Denitrification and phosphorus removal performance of salt-containing food industry wastewater
In order to study the nitrogen and phosphorus removal performance of salt-containing food industry wastewater,the different doses of salinity were introduced into the food industry wastewater treatment system and the mode of operation was selected as anaerobic/anoxic/aerobic(A/A/O).The variation of different indicators including chemical oxygen demand(COD),NH4+-N,NO2--N,NO3--N,PO43--P were analyzed,and the influence mechanism about different concentrations of salinity on the nitrogen and phosphorus removal performance for the food industry wastewater was revealed combining with sludge properties and functional microorganisms.The results showed that the introduced salinity not only improved the COD degradation with the value increasing from 84.08%to 90.33%,but also improved phosphorus release of phosphorus removing bacteria and nitrification.The efficiency of NH+4-N increased from 95.79%to 98.85%.However,it restrained the absorption phosphorus of phosphorus removing bacteria in aerobic phase.The denitrification performance was enhanced under low salinity(0.5 g/L)condition,but was decreased when the salinity increased to 3.0 g/L.The extracellular polymeric substance(EPS)increased with salinity and the EPS was 38.81 mg/g volatile suspended solid(VSS)under the 3.0 g/L salinity condition.The introduced salinity increased the relative abundance of microbial community and changed its structure,which enhanced denitrifying bacteria enrichment including Chloroflexi、Actinobacteriota and Planctomy-cetota.It was also found that salinity increased the abundance of Caldilineaceae、Ferruginibacter and Kouleothrix but restrained the abundance of Candidatus_Competibacter.All of them guaranteed the stable nitrogen and phos-phorus removal of treatment system.
salinityfood industry wastewaterdenitrification and phosphorus removalextracellular polymeric substancefunction microbial
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