Background Groundwater pollution by arsenic and associated components is a common problem in the entire Carpathian Basin. Where arsenic in groundwater is concerned, Hungary is the most seriously affected of the EU and accession States. Approximately 400 towns and villages in Hungary have arsenic levels greatly exceeding those set by EU and the World Health Organisation (WHO) guidelines. Within the project area, 170 000 people are supplied with drinking water derived from groundwater which contains arsenic levels 30 times higher than specified by EU norms, as well as variable amounts of methane, ammonia, iron and manganese. The EU has determined that water quality must be in line with EU norms by 2009. Objectives The SUMANAS project’s first objective was to create a groundwater-management decision-support system, based on hydro-geological models, taking into account local needs, cost aspects and best practices. Using the Gyula region of Hungary as its main test site, the project intended to develop a management plan for Southern Hungarian regions with high arsenic content in their groundwater. The second objective was to demonstrate an innovative arsenic-removal technology, which can treat the groundwater types of Southern Hungary. Finally, the project aimed to disseminate the methodology and technology to other regions in the EU, as well as to accession countries. Results The SUMANAS project achieved its objectives: it constructed and now operates a pilot that is able to remove ammonia, methane and arsenic from water in two steps with 98% efficiency. The project also assessed the scale of the arsenic content of the groundwater in South-Hungary and assessed the costs of implementing arsenic reduction technology. However, the foreseen management plan was not adequately prepared and it is not clear what its use in the future will be. The technology for arsenic removal involves a low cost adsorbent, the lifetime and cost effectiveness of which is extended by regeneration. The technology was demonstrated at 6 sites in Hungary and Romania as part of the project. The pilot can be moved everywhere, as it is a mobile station. The pilot removes arsenic, methane, iron, ammonium and manganese at the rate of 100 m3 water per day. Arsenic is removed (adsorbed) completely as soon as water filtrates through the filter units. The ammonium removal technology does not require any chemicals, and the effective arsenic removal also does not require continuous chemical dosing. The pilot technology functions in the following way: groundwater firstly enters the aeration unit, it then passes via the ammonia filter to the two arsenic removal filters, and is finally collected in a clean water storage tank. The treatment steps are summarised below: 1. Aeration: this serves 2 purposes, to remove methane (98% removal achieved) and to oxygenate the water. This is needed prior to the second step. 2. Ammonia removal: this is a biological step using only natural bacteria for converting the ammonia into nitrate. The step is fully functional after 4-5 days of operation. 3. Arsenic removal: Arsenic is removed in general by the first filter, with the second filter acting as a reserve. Both Arsenic III and V are removed through the use of an adsorbent. The treatment costs of the new pilot is about 10 cent/m3 for a complete treatment. The Basic Cost Benefit Analysis showed that the operation and maintenance costs of the pilot are about 38 cents/m3 of arsenic free water. Costs for a full scale plant are estimated to be even lower and this pilot technology is easily scalable to a full size plant. The project participants have agreed that the pilot should continue to operate for demonstrative purposes. The pilot will therefore remain temporarily at the last site of its operation in Óföldeák. After the pilot obtains its general approval for application in Hungary, the pilot’s complex arsenic removal technology will be considered officially part of the Hungarian drinking water improvement programme, and could be used in several places in Hungary. Furthermore, the partner SELOR will try to realise the new demonstrative operation of the pilot, either in Hungary or somewhere else in Europe. Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section).