Tanning process is a polluting activity due to the release of toxic agents into the environment. One of the most important of those toxic chemicals is chromium. Different alternatives have been proposed for the removal of this metal from tanning waste water which include the optimization of the productive processes, physicochemical and biochemical waste water treatment. In this study, the biological adsorption process of trivalent chromium was carried out in synthetic water and tannery waste water through two types of native green microalgae, called Chlorella vulgaris and Scenedesmus acutus in Free State and immobilized in PVA state. This, considering that cellular wall of microalgae has functional groups like amines and carboxyl that might bind with trivalent chromium. Statistical significance of variables as pH temperature, chromium and algae concentrations was evaluated just like bio sorption capacity of different types of water and kind of bioadsorbent was calculated to determine if this process is a competitive solution comparing to other heavy metal removal processes.

En este trabajo se describe la técnica de inmovilización de microalgas en esferas de alginato de calcio. Se emplearon las especies Scenedesmus ovalternus y Chlorella vulgaris, se determinó la estabilidad de las esferas, la cinética de crecimiento y la concentración de las microalgas en el interior de las esferas. Chlorella vulgaris alcanzó mayores densidades poblacionales y tasas de crecimiento más altas cuando se inmovilizó en concentraciones del 10 % v/v con el alginato (1,31*106 cél/ml). Para Scenedesmus ovalternus se observó una mayor densidad poblacional y una mayor tasa de crecimiento cuando se inmovilizó en concentraciones del 20 % v/v (7,06*105 cél/ml). Estos resultados son útiles para aplicaciones prácticas de las algas encapsuladas, tales como el biomonitoreo o la biorremediación.Immobilization of Microalgae Scenedesmus ovalternus (Scenedesmaceae) and Chlorella vulgaris (Chlorellaceae) in Calcium Alginate BeadsThis paper describes the immobilization technique of microalgae in calcium alginate beads. Scenedesmus ovalternus and Chlorella vulgaris species were used. The stability of beads, the kinetics of growth and the concentrations of microalgae inside the beads were determined. The higher density and the upper growth rate of Chlorella vulgaris occurred when it was immobilized in alginate at a concentration of 10 %v/v (1,31*106 cél/ml). Scenedesmus ovalternus achieved a higher population density and an elevated growth rate when it was immobilized at a concentration of 20 % v/v (7,06*105 cél/ml). These results are useful for subsequent applications of the encapsulated algae, such as biomonitoring and bioremediation.

Cylindrospermopsin is an emerging cyanotoxin that can lead to phytotoxicity through different mechanisms. The presence of CYN in irrigation waters is of concern due to potential accumulation in plants, increasing the risk of human exposure by the consumption of vegetables. In this case, it is proposed to evaluate the effects of CYN on a crop considered staple food in Colombia, such as Solanum tuberosum, group Phureja var Criolla Colombia, known as “yellow potato”. This work evaluates for the first time the effects of CYN in potato plants exposed to this toxin using two different irrigation systems, surface and sprinkler irrigation. The parameters evaluated were CYN bioaccumulation and biotransformation in different parts of the potato plants irrigated with water containing CYN at environmentally relevant concentrations (84.65, 33.80, 3.05 and 3.05 µg/L after first, second, and third to fourth applications, respectively) and changes in nutritional mineral content in tubers. For this purpose, the concentrations of CYN and its potential metabolites in leaves, stem, roots, and tubbers of the plants exposed to the toxin were determined by Ultra-high Performance Liquid Chromatography–MS/MS (UHPLC-MS/MS). Mineral content was determined by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). CYN bioaccumulation was detected only in aerial parts of plants with sprinkler irrigation. A total of 57 CYN metabolites were found, and the main differences obtained in CYN biotransformation are linked to tissues and exposure conditions. There are significant differences in levels of Ca, K, Mg, Na, P, Cu, Fe, Mn, and Zn in tubers depending on CYN treatment, with higher contents after surface irrigation, and lower content with sprinkler application. These results demonstrate that the exposure conditions are an important factor for the potential presence and effects of CYN in potato plants.