ABSTRACT
118Treated wastewater may be reused for crop irrigation. This contributes to recovery of water and nutrients, and at the same time it helps to reduce pollution discharge to receiving water bodies. Despite these advantages of reuse of treated wastewater, there is little experience of this in Colombia and Latin America. In part, this condition is explained by the lack of studies that show the potential of reuse comparing the traditional wastewater treatment options without reuse versus the options with reuse. In this research, the financial viability of reuse of treated wastewater for the irrigation of sugarcane crops in the Upper Cauca river basin in Colombia was studied. The study included three cases, with different characteristics of wastewater (BOD5 between 164 and 233 mg/L), flows (between 369 and 7,600 L/s), rainfall levels (between 1,009 and 1459 mm/year) and irrigation requirements (0.34 and 1.08 L/s-ha). For both scenarios, the same baseline was considered. Cost-Benefit Analysis CBA was used to compare the options (with and without reuse of treated wastewater). Cost of initial investment and O&M were considered. Benefits were considered like avoid cost in use of fertilizers, reduction of taxes for water use and discharges directly to water bodies and investment and O&M costs of infrastructure for irrigation with groundwater. The results of the CBA and sensitivity analysis show that there are two key factors that influence financial viability of treated wastewater for sugarcane crop irrigation: 1) the water balance and irrigation requirements, and 2) costs corresponding to the management of wastewater for agricultural irrigation, including additional treatment (when it is required) and the infrastructure to bring the treated wastewater to crops. The financial viability of reuse in the study area was limited because the values of tax for wastewater discharges and water tariffs in Colombia do not correspond to the values they should have.
