Efficient treatment of swine farm wastewater using a combined SBR and Chlorella bioreactor
Swine farm wastewater is a significant component of agricultural wastewater.In this study,we aimed to establish a combined sequencing batch reactor(SBR)and Chlorella bioreactor for efficient treatment of swine farm wastewater to meet discharge standards.We compared the degradation efficiency of activated sludge from three wastewater treatment plants,determined the optimal treatment conditions for the SBR process,and conducted full-scale purification of SBR effluent using Chlorella sp.FACHB-9.Response surface experiments,microbial community structure analysis,and swine farm wastewater degradation experiments were conducted to identify optimal operating conditions for the SBR process and to observe microbial composition changes before and after activated sludge domestication.The SBR process achieved the highest total nitrogen(TN)removal rate(70.22％)when using activated sludge from the Hanxi Wastewater Treatment Plant,with mixed liquid suspended solids(MLSS)at 5 082 mg/L,aeration start-stop time of 6.5 h∶1.5 h,and a temperature of 27.7 ℃.Microbial community structure analysis showed increases in Pseudomonas,Peptostreptococcus,and Nitrospira populations during domestication,accounting for 13.98％,10.79％,and 6.26％during the SBR stabilization period,respectively.Stable concentrations of chemical oxygen demand(COD)and NH4+-N in the SBR effluent were 31 and 3.5 mg/L,respectively.After cultivation with Chlorella sp.FACHB-9,NH4+-N,TN,and total phosphorus(TP)concentrations in the final effluent were significantly reduced to 0.5,1.5,and 0.23 mg/L,respectively,with an algal protein yield of 0.111 g/L.The concentration of fecal coliforms in the final effluent was 9 143 MPN/L,meeting Class Ⅴ of the Environmental Quality Standards for Surface Water(GB 3838-2002).The SBR process effectively eliminated NH4+-N and COD from swine farm wastewater and Chlorella sp.FACHB-9 efficiently removed residual nitrogen and phosphorus while producing valuable algal proteins.This combined process presents an excellent opportunity to recycle farm wastewater.
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