ZHAO Bei,ZHANG Hai-xiang,LI Li,et al.Risk Assessment for Water Quality of Distribution Network in Areas Using Self-supply Wells after Water Source Replacement[J].China Water & Wastewater,2021,37(13 13):32-39.
Risk Assessment for Water Quality of Distribution Network in Areas Using Self-supply Wells after Water Source Replacement
China Water & Wastewater[ISSN:1000-4062/CN:12-1073/TU]
volume:
第37卷
Number:
13 13
Page:
32-39
Column:
Date of publication:
2021-07-01
- Abstract:
- After the South-to-North Water Diversion Project completely finished, the water supply guarantee rate of intake cities had been improved. In order to protect groundwater resource, the city in northern China was promoting the water source replacement in areas using self-supply wells. For obvious decrease of the alkalinity, hardness, nitrate, chloride and sulfate, the water quality of consumers in different areas using self-supply wells had all been significantly improved after water source replacement, while the turbidity and total iron of tap water increased in some communities during the initial stage. By analyzing of pipe scales, the corrosion layers in old pipes were thick, loose, and mainly goethite with poor stability, which were tending to release iron after water source replacement. The prediction risk level of “red water”, determined by the water quality diversity index, as well as combining the pipe condition, the disinfectant concentration of new water source and the water consumption, was conformed to the actual monitoring results. According to simulated water source displacement test, it took 3 months for the increased turbidity and total iron in the tap water in cast iron pipes with age greater than 20 years to stabilize and meet the standard when the stagnation time was 4 h. The main component of pipe scales was basically as same as the initial ones during 508 days of operation, which meant high risk of “red water” recurring when water quality changed.
Last Update:
2021-07-01