A carbon footprint (CF) analysis is the sum of the estimated carbon dioxide and other greenhouse gas (GHG) emissions associated with a particular activity or industry. Without a standardized protocol for developing a CF of water production, U.S. utilities must draw on the experiences of other nations and adapt approaches used in other industries. In the United Kingdom, mandatory regulation of emissions for large industry has spurred collaborative development of CF methods for the water industry. British and Australian utilities are conducting CF analyses and using this information to better understand the environmental impact of their water production. First, various utility activities are defined, information about power and potential GHG emissions is gathered, and the GHGs are converted to carbon dioxide equivalents to create a CF assessment. The utility can then use this baseline CF as a management tool to guide decisions about sustainable operations and construction projects as well as future resources and treatment and transmission facilities.

The objectives for coagulation-based processes have changed significantly as a consequence of new goals for lower treated-water turbidity and criteria for total organic carbon (TOC) removal to meet requirements for enhanced coagulation. Although the application of coagulation for TOC removal has garnered considerable interest, the capability to maintain effective turbidity removal is a higher priority and cannot be compromised. This article describes evaluations for assessing this broader view of the coagulation process and underlines the necessity of identifying coagulant adjustments that not only remove TOC but also achieve effective particulate removal. Several basic coagulation adjustments are available for improving capability to meet goals for TOC and turbidity removal, including changes in pH and coagulant dose, use of alternative coagulant chemicals, and changes in the order of chemical addition.

Zone 7 of Alameda County Flood Control and WaterConservation District, in coordination with Black & Veatch, conducted a 9-month pilot study to determine preliminary design parameters for a new water treatment plant (WTP). The pilot study was performed to verify the performance of membrane filters and to establish preliminary design parameters for the submerged membrane process, followed by ozonation and biological granular activated carbon filtration. The pilot testing was conducted using water from the Patterson Pass WTP reservoir. The process included coagulation with either ferric chloride or polyaluminum chloride, flocculation, sedimentation, membrane filtration, ozonation, and filtration using biological granular activated carbon (BAC). The goals of the study were as follows:1. Determine the potential effectiveness of ozone and BAC for removing geosmin and MIB. 2. Determine the impacts of different levels of pathogen inactivation, i.e., 0.5-log Giardia and 2-log virus inactivation. 3. Monitor the formation of bromate under various conditions of ozone oxidation for different levels of pathogen inactivation as well as for taste and odor control, and evaluate bromate mitigation strategies, if necessary.The results of the study showed that the use of ozone achieved 2.0-log virus inactivation and 0.5-log Giardia inactivation. It also decreased the disinfection by-product formation and effectively controlled geosmin and removed a significant fraction of the MIB during a taste and odor event. Because the raw water bromide concentrations were low, bromate formation remained below the regulated level of 0.010 mg/L. However, in one instance, bromate mitigation was utilized by applying sulfuric acid to lower the pH to less than 7.1, which reduced bromate formation to less than 0.010 mg/L.

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