Experimental Study on Treating and Recycling of Steel Rolling Wastewater by Constructed Wetland Enhanced with Sulfur Autotrophic Denitrification

摘要

A series of ordinary constructed horizontal subsurface flow wetland devices (HF(ord)) and constructed wetland enhanced with sulfur autotrophic denitrification (HFsad) were built and utilized to treat steel rolling wastewater with low organic carbon, exploring the feasibility of applying sulfur autotrophic denitrification technology to enhance denitrification capacity of constructed wetlands. Results showed that HF_(ord) had a good performance on removing turbidity, DO, COD and TP of steel rolling wastewater but unsatisfying effect on nitrogen pollutants removal. The average removal rate of TN in HF_(ord) was 25.2%, but on this basis, HFsad could remove 45.0% of TN contaminants subsequently, contributing to an average TN removal rate of 58.0%, with about 5 times the denitrification capacity equivalent to HF_(ord). The analysis result of microbial communitv structure and observation results of fillers and monitored sulfate both provided proofs for the occurrence of sulfur autotrophic denitrification. Therefore, constructed wetlands combined with sulfur autotrophic denitrification can be applied in the treatment of steel rolling wastewater with low C/N ratio, with better reuse feasibility in processes of steel and iron production, reducing emitted pollutants and water consumption, which can provide a new technical route for ecological wastewater treatment and water recycling in iron and steel industry.