Nitrogen removal of wastewater with low C/N ratio by straw and steel slag mixed fillers
To investigate the impact of crop straw and steel slag on nitrogen removal from low carbon-to-nitrogen ratio(C/N)sewage,this study employed wheat straw(W group),rice straw(R group),wheat straw + steel slag(WF group),and rice straw + steel slag(RF group)as packing materials in an anaerobic circulation system for treating sewage.The effectiveness of these six different packing systems in removing nitrate nitrogen(NO3--N)was evaluated.The results demonstrated that the NO3--N removal rates for the W,R,WF,and RF groups were 94.99%,86.70%,98.75%,and 94.70%respectively.Compared with the WF and RF groups which utilized mixed packings of straw and steel slag,the pure straw packing systems(W and R groups)exhibited higher rates of NO3--N removal but resulted in elevated concentrations of dissolved organic carbon(DOC)during the treatment process.The presence of iron-containing compounds released from the steel slag in both WF and RF groups facilitated organic matter consumption,thereby maintaining a lower DOC concentration level throughout the treatment process to prevent potential secondary pollution caused by high DOC concentration.After comprehensive consideration,the utilization of a wheat straw + steel slag mixed filler could effectively prevent secondary pollution in the process of nitrogen removal while maintaining efficient nitrogen removal,making it more suitable for practical applications in low C/N ratio sewage treatment.
strawsteel slagnitrogen removaldenitrification process
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