Innovative method for the brine treatment by electrokinetic principles integrated with solar photovoltaic plants.

With the growing world population and industrial production, the demand for water has been continuously increasing. By 2030, it was estimated that 60.0 % of the world population will not have access to freshwater, which is about 2.50 % of the total global water. For this, a total of over 17,000 operational desalination plants have been constructed worldwide. However, the key barriers to expansion of the desalination treatments are the brine production and energy consumption. In fact, the brine production is 50.0 % higher than the freshwater, and its treatments could account for 5.0-33.0 % of total desalination cost. Here, a new theoretical approach for brine treatments integrated to solar photovoltaic plants (PVs) to supply renewable energy to the whole system has been proposed. This approach consists in combining electrokinetic and electrochemical phenomena to dilute the brine, by using an alkaline clay with high buffering power. This method substantially desalinates the brine to produce new treated seawater, using clean energy, optimizing energetic and management costs. Some hypotheses and secondary effects should validate the model, e.g., relatively high Ca2+ promotes the electro-migration; the Cl2 production reduces the Cl- concentrations; and the production of H2 can be used to store energy. A practical example for PVPs design is shown.

Optimization of energy consumptions of oxidation tanks in urban wastewater treatment plants with solar photovoltaic systems.

This paper combines solar photovoltaic (PV) to wastewater treatment plants (WWTPs). A new methodology is proposed to design solar PV to reduce energy consumptions of aeration thanks in WWTPs. New analytical equations and parameters, based on the air temperatures, solar irradiations, biological kinetics, dissolved oxygens, mechanical oxygenations, are introduced to obtain the peak power of PV that maximize the auto-consumptions of aeration blowers installed in the oxidation tanks of WWTPs. The method allows a direct preliminary design and a calibrated estimation for energy power. To justify this method, three aspect are mainly discussed: (i) the oxidation tanks consume up to 30% of the energy of a WWTP; (ii) the temperature of wastewater is variable during the year, in the smaller WWTPs; (iii) the dissolved oxygen reduces, increasing temperature of wastewater. This methodology will support the sector in making decision over PV investments, helping wastewater utilities to consider sustainable management practices. Therefore, a further contribute to develop the integration of renewable energy sources combined with wastewater sectors is activated.

Enhanced electrokinetic treatment of marine sediments contaminated by heavy metals and PAHs.

Dredged sediments contaminated by heavy metals and PAHs were subjected to both unenhanced and enhanced electrokinetic remediation under different operating conditions, obtained by varying the applied voltage and the type of conditioning agent used at the electrode compartments in individual experiments. While metals were not appreciably mobilized as a result of the unenhanced process, metal removal was found to be significantly improved when both the anodic and cathodic reservoirs were conditioned with the chelating agent EDTA, with removal yields ranging from 28% to 84% depending on the contaminant concerned. As for the effect on organic contaminants, under the conditions tested the electrokinetic treatment displayed a poor removal capacity towards PAHs, even when a surfactant (Tween 80) was used to promote contaminant mobilization, indicating the need for further investigation on this issue. Further research on organics removal from this type of materials through electrokinetic remediation is thus required. Furthermore, a number of technical and environmental issues will also require a careful evaluation with a view to full-scale implementation of electrokinetic sediment remediation. These include controlling side effects during the treatment (such as anodic precipitation, oxidation of the conditioning agent, and evolution of toxic gases), as well as evaluating the potential ecotoxicological effects of the chemical agents used.