High arsenic (As) levels in drinking water supplies cause several health issues such as cancers as well as cardiovascular/neurological implications. An EU directive has therefore determined that the new Maximum Contaminant Level (MCL) is 10 µgAs/L.
The EU-funded AQUASZERO project is working on developing low-cost adsorbent materials for use in water treatment systems to efficiently remove As and fulfil regulatory requirements.
In the first year of the project, work focused on developing iron (Fe)-based adsorbent materials to optimise As removal. Project partners from Greece, England,Spain and Romania created a European As concentration map representing As levels in groundwater. A leaching test procedure was developed for use in the project after examining leaching behaviours of currently used As adsorbents. This was followed by a comprehensive cost analysis that confirmed the economic viability of the proposed AQUASZERO product.
Lab-scale production of single Fe oxyhydroxides and binary Fe–manganese (Mn) oxyhydroxides was successful after evaluating and optimising parameters such as Fe/Mn ratio, pH and reagents. Based on results and characterisation of the physicochemical properties of the final adsorbent, the optimum reactor design and configuration was determined for pilot-scale studies. Suitable sludge handling and treatment techniques were selected for the solid adsorbents and optimised after extensive evaluation.
In the project's second year, pilot-scale production of the two selected adsorbent materials — AquAsZero–Fe and AquAsZero–Fe/Mn — was realised. Rapid small-scale column adsorption tests with As (V) and As (III) at concentrations of 500 µg/L were conducted to compare performance of commercial adsorbents with AQUASZERO adsorbents. Both adsorbents showed over 30 % higher arsenate adsorption capacities (at around 11.5 µg/mg) than the two commercial adsorbents. The AQUASZERO adsorbents also met the regulatory requirements for leached arsenic limits and non-toxicity for landfill disposal. The AquAsZero–Fe/Mn adsorbent is the most efficient in AS (III) and As (V) removal, whereas the AquAsZero–Fe is more cost effective for water containing mostly As (V).
Project outcomes were highly successful and won national awards for innovation in Greece in 2011. Patent applications were also filed. Future work will focus on disseminating results and strategising to facilitate commercialisation of AQUASZERO adsorbents and related technologies. This should increase the competitiveness of participating companies and enable water treatment system manufacturers to meet the new MCL cost effectively.