Solar Disinfection of Pseudomonas aeruginosa in Harvested Rainwater: A Step towards Potability of Rainwater

Abstract

Efficiency of solar based disinfection of Pseudomonas aeruginosa (P. aeruginosa) in rooftop harvested rainwater was evaluated aiming the potability of rainwater. The rainwater samples were exposed to direct sunlight for about 8–9 hours and the effects of water temperature (°C), sunlight irradiance (W/m2), different rear surfaces of polyethylene terephthalate bottles, variable microbial concentrations, pH and turbidity were observed on P. aeruginosa inactivation at different weathers. In simple solar disinfection (SODIS), the complete inactivation of P. aeruginosa was obtained only under sunny weather conditions (>50°C and >700 W/m2) with absorptive rear surface. Solar collector disinfection (SOCODIS) system, used to improve the efficiency of simple SODIS under mild and weak weather, completely inactivated the P. aeruginosa by enhancing the disinfection efficiency of about 20% only at mild weather. Both SODIS and SOCODIS systems, however, were found inefficient at weak weather. Different initial concentrations of P. aeruginosa and/or Escherichia coli had little effects on the disinfection efficiency except for the SODIS with highest initial concentrations. The inactivation of P. aeruginosa increased by about 10–15% by lowering the initial pH values from 10 to 3. A high initial turbidity, adjusted by adding kaolin, adversely affected the efficiency of both systems and a decrease, about 15–25%; in inactivation of P. aeruginosa was observed. The kinetics of this study was investigated by Geeraerd Model for highlighting the best disinfection system based on reaction rate constant. The unique detailed investigation of P. aeruginosa disinfection with sunlight based disinfection systems under different weather conditions and variable parameters will help researchers to understand and further improve the newly invented SOCODIS system.

A review on physicochemical and microbiological contamination of roof-harvested rainwater in urban areas

“…Welldesigned rainwater harvesting systems with clean catchments, covered cisterns and storage tanks, as well as simple treatment supported by good hygiene practices can offer water for these non-potable uses with very low health risk. Common available treatments for harvested rainwater are: the application of settling tanks, disinfection combined with membrane filtration, reverse osmosis (Wang et al, 2014a,b), heat treatment (Spinks et al, 2006), solar disinfection-SODIS (Amin et al, 2014a(Amin et al, , 2014bAhammed et al, 2014) and slow sand filtration followed by chlorination (Moreira Neto et al, 2012). Silver ions combined with conventional filtration and settling mechanisms is another type of affordable treatment that offers good results (Adler et al, 2011).…”

Comparative analysis of solar pasteurization versus solar disinfection for the treatment of harvested rainwater

“…heavy metals and dust) [2–4]. Depending on the roof maintenance, leaves, animal faecal matter (which may contain chemicals such as phosphorous, nitrogen and trace elements) [4] and other debris particles, may also wash into the rainwater storage tank after a rain event and negatively affect the microbial quality of the tank water [4–6]. …”

“…In developing countries, particularly, researchers seek cost- and time-effective treatment methods in order to improve the quality of harvested rainwater, for utilisation as a potable water source and for other domestic activities [6]. Solar disinfection (SODIS) and solar pasteurization (SOPAS) systems have been considered as efficient and cost-effective treatment methods for harvested rainwater [1, 6]. …”

“…A SODIS system is based on the effect of ultra-violet (UV) light and heat from the sun, which inactivates microorganisms [6, 10]. A very simple example of a SODIS system is outlined by Amin and Han [1] and Amin et al [6] where a transparent container is filled with harvested rainwater, placed onto a reflective surface and is exposed to direct sunlight for at least 6 to 8 hrs.…”

A study of the bacteriological quality of roof-harvested rainwater and an evaluation of SODIS as a suitable treatment technology in rural Sub-Saharan Africa

“…Amin and co-workers [14] viewed the coupling of harvested rainwater and SODIS as an easy approach for poor communities living in the developing world in accessing potable water using efficient and cost effective point of use treatment methods. However, while SODIS and HRW technologies are suitable in a Ugandan setting, little has been done to evaluate their efficacy in Ugandan rural conditions.…”