Rapid start-up and nitrogen loading response of single-stage partial nitritation–anammox system using multi-channel internal circulation - Binquan Wang; Haoshuai Ji; Ting Wu; Hong Chen; Mohd Fadhil Md Din; Jiao Jin; Zhihua Liu; Zhaohui Jiang; Weiyu Zhang; Sen Yan (Bioresource Technology, 2026)