Highlights  The General Lake Model (GLM) is stress tested against 32 globally distributed lakes.  There was low correlation between input data uncertainty and model performance.  Model performance related to lake-morphometry, light extinction and flow regime; deep, clear lakes with high residence times had the lowest model error.

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Chlorination and UV irradiation of RBC (rotating biological contactor)-treated light GW (greywater) was investigated. The ability of chlorine and UV to inactivate indictor bacteria (FC - Faecal Coliforms, HPC - Heterotrophic Plate Count) and specific pathogens (P.a. - Pseudomonas aeruginosa sp., S.a. - Staphylococcus aureus sp.), was assessed and their regrowth potential was examined. The RBC removed 88.5-99.9% of all four bacteria groups. Nevertheless, the treated GW had to be disinfected. Most of the chlorine was consumed during the first 0.5 h, while later its decay rate decreased significantly, leaving enough residual after 6 h to prevent regrowth and to further inactivate bacteria in the stored GW effluent. Under exposure to low UV doses (≤69 mJ/cm(2)) FC was the most resistant bacteria group, followed by HPC, P.a. and S.a. Exposure to higher doses (≤439 mJs/cm(2)) completely inactivated FC, P.a. and S.a., while no further HPC inactivation was observed. FC, P.a. and S.a. did not exhibit regrowth after exposure to all the UV doses applied (up to 6 h storage). HPC did not exhibit regrowth after exposure to low UV doses (19-69 mJ/cm2), while it presented statistically significant regrowth in un-disinfected effluent and after exposure to higher UV doses (147-439 mJ/cm(2)).

Greywater reuse can significantly reduce domestic water consumption. While the benefits are promising, risks are still under debate. Using a quantitative microbial risk-assessment model, we assessed the health risks associated with greywater reuse. The pathogens Salmonella enterica, Shigella spp., and Staphylococcus aureus were evaluated due to their possible prevalence in greywater and limited information regarding their potential risk with relation to greywater reuse for irrigation. Various exposure scenarios were investigated. Monte Carlo simulation was used and results were compared to the maximum "acceptable" limit of 10 −6 disability-adjusted life years (DALY) set by the World Health Organization. Safe reuse was met for all worst-case exposure scenarios for Staphylococcus aureus, Salmonella enterica and Shigella spp. If their concentrations were kept below 10,000, 50 and 5 cfu/100 mL, respectively. For the best-practice (more realistic) scenarios, safe reuse was met for Staphylococcus aureus if its concentration was kept below 10 6 cfu/100 mL. Salmonella enterica met the safe reuse requirements if a maximum concentration of 500 cfu/100 mL was maintained and Shigella spp. if a maximum concentration was lower than 5 cfu/100 mL. Based on reported concentrations of these bacteria in greywater, proper treatment and disinfection are recommended.