Environmental risk assessment of pharmaceutical pollutants in the Oro River Sub-basin (Colombia).

Pharmaceuticals and Personal Care Compounds (PPCPs) are contaminants present in wastewater and in the receiving surface waters, which have no regulations and can bring on environmental risks. In this study, we evaluated the presence of six PPCPs in the Oro River Sub-basin (Colombia) and the environmental risk associated with them. We have verified that the monitored rivers show the presence of Ibuprofen, Cephalexin and Carbamazepine; the first ones (Ibuprofen and cephalexin) were those that presented higher concentrations since they are widely prescribed in Colombia. Pharmaceutical compound concentrations in the rivers downstream of the wastewater treatment plants from Floridablanca were higher than in other monitoring sites being a significant point source of contamination. This wastewater treatment plant receives hospital discharges from the city, including internationally recognized clinics accepting patients from different parts of the country. The environmental risk assessment showed that ibuprofen and Cephalexin have a higher impact on aquatic organisms.

Model assessment of the prevailing fouling mechanisms in a submerged membrane anaerobic reactor treating low-strength wastewater.

Three models (blocking laws, combined and resistance-in-series) were applied to identify the prevailing fouling mechanisms in a submerged membrane in an up-flow anaerobic sludge blanket reactor treating municipal wastewater. Experimental runs were carried out at lab-scale with filtration periods of 4 and 10 min, followed by relaxation periods of one minute with and without nitrogen bubbling. In all conditions excepting one (IF4R), the blocking laws model showed a predominance of cake formation. With the combined model, cake formation coupled with intermediate, standard and complete fouling had the better fits in all conditions, excepting IF4 and IF4R. When sewage was fed, both models pointed at intermediate fouling in the absence of gas bubbling. The resistance-in-series model identified the positive effect of gas bubbling and a post-cake fouling behavior, not shown by the other two models. This modeling approach could be applied for achieving longer filtration runs in submerged UF membranes.