AWWA water science最新文献

Colloidal gas aphrons (CGAs) have proven successful in separating both long- and short-chain PFAS from water; however, little information is available on the impact of surfactants used for aphron generation. This study assesses the use of five cationic surfactant-generated CGAs in batch experiments to remove PFAS from two site groundwaters. The results found that lauric arginate ethyl ester (LAE), a food-grade surfactant used to generate CGAs, had the best performance, removing over 80% of PFAAs in a single stage. Removal rates were consistent between high- and low-concentration waters, indicating its versatility. The addition of a second stage of treatment improved PFAS removal, particularly for short-chain PFAS, as the first stage predominantly removed long-chain PFAS due to their greater presence in the initial water. Higher salinity and saponins reduced the removal rates due to competitive sorption. Overall, the success of a food-grade surfactant for CGA generation is significant in terms of water treatment.

This study produced a comprehensive drinking water ozone-biofiltration evaluation by assessing performance at a newly commissioned facility with varying hydraulic and ozonation operations. In brief, 30 water quality, operational, and biological parameters were collected at 11 locations throughout the treatment train at least every other week for an entire year. Seasonal and environmental variation seemed to influence treatment performance more than operational changes (i.e., ozone or hydraulic re-rating). However, media adenosine triphosphate (ATP), an indicator of biomass, was sensitive to hydraulic variability. Organic carbon was identified as a reliable performance metric, particularly when total organic carbon (TOC) and dissolved organic carbon (DOC) shared a strong linear relationship. Carboxylic acid removal also served as a useful long-term monitoring tool for assessing ozone-biofilter performance. This study establishes a critical benchmark for capturing the effects of intermittent ozonation, variable hydraulic loading, and seasonal transitions that utilities can utilize to better understand ozone-biofiltration processes in drinking water treatment systems.

This study provides a comprehensive evaluation of the effectiveness of 280 nm UV LEDs in enhancing chlorine disinfection in natural water sources. The results of this work indicate sequential treatments (UV-chlorine and chlorine-UV) further enhanced the disinfection efficiency of T1 in natural waters, especially at higher UV doses, such as 40 mJ cm⁻². The log reduction value for the chlorine-UV sequence reached 6.65, slightly higher than the 6.29 for the UV-chlorine sequence, suggesting that sequencing influences disinfection efficacy at higher fluences. UV LED-enhanced chlorine disinfection did not significantly alter concentrations of THMs and HAAs. Overall, the findings of this study open new avenues for the application of UV LEDs in drinking water disinfection, demonstrating their potential as an alternative to traditional disinfection methods. Future research should further explore the effects of UV-chlorine combined treatments under different water quality conditions to optimize disinfection processes and provide theoretical support for innovation in water treatment technologies.

Water distribution systems (WDS) are critical infrastructures essential for human well-being and economic prosperity. However, climate change (CC) is increasingly causing variational environmental stress and natural disasters that threaten the integrity of these systems. Without resilient and sustainable WDS, societies will struggle to function effectively. This review article examines the impact of CC on the integrity of WDS, focusing on physical, hydraulic, and water quality aspects. It presents a synthesis of recently published peer-reviewed journal articles that address these dimensions, while acknowledging their synergistic interrelationships. The paper presents adaptation strategies and highlights utility case studies aimed at strengthening the resilience of WDS against the impacts of CC.

This review introduces a novel risk-based management framework for asbestos cement (AC) pipes in drinking water systems, emphasizing maintenance practices and occupational health risks while harmonizing global regulatory and utility practices. Inhalation risks are well established, but WHO guidance indicates negligible risks from ingestion, not warranting regulatory limits. The framework addresses gaps in fiber release monitoring, standardizing protocols to minimize occupational exposure. AC pipes, deployed since the 1920s, persist in many systems despite phase outs. The study highlights deficiencies in fiber release under varying water corrosivity, advocating management of aging infrastructure through GIS tracking, non-destructive testing (NDT), and phased replacement, informed by case studies from Australia and New Zealand. Airborne exposure underscores the need for standardized protocols. Public engagement and evidence-based decisions are essential where immediate replacement is not mandated. This global synthesis integrates regulatory guidance, utility practices, and health data into an actionable framework.

Gel-type anion exchange (AEX) resin performance is impacted by internal mass transfer, which is represented by the solid-phase intraparticle diffusion coefficient (D_s). Importantly, D_s values are required inputs to ion exchange treatment process models but are rarely reported. Previous experiments using gel-type AEX resins exhibited external mass transfer control, preventing D_s estimation for several anions, including perfluoroalkyl substances. To reduce external mass transfer resistance and allow D_s estimation, a stainless-steel centrifugal stirrer device was standardized and validated with nitrate (model anion). Initially, experiments were conducted across mixing speeds (750–1750 rpm) to balance (1) maximizing external mass transfer and (2) preventing flow disturbances. Subsequently, experiments used an optimized speed to estimate nitrate D_s at multiple initial concentrations on three gel-type AEX resins. The developed methodology was useful for determining nitrate D_s and should enable improved D_s estimates for other contaminants, including perfluoroalkyl substances, needed for ion exchange treatment process models.

Manganese (Mn) in drinking water poses aesthetic, health, and operational concerns. One common removal method involves adsorbing soluble Mn(II) onto manganese (III/IV) oxide (MnO_x)-coated media, but this approach typically relies on chemical reagents for surface regeneration. In systems lacking chemical storage, dosing, and containment capacity, this may be impractical. This study demonstrated an alternative regeneration technique using an electrochemical reactor for in situ oxidant production at conditions relevant to drinking water treatment. The reactor generated oxidants, likely free chlorine, and increased the pH of the applied water. Across batch-scale recirculating, intermittent regeneration, and single-pass continuous regeneration experiments, electrochemically regenerated MnO_x-coated media produced ~90% removal of Mn(II), achieving a common treatment goal of 0.02 mg/L. Regeneration was also confirmed by analyzing the average oxidation state of the MnO_x surface. Performance depended on several factors, such as raw water Mn, applied voltage, and alkalinity. Although modeling and Mn fractionation suggested limited homogenous oxidation of Mn(II), the formation of some colloidal MnO_x may have confounded results in some experimental situations. These findings highlight a promising, reagent-free strategy for regenerating oxide-coated media, expanding its applicability for water treatment, especially in isolated systems and point-of-use applications.