CHENQi,LUZhi-li,LIGui-wei,et al.Occurrence of and Response to Large?scale Manganese-caused “Yellow Water” Events in a Southern City[J].China Water & Wastewater,2023,39(9):39-44.
Occurrence of and Response to Large?scale Manganese-caused “Yellow Water” Events in a Southern City
China Water & Wastewater[ISSN:1000-4062/CN:12-1073/TU]
volume:
第39卷
Number:
第9期
Page:
39-44
Column:
Date of publication:
2023-05-01
- Keywords:
- drinking water; yellow water; manganese; drinking water distribution system; source water switch; powdered activated carbon
- Abstract:
- Complaints about yellow water in drinking water distribution system (DWDS) in a southern city since 2019 accounted for 50% of user complaints about water quality problems. By analyzing the pattern of yellow water occurrence in the water supply area of several water treatment plants (WTPs), it was found that the main color-causing component of the large-scale yellow water events that occurred in July and August 2019 was manganese, which was directly related to the increase of manganese concentration in the finished water to more than 0.02 mg/L. Yellow water with Mn concentration exceeding the standard limit of 0.1 mg/L reflected the problem of Mn deposition and re?release in DWDS. The Mn concentration was significantly and positively correlated with the chromaticity of yellow water samples. The small-scale yellow water events with iron and manganese being the main color-causing components was mainly caused by corrosion of DWDS and the deposition and re-release of Mn. WTPs with yellow water events had no concentrated yellow water complaints after switching the reservoir water back to river water with lower Mn(Ⅱ) concentrations. For another WTP that had been using reservoir water, after the Mn concentration of reservoir water increased, the efficiency of Mn control was not effectively reduced by increasing the dose of chlorine and sodium hydroxide. Then 5 mg/L powdered activated carbon and 1 mg/L chlorine were added simultaneously, and the Mn in the finished water was rapidly controlled below 0.01 mg/L by catalytic oxidation mechanisms, which successfully suppressed the yellow water occurrence in DWDS. The concentration of Mn in the influent also decreased after the depth of the reservoir water uptake location was reduced. In conclusion, monitoring Mn(Ⅱ) concentration in source water, taking efficient Mn removal measures, maintaining the Mn concentration in the finished water below 0.02 mg/L and renewing DWDS are critical for controlling yellow water events.
Last Update:
2023-05-01