The microbial quality and the use of sodis to treat harvested rainwater in rural areas of Uganda case study: Makondo-Lwengo Masaka

2019-11-22T18:02:07Z (GMT) by Rosemary Nalwanga

While harvested rainwater (HRW) is promoted in rural areas o f Uganda, little attention has been given to its quality. The current study was carried out to investigate the quality o f HRW in the rural area o f Mokondo-Lwengo, Uganda and to determine the effectiveness o f solar water disinfection (SODIS) to treat drinking water in rural households. Households with HRW systems o f different materials were randomly selected and trained in SODIS treatment using 2 liter PET bottles. Following a preliminary short study over 4 months, a year long study was conducted to investigate any seasonal variation. Physiochemical parameters (temperature, pH and TDS) o f the raw HRW were tested on site while the samples for microbial analysis were transported for analysis at Makerere University.

Results showed that the HRW met the required physiochemical drinking water standards. However, o f the 462 raw HRW samples, 409 (88.5%) were found to be microbiologically contaminated and unsafe for drinking without treatment. Clostridium perfringens was never found.

Lack o f cleaning o f the HRW systems; the manual abstraction o f water due to faulty taps; overhanging vegetation around the HRW systems; the poor condition o f drainage o f water collection area, season, the number of rainfall events in a month and the amount o f rainfall received by a system, were the most significant factors influencing the microbial quality o f the HRW.

Following SODIS treatment, the treatment efficiency ranged from 61.2%-100% with the highest treatment efficiencies occurring during the dry months o f the year.

When a 25L borosilicate glass tube fitted with a compound parabolic collector (BGTR-CPC) was evaluated, bacterial inactivation to below the limit o f detection (<1CFU/I00ml.) was obtained in 85% o f experiments.