Eugenio Muñoz Camacho

Boron Removal by Processes of Chemosorption

Abstract In this article, the results of the application of a boron removal treatment based on a process of chemosorption on liquid waste of urban, agricultural, or industrial origin is presented. The isotherms of the process have been established and a study of the influence of the different variables in the tests in columns has been carried out. The results obtained indicate that the process of chemosorption shows strongly favorable isotherms, and moreover it is notably influenced by the variable “flow rate,” making the breakthrough point appear earlier and the curves move towards the left. However, important differences in the curves for the variable “dimensions of the bed” have not been observed. Furthermore, a pH‐dependent mechanism for the treatment process of boronated effluents by means of chemosorption with the specific Amberlite IRA-743 resin was developed. According to breakthrough point data, experimentally achieved in elution tests for the maximum value allowed by environmental legislation, of 3 mg B L−1, a double mechanism is proposed. It can be suggested that for basic pH the mechanism corresponds to stereospecific reactivity between the borate ion and hydroxide groups of the N‐methylglucamine active site of the resin in cis‐position, a maximum appearing between pH 8.5 and 9.5, corresponding to borate ion predominance. On the other hand, a mechanism based on the hydrogen bridge bond formation reaction between the ionized amino group of the resin and boric acid is suggested for neutral and slightly acid pH. This last reaction differentiates this resin from the other absorbents used for boron removal in industrial wastes, such as metallic oxides, clays, humic acids, and so on.

Costs and feasibility of repowering wind farms

ABSTRACT The aim of this paper is to determine the main costs and the feasibility of repowering wind farms. For this purpose, two study methods, which depend on legal and wind turbines issues, have been considered. They will provide nine alternatives, whose study will be developed. The methodology has been applied to the particular case of Galicia (North-West of Spain), where there is a good onshore wind resource. Calculations indicate the costs, the Net Present Value (NPV), the Internal Rate of Return (IRR), and the Pay-Back Period of these alternatives. In addition, a sensitivity study has analyzed the main variables of dependence in repowering wind farms. Results show that repowering can be a new alternative for onshore wind farms in areas where old wind turbines are currently installed.