Effects of Resources Exploitation on Water Quality: case studies in Salt Water Intrusion and Acid Mine Drainage

Throughout the world, pressures on water resources are increasing, mainly as a result of human activity. Because of their accessibility, groundwater and surface water are the most used reservoirs. The evaluation of the water quality requires the identification of the interconnections among the water reservoirs, natural landscape features, human activities and aquatic health. This study focuses on the estimation of the water pollution linked to two different environmental issues: salt water intrusion and acid mine drainage related to the exploitation of natural resources. Effects of salt water intrusion occurring in the shallow aquifer north of Ravenna (Italy) was analysed through the study of ion- exchange occurring in the area and its variance throughout the year, applying a depth-specific sampling method. In the study area were identified ion exchange, calcite and dolomite precipitation, and gypsum dissolution and sulphate reduction as the main processes controlling the groundwater composition. High concentrations of arsenic detected only at specific depth indicate its connexion with the organic matter. Acid mine drainage effects related to the tin extraction in the Bolivian Altiplano was studied, on water and sediment matrix. Water contamination results strictly dependent on the seasonal variation, on pH and redox conditions. During the dry season the strong evaporation and scarce water flow lead to low pH values, high concentrations of heavy metals in surface waters and precipitation of secondary minerals along the river, which could be released in oxidizing conditions as demonstrated through the sequential extraction analysis. The increase of the water flow during the wet season lead to an increase of pH values and a decrease in heavy metal concentrations, due to dilution effect and, as e.g. for the iron, to precipitation.

Measurement of the atmospheric muon charge ratio with the OPERA detector

The atmospheric muon charge ratio, defined as the number of positive over negative charged muons, is an interesting quantity for the study of high energy hadronic interactions in atmosphere and the nature of the primary cosmic rays. The measurement of the charge ratio in the TeV muon energy range allows to study the hadronic interactions in kinematic regions not yet explored at accelerators. The OPERA experiment is a hybrid electronic detector/emulsion apparatus, located in the underground Gran Sasso Laboratory, at an average depth of 3800 meters water equivalent (m.w.e.). OPERA is the first large magnetized detector that can measure the muon charge ratio at the LNGS depth, with a wide acceptance for cosmic ray muons coming from above. In this thesis, the muon charge ratio is measured using the spectrometers of the OPERA detector in the highest energy region. The charge ratio was computed separately for single and for multiple muon events, in order to select different primary cosmic ray samples in energy and composition. The measurement as a function of the surface muon energy is used to infer parameters characterizing the particle production in atmosphere, that will be used to constrain Monte Carlo predictions. Finally, the experimental results are interpreted in terms of cosmic ray and particle physics models.

Continuous-Flow Magnetic Separation with Permanent Magnets for Water Treatment

More efficient water treatment technologies would decrease the water bodies’ pollution and the actual intake of water resource. The aim of this thesis is an in-depth analysis of the magnetic separation of pollutants from water by means of a continuous-flow magnetic filter subjected to a field gradient produced by permanent magnets. This technique has the potential to improve times and efficiencies of both urban wastewater treatment plants and drinking water treatment plants. It might also substitute industrial wastewater treatments. This technique combines a physico-chemical phase of adsorption and a magnetic phase of filtration, having the potential to bond magnetite with any conventional adsorbent powder. The removal of both Magnetic Activated Carbons (MACs) and zeolite-magnetite mix with the addition of a coagulant was investigated. Adsorption tests of different pollutants (surfactants, endocrine disruptors, Fe(III), Mn(II), Ca(II)) on these adsorbents were also performed achieving good results. The numerical results concerning the adsorbent removals well reproduced the experimental ones obtained from two different experimental setups. In real situations the treatable flow rates are up to 90 m3/h (2000 m3/d).