Combined impact of prevention/minimization, treatment for reuse, and enhanced self-purification to improve the water resource quality

Alberto Galvis, Peter van der Steen, Hubert Gijzen

Thursday 2 july 2015

9:15 - 9:30h at Asia (level 0)

Themes: (T) Hydro-environment, (ST) Impacts of pollutants on the water environment

Parallel session: 10G. Environment - Impact

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 and expensive, and will not be able to address the rapidly growing wastewater challenge globally. In order to be able to efficiently address this problem, it is important to adopt an integrated approach that includes a decrease and control of contamination at its source. In this context, the conceptual model of the Three Steps Strategic Approach (3-SSA) was developed, consisting of: 1) minimization and prevention, 2) treatment for reuse and 3) stimulated natural self-purification. The present study was oriented towards comparing the 3-SSA (unconventional strategy) with the conventional approach, which considers a ‘business as usual scenario’ of high water use, end-of-pipe wastewater treatment and conventional water supply providing drinking water quality for all uses. The study area is the Upper Cauca river basin, which extends from La Balsa station (km 27) to the Anacaro station (416 km). The Cauca River is the second most important fluvial artery of Colombia and the main hydric source of the Colombian southwest. 2-SSA scenario includes reduction in water consumption, reuse of treated wastewater in housing and sugarcane crops and prioritization of investments to maximize impact in improving the water quality of the Cauca River in the study area, targeting interventions in municipalities and watersheds with the highest pollutant load. This study defines a baseline (2013, summer condition) and projects scenarios for conventional and unconventional strategies towards 2033. Results show that with the unconventional strategy higher pollutant load removals are achieved. The cost-benefit analysis also favors unconventional strategy, and the application of dynamic modelling MIKE 11 shows a higher minimum DO compared to the minimum DO obtained with the conventional approach.