Sludge fermentation liquid addition attained advanced nitrogen removal in low C/N ratio municipal wastewater through sho
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RESEARCH ARTICLE
Sludge fermentation liquid addition attained advanced nitrogen removal in low C/N ratio municipal wastewater through short-cut nitrification-denitrification and partial anammox Shengjie Qiu, Jinjin Liu, Liang Zhang, Qiong Zhang, Yongzhen Peng (✉) National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, China
HIGHLIGHTS
GRAPHIC ABSTRACT
• Sludge fermentation liquid addition resulted in a high NAR of 97.4%. + • Extra NH4 -N from SFL was removed by anammox in anoxic phase. • Nitrogen removal efficiency of 92.51% was achieved in municipal wastewater. • The novel system could efficiently treat low COD/N municipal wastewater.
ARTICLE INFO Article history:
Received 25 February 2020 Revised 17 July 2020 Accepted 17 July 2020 Available online 8 September 2020 Keywords: Sludge fermentation liquid Municipal wastewater Advanced nitrogen removal Short-cut nitrification Partial anammox
ABSTRACT Biological nitrogen removal of wastewater with low COD/N ratio could be enhanced by the addition of wasted sludge fermentation liquid (SFL), but the performance is usually limited by the introducing ammonium. In this study, the process of using SFL was successfully improved by involving anammox process. Real municipal wastewater with a low C/N ratio of 2.8–3.4 was treated in a sequencing batch reactor (SBR). The SBR was operated under anaerobic-aerobic-anoxic (AOA) mode and excess SFL was added into the anoxic phase. Stable short-cut nitrification was achieved after 46d and then anammox sludge was inoculated. In the stable period, effluent total inorganic nitrogen (TIN) was less than 4.3 mg/L with removal efficiency of 92.3%. Further analysis suggests that anammox bacteria, mainly affiliated with Candidatus_Kuenenia, successfully reduced the external ammonia from the SFL and contributed approximately 28%–43% to TIN removal. Overall, this study suggests anammox could be combined with SFL addition, resulting in a stable enhanced nitrogen biological removal. © Higher Education Press 2020
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Introduction
Biological nutrients removal (BNR) has been gobally applied to treat domestic sewage in the world and the nitrogen removal performance is determined by the carbon
✉ Corresponding author E-mail: [email protected]
source in the influent (Qu et al., 2019). When carbon source in wastewater is insufficient, complete denitrification is difficult to achieve, resulting in low nitrogen removal efficiency (NRE). To achieve efficient nitrogen removal in carbon source-limited wastewater, extra carbon source is usually required to promote the denitrification in the anoxic phase of the secondary or tertiary treatments. However, external carbon source increases the operational costs as well as the production of waste activated sludge.
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Front. Environ. Sci. Eng. 2021, 15(2): 26
Thus, more cost-effective and economical alternatives to external carbon source are ideal. Organics from excess sludge has been considered
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