Effect of Inlet/Outlet Configuration on Water Quality in a Rainwater Harvesting Tank

Janith Dissanayake,Mooyoung Han

doi:10.3390/w12071970

Abstract

Rainwater harvesting (RWH) has attracted global attention as a solution for the urban water crisis; however, the water quality can be impacted by particulate matter and soluble contaminants. Therefore, the inlet and outlet configurations of the storage tank should be designed to minimize bottom sediment resuspension and prevent the transport of soluble contaminants. Thus, this study investigated the effects of the inlet and outlet configurations of a rainwater storage tank on particle resuspension and residence time distribution for an instantaneous input of a conservative tracer. It was observed that J type inlets can reduce sediment resuspension by more than 50% while detaining and mixing a conservative pollutant, thus preventing the concentration from reaching the outlet as a plug flow. Although inlet height did not have a significant influence on the quality of water at the outlet, parameters such as inflow velocity and outlet height exerted a considerable influence on sludge resuspension and residence time distribution. The experiments also highlighted the importance of regulating the initial water level of the storage tank and regular flushing of bottom sediment to maintain the stored water quality.

Highlights

IntroductionApproximately 500,000 children die every year worldwide [2]
Potable water is an essential human requirement
As this paper investigates the influence of inlet/outlet configurations on bottom sediment resuspension while there is an inflow, turbidity was measured until the tank reached full capacity

Summary

Introduction

Approximately 500,000 children die every year worldwide [2] This crisis is exacerbated by climate change, environmental pollution, and rapid urbanization, which cause existing water bodies to become depleted or unusable. Rainwater can be collected from impervious surfaces, such as the roof of a house, as shown, stored and treated to meet the water quality standards for its intended use. This practice of rainwater harvesting (RWH) in urban centers has the potential to avert urban crises by providing an alternative source of water, and by reducing urban runoff and the demand imposed on central drinking water supply systems [4,5,6]

Methods

Results

Conclusion