Optimization of nitrate removal from wastewater with a low C/N ratio using solid-phase denitrification

Zhang, Qian; Ji, Fangying; Xu, Xiaoyi

Optimization of nitrate removal from wastewater with a low C/N ratio using solid-phase denitrification

2016

Zhang, Qian | Ji, Fangying | Xu, Xiaoyi

In this study, the optimization of nitrate removal from wastewater with a low C/N ratio using solid-phase denitrification was investigated. Biodegradable polymer, an attractive alternative to liquid carbon sources for biological denitrification, was used as a carbon source and biofilm support for nitrate removal. An experiment was conducted based on a central composite design (CCD) with response surface methodology (RSM). A secondary polynomial regression with nitrate removal efficiency as response value was developed. Based on statistical analysis, the nitrate removal model was highly significant with very low probability values (<0.0001). At the optimal conditions for nitrate removal (hydraulic retention time (HRT), 3.5 h; influent NO₃ ⁻-N concentration, 14.73 mg/L; and influent CODCᵣ concentration, 15.00 mg/L), the nitrate removal efficiency was 99.23 %. The results of an ANOVA and response surface analysis showed that HRT, influent NO₃ ⁻-N concentration, influent CODCᵣ concentration, and the interaction between the HRT and influent CODCᵣ concentration significantly affected the nitrate removal efficiency (P < 0.05). In solid-phase denitrification process, electron donor for denitrification could be obtained by biological degradation of biodegradable polymer. Therefore, the influent CODCᵣ concentration has no major effect on nitrate removal efficiency compared with that of HRT and influent NO₃ ⁻-N concentration.

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