc and SRF were significantly reduced.Zeta potential,particle size distribution,three-dimension excitation emission matrix?3D-EEM?,combined with bound water content and scanning electron microscope?SEM?and other methods were used to explore iron powder activated peroxymonosulfate combined with straw?Fe⁰+PMS+WS?to improve synergy mechanism of sludge dewatering performance,and paid attention to the subsequent treatment and disposal of sludge.The main research contents and conclusions are as follows:Determination of optimal dose of conditioner by Single-factor Dosage Experiment.After pretreatment,Wc decreased to 73.24%,and SRF decreased from 16.5±0.3×10¹²m changed the sludge from electronegativity to neutral.After layered treatment of EPS,the cracking mechanism of sludge is reflected by changes in the content of protein and polysaccharide and the three-dimensional fluorescence intensity.The process of sludge particle size changing from small to large better revealed synergy.SEM and optical microscopy results clearly show that the combination of Fe⁰+PMS+WS formed a more porous sludge cake structure.The compression coefficient showed that the addition of straw formed a skeleton structure and improved the permeability of the sludge filter cake.The bound water content was reduced from 3.17±0.1g/g TSS to 0.28±0.2 g/g TSS by differential scanning calorimeter?DSC?and thermogravimetric analyzer?TGA?.Fe⁰+PMS and WS can give full play to their respective advantages.The recycling and reuse of iron powder and the addition of straw can increase the heat value of sludge,and can effectively accelerate the dehydration capacity of sludge cake under air drying.After 12 hours in the open air,the water content of the sludge cake dropped to 25%,and the low heating value increased significantly,which was beneficial to the sludge incineration disposal.Economic analysis revealed the development potential of the technology.