Advancing performance evaluation standards for household water treatment technologies.

Diarrheal illnesses and fatalities continue to be major issues in many regions throughout the world. Household water treatment (HWT) technologies (including both point-of-use (POU) and point-of-entry (POE) treatment solutions) have been shown as able to deliver safe water in many low-income communities. However, as shown herein, there are important inconsistencies in protocols employed for validating performance of HWTs. The WHO does not stipulate influent concentration as a parameter that could influence removal efficacy, nor does it indicate an influent concentration range that should be used during technology evaluations. A correlation between influent concentration and removal is evidenced herein (R2 = 0.88) with higher influent concentrations resulting in higher log-removal values (LRVs). The absence of a recommended standard influent concentration of bacteria (as well as for viruses and protozoa) could have negative consequences in intervention efforts. Recommendations are provided that regulatory bodies should specify an influent concentration range for testing and verification of HWT technologies.

A systematic review of waterborne disease burden methodologies from developed countries.

The true incidence of endemic acute gastrointestinal illness (AGI) attributable to drinking water in Canada is unknown. Using a systematic review framework, the literature was evaluated to identify methods used to attribute AGI to drinking water. Several strategies have been suggested or applied to quantify AGI attributable to drinking water at a national level. These vary from simple point estimates, to quantitative microbial risk assessment, to Monte Carlo simulations, which rely on assumptions and epidemiological data from the literature. Using two methods proposed by researchers in the USA, this paper compares the current approaches and key assumptions. Knowledge gaps are identified to inform future waterborne disease attribution estimates. To improve future estimates, there is a need for robust epidemiological studies that quantify the health risks associated with small, private water systems, groundwater systems and the influence of distribution system intrusions on risk. Quantification of the occurrence of enteric pathogens in water supplies, particularly for groundwater, is needed. In addition, there are unanswered questions regarding the susceptibility of vulnerable sub-populations to these pathogens and the influence of extreme weather events (precipitation) on AGI-related health risks. National centralized data to quantify the proportions of the population served by different water sources, by treatment level, source water quality, and the condition of the distribution system infrastructure, are needed.

Performance results from the Tucumán solid waste bioreactor.

Performance results obtained from a 6200 ton demonstration-scale anaerobic bioreactor, constructed on the Pacara Pintada Landfill in Tucumán, Argentina, are described. The operational aspects over a 30-month period for the Tucumán bioreactor demonstrate the ability to maintain the bioreactor in the mesophilic range, with the result that the generation and collection of the biogas has been maintained at accelerated rates with a rate constant of approximately 0.5 year(-1). Field measurements of metal concentrations in leachate indicated significant attenuation over time. Refuse subsidence, measured over a 28-month period, ranged from 4% to 19%, with an average of 11% subsidence across the Tucumán cell.

PAH deposition to snow surface. Chemical analysis and interpretation of results.

The urban snowpack effectively acts as a collection device for atmospheric-deposited PAHs. When these PAHs are flushed out in a short time interval along with springtime snowmelt, these cause shockloading to receiving waters. In order to assess the PAH deposition and accumulation in urban snowpacks, a deposition survey of PAH for the winter months of 1991-92 from the city of Sault Ste. Marie, Ontario, Canada was undertaken. The results of the survey are interpreted in view of prevailing meteorology and various emission sources in the study area. The relative PAH deposition levels (to BaP) are compared with relative source emission fingerprints to examine consistency in sampling and analysis. While analyzing the PAH samples using the ASTM (1987) method, the problem of concentration levels being below the detection level was encountered. The ASTM method for PAH analysis was modified to enhance the detection limit of the PAHs by concentrating the PAH extract to very low volumes, on the order of 200-300 microL.