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Quality of greywater treated in biochar filter and risk assessment of gastroenteritis due to household exposure during maintenance and irrigation
- Dalahmeh, S.S., Lalander, C., Pell, M., Vinnerås, B., Jönsson, H.
- Journal of applied microbiology 2016 v.121 no.5 pp. 1427-1443
- Escherichia coli, Rotavirus, Salmonella, biochar, biochemical oxygen demand, filters, gardens, gastroenteritis, green onions, ingestion, irrigation, recycling, risk, summer, wastewater, wastewater treatment, Jordan
- AIM: This study evaluated treatment of greywater (GW) by a biochar filter in Jordan and assessed the annual risks of infection (Pᵢ‐ₐₙₙᵤₐₗ), annual risk of disease (Pd‐ₐₙₙᵤₐₗ) and disease burden (in disability‐adjusted life years; DALYs) of gastroenteritis caused by Salmonella spp. and rotavirus due to ingestion of GW during system maintenance and consumption of green onions irrigated with treated and nontreated GW. METHODS AND RESULTS: The biochar filter efficiently removed 93% of biochemical oxygen demand (BOD₅) and 85% of solids, while removal of Escherichia coli was insignificant. Treatment of GW decreased the median Pd‐ₐₙₙᵤₐₗ due to ingestion of GW from 1·39 × 10⁻² to 6·0 × 10⁻³ for Salmonella spp. but did not affect Pd‐ₐₙₙᵤₐₗ caused by rotavirus (9·73 × 10⁻¹ to 1·0). Consumption of onions irrigated with treated GW had a median Pd‐ₐₙₙᵤₐₗ of 1·25 × 10⁻⁹ to 1·2 × 10⁻⁸ for Salmonella spp. and 4·96 × 10⁻⁴ to 4·37 × 10⁻³ for rotavirus infection, which was 99·9 and 90% lower, respectively, than the risk when consuming onions irrigated with nontreated GW. The highest risks of gastrointestinal disease were thus associated mainly with direct ingestion of GW when maintaining the system. CONCLUSIONS: Garden produce irrigated with GW treated in biochar filter did not display intolerable risks of rotavirus‒based gastroenteritis during summer season in the study area given that the produce is harvested 1 to 2 days, and washed, before consumption. SIGNIFICANCE AND IMPACT OF THE STUDY: This study contributes to scientific‐based knowledge on the suitability of biochar filters for onsite greywater treatment and confirms the microbial safety of recycling treated greywater for garden irrigation.