CARACTERIZACIÓN QUÍMICA Y AGRONOMICA DE LAS AGUAS RESIDUALES DEL YACIMIENTO CASTELLANO, PINAR DEL RIO/Chemical and agronomic characterization of sewage water from the Castellano deposit, Pinar del Rio

The reuse of sewage water in agriculture results in a future need in many countries, since this sector employs almost 70 % of available freshwater, and there have been reports on critical levels of water deficit in many regions around the world. Cuba is not exempt from these problems, and its national politics towards water promotes the implementation of this practice. Therefore, in the current paper, an attempt has been carried out to characterize and to assess the quality of mining sewage water and its use in agriculture. To achieve successfully this aim, five punctual samples were collected from the creek "Biajaca", where sewage waters coming from Minas Castellano, in Minas de Matahambre, Pinar de Río are discharged. These five punctual samples to form one composed sample were combined and so the pH and electrical conductivity were measured. After filtering and keeping the proper conservation, the following elements Na, K, Ca, Mg, B, Al, Bi, Cd, Co, Cr, Cu, Fe, Li, Mn, Ni, Pb, Sr, Tl, Zn, As, Be, Sb, Se, Mo, V, Ti, S, P, Rb were determined through digestion in microwave and analysis by ICP-OES. On the other hand, the ions [F.sup.-], [Cl.sup.-], N[O.sub.2.sup.-], [Br.sup.-], N[O.sub.3.sup.-], P[O.sub.4.sup.3-], S[O.sub.4.sup.2-] were determined by ion-exchange liquid chromatography. The results showed that it is a type of water characteristic of the study area, with an acid pH and salinity, permeability and toxicity indicators suitable for its usage in agriculture, as long as its acidity is pre-neutralized. Key words: water quality, permeability, water reuse, salinity, toxicity La reutilización de las aguas residuales en la agricultura es una necesidad futura en muchos países, ya que este sector emplea casi el 70 % del agua dulce disponible y se han reportado niveles de déficit hídrico críticos en muchas regiones del mundo. Cuba no está exenta de estos problemas y su política nacional del agua promueve la aplicación de esta práctica. Por esta razón, en el presente trabajo se caracterizó y evaluó la calidad de las aguas residuales mineras para su uso en la agricultura. Se colectaron cinco muestras puntuales en el arroyo "Biajaca" donde descargan aguas residuales provenientes de las Minas Castellano, en Minas de Matahambre, Pinar de Río. Las cinco muestras puntuales se combinaron formando una muestra compuesta y se midió el pH y conductividad eléctrica. Tras el filtrado y la adecuada conservación, se determinaron los elementos Na, K, Ca, Mg, B, Al, Bi, Cd,