AWWA water science最新文献

This research provides new insights on the application of weak-base (WB) anion exchange resins (AERs) for groundwater treatment of six perfluoroalkyl acids (PFAAs) with different properties. Continuous-flow column adsorption and regeneration experiments involving WB, polyacrylic, and WB, polystyrene resins were conducted considering salt-only regeneration solutions and two representative strong-base (SB)-AERs of analogous polymer composition and a third solution of methanol/salt used as baseline for comparison. The WB, polyacrylic resin was regenerated using salt-only solutions of NaOH due to deprotonation of the tertiary amine functional group at alkaline pH. However, organic cosolvent was required to weaken the hydrophobic interactions between PFAAs and the nonpolar WB, polystyrene resin. Removal was predominantly influenced by polymer composition with free-base WB-AERs exhibiting similar selectivity and higher capacity as SB resin counterparts. This work highlights WB-AER selection based on PFAA-selective removal and more sustainable regeneration strategies.

Since publication of their article, Whelton et al. (2023) identified that a figure was referenced where the supplementary materials should have been referenced, and that the supplementary materials did not include important information.

The second paragraph of Section 4.3 read the following:

A drinking water chemical analysis “fire package” was proposed during the Marshall Fire response (Figure 1), and should be revised as more VOC and SVOC data becomes available.

The reference to Figure 1 for the “fire package” was incorrect and should have read the following:

A drinking water chemical analysis “fire package” was proposed during the Marshall Fire response (Appendix S1), and should be revised as more VOC and SVOC data becomes available.

The information provided in Appendix S1 was incomplete and was missing pages related to the S-3.2 enclosures. A file with the complete supporting information has replaced the previously published version.

Following the 2021 Marshall Fire in Colorado, this study was conducted to better understand private well and plumbing damage and to develop public health guidance. More than 20 post-fire drinking water well guidance documents with varied recommendations were found. Approximately 227 wells were located in the fire footprint. Seventeen properties were visited, and a subset of wells were sampled for organic and inorganic contaminants. Property debris was also collected. Benzene, toluene, and 19 semi-volatile organic compounds (SVOCs) were detected in water extracts of property debris. No wells contained volatile organic compound contamination. Two shallow wells (12 and 15 ft) had debris contamination; one well contained notable SVOC contamination. One multi-home unregulated well system was extensively damaged, lost pressure, and had not been repressurized 11 months after the fire due to financial and technical challenges. Study results highlight the need for follow-up work to understand well system damage and household response.

Full-scale sampling at 16 facilities illustrated that NDMA precursor concentrations, measured by adding chloramine under Uniform Formation Conditions (NDMA_UFC), increased across biofiltration at 7 of 16 facilities (by 3–48 ng/L or 12%–296%) but stayed the same or decreased (by up to 5 ng/L or 24%) at the other nine facilities. Increases in NDMA_UFC concentrations were attributed to both particulate and soluble precursors. Only two facilities had an increase in NDMA_UFC greater than 10 ng/L. However, NDMA_UFC concentrations in the biofilter effluent from five facilities exceeded 10 ng/L during one or more sampling events. For these facilities, testing at multiple scales showed that mitigation steps could include pretreatment with ozone (which resulted in overall lower NDMA_UFC), increased free chlorine contact time prior to ammonia addition, and/or optimized biofilter design and operation.

The formation