Access to clean drinking water has been identified by the National Academy of Engineering as one of the Grand Challenges of the 21st century. This thesis investigated clean drinking water access in the greater Phoenix area, specifically with regards to drinking water quality standards and management strategies. This research report…
Access to clean drinking water has been identified by the National Academy of Engineering as one of the Grand Challenges of the 21st century. This thesis investigated clean drinking water access in the greater Phoenix area, specifically with regards to drinking water quality standards and management strategies. This research report provides an introduction to water quality, treatment, and management; a background on the Salt River Project; and an analysis on source water mix and drinking water quality indicators for water delivered to Tempe, Arizona water treatment facilities.
City managers and policy makers are increasing looking to environmental systems to provide beneficial services for urban systems. Constructed wetland systems (CWS), highly managed and designed wetland ecosystems, are being utilized to remove pollution, particularly excess nitrogen (N), from treated wastewater. Various wetland process remove N from effluent, such as…
City managers and policy makers are increasing looking to environmental systems to provide beneficial services for urban systems. Constructed wetland systems (CWS), highly managed and designed wetland ecosystems, are being utilized to remove pollution, particularly excess nitrogen (N), from treated wastewater. Various wetland process remove N from effluent, such as denitrification, direct plant uptake, and soil accumulation. Emergent macrophytes provide direct uptake of N and improve conditions for microbially-mediated N processing. The role of different macrophytes species, however, is less understood and has primarily been examined in mesocosm and microcosm experiments and in mesic environments. I examined the effects of community composition on N removal and processing at the whole ecosystem scale in an aridland, constructed wetland (42 ha) through: 1) quantifying above- and belowground biomass and community composition from July 2011 \u2014 November 2012 using a non-destructive allometric technique, and; 2) quantifying macrophyte N content and direct macrophyte N uptake over the 2012 growing season. Average peak biomass in July 2011 & 2012 was 2,930 g dw/m2 and 2,340 g dw/m2, respectively. Typha spp. (Typha domingensis and Typha latifolia) comprised the majority (approximately 2/3) of live aboveground biomass throughout the sampling period. No statistically significant differences were observed in macrophyte N content among the six species present, with an overall average of 1.68% N in aboveground tissues and 1.29% N in belowground tissues. Per unit area of wetland, Typha spp. retained the most N (22 g/m2); total N retained by all species was 34 g/m2. System-wide direct plant N uptake was markedly lower than N input to the system and thus represented a small portion of system N processing. Soil accumulation of N also played a minor role, leaving denitrification as the likely process responsible for the majority of system N processing. Based on a literature review, macrophyte species composition likely influences denitrification through oxygen diffusion into soils and through the quality and quantity of carbon in leaf litter. While this study and the literature indicates Typha spp. may be the best species to promote wetland N processing, other considerations (e.g., bird habitat) and conditions (e.g., type of wastewater being treated) likely make mixed stands of macrophytes preferable in many applications. Additionally, this study demonstrated the importance of urban wetlands as scientific laboratories for scientists of all ages and as excellent stepping-off points for experiments of science-policy discourse.
Managed Aquifer Recharge is an increasingly prevalent solution to sustain water availability in arid regions. Recharge of groundwater resources using treated wastewater effluent is one type of managed aquifer recharge that offers long-term sustainable water management. However, there are some concerns regarding the reuse of wastewater and its potential to…
Managed Aquifer Recharge is an increasingly prevalent solution to sustain water availability in arid regions. Recharge of groundwater resources using treated wastewater effluent is one type of managed aquifer recharge that offers long-term sustainable water management. However, there are some concerns regarding the reuse of wastewater and its potential to increase exposures to antibiotic resistant bacteria and antibiotic resistance genes that could affect human health. Antibiotic resistance genes can confer the ability for bacteria to resist antibacterial treatment, rendering their presence in water supplies as an area of research needed to evaluate where environmental “hot spots” of potential antibiotic resistance disseminate. To evaluate the occurrence of antibiotic resistant bacteria and antibiotic resistance genes, sampling of an Arizona managed aquifer recharge facility was performed, with target antibiotic resistance genes measured using quantitative polymerase chain reaction. The occurrence of antibiotic resistance genes was evaluated at several sampling wells and in sediments to examine trade-offs between water quantity benefits and water quality issues. The goal of this work is to inform management operations for secure water quality in the face of climate change.
