The effects of temperature and pH on the water treatment performance of a point-of-use (POU) coagulant/disinfectant product were evaluated. Cold temperatures (ϳ5°C) reduced the bactericidal efficiency of the product with regard to Escherichia coli and total coliform log 10 reductions. There is evidence that point-of-use (POU) water treatment and safe storage techniques can be effective interventions to prevent diarrheal diseases in humanitarian emergency contexts (1). Water quality objectives for humanitarian relief (2) consist of no Escherichia coli per 100 ml, a free chlorine residual (FCR) of 0.5 mg/liter (30 min contact time and pH Ͻ 8), and turbidity of less than 5 nephelometric turbidity units (NTU).Coagulant/disinfection products (CDPs) are a POU water treatment option that provide microbial quality improvements, turbidity reductions, and a posttreatment FCR. Most commercially available CDPs are sachets containing a coagulant (e.g., ferric sulfate) and a disinfectant (e.g., calcium hypochlorite) along with other chemical components (e.g., oxidizing agents, flocculant aids, etc.) for a predetermined treatment volume. Cold temperatures (Ͻ5°C) can affect coagulant-assisted treatment processes (3), and alkaline pH levels (Ͼ8) can render free residual chlorination less effective (4). Thus, the effects of pH and temperature (under extreme conditions) should be an important part of the evaluation of the treatment efficiency of CDPs and were the objective of this study.Treatment efficiencies (i.e., bacterial removal, turbidity reductions, and FCR levels) were evaluated against current humanitarian water treatment objectives (2) and recent quantitative microbial risk assessment (QMRA)-based criteria for the evaluation of POU treatment options (5). This study focused on bacterial water quality improvements (i.e., E. coli removal), the microbial quality criterion in relief situations.Treatment steps of a CDP (PUR; Procter & Gamble Co., Pakistan) were adapted to a laboratory setup, namely, mixing (for 5 min), settling (for 5 min), cloth filtration, and continued disinfection (for 20 min). A Kemwater Flocculator 2000 (Kemira, Sweden) stirring paddle was set at 250 rpm to provide uniform mixing. A commercially available cloth (J-Cloth; Associated Brands, Canada) was used as the filtration material to simulate a worstcase scenario for this step. This was in line with the objective of evaluating the CDP's performance under simulated extreme conditions.The test water was a 1:5 dilution of primary settled wastewater (Station d'epuration Est, Québec) in dechlorinated tap water (5). Treatment efficiencies were tested under different conditions, namely, "reference" (pH 7, 20°C), "extreme pH" (pH 9, 20°C), and "cold temperature" (pH 7, 5°C). When needed, pH was adjusted with NaOH and H 2 SO 4 . A crushed ice jacket around the mixing vessel kept test water at 5 Ϯ 1°C. Turbidity was adjusted to approximately 100 NTU using a kaolin clay slurry. In order to further examine the temperature and pH effect on the different underpinnin...

This CDP has the potential to attain humanitarian drinking water quality objectives when not operating under extreme conditions; consistently achieving E. coli log10 reductions between 4·5 and 5·2 resulting in treated water with E. coli concentrations mostly below the <1 MPN per 100 ml target level.