Study On The Dewatering Effect And Mechanism Of Mineral Fenton-like Advanced Oxidizing Sludge Dewatering Agent

In the traditional“sludge concentration-chemical conditioning-Sludge mechanical dewatering”treatment process,the moisture content of the sludge is only reduced to about80%,has been unable to meet the increasingly stringent sludge disposal requirements.It must make sludge cake moisture content dropped to below 60%or less by deep dewatering of sludge.However,there are some problems in the traditional sludge dewatering agent,which makes it one of the hotspots to study the new high efficiency sludge dewatering agent.As a multi-functional material,montmorillonite is widely used in the field of environmental protection.In this study,montmorillonite?MMT?was used as the sludge floc skeleton.Through modification,two kinds of mineral sludge dewatering agents were developed:MMT-nanoZnO₂ and H₂O₂/MMT-CTAB₂.The following results are obtained by the material characterization analysis and the experiment of sludge dewatering experiment.?1?Mixing H₂O₂.with montmorillonite modified by zinc ion to synthetize the MMT-nanoZnO₂,Through analysis and characterization,it is proved that the materials has synthetized Successfully.Moveover,it is proved by hydroxyl radicals test that the MMT-nanoZnO₂ can produce hydroxyl radicals under the condition of weak acid without ferric salt.While dosing 0.2 g/gDS Under the condition of pH=4,the experimental study of sludge showed that Fenton reaction has the highest activity of MMT-nanoZnO₂,has the best performance of sludge dewatering.Sludge SRF,CST and the moisture content of the cake respectively from the original 7.19×10¹² cm/g,65 s and 88.53%down to 8.31×10¹¹ cm/g,17 s and 76.35%,Protein?PN?and polysaccharide?PS?content of LB-EPS from the original sludge 709.5 mg/L and 108 mg/L reduce to 295 mg/L and 25 mg/L.The sludge dewatering performance improved significantly in the flocs skeleton function of MMT and Fenton oxidation reaction of MMT-nano ZnO₂ in weak acid environment.Therefore,MMT-nanoZnO₂can be used as environmental friendly and high-efficiency sludge dewatering agent.?2?MMT-CTAB₂,the material that MMT modified 2 times the cation exchange capacity?CEC?of CTAB has the best effect of sludge Zeta improvement,sludge floc size enlargement and SRF reducing,When adding amount of 0.3 g/gDS,Zeta potential and sludge floc size can increases from-15.9 mv and 3.6?m to-3.5 mv and 79.5?m respectively,at the same time,sludge SRF can reduce from 6.40×10¹² cm/g to 2.98×10¹² cm/g at the dosage of 0.1g/gDS.After hydroxyl radicals tests,the MMT-CTAB₂ still have the function of catalyzing hydroxyl radical from H₂O₂.While dosing 0.1 g/gDS MMT-CTAB₂ and 2 mmol/gDS H₂O₂Under the condition of p H=4,the experimental study of sludge showed that Fenton reaction has the highest activity H₂O₂/MMT-CTAB₂,has the best performance of sludge dewatering.Sludge SRF,CST and the moisture content of the cake respectively from the original 6.40×10¹² cm/g,64 s and 87.88%down to 7.32×10¹¹ cm/g,15 s and 74.19%,Protein?PN?and polysaccharide?PS?content of LB-EPS from the original 679.3 mg/L and 102 mg/L reduce to291.4mg/L and 23 mg/L.H₂O₂/MMT-CTAB₂ improve sludge dewatering performance mainly through improving the structure of the sludge and the degradation of sludge EPS.Therefore,H₂O₂/MMT-CTAB₂ can be used as environmental friendly and high-efficiency sludge dewatering agent.?3?In order to prove the effectiveness and wide applicability of the two kinds of agents and wide applicability,two different sludge cake moisture content was determined after adding conditioners.the results show that the cake moisture of sludge?the value of VSS/TSS about 35%?can ruduce from around 81.5%to 72.69%and 69.76%respectlly after dosing MMT-nanoZnO₂?0.05 g/gDS?and?1 mmol/gDS?H₂O₂/?0.1 g/gDS?MMT-CTAB₂,making it lower than 78.5%via PAM,and the cake moisture of sludge?the value of VSS/TSS about45%?can ruduce from around 83.9%to 73.61%and 70.56%respectlly after dosing MMT-nanoZnO₂?0.1 g/gDS?and?2 mmol/gDS?H₂O₂/?0.1 g/gDS?MMT-CTAB₂,making it lower than 79.7%via PAM.Therefore,MMT-nanoZnO₂ and H₂O₂/MMT-CTAB₂ have a wide range of applicability while having high dehydration performance.