En la agroindustria, las materias primas son sometidas a procesos de adecuación o transformación para darle valor agregado, mediante la implementación de operaciones unitarias para facilitar su consumo; generando una de las principales problemáticas ambientales en nuestro medio, la alta producción de residuos. En algunos casos estos residuos son tratados; hasta reducir el impacto negativo que su emisión, vertimiento o disposición pudiera generar; convirtiéndolos en un producto útil y de mayor valor agregado que solucione una problemática y genere ingresos económicos adicionales. En esta revisión se describen algunas investigaciones desarrolladas tendientes al aprovechamiento de los residuos generados en las agroindustrias.

In the clarification of the potable water chemicals like aluminum sulphate is use to remove colloidal matter and organic substances, improving the quality of the water. High residual aluminum concentrations in the potable water have implications in the human health, being necessary the alternative coagulants development, environmentally acceptable to replace them. In this investigation the properties that have the cactus Opuntia ficus-indica and alum in the water clarification of the Magdalena River in Magangué, Bolivar province (Colombia), as coagulant were evaluated. Finally, the efficiency that has mucilage extracted of the cactus Opuntia ficus-indica as natural coagulant was shown. In low-turbidity water like this, the agitation speed has an impact on the action clearer because this achieves reach the more dispersed particles increasing the efficiency of the clarification process.

The antibacterial photocatalytic activity of TiO₂ supported over two types of substrates, borosilicate glass tubes (TiO₂/SiO₂-borosilicate glass tubes (BGT)) and low-density polyethylene pellets (TiO₂-LDPE pellets), which were placed in a compound parabolic collectors (CPC) reactor, was evaluated against Enterobacter cloacae and Escherichia coli under sunlight. Three solar photocatalytic systems were assessed, suspended TiO₂, TiO₂/SiO₂-BGT and TiO₂-LDPE pellets, at three initial bacterial concentrations, 1 × 10⁵; 1 × 10³; 1 × 10¹ CFU/mL of E. coli and total bacteria (E. cloacae and E. coli). The solar photo-inactivation of E. coli was achieved after two hours with 7.2 kJ/L of UV-A, while total bacteria required four hours and 16.5 kJ/L of UV-A. Inactivation order of E. coli was determined, as follows, suspended TiO₂/sunlight (50 mg/L) > TiO₂-LDPE pellets/sunlight (52 mg/L) > TiO₂/SiO₂-BGT/sunlight (59 mg/L), the best E. coli. inactivation rate was obtained with TiO₂-LDPE pellets/sunlight, within 4.5 kJ/L and 90 min. The highest total bacteria inactivation rate was found for TiO₂/sunlight (50 mg/L) and TiO₂-LDPE pellets/sunlight (52 mg/L), within 11.2 kJ/L and 180 min. TiO₂ deposited over LDPE pellets was the most effective material, which can be successfully used for water disinfection applications. Bacterial regrowth was assessed 24 h after all photocatalytic treatments, none of those microorganisms showed any recovery above the detection limit (2 CFU/mL).

Biocoagulants have emerged as an environmentally friendly and efficient alternative to surface water clarification, allowing the use of agro-industrial waste as a bioavailable source for the treatment of high turbidity water. The objective of this research was to compare the efficiency in the surface water coagulation process of the Magdalena river using aluminum sulfate and tamarind seeds (Tamarindus indica) dissolved in aqueous solution and saline solution. The clarification process was carried out by testing jar, for this was performed an extraction of the hot and cold tamarind coagulant which were evaluated in conjunction with an inorganic coagulant in different mother dilutions (distilled water and saline) at concentrations of 35 and 40 mg/L and at a stirring speed of 100 and 200 rpm. The parameters of pH, electrical conductivity (S/cm), turbidity (NTU) and color (UPC) were measured during the clarification process. The results show a 97.2% reduction in inorganic treatment (SAL) compared to initial turbidity and a decrease in natural cold extracted (STF) and hot (STC) treatments of 58.2% and 39.1% respectively, when diluted in aqueous solution. While diluting in saline solution there was a greater removal of turbidity when applying aluminum sulfate, followed by STF and STC treatment, with removal values of 99%, 75% and 53% respectively. The highest coagulating activity occurred when applying a dose of 40mg/L and when diluting treatments in NaCl with maximum reported values for SAL, STF and STC treatment of 93%, 85% and 59%. Tamarind seeds proved to be an efficient coagulant for water clarification