Validation of the Three-Step Strategic Approach for Improving Urban Water Management and Water Resource Quality Improvement

The impact on water resources caused by municipal wastewater discharges has become a critical and ever-growing environmental and public health concern. So far, interventions have been positioned largely 'at the end of the pipe', via the introduction of high-tech and innovative wastewater treatment technologies. This approach is incomplete, inefficient and expensive, and will not be able to address the rapidly growing global wastewater challenge. In order to be able to efficiently address this problem, it is important to adopt an integrated approach such as the three-step strategic approach (3-SSA) consisting of (1) minimization and prevention, (2) treatment for reuse and (3) stimulated natural self-purification. In this study, the 3-SSA was validated by applying it to the Upper Cauca river basin, in Colombia and comparing it to a conventional strategy. The pollutant load removed was 64,805 kg/d Biochemical Oxygen Demand BOD5 (46%) for the conventional strategy and 69,402 kg/d BOD5 (50%) for the unconventional strategy. Cost benefit analysis results clearly favoured the 3-SSA (unconventional strategy): NPV for the conventional strategy = −276,318 × 103 Euros, and NPV for the unconventional strategy (3-SSA) = +338,266 × 103 Euros. The application of the 3-SSA resulted in avoided costs for initial investments and operation and maintenance (O&M), especially for groundwater wells and associated pumps for sugar cane irrigation. Furthermore, costs were avoided by optimization of wastewater treatment plants (WWTPs), tariffs and by replacement of fertilizers.