Household Water Treatment Systems Research Articles

Seasonal fluctuations and mobility of arsenic in groundwater resources, Anchorage, Alaska

Abstract There are approximately 12,000 private wells in the Municipality of Anchorage, Alaska, USA, that supply drinking water to thousands of homeowners. The results presented in this paper are from a study conducted to understand the speciation and seasonal fluctuations of As in the groundwater of Anchorage. A total of eight private drinking water wells were sampled from May to October, 2007, to determine inorganic species of As (III/V) and other physiochemical parameters of the groundwater. Arsenic concentrations above Environmental Protection Agency (EPA) drinking water standard of 10 μg/L had been previously measured in all of these eight wells by the Municipality of Anchorage. Seven of the wells draw water from glaciofluvial aquifers and one well taps into the older bedrock aquifer on the mountain-side. In-situ measurements as well as groundwater samples were collected from each well and inorganic species of As (III/V) were separated in the field using anion exchange columns. Elemental analysis was conducted by inductively coupled plasma mass spectrometry (ICP-MS), major anions by ion chromatography (IC), and Fe (II) and total Fe were measured in the field with a portable spectrophotometer. The groundwater was neutral to basic ranging in pH from 7.6 to 8.8, dissolved O2 was generally 0.1–1.0 mg/L and specific conductance ranged from 300 to 1000 μS/cm. Most of the groundwater is classified as Ca–Mg–HCO3 and dissolved As concentrations ranged from below detection (∼0.5 μg/L) to 117 μg/L with arsenite as the dominant species. Filtered and unfiltered water samples had less than 1% difference in As concentrations suggesting that most As occurs in the dissolved form. Arsenic concentrations were positively correlated with water levels indicating that the highest As concentrations occur in the aquifer during recharge events. Positive relationships with dissolved Fe and supersaturation with respect to secondary Fe oxides indicates that the As is likely associated with the Fe oxides that are partially dissociated under the dominating reducing conditions of the aquifers. There is also evidence of a positive relationship between As and SO 4 2 - which indicates that some of the As may be associated with the oxidation of Fe-bearing sulfides such as pyrite or arsenopyrite, however, this is thought to be a less important process for this system compared to Fe reduction. Most of the groundwater samples indicate supersaturation with respect to carbonates such as calcite, dolomite and siderite and there is a positive relation between As and HCO 3 - indicating that carbonate buffering is an important process in the groundwater geochemistry of As. In some cases homeowners filter their tap water with household water treatment systems which have a range of As removal effectiveness from about 25–100%.

Household water treatment systems: A solution to the production of safe drinking water by the low-income communities of Southern Africa

One of the United Nations Millennium Development Goals is to reduce to half by 2015 the number of people, worldwide, who lack access to safe water. Due to the numerous deaths and illnesses caused by waterborne pathogens, various household water treatment devices and safe storage technologies have been developed to treat and manage water at the household level. The new approaches that are continually being examined need to be durable, lower in overall cost and more effective in the removal of the contaminants. In this study, an extensive literature survey was conducted to regroup various household treatment devices that are suitable for the inexpensive treatment of water on a household basis. The survey has resulted in the selection of four household treatment devices: the biosand filter (BSF), bucket filter (BF), ceramic candle filter (CCF) and the silver-impregnated porous pot filter (SIPP). The first three filters were manufactured in a Tshwane University of Technology workshop, using modified designs reported in literature. The SIPP filter is a product of the Tshwane University of Technology. The performance of the four filters was evaluated in terms of flow rate, physicochemical contaminant (turbidity, fluorides, phosphates, chlorophyll a, magnesium, calcium and nitrates) and microbial contaminant (Escherichia coli, Vibrio cholerae, Salmonella typhimurium, Shigella dysenteriae) removals. The flow rates obtained during the study period were within the recommended limits (171l/h, 167l/h, 6.4l/h and 3.5l/h for the BSF, BF, CCF and SIPP, respectively). Using standard methods, the results of the preliminary laboratory and field studies with spiked and environmental water samples indicated that all filters decreased the concentrations of contaminants in test water sources. The most efficiently removed chemical contaminant in spiked water was fluoride (99.9%) and the poorest removal efficiency was noted for magnesium (26–56%). A higher performance in chemical contaminant removal was noted with the BF. For pathogenic bacteria, the mean percentage removals ranged between 97% and 100%. Although the concentrations of most chemical parameters were within the recommended limits in raw surface water, poor removal efficiencies were recorded for all filters, with the poorest reduction noted with fluorides (16–48%). The average turbidity removals from surface water ranged between 90% and 95% for all filters. The highest bacterial removal efficiency was recorded by the SIPP (99–100%) and the lowest by the BF (20–45%) and the BSF (20–60%). Extensive experimental studies with various types of raw surface water will still determine the long-term performance of each filter, as well as the filters that can be recommended to the communities for household treatment of drinking water.

