Treatment of artificial secondary effluent for effective nitrogen removal using a combination of corncob carbon source and bamboo charcoal filter

•A new combination of corncob carbon source and bamboo charcoal filter for effective nitrogen removal was successfully implemented.•Use of corncobs as a new solid carbon source facilitates recycling of an agricultural waste that is extensively available.•Bamboo charcoal is an ideal filter material of denitrification and plays a role in the storage and supply of the organic matter.•Material balances of carbon and nitrogen during the whole process were analysed.

Nitrogen from secondary effluents has endangered the aquatic environment and human health. A new experimental setup combining a corncob carbon source and bamboo charcoal filter (BCF) was used to effectively purify artificial sewage treatment plant tail water that had high nitrate and nitrogen content, and a low carbon to nitrogen (C/N) ratio. The nitrogen concentration in the reactor's effluent was below the limit of 15 mg/L when the influent COD concentration was 20 mg/L–60 mg/L, the influent NO3−-N concentration was 15 mg/L–30 mg/L, and the hydraulic retention time (HRT) was 1 h–4 h. The reactor's maximum volumetric load of total nitrogen was 0.585 kg/(m3 d). The COD and NO3−-N balances of the reactor indicated that 4.77 g corncob was required to remove 1 g NO3−-N and 2 g corncob was required to release 1 g COD.