Illumina amplicon-based sequencing was coupled with ethidium monoazide bromide (EMA) pre-treatment to monitor the total viable bacterial community and subsequently identify and prioritise the target organ- isms for the health risk assessment of the untreated rainwater and rainwater treated using large-volume batch solar reactor prototypes installed in an informal settlement and rural farming community. Taxonomic assignments indicated that Legionella and Pseudomonas were the most frequently detected genera contain- ing opportunistic bacterial pathogens in the untreated and treated rainwater at both sites. Additionally, My- cobacterium, Clostridium sensu stricto and Escherichia/Shigella displayed high (≥80%) detection frequencies in the untreated and/or treated rainwater samples at one or both sites. Numerous exposure scenarios (e.g. drinking, cleaning) were subsequently investigated and the health risk of using untreated and solar reactor treated rainwater in developing countries was quantified based on the presence of L. pneumophila, P. aeruginosa and E. coli. The solar reactor prototypes were able to reduce the health risk associated with E. coli and P. aeruginosa to below the 1 × 10−4 annual benchmark limit for all the non-potable uses of rainwa- ter within the target communities (exception of showering for E. coli). However, the risk associated with in- tentional drinking of untreated or treated rainwater exceeded the benchmark limit (E. coli and P. aeruginosa). Additionally, while the solar reactor treatment reduced the risk associated with garden hosing and showering based on the presence of L. pneumophila, the risk estimates for both activities still exceeded the annual benchmark limit. The large-volume batch solar reactor prototypes were thus able to reduce the risk posed by the target bacteria for non-potable activities rainwater is commonly used for in water scarce regions of sub-Saharan Africa. This study highlights the need to assess water treatment systems in field tri- als using QMRA.
Bibliographical noteFunding Information: The authors wish to thank the Centre for Proteomic & Genomic Research (CPGR), Illumina and Whitehead Scientific for funding the Illumina Miseq sequencing through their Core Lab Competition. The authors would particularly like to thank Drs Shane Murray and Jeanne Korsman from CPGR for their assistance during the Illumina MiSeq sequencing. The financial assistance from the European Union 's Horizon 2020 Research and Innovation Program under grant agreement no. 688928 (WATERSPOUTT H2020-Water-5c) is also acknowledged. Publisher Copyright: © 2020 Elsevier B.V. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.
- Rainwater harvesting
- Solar disinfection
- Sub-Saharan Africa