Mainstream nitrogen separation and side-stream removal to reduce discharge and footprint of wastewater treatment plants. (1st January 2021)

• Record Type: Journal Article
• Authors: Zhou, Zhen; Wang, Kaichong; Qiang, Jiaxin; Pang, Hongjian; Yuan, Yao; An, Ying; Zhou, Chuanting; Ye, Jianfeng; Wu, Zhichao
• Is Part Of: Water research. Volume 188(2021)
• Publication Date: 2021-01-01
• Subjects: Wastewater treatment -- Nitrogen removal -- Space -- Energy -- Ion exchange; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2020.116527
• Languages: English
• ISSNs: 0043-1354

Abstract

Highlights: A sustainable strategy by moving nitrogen from mainstream to side stream was studied. A cycle of ammonium exchange, regeneration, and nitrogen removal (AERN) was designed. AERN cycle rapidly separates NH4 + from wastewater for further removal or recycle. Two AERN-based systems removed 86.8% and 93.7% nitrogen at HRT of 8.9 and 3.5 h. AERN-based processes reduced 59.9–71.7% land occupancy and 2.3–31.0% treatment cost. Abstract: The activated sludge process is efficient for pollutant removal, but was criticized for its large upfront investment and land area requirements. Improving nitrogen removal to levels sufficient to reduce eutrophication is a challenge to conventional nitrification and denitrification, which is limited by process configuration (with nitrate recirculation) and environmental inhibition. To satisfy stringent discharge standards within a compact plant footprint, a sustainable strategy by moving nitrogen removal from mainstream to side-stream is designed by a cycle of ammonium exchange, regeneration and nitrogen removal (AERN), combined with biological and physiochemical technologies. Ammonium was rapidly captured by ion exchangers, then exchanged into regenerant, and converted to N2 by chlorination or Sharon-anaerobic ammonia oxidation in the side-stream. The AERN cycle can be combined with a high-rate anaerobic/aerobic process and chemical phosphorus removal to construct a HAERN process, or inserted between a coagulation-sedimentation tank and a membrane bioreactor to construct a CAERNM process. Two AERN-based systems both achieved efficient pollutants removal (especially for nitrogen removal of 86.8–93.7%) in long-term running, and didn't impair exchange capacity and properties of ion exchangers. Compared with the conventional anaerobic/anoxic/aerobic process, AERN-based processes reduce land occupancy, upfront investments, and treatment costs by 59.9–71.1%, 25.5–38.0% and 2.3–31.0%, respectively. Graphical abstract: Image, graphical abstract