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Factors affecting uranium removal from brackish groundwater using a direct solar powered ultrafiltration-nanofiltration/reverse osmosis membrane system were investigated during a field trial in the Australian outback. The key variables were uranium speciation (as a function of pH), groundwater type as well as energy variation over the course of a day. It was found that uranium was retained by the membranes over the pH range 3-11, but strongly adsorbed to membranes at pH 4-7. The speciation of uranium at pH 4-7 explained the adsorption to the membrane. The presence of other inorganic species, in particular calcium, was a likely cause of uranium co-precipitation at pH 10-11. During solar energy experiments, it was found that the specific energy consumption increased over the course of the day. This indicated fouling through precipitation on the membranes which caused reduced retention of uranium towards the end of the solar day. (C) 2009 Elsevier B.V. All rights reserved.

Influence of organic matter (OM) on uranium removal mechanisms by ultrafiltration (UF) over a pH range of 3-11 was investigated. Humic, alginic and tannic acid were used as OM. it was found that uranium adsorbed strongly to the membrane while retention by size exclusion did not occur. Adsorption was dependent on pH and type of OM used. Speciation predictions performed using Visual Minteq explain some of these results. In the absence of OM, uranium primarily adsorbed to the membrane at pH 5 and 7 where UO2OH+ and UO2CO3 were the dominant species. In the presence of humic acid (HA), uranium adsorption increased in the acidic range, especially at pH 3 (from 11% to 74%) due to the complexation. The structure of alginic acid (AA) did not favour complexation with uranium and therefore did not have a significant influence on its behaviour in UF. The exception was at pH 3 where adsorption increased from 11% to 52%. At this pH no charge repulsion between the uranium species and the AA occurs and complexation is favoured. The highest effect on uranium adsorption was obtained in the presence of tannic acid (TA) at pH 10 and I I where adsorption increased from 20% up to 100%. Uranium is most likely forming complexes with the gallic acid fraction of the dissociated TA. (C) 2009 Elsevier B.V. All rights reserved.

To reduce child mortality and improve health in Ghana boreholes and wells are being installed across the country by the private sector, NGO's and the Ghanaian government. Water quality is not generally monitored once a water source has been improved. Water supplies were sampled across Ghana from mostly boreholes, wells and rivers as well as some piped water from the different regions and analysed for the chemical quality. Chemical water quality was found to exceed the WHO guidelines in 38% of samples, while pH varied from 3.7 to 8.9. Excess levels of nitrate (NO3-) were found in 21% of the samples, manganese (Mn) and fluoride (F-) in 11% and 6.7%, respectively. Heavy metals such as lead (Pb), arsenic (As) and uranium (U) were localised to mining areas. Elements without health based guideline values such as aluminium (Al, 95%) and chloride (Cl, 5.7%) were found above the provisional guideline value.Economic information was gathered to identify water costs and ability to pay. Capital costs of wells and boreholes are about 1200 pound and 3800 pound respectively. The majority of installation costs are generally paid by the government or NGO's, while the maintenance is expected to be covered by the community. At least 58% of the communities had a water payment system in place, either an annual fee/one-off fee or "pay-as-you-fetch". The annual fee was between 0.3-21 pound, while the boreholes had a water collection fee of 0.07-0.7 pound/m(3), many wells were free. Interestingly, the most expensive water (2.9-3.5 pound/m(3)) was brought by truck. Many groundwater sources were not used due to poor chemical water quality. Considering the cost of unsuccessful borehole development, the potential for integrating suitable water treatment into the capital and maintenance costs of water sources is discussed. Additionally, many sources were not in use due to lack of water capacity, equipment malfunction or lack of economic resources to repair and maintain equipment. Those issues need to be addressed in combination with water quality, coordinated water supply provision and possible treatment to ensure sustainability of improved water resources. (C) 2010 Published by Elsevier B.V.

In order to provide safe drinking water in isolated communities where water supply and electrical infrastructure is limited, a system combining solar energy and advanced water treatment technology (a two-staged membrane process with ultrafiltration followed by nanofiltration/reverse osmosis) has been developed. The objective of this study is to model the speciation of commonly occurring and sometimes health-threatening trace contaminants, and then to evaluate the impact of speciation on fluoride, arsenic, and magnesium retention by nanofiltration/reverse osmosis. A series of experiments were performed in central Australia in late 2005 to assess elemental retention with four different membrane modules (BW30, ESPA4, NF90, and TFC-S) at various pH values between 3 and 11 at two different source waters (Pine Hill Station and Ti Tree Farm). The removal of fluoride and arsenic was observed to be independent of pH, while magnesium removal is pH dependent. Compound speciation is considered to explain dependence observations. Membrane type was found to impact retention. The results obtained in this study will provide valuable information on the reliability and the optimization windows of the renewable energy powered desalination system that has been developed

This study focuses on Ghana. The majority of the Ghana’s population (58%) live in rural areas. Many of these people live without the national infrastructure such as electricity grid and water services [3] and 66% of these people rely on surface water as a drinking water source, exposing them to waterborne diseases, such as diarrhoea, guinea worm and schistosomiasis [4, 5]. Unsafe water is a major cause of illness in the country, where one in ten children dies before the age of five [4]. The supply of clean water is limited by a lack of infrastructure, capacity and financial resources [6]. In an attempt to supply clean water boreholes are being drilled, which limits the contamination from waterborne diseases. However, waters are rarely monitored following bore construction for the presence of inorganic contaminants such as arsenic and fluoride [7-10]. Elevated concentrations above the WHO drinking water guidelines have been found of iron, manganese, arsenic, fluoride, lead and chromium in water sources in Ghana [11]. These may be naturally present in the groundwater, or may be caused by land-use and industry. Gold mining is one of the main industries in Ghana accounting for 44% of Ghana’s export earnings [12]. The large-scale extraction taking place in mainly Western and Ashanti region e.g. Bibiani and Obuasi, brings with it arsenic, mercury and sulphur contamination to water bodies, soil and even air pollution causing acid rain and degradation to the surrounding environment and impacts on human health [13-15]. Since legalisation of small-scale gold mining extraction in 1989, many people make a living through gold mining, employing extraction methods that inevitably release mercury into surrounding water sources [12, 16]. Although the major gold mining has taken place