Study On Sludge Conditioning Process Of Two-phase Baffled Bioleaching Reactor

In recent years,bioleaching has been widely applied for sludge conditioning in municipal wastewater treatment plants.However,the higher concentration of dissolved organic matter?DOM?inhibits the activity of Acidithiobacillus ferrooxidans?A.f?in bioleaching,which causes a long leaching period and a high cost.In order to alleviate the toxic effect of DOM on A.f,in this study a novel baffled bioreactor?two-phase,acidification phase and leaching phase?was designed and used to carry out the following research:?1?investigating the effect of using this reactor on the process of sludge conditioning;?2?investigating the effects of two parameters?reflux ratio of sludge,addition of energy substances FeSO₄·7H₂O?on sludge conditioning process of bioleaching reactor.?1?Reactors in three different operating modes,which were divided into phase-separated four compartments bioreactor?the first compartment was the acidification phase,and the second to the fourth compartments were the leaching phase?,non-phase-separated four compartments bioreactor?the first to fourth compartments were leaching phase?,and non-phase-separated three compartments bioreactor?the first to third compartments were leaching phase?,investigating the effect of different operation modes on the sludge properties and microbial community distribution in each compartment.The results showed that the phase separation treatment was beneficial to improve the dewatering performance of the sludge and maintain the reactor's long-term operation.Compared with non-phase-separated treatment,the start-up time of phase-separated treatment was significantly shortened by 3 days,dehydration performance was increased by 14.2%,solvability chemical oxygen demand?SCOD?concentration was decreased by 26.8%?30.4%,the relative abundance of A.f in each compartment increased significantly,with the largest increase in the fourth compartment,14.4%?50.0%.The specific resistance to filtration?SRF?,capillary sunction time?CST?,SCOD,and Zeta potential of the sludge after phase separation treatment were 0.12?10¹³ m/kg,9.7 s,98.0 mg/L,and-2.7 mV,which were 96.9%,69.2%,84.2%,and 82.5%lower than the original sludge,respectively.?2?Using two-phase baffled bioleaching as the reactor configuration?phase-separated four compartments?,investigating the effects of three different reflux ratios?15.0%in the first compartment,and 10.0%in second compartment;25.0%in the first compartment;40.0%in the first compartment?on the sludge conditioning process of using this reactor were studied.The results showed that with the increase of the reflux ratio of the first compartment,the start-up time of the reactor was shortened and then basically unchanged,the CST decreases slowly,and the SCOD concentration rises slowly,the suitable reflux ratio in this study was 25.0?40.0%.Compared with the first compartment reflux ratio of 15.0%,the start-up time was reduced by 4 d at the first compartment reflux ratio of 25.0%,the CST was reduced by 10.2%,and the SCOD concentration was increased by 5.9%;compared with the first compartment reflux ratio of 40.0%,the operating cycle was the same at the first compartment reflux ratio of 25.0%,the CST was increased by 4.2%,and the SCOD concentration was reduced by 3.1%.When the first compartment reflux ratio was 25.0%,the SRF,CST,SCOD,and Zeta potential of the treated sludge were 0.10?10¹³ m/kg,12.3 s,196.7mg/L,and-1.1 mV,respectively,which were 96.0%,75.8%,52.7%,and 92.5%lower than the original sludge,respectively.?3?Using two-phase baffled bioleaching as the reactor configuration?phase-separated four compartments?,investigating the influence of the dosage of energy material FeSO₄·7H₂O?2,6,10 g/L?on the sludge conditioning process of using this reactor was studied.The results showed that with the increase of the dosage,the start-up time of the reactor was gradually shortened,the CST first decreases and then slowly rises,and the SCOD concentration gradually rises.The appropriate dosage in this study was 6?10 g/L.Compared with the dosage of 6,10 g/L,the acidification process could not be completed when the dosage was 2 g/L;compared with the dosage of 10 g/L,the start-up time was increased by 2 days at the dosage was6 g/L,CST was reduced by 9.3%,and SCOD concentration was decreased by 12.0%.When the the dosage was 6 g/L,the SRF,CST,SCOD,and Zeta potential of the treated sludge were 0.13?10¹³ m/kg,14.7 s,203.2 mg/L,and-1.9 mV,which were94.8%,71.1%,51.1%,and 87.0%lower than the original sludge,respectively.