Human Health Impact of Cross-Connections in Non-Potable Reuse Systems
Abstract
:1. Introduction
2. Materials and Methods
2.1. Literature Review
2.2. Pathogen Health Impact
2.2.1. QMRA
- S is the fraction of people in the exposed population susceptible to each reference pathogen
- DR(...) is a dose-response function for the reference pathogen
- DF is the dilution factor (i.e., the total volume of water in which the intrusion is mixed)
- V is the volume of water ingested per day
- n is the number of days of exposure
- C is the pathogen concentration in the wastewater or greywater
- LRT is the total log reduction target for each reference pathogen
- fr is the cross-connection exposure fraction (i.e., exposed users/total users per year)
- Pinfnon-potable is the annual risk from non-potable reuse without a cross-connection event
2.2.2. Exposure Routes
2.2.3. Pathogen Dose-Response
2.2.4. Characterization of Pathogens in Waters
2.2.5. Pathogen LRTs
2.3. Non-Potable LRTs without Cross-Connection Event
3. Results
3.1. Cross-Connection Characteristics
3.2. Daily Event Risk
3.2.1. Reclaimed to Potable Water Event
3.2.2. Greywater/Wastewater to Non-Potable
3.2.3. Comparison of Intrusion Scenario Daily Event Risks
3.3. Predicted Annual Risk
3.3.1. Reclaimed to Potable
3.3.2. Wastewater/Greywater to Non-Potable
3.3.3. Comparison of Target Dilution Factor
3.3.4. Comparison of Target Exposure Fraction
3.4. LRTs without Cross-Connection
4. Discussion
4.1. How Important Are Cross-Connection Events between Potable and Non-Potable Water?
4.2. How Important Were the Cross-Connection Assumptions Built into the Domestic LRTs?
4.3. What Type of Contamination Events Have the Most Predicted Health Impact in ONWS?
4.4. What Is the Acceptable Fraction of ONWS Users Impacted by Contamination Events?
4.5. Important QMRA Assumptions
4.6. How Can These Findings Be Used?
5. Conclusions
- There is a lack of data in the United States on cross-connection events in domestic, non-potable water systems
- The predicted health impact of contamination of potable water by reclaimed water varied from negligible to exceeding the annual health benchmark, depending on characteristics of the contamination event.
- Contamination of non-potable reclaimed water with wastewater had higher predicted health impact per event than contamination of potable water by reclaimed water. However, the fraction of users that are exposed and magnitude of these events remain uncertain.
- Domestic non-potable reuse LRTs generally decreased by an order of magnitude (or less) when potable water contamination events were assumed not to exist.
- Based on the QMRA results of cross-connection events, the fraction of users that can be exposed in domestic, onsite non-potable water systems to maintain the annual health benchmark should be less than 1 impacted person per 10,000 users for contamination of non-potable reclaimed water by undiluted wastewater or 1 per 1000 for contamination of potable water by reclaimed wastewaters and domestic greywaters.
Supplementary Materials
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
References
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Norovirus (Genome Copies) b | Rotavirus (FFU) | Cryptosporidium (oocysts) b | Giardia (Cysts) | Campylobacter (CFU) | Salmonella (CFU) | |
---|---|---|---|---|---|---|
Wastewater 1000-person collection | ||||||
Indoor use with CC a | 11.2/8.4 | 8.8 | 6.8/5.9 | 6.1 | 6.0 | 3.8 |
Indoor use without CC | 9.8/7 | 8.1 | 6.3/5.4 | 5.0 | 5.5 | 2.9 |
Greywater 1000-person collection | ||||||
Indoor use with CC a | 8.8/6.0 | 6.4 | 4.5/3.6 | 3.8 | 3.7 | 1.6 |
Indoor use without CC | 7.9/5.1 | 6.0 | 4.1/3.2 | 3.4 | 3.3 | 0.7 |
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Schoen, M.E.; Jahne, M.A.; Garland, J.L. Human Health Impact of Cross-Connections in Non-Potable Reuse Systems. Water 2018, 10, 1352. https://doi.org/10.3390/w10101352
Schoen ME, Jahne MA, Garland JL. Human Health Impact of Cross-Connections in Non-Potable Reuse Systems. Water. 2018; 10(10):1352. https://doi.org/10.3390/w10101352
Chicago/Turabian StyleSchoen, Mary E., Michael A. Jahne, and Jay L. Garland. 2018. "Human Health Impact of Cross-Connections in Non-Potable Reuse Systems" Water 10, no. 10: 1352. https://doi.org/10.3390/w10101352