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Enhanced Coagulation with Mn(III) Pre-Oxidation for Treatment of Micro-Polluted Raw Water

1
Institute of Coastal and Offshore Engineering, Zhejiang University, Zhoushan 316000, China
2
The Architectural Design & Research Institute of Zhejiang University Co., Ltd., Hangzhou 310058, China
3
Zhejiang Key Laboratory of Drinking Water Safety and Distribution Technology, College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, China
4
Department of Biological and Environmental Engineering, Jiyang College of Zhejiang A & F University, Zhuji 311800, China
5
Huzhou Water Group, Huzhou 313000, China
*
Author to whom correspondence should be addressed.
Water 2019, 11(11), 2302; https://doi.org/10.3390/w11112302
Received: 7 October 2019 / Revised: 1 November 2019 / Accepted: 2 November 2019 / Published: 3 November 2019
(This article belongs to the Section Water and Wastewater Treatment)
Mn(III) oxidation technology has attracted increasing interest in recent years because of its fast decontamination kinetics and second-pollution-free characteristic. Whether it can be used as a pre-oxidation step to enhance conventional coagulation process remains to be evaluated. Herein, an Fe-coagulation/sedimentation process combined with Mn(III) pre-oxidation (Mn(III)+C/S), hypochlorite pre-oxidation (Cl2+C/S), and permanganate pre-oxidation (PM+C/S) was applied to treat simulated micro-polluted raw water. The removal performance of routine water quality indices (turbidity, dissolved organic carbon, total nitrogen, nitrate-nitrogen, ammonia-nitrogen, Pb(II), and Cr(VI)) and the emerging pollutants (acesulfame, carbamazepine, bisphenol S, and nano-ZnO) created by these three processes were researched. The mechanism of how Mn(III) pre-oxidation influences C/S was explored by identifying the transformation products of Mn(III), measuring the timely variation of flocs’ zeta potential and size, and scanning flocs’ micromorphology. Compared to Cl2+C/S and PM+C/S, Mn(III)+C/S exhibited its superiority in removing dissolved organic carbon (72.9%), total nitrogen (31.74%), and emerging pollutants (21.78%–93.49%). The enhanced removal of these contaminants by Mn(III)+C/S found its explanation in the strong oxidation power of Mn(III) and the multiple roles of in-situ formed MnO2 (e.g., flocculation core, adsorption co-precipitant, and densification agent). The acute toxicity tests confirmed that water treated by Mn(III)+C/S did not show a significant change in the associated toxicity. The findings of the present study indicate that Mn(III) oxidation technology shows great potential as an alternative to pre-oxidation technology of waterworks.
Keywords: pre-oxidation; enhanced coagulation; Mn(III); emerging pollutants; micro-polluted raw water pre-oxidation; enhanced coagulation; Mn(III); emerging pollutants; micro-polluted raw water
MDPI and ACS Style

Yan, D.; Sun, Z.; Wang, J.; Wang, L.; Pan, R.; Wu, Q.; Liu, X. Enhanced Coagulation with Mn(III) Pre-Oxidation for Treatment of Micro-Polluted Raw Water. Water 2019, 11, 2302.

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