Comparison of treatment process sustainability at water plants in the Sacramento region

With greenhouse gas (GHG) a suspected contributor to climate change and poor air quality, drinking water utilities are becoming more concerned about reducing GHG emissions. This study compares the total emissions of equivalent carbon, i.e., carbon footprint, for different processes used at 11 facilities in the Sacramento, California, region. Conventional treatment, microfiltration, pressure filtration, slow sand filtration, and ballasted flocculation were considered in terms of the environmental effects of construction, staff transportation, chemical consumption, energy consumption, and sludge production. Results indicated that the carbon footprints of the processes used at urban facilities are quite similar. For rural plants, the carbon footprints differed, with slow sand filtration producing a larger carbon footprint than the other processes studied. The procedures described here should help water providers better evaluate the emission consequences of the treatment processes they choose.