Hard water causes many problems in domestic and industrial usage, which has to be removed using costeffective technologies. To achieve this, the main goal of this study is to assess and optimize the factors controlling water softening applications. The research approach included a combined use of batch and column experiments performed in laboratory conditions through the ion exchange process, evaluating the effectiveness of natural and homoionic clinoptilolite on the removal characteristics of divalent cations. The equilibrium data could be fitted by both the Langmuir and the Freundlich models, even though it was fitted better by the Langmuir model with a maximum adsorption capacity of 10.5 mg g -1 for homoionic clinoptilolite (HC) and 9.68 mg g -1 for the natural clinoptilolite (NC). The adsorption kinetics can be successfully fitted to pseudo-second order kinetic model and the results of the intraparticle diffusion model suggest intraparticle diffusion was not the only rate-controlling step. It was also observed that the statistics indices of agreements from non-linear Thomas model were higher than that linear Thomas model. Nevertheless, the slope of the breakthrough curve for the linearized method decreased with increasing time as compared to non-linear method, thereby resulting in a slightly steeper slope for the nonlinear method and reducing the adsorption capacity. The study also concludes that the non-linear method is slightly more effective in predicting the performance of the selective removal efficiency of hardness ions. Results illustrate that clinoptilolite may be used as an alternative to more costly materials, due to its low cost and high abundance.

Population pressure, urbanization, and industrial developments, among other factors, have resulted in severe degradation of environmental resources such as wetlands. Thus, a groundwater model (MODFLOW) was integrated with a particle tracking MODPATH model to simulate the hydrodynamic flow head field and to analyze the vulnerability of the Salburua ecosystem and propose control measures to protect the riparian area. The simulations show that pathways of particle tracking originating at potential contaminant sources will tend to migrate downwards towards the sensitive ecosystem, which suggests that the quality of the hydrological ecosystem is likely to deteriorate in the future. Variation in exit points of particles indicates that the time-related capture areas are affected by changes of the hydraulic gradients. Two control measures of potential sources of pollutants in the vicinity of the Salbarua ecosystem were analyzed. The study results suggest that the travel time-related capture zone with a funnel-and-gate system is much smaller than without the control alternative, which indicates that the gate configuration has an effect on capture zone size and shape and on the residence time with a better attenuation performance. It is also shown that a leakage-proof barrier is less effective for point-source containment, assuming that hydraulic control performance and cost-efficiency are the criteria for pollution control effectiveness. Instead, a program of monitoring wells would effectively characterize water quality in the aquifer and provide a decision support system. This approach may be used in helping water managers to develop more physically based and quantitative protection strategies.

The estimation of soil hydraulic properties in the vadose zone has some issues, such as accuracy, acquisition time, and cost. In this study, an inexpensive automated test column (ATC) was developed to characterize water flow in a homogeneous unsaturated porous medium by the simultaneous estimation of three hydraulic state variables: water content, matric potential, and water flow rates. The ATC includes five electrical resistance probes, two minitensiometers, and a drop counter, which were tested with infiltration tests using the Hydrus-1D model. The results show that calibrations of electrical resistance probes reasonably match with similar studies, and the maximum error of calibration of the tensiometers was 4.6% with respect to the full range. Data measured by the drop counter installed in the ATC exhibited a high consistency with the electrical resistance probes, which provides an independent verification of the model and indicates an evaluation of the water mass balance. The study results show good performance of the model against the infiltration tests, which suggests a robustness of the methodology developed in this study. An extension to the applicability of this system could be successfully used in low-budget projects in large-scale field experiments, which may be correlated with resistivity changes.