Solar Powered Microplasma-Generated Ozone: Assessment of a Novel Point-of-Use Drinking Water Treatment Method

Abstract

Ozonation is widely used in high-income countries for water disinfection in centralized treatment facilities. New microplasma technology has reduced the energy requirements for ozone generation dramatically, such that a 15-watt solar panel is sufficient to produce small quantities of ozone. This technology has not been used previously for point-of-use drinking water treatment. We conducted a series of assessments of this technology, both in the laboratory and in homes of residents of a village in western Kenya, to estimate system efficacy and to determine if the solar-powered point-of-use water ozonation system appears safe and acceptable to end-users. In the laboratory, two hours of point-of-use ozonation reduced E. coli in 120 L of wastewater by a mean (standard deviation) of 2.3 (0.84) log-orders of magnitude and F+ coliphage by 1.54 (0.72). Based on laboratory efficacy, 10 families in Western Kenya used the system to treat 20 L of household stored water for two hours on a daily basis for eight weeks. Household stored water E. coli concentrations of >1000 most probable number (MPN)/100 mL were reduced by 1.56 (0.96) log removal value (LRV). No participants experienced symptoms of respiratory or mucous membrane irritation. Focus group research indicated that families who used the system for eight weeks had very favorable perceptions of the system, in part because it allowed them to charge mobile phones. Drinking water ozonation using microplasma technology may be a sustainable point-of-use treatment method, although system optimization and evaluations in other settings would be needed.

Decentralized solar-powered drinking water ozonation in Western Kenya: an evaluation of disinfection efficacy

“…Though chlorination following filtration would also be expected to reduce bacterial and viral concentrations as a disinfection step, the taste of chlorinated water is often unacceptable in low- and middle-income communities ( Roma et al , 2014 ; Rosa & Clasen, 2017 ; Rothstein et al , 2015 ). By contrast, in a small study of POU ozonation in Kenya, we found the taste of the finished water to be acceptable ( Dorevitch et al , 2020 ).…”

“…Although bacterial concentrations decreased substantially, viruses may persist following filtration, and a disinfection step should further decrease concentrations of viruses. We have demonstrated previously that ozonation eliminated coliphage viruses from sewage samples ( Dorevitch et al , 2020 ), though chlorination is certainly effective in reducing viruses ( WHO, 2017 ). Cryptosporidium spp .…”

“…As a result, the reported LRVs likely under-estimate actual system performance. The research did include measures of ozone concentration in the disinfection process, though this has been measured during smaller scale laboratory trials, with concentrations of 0.28–0.40ppm ( Dorevitch et al , 2020 ). This research did not address community perspectives.…”

“…New microplasma technology has made it possible to produce ozone using small, scalable units, with three times the efficiency of conventional dielectric barrier discharge or corona ozone reactors ( Kim et al , 2017 ; Simek & Clupek, 2002 ). We recently evaluated that technology as a POU water treatment in Kisian, Kenya ( Dorevitch et al , 2020 ). Ten families were asked to ozonate their household stored water in 20L containers for a two-hour period before using the water for drinking.…”

Disinfection of Wastewater by UV-Based Treatment for Reuse in a Circular Economy Perspective. Where Are We at?

“…Necessarily, over the years, other chemicals have been identified as a possible alternative to chlorine in the disinfection of WW, such as chlorine dioxide, ozone and peracetic acid. As regards ozone, among the main disadvantages are the high costs, including energy costs and the operative and management difficulties related to its instability [ 33 ]. Ozonation also leads to the formation of bromate as DBP in waters containing the bromide ion (Br − ) [ 29 , 34 ].…”