Feasibility of Treatment Wetlands for Municipal Wastewater in Colombia: Emergy Evaluation of Treatment Alternatives

Colombia’s main water bodies have been seriously polluted due to mismanagement of domestic, agricultural, and industrial wastewater. While the country’s wastewater infrastructure has expanded in the past decades, the selection of the existing treatment technologies has excluded important aspects that could compromise their sustainability. Colombia and similar countries are in great need for inexpensive and sustainable wastewater treatment systems that are not technologically sophisticated and that do not require intensive management. Thus, the main goal of this study was to quantify the performance and emergy requirements of a municipal wastewater treatment wetland, and to compare this technology to others typically used in the region. A treatment wetland model, which focused on pollutant removal, was developed. Using the results from this model and data from the literature, the emergy required for construction and maintenance of the modeled wetland and two existing facilities (a stabilization ponds system and a sequential batch reactor) was evaluated. The emergy evaluations were used to estimate a number of indices to allowed comparison among the three systems. The total emergy of the treatment wetland was 2.88E+17 sej/yr, compared to 6.65E+16 sej/yr for the stabilization ponds, and 8.86E+17 sej/yr for the sequential batch reactor. The stabilization ponds yielded the best results for nine of the thirteen indices presented. Therefore, It was concluded from this study that a system of stabilization ponds can provide basic municipal wastewater treatment for the lowest cost, although more advanced treatment can be achieved with a treatment wetland if resources are available.