Treatment of tapioca processing wastewater in a sequencing batch reactor: Mechanism of granule formation and performance

• Published in: Journal of environmental management 2018-07, Vol.218, p.39-49
• Main Authors: Truong, Hong Thi Bich, Nguyen, Phuoc Van, Nguyen, Phuong Thi Thanh, Bui, Ha Manh
• Format: Article
• Language: English
• Subjects: Aerobic granular sludge; Granulation; Sequencing batch reactor; Tapioca processing wastewater
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2018.04.041

The formation of aerobic granular sludge was carried out in a sequencing batch reactor (SBR) for tapioca processing wastewater treatment. The effect of organic loading rates (OLRs) in the range of 2.5–10.0 kg COD m−3 day−1 on the granulation was investigated. The size and settleability of the aerobic granular sludge increased with increasing OLR from 2.5 to 7.5 kg COD m−3 day−1. The mature granules had an average size of 2.5 mm and good settleability with the sludge volume index (SVI) lower than 50 mL g−1. The granules had a layered structure consisting of anoxic sludge core with nematodes and an outer aerobic layer surrounded by stalked ciliates. Removal efficiencies of chemical oxygen demand (COD) and NH4+-N reached 90.0%–93.0% and 86.6%–92.5%, respectively. Simultaneous nitrification and denitrification at the OLR of 7.5 kg COD m−3 day−1 resulted in the improvement of total nitrogen (TN) removal efficiency to 66.1%. [Display omitted] •The mature granules had average size of 2.5 mm, sludge volume index around 50 mL g−1.•The granule structure consisted of anoxic core and outer aerobic layer.•Chemical oxygen demand removal efficiency was 90–93%.•Nitrification and denitrification occurred simultaneously in the reactor.•NH4+-N and total nitrogen removal efficiencies were 86.6–92.5%, 49.7–66.1%, respectively.