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.