The Influence of Differing Sand Media On the Performance of the Biosand Intermittent Slow Sand Filter

The Influence of Differing Sand Media On the Performance of the Biosand Intermittent Slow Sand FilterThe biosand filter is an affordable household water treatment system appropriate for use in many developing countries. Sand derived from crushed rock is recommended for the filter, but it is not always locally available. This study compares the performance of twelve biosand filters, four each using sand media from three different sources: ocean beach, river beach, and rock quarry. Twenty liters of...Author(s)William F. DukeAsit MazumderSourceProceedings of the Water Environment FederationSubjectSession 10 - Design for ImplementationDocument typeConference PaperPublisherWater Environment FederationPrint publication date Jan, 2009ISSN1938-6478SICI1938-6478(20090101)2009:1L.602;1-DOI10.2175/193864709793848068Volume / Issue2009 / 1Content sourceDisinfection and Reuse SymposiumFirst / last page(s)602 - 615Copyright2009Word count201Subject keywordsHousehold water treatmentpoint-of-use water treatmentintermittent slow sand filtrationbiosand filter

Assessing the sustainability of the silver-impregnated ceramic pot filter for low-cost household drinking water treatment

A low-cost technology to treat water at the household level is the ceramic silver-impregnated pot filter (CSF). The CSF consists of a pot-shaped filter element that is placed in a plastic receptacle. The ceramic pot filter is a promising treatment system to supply safe drinking water especially to people living in rural areas. The focus of this study was to assess the sustainability of a household drinking water treatment system based on five criteria: (i) accessibility, (ii) water quality, (iii) water production, (iv) functionality, and (v) environmental footprint. The removal of Escherichia coli and protozoan (oo)cysts was found to be significant, which was supported by the reduction in diarrhoea cases observed by CSF users in a recent field study. The retention of MS2 bacteriophages as an indicator for virus removal was, however, found to be unsatisfactory. It is therefore recommended that research on virus removal by CSF continues, especially in relation to the colloidal silver application and other potential additives. The criterion of water production was shown to be the limiting factor, because it reduced substantially during treatment of surface water. The fast clogging of the CSF during the first hours of use was caused neither by inorganic nor organic fouling, but by colloidal particles. Two direct effects may be identified from the decreasing flow rate: frequent scrubbing and higher water prices. Frequent scrubbing results in a higher risk of recontamination and breakage. Based on this finding the authors recommend an optimization study to increase the initial flow rate without sacrificing the removal efficiency.

05/02164 A novel TiO 2-assisted solar photocatalytic batch-process disinfection reactor for the treatment of biological and chemical contaminants in domestic drinking water in developing countries

A low-cost technology to treat water at the household level is the ceramic silver-impregnated pot filter (CSF). The CSF consists of a pot-shaped filter element that is placed in a plastic receptacle. The ceramic pot filter is a promising treatment system to supply safe drinking water especially to people living in rural areas. The focus of this study was to assess the sustainability of a household drinking water treatment system based on five criteria: (i) accessibility, (ii) water quality, (iii) water production, (iv) functionality, and (v) environmental footprint. The removal of Escherichia coli and protozoan (oo)cysts was found to be significant, which was supported by the reduction in diarrhoea cases observed by CSF users in a recent field study. The retention of MS2 bacteriophages as an indicator for virus removal was, however, found to be unsatisfactory. It is therefore recommended that research on virus removal by CSF continues, especially in relation to the colloidal silver application and other potential additives. The criterion of water production was shown to be the limiting factor, because it reduced substantially during treatment of surface water. The fast clogging of the CSF during the first hours of use was caused neither by inorganic nor organic fouling, but by colloidal particles. Two direct effects may be identified from the decreasing flow rate: frequent scrubbing and higher water prices. Frequent scrubbing results in a higher risk of recontamination and breakage. Based on this finding the authors recommend an optimization study to increase the initial flow rate without sacrificing the removal efficiency.

An innovative approach to small town water quality improvements

Innovative solutions are required to meet the conflicting criteria of service level, community need, community desire, cost and risk to the supply authority in the delivery of water quality improvements to small regional communities. Grampians Region Water Authority services 74 towns in North-Western Victoria, an area of generally low rainfall, sparse settlement and few natural waterways. Town populations range from 10 to 13,000, with 56 towns having less than 500 people. A Water Quality Improvement Plan was recently developed by Grampians Water to address these natural difficulties. The plan examined a broad range of alternatives beyond the single-pipe reticulated supply system, including dual-pipe reticulation, rainwater sources and household water treatment systems for achieving target quality levels. The key findings were:• regional treatment plants are not economical if towns are more than 25 km apart• salinity is a major influence on strategy• for low salinity supplies, conventional treatment is most economical• for marginal salinity supplies, a two stage process involving conventional treatment and desalination is appropriate• desalination provides a total solution for high salinity groundwater supplies• drinking quality can only be economically achieved in very small towns by using household treatment of rainwater in a dual supply system. The resultant strategies and implementation issues outlined reveal some significant variations to the conventional approach.