Achieving mainstream nitrogen removal via the nitrite pathway from real municipal wastewater using intermittent ultrasonic treatment

Min Zheng; Shuang Wu; Qian Dong; Xia Huang; Zhiguo Yuan; Yanchen Liu

doi:10.1016/j.ultsonch.2018.07.033

Achieving mainstream nitrogen removal via the nitrite pathway from real municipal wastewater using intermittent ultrasonic treatment

Ultrason Sonochem. 2019 Mar:51:406-411. doi: 10.1016/j.ultsonch.2018.07.033. Epub 2018 Aug 2.

Authors

Min Zheng¹, Shuang Wu², Qian Dong², Xia Huang², Zhiguo Yuan¹, Yanchen Liu³

Affiliations

¹ State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China; Advanced Water Management Centre, The University of Queensland, St Lucia, QLD 4072, Australia.
² State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
³ State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China. Electronic address: liuyc@mail.tsinghua.edu.cn.

PMID: 30249372
DOI: 10.1016/j.ultsonch.2018.07.033

Abstract

Achieving mainstream nitrogen removal via the nitrite pathway (NH₄⁺ → NO₂^- → N₂) is highly beneficial for energy neutral/positive wastewater treatment. Our previous batch assays revealed that ultrasonic treatment can suppress nitrite-oxidizing bacteria (NOB) while enhancing the activity of ammonia-oxidizing bacteria (AOB). Based on this concept, this study investigated the feasibility of applying ultrasonication to achieve the nitrite pathway in mainstream wastewater treatment. Two lab-scale sequencing batch reactors were set-up in parallel and fed with real municipal wastewater. With 100% of the sludge treated every 12 h at a treatment energy input of 0.066 kJ per mg mixed liquor suspended solids, the nitrite pathway was rapidly (within two weeks) established in the experimental reactor with stable effluent nitrite accumulation ratio (NO₂^-/(NO₂^- + NO₃^-)) of above 80% and significantly decreased NOB population. In comparison, the control reactor always possessed the conventional nitrification and denitrification pathway. Economic analysis indicated that energy consumption is too high for practical applications. However, this technology may be used in conjunction with other technologies, whereby this ultrasonic treatment can be used infrequently (e.g. once every few months) when the nitrite pathway becomes unstable.

Keywords: Intermittent ultrasonic treatment; Mainstream nitrogen removal; Municipal wastewater; Nitrite pathway; Nitrite-oxidizing bacteria (NOB) suppression.