Study of nitrogen removal from micro-polluted surface water by the sulfur-iron autotrophic denitrification CRI

China Daihai Ecological Water Replenishment Project adopts Yellow River water as the water replenishment source, which belongs to the micro-polluted surface water with the water quality characteristics of low carbon to nitrogen ratio and high DO, and there is the problem of exceeding the standard of TN with NO_3-N as the main pollution characteristic. In this study, for this kind of micro-polluted surface water, three sulfur-iron autotrophic denitrification CRI with different packing materials were used to carry out a comparative experimental study on the effect of nitrogen removal. The results showed that the CRI with the mass ratio of zeolite: sulfur: sponge iron: coconut shell activated carbon=1:2:1:1 as the filler (loading thickness of 90 cm) had the strongest removal ability of NO3-N and TN in the micro-polluted surface water, with an average removal rate of 94.66% and 79.01%, and the TN purified by this CRI met the target water quality requirements of class V water of surface water. The research results can provide a new reference for nitrogen removal technology for micro-polluted surface water used as a recharge water source in ecological recharge projects.