Zeolite Cast Plus Type Sbr Denitrification Process Real-time Control Parameters

Nitrification efficiency could be markedly enhanced when zeolite being added into biological wastewater treatment systems in many previous studies.This study concentrated on two kinds of hybrid sequencing batch reactors(SBRs) with natural zeolite and artificial zeolite added,respectively.Synthetic,domestic,and phenol-containing wastewaters were treated and the system performances were studied.A real-time control model was firstly put forward to optimize the SBRs operation,and cost analyses were carried out for both reactors under real-time control conditions.This study especially focused on developing promising options for the upgrade of wastewater treatment facilities with nitrogen removal being considered.In static adsorption experiments of synthetic wastewater,ammonia nitrogen adsorption by natural zeolite or artificial zeolite was found to well fit the Freundlich and Langmuir isotherms, especially the latter one.The static saturated adsorption capacities for natural zeolite and artificial zeolite were 8.21 mg g^-1 and 17.92 mg g^-l,respectively,which was affected by adsorption time, NH_3-N concentration,zeolite concentration,pH,and temperature.In the static adsorption experiments of domestic wastewater,natural zeolite showed less adsorption capacity for COD while no COD adsorption effect was observed for artificial zeolite,and both of them have little TP adsorption capacities.A real-time control model for optimization of aeration time in zeolite added SBR(zeo-SBR) was set up,which could be applied to the treatment of synthetic,domestic and phenol-containing wastewaters.Under real-time control conditions,in which dDO/dt and dORP/dt were adopted as indicators of COD degradation while dpH/dt as an indicator of nitrification,COD removal rates and NH_3-N removal rates in zeo-SBR remained above 92%and 99%,respectively,when influent COD being 300-800 mg L^-1 and NH_3-N 15-60 mg L^-1.Based on an additional batch experiment,a real-time control model was also put forward with pH as an indicator of denitrification for optimization of anoxic time.No obvious difference was observed in pollutant removal rates between control SBR and zeo-SBR.However,zeo-SBR exhibited a higher specific nitrification rate and a shorter hydraulic retention time(HRT),compared to control SBR.With low zeolite dosed,the nitrification in zeo-SBR was enhanced:a large amount of NH₄⁺ adsorded to the surface of zeolite,which created a better living environment for nitrifiers,thus improved their nitrification activities.Temperature and phenol concentration affected nitrification rate significantly.When temperature varied between 8-13℃,nitrogen could not be effectively removed in zeo-SBR.Carbon source addition was an effective remedy to increase nitrogen removal via assimilation,which made the effluent water quality meet the discharge standard I(A) of GB18918-2002.Phenol was toxic to nitrifiers in zeo-SBR,and pH and alkalinity should be carefully monitored when phenol-containing wastewater being treated.Cost analysis showed that artificial zeolite was expensive and could only be applied in model investigations.When encountered with influent of high NH_3-N concentration,SBR with natural zeolite added(Nzeo-SBR) turned to be a promising reactor with lower operation cost and shorter operation duration.Under the condition of low NH_3-N concentration,although no obvious advantage in cost,Nzeo-SBR was still an effective option for the upgrade of wastewater treatment system when nitrogen removal needed for improvement,as operation duration was significantly shortened.