Aluminum sulfate is one of the most used chemical coagulants in the world, but research has shown that high concentrations of aluminum in the body are associated with neuropathological conditions. Because of this, different alternatives have been evaluated such as natural coagulants, which are considered safe for human health and contain fewer contaminants than chemicals due to their biodegradation properties. The main objective of this study was to evaluate the efficiency of mixing nopal mucilage and cassava starch for turbidity removal in water purification. In this paper, test jars and the treatment equipment (TA-scale FQ-005/PE manufactured by Generatoris SA de CV of Mexico) was applied in order to measure turbidity and pH parameters before and after the process of coagulation–flocculation, which was applied to water from the Magdalena River in Colombia. Samples from two sampling periods were assessed. One was evaluated during the rainy season and the other was evaluated without precipitation (drought) with initial turbidities of 316 NTU and 80 NTU, respectively. It was found that aluminum sulfate as a coagulant reference obtained better turbidity removal results (up to 99%) as compared to nopal (up to 60.4%), and nopal–starch combination of cassava (up to 67%), indicating that this mixture increases the effectiveness of natural coagulants used individually. Our results indicate that this should be considered as an alternative in the water purification process.

This study compared the effectiveness of the Project-Based Learning method (PBL) with the conventional teaching method in developing cross-curricular skills and improving academic performance among 1064 undergraduate students at the north coast of Colombia. A t–student test, Welch test, and the Tau Kendall correlation coefficient were used to analyse the PBL and non-PBL groups in 40 Economic Integration courses in three years. A pre-test, post-test, and achievement of academic objectives questionnaire was applied, as well as a verification test of previous knowledge and a focus group at the end of the courses. It was observed that the PBL method is superior in the development of problem-solving and teamwork skills only of five observed. The application of the PBL method was associated with the fulfilment of two of the five academic objectives analysed, which is confirmed by the feedback from the focus groups. This research contributes to the analysis of the usefulness of teaching methods in different geographical contexts.

This article analyzed 26 countries’ long-term relationship between the nominal exchange rate, international palm oil prices, and exports competitiveness from 2007 to 2015. Unit root tests, Kao-Padroni joint tests, a fully modifiable ordinary least squares, and a dynamic ordinary least squares model were used. It was found that an increase in the exchange rate favored palm oil exports’ competitiveness as well as a decrease in its price. This study determines the competitiveness of crude and refined palm oil exports through non-conventional statistical analysis.

Water purification is indispensable to guarantee safe human consumption and to prevent diseases caused by the ingestion of contaminated water. This requires a series of water treatment processes which require investment. However, the economic limitations of rural communities hinder their ability to implement such water-treatment systems, as is the case in Ciénaga Grande of Santa Marta ("Large Swamp", in English) in Colombia. Low-cost systems can be used instead as simple and safe alternatives. Therefore, the objective of this work was to evaluate non-conventional, low-cost water processes to purify the water from the collection point of two stilt house villages in Ciénaga Grande of Santa Marta. These include: 1) Using two natural coagulants, Moringa Oleifera and Cassia Fistula; 2) filtration through a biosand filter and a carbon activated filter; and 3) disinfection through UV-C Radiation and through solar disinfection. The results showed a turbidity values reduction between 52% and 96% using the two natural coagulants; both turbidity and total coliforms achieved reductions of 98.4% and 76.9%, respectively in the filtration process; and removal of total coliforms up to 98.8% in the disinfection process. Despite the high rates of reduction in the different parameters, the water does not comply with the recommended limits for safe drinking water.

This Article analyses the effectiveness of Simulation-Based Learning Model ASEAN Meeting in enhancing critical thinking skills and academic performance compared to the conventional teaching method among 216 International Relations undergraduate students on the north coast of Colombia. A t–student test, Welch test, and the Kendall Tau correlation coefficient were used to analyses the perceptions and academic performance from 216 undergraduate Asia Pacific Politics courses for two years. A pre-test, post-test, and achievement of academic objectives questionnaire were applied, as well as a verification test of previous knowledge and focus groups at the end of the courses. It was found that simulations fostered an inquiry-based attitude to represent a countrýs agenda not achieved through the conventional method, thus enhancing deductive and inductive reasoning, recognizing assumptions, and drawing inferences capabilities.