Bacterial-assisted adsorption technology for arsenic removal from water (BATA)

The health of millions of people world-wide is at risk due to the use of drinking arsenic-contaminated water. Furthermore the use of contaminated tube wells as irrigation source is generating worldwide concern on As accumulation and mobilization in agricultural topsoil. In recent years, a range of inexpensive, iron-based, water clean-up technologies have been developed to address the major problem of As-rich drinking water. Pilot studies based on the use of ZVI are randomly presented in literature and most of them are based on short term experiments, hence there is need of increase knowledge on ZVI performance to remove As on long term basis and to evaluate the influence of different parameters (water chemistry, system hydraulic, As speciation) on material performance and to assess ecological impact of the proposed technology. The possible use of AsIII oxidising bacteria has been investigated as effective oxidation step overcoming drawbacks of chemical oxidation in biofilter studies coupled with As removal treatment based on Fe adsorbents. The survey of study sites and sampling will be conducted according to operative indications of ARPALombardia. Speciation of As will be carried out by Ion Chromatography in combination with ICP-MS and iron speciation will be determined on site by spectrophotometric methods. Description of functional bacterial communities in As rich waters will be performed by a metagenomic approach using specific molecular probes for genes coding for enzymes involved in arsenic, iron and sulfur cycles. Biodiversity and phylogeny of the genes present in different samples will be evaluated by Next generation bar-coded sequence technologies. New indigenous AsIII oxidising strains will be isolated and characterised according to phenotypic and molecular methods. AsIII oxidising activity will be evaluated also in the presence of organic and inorganic pollutants eventually recovered in ground waters. The most effective bacteria will be produced at large scale in a 60 L-bioreactor in order to be used in lab- and pilot-scale experiments. These treatments will be conducted with different iron-based adsorbing materials. Long term studies will be conducted considering physic-chemical parameters that affect removal performance. The choice of “environment friendly” coatings will be considered to extend the ironmaterial duration and the use of AsIII oxidizing selected bacteria will be included to improve the efficiency of the proposed process. Based on results and on expertise acquired, innovative strategies will be proposed for the implementation of a pilot scale process for arsenic removal from ground waters.