Evolution of water quality in rainwater harvesting systems during long-term storage in non-rainy seasons

Zan Gao; Qionghua Zhang; Yufei Wang; Xinyue Jv; Mawuli Dzakpasu; Xiaochang C Wang

doi:10.1016/j.scitotenv.2023.168784

Evolution of water quality in rainwater harvesting systems during long-term storage in non-rainy seasons

Sci Total Environ. 2024 Feb 20:912:168784. doi: 10.1016/j.scitotenv.2023.168784. Epub 2023 Nov 23.

Authors

Zan Gao¹, Qionghua Zhang², Yufei Wang¹, Xinyue Jv¹, Mawuli Dzakpasu³, Xiaochang C Wang⁴

Affiliations

¹ Key Lab of Northwest Water Resource, Environment, and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an 710055, China.
² Key Lab of Northwest Water Resource, Environment, and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an 710055, China; International Science & Technology Cooperation Center for Urban Alternative Water Resources Development, Xi'an 710055, China. Electronic address: qionghuazhang@126.com.
³ International Science & Technology Cooperation Center for Urban Alternative Water Resources Development, Xi'an 710055, China; School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.
⁴ Key Lab of Northwest Water Resource, Environment, and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an 710055, China; International Science & Technology Cooperation Center for Urban Alternative Water Resources Development, Xi'an 710055, China.

PMID: 38000760
DOI: 10.1016/j.scitotenv.2023.168784

Abstract

The development of rainwater utilization strategies has relied on rainwater harvesting (RWH) systems for centuries to alleviate the pressure on water resources. However, there are still significant knowledge gaps regarding the changes in water quality in RWH systems during long-term storage in non-rainy seasons. This study evaluated the water quality processes in RWH systems through static rainwater storage experiments for approximately 60 days. The results revealed that nutrients in rainwater accumulated in sediment during storage. Disturbance and redox conditions at the rainwater-sediment interface contribute to the release of sedimentary facies materials. The rainwater showed distinct DO stratification, with the biochemical reactions of sedimentary facies being the primary factor driving oxygen consumption. ORP and turbidity showed positive correlations with COD (r = 0.582; 0.572), TOC (r = 0.678; 0.681), TN (r = 0.452; 0.439), and NH₄⁺-N (r = 0.502; 0.553) (P < 0.05). The regulation of water quality and extension of the usage cycle were identified as critical factors influenced by DO. In addition, bacteria share similar ecological niche preferences. These findings provide scientific evidence for the high-quality reuse of rainwater in decentralized RWH systems during long-term storage in non-rainy seasons.

Keywords: Rainwater harvesting; Rainwater quality; Rainwater utilization; Redox reactions; Sediment.