The viability of artificial surface treatments as a mechanism for domestic rain water harvesting

Abstract

The main objective of this study was to assess the feasibility of using paraffin wax as an alternative surface treatment for rainwater harvesting in the high rainfall zone of Kabarole district, Western Uganda. Specifically, the paper assesses the efficiency of paraffin wax in terms of quantity and quality of runoff. A complete randomized block experimental design was setup in three replications based on a slope of 1%, 3% and 5%. The treatments included: wax on bare soil (W), wax on sand (WS), wax on gravel (WG), wax on rice husk ash (WA) and a bare surface with short grass (C). Daily rainfall and runoff was collected from each experimental unit between April 2016 to May 2017. Water quality analysis of runoff for physical, chemical and microbial contamination was conducted. Average monthly runoff efficiency ranged from 56 to 93% for WG, 35–81% for WS, 34–71 for W, 30–71% for WA and 12–56% for C. Rainfall threshold values were estimated at 0.4 mm, 0.5 mm, 1.1 mm, 1.8 mm, and 4.6 mm of rainfall for WG, WS, W, WA and C, respectively. All physiochemical parameters were within WHO guidelines while E. coli contamination was observed in some samples for all treatments. Both the control and WG treatments had the lowest yield cost/m3/yr compared to the other treatments.