The microbiological indicators traditionally used to assess fecal contamination are insufficient to identify the source. The aim of this study was to detect microbial markers to identify the source of fecal pollution in the Bogotá River (Colombia). For this, we determined non-discriminating indicators such as Escherichia coli, somatic coliphages and phages infecting strain RYC2056 of Bacteroides, and potential source tracking markers as phages infecting strains GA17, HB13, and CA8 of Bacteroides, sorbitol-fermenting bifidobacteria, and molecular markers of Bifidobacterium adolescentis, Bifiodobacterium dentium, and Bacteroidetes in raw municipal wastewaters, slaughterhouse wastewaters, and the Bogotá River. Bacteriophages infecting Bacteroides strain GA17 and the molecular markers identified the wastewater sources. In contrast, sorbitol-fermenting bifidobacteria failed regarding specificity. In the Bogotá River, phages infecting strain GA17 were detected in all samples downstream of Bogotá, whereas they should be concentrated from 1 l samples in upstream samples containing less than 103E. coli/100 ml to be detected. In the river water, the fraction of positive detections of molecular markers was lower than that of phages infecting strain GA17. The ratio SOMCPH/GA17PH was shown also to be a good marker. These results provide information that will allow focusing measures for sanitation of the Bogotá River.

Gold mining uses chemicals that are discharged into rivers without any control when there are no good mining practices, generating environmental and public health problems, especially for downstream inhabitants who use the water for consumption, as is the case in Monterrey township, where the Boque River water is consumed. In this study, we evaluate Boque River water quality analyzing some physicochemical parameters such as pH, heavy metals, Hg, and cyanide; bioassays (Lactuca sativa, Hydra attenuata, and Daphnia magna), mutagenicity (Ames test), and microbiological assays. The results show that some physicochemical parameters exceed permitted concentrations (Hg, Cd, and cyanide). D. magna showed sensitivity and L. sativa showed inhibition and excessive growth in the analyzed water. Mutagenic values were obtained for all of the sample stations. The presence of bacteria and somatic coliphages in the water show a health risk to inhabitants. In conclusion, the presence of Cd, Hg, and cyanide in the waters for domestic consumption was evidenced in concentrations that can affect the environment and the health of the Monterrey inhabitants. The mutagenic index indicates the possibility of mutations in the population that consumes this type of water. Bioassays stand out as an alert system when concentrations of chemical contaminants cannot be analytically detected.

The reuse of biosolids in agriculture and its inclusion within the circular economy model requires evaluating and analyzing factors that intervene in its management. The objective of the study was to analyze those factors that influence the management and use of biosolids. Fifty-three actors were questioned, and their answers were analyzed using two prospective methods and Social Network Analysis (SNA) identifying between 14 and 19 variables. Six should be prioritized due to their criticality and potential in management and reuse scenarios. It was observed that the formulation of objectives, such as the improvement of infrastructure, creation of an institutional policy, and the establishment of definitions for the kinds of biosolids, are opposed by internal agents. Seven key actors and four to six determining agents were identified in the scenarios. The network of management and use of biosolids in agriculture presented low density (0.28) and the exclusive action of three key actors. Consequently, the participation of a greater number of better-connected actors is required to project networks with a higher density (between 0.49 and 0.57), facilitating the diffusion of information and the inclusion of new actors not previously contemplated. The application of prospective and SNA methodologies focused on biosolids allows the prioritization of determinants, the evaluation of the level of involvement and communication between actors, and other aspects that have not been considered previously in the management of WWTPs in Colombia.

The difficulties in the management and use of biosolids in Colombia make it necessary to evaluate and analyze the factors involved through various methodologies to achieve the effective management and recycling of this type of waste. The objective of this study was to evaluate the management of sludge and biosolids from a WWTP in a Colombian municipality through the application of three methodologies (SWOT/TOWS, surveys, and stakeholder (player) weighing) for their subsequent use in agriculture. As a result, strategies were proposed at the regulatory, organizational policy, and entity integration levels, among others. It was identified that about 93.6% of the people surveyed had a positive attitude towards the use of biosolids in agriculture, despite recognizing the existence of a risk (27.3%) in this type of practice. On the other hand, regarding the communication of WWTP management of these wastes, they perceived that it to be absent (65%) and the lack of knowledge regarding the destination of these wastes was even greater (72.7%). Through the weighting of actors, 16 players were classified with whom it is necessary to work closely, regularly, or occasionally. The methodologies proposed will allow similar WWTPs to optimize their processes through continuous improvement and joint work between the different entities and communities. It is recommended that other methodologies be used to evaluate player position level in relation to planned strategies, as well as the level of associations of one player with another, independent of power and influence.