This study examined bacteria and nutrient quality in tile drainage and shallow ground water resulting from a fall land application of liquid municipal biosolids (LMB), at field application rates of 93,500 L ha(-1), to silt-clay loam agricultural field plots using two different land application approaches. The land application methods were a one-pass AerWay SSD approach (A), and surface spreading plus subsequent incorporation (SS). For both treatments, it took between 3 and 39 min for LMB to reach tile drains after land application. The A treatment significantly (p < 0.1) reduced application-induced LMB contamination of tile drains relative to the SS treatment, as shown by mass loads of total Kjeldahl N (TKN), NH(4)-N, Total P (TP), PO(4)-P, E. coli., and Clostridium perfringens. E. coli contamination resulting from application occurred to at least 2.0-m depth in ground water, but was more notable in ground water immediately beneath tile depth (1.2 m). Treatment ground water concentrations of selected nutrients and bacteria for the study period ( approximately 46 d) at 1.2-m depth were significantly higher in the treatment plots, relative to control plots. The TKN and TP ground water concentrations at 1.2-m depth were significantly (p < 0.1) higher for the SS treatment, relative to the A treatment, but there were no significant (p > 0.1) treatment differences for the bacteria. For the macroporous field conditions observed, pre-tillage by equipment such as the AerWay SSD, will reduce LMB-induced tile and shallow ground water contamination compared to surface spreading over non-tilled soil, followed by incorporation.

The wide spread occurrence of geogenic arsenic in Bangladesh groundwater drastically reduced the safe water access across the country. Since its discovery in 1993, different mitigation options tested at household and community scale have resulted in limited success. The main challenge is to develop a simple, cost-effective, and socially acceptable option which the users can install, operate and maintain by themselves. In an arsenic hotspot of southeastern Bangladesh, 841 arsenic removal filter (ARF), 190 surface water filter membrane, 23 pond sand filter (PSF), 147 rain water harvester (RWH) and 59 As-safe tubewell were distributed among the severely exposed population by AsMat, a Sida supported project. After 3-4 years of providing these safe water options, this study was carried out during 2009-2010 for performance analysis of these options, in terms of technical viability and effectiveness and thus to evaluate the preference of different options to the end users. Household and community based surveys were done to make an assessment of the current water use pattern as impact of the distributed options, overall condition of the options provided and to identify the reasons why these options are in use and/or abandoned. In total, 284 households were surveyed and information was collected for 23 PSF, 147 RWH, and 59 tubewells. None of the filters was found in use. Among other options distributed, 13% of PSF, 40% RWH, and 93% of tubewell were found functioning. In all cases, tubewells were found As-safe. About 89% of households are currently using tubewell water which was 58% before. Filter was abandoned for high cost and complicated maintenance. The use of RWH and PSF was not found user friendly and ensuring year round water quality is a big challenge. Arsenic-safe tubewell was found as a widely accepted option mainly because of its easy operation and availability of water, good water quality and negligible maintenance. This study validated tubewell as the most feasible drinking water supply option and this evaluation holds significance for planning water supply projects, improving mitigation policy as well as developing awareness among users.

Temporal and seasonal variability of As concentrations in groundwater were evaluated in As-affected areas of Matlab, southeastern Bangladesh. Groundwater samples from 61 randomly selected tubewells were analyzed for As concentrations over a period of three years and four months (from July 2002 to November 2005) and monitored seasonally (three times a year). The mean As concentrations in the sampled tubewells decreased from 153 to 123 μg/L during July 2002 to November 2005. Such changes were pronounced in tubewells with As concentration >50 μg/L than those with As concentrations <50 μg/L. Similarly, individual wells revealed temporal variability, for example some wells indicated a decreasing trend, while some other wells indicated stable As concentration during the monitoring period. The mean As concentrations were significantly higher in Matlab North compared with Matlab South. The spatial variations in the mean As concentrations may be due to the differences in local geological conditions and groundwater flow patterns. The variations in mean As concentrations were also observed in shallow (<40 m) and deep (>40 m) wells. However, to adequately evaluate temporal and seasonal variability of As concentration, it is imperative to monitor As concentrations in tubewells over a longer period of time. Such long-term monitoring will provide important information for the assessment of human health risk and the sustainability of safe drinking water supplies.

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