Fit-for-purpose wastewater treatment: Testing to implementation of decision support tool (II).

This paper is the second in a series of two papers. In Paper I, a decision support tool (DST), FitWater, was developed for evaluating the potential of wastewater treatment (WWT) trains for various water reuse applications. In the present paper, the proposed DST has been tested and implemented. FitWater has been tested with several existing WWT plants in Canada and the USA, demonstrating FitWater's effectiveness in estimating life cycle cost (LCC), health risk, and energy use. FitWater has also been implemented in a newly planned neighbourhood in the Okanagan Valley (BC, Canada) by developing 12 alternative WWT trains for water reuse in lawn and public parks irrigation. The results show that FitWater can effectively rank WWT train alternatives based on LCC, health risk, amount of reclaimed water, energy use, and carbon emissions. Moreover, functions have been developed for the variation of unit annualized LCC and energy intensity per unit log removal of microorganisms in different treatment technologies with varying plant capacities. The functions have power relations, showing the economies of scale. FitWater can be applied to identify a cost-effective, risk-acceptable, and energy efficient wastewater treatment train with a plant capacity of 500m3/day or more. Furthermore, FitWater can be used to assess potential economic impacts of developing microbiologically stringent effluent standards. The capability of FitWater can be enhanced by including physio-chemical quality of wastewater, additional treatment technologies, and carbon emissions from wastewater decomposition processes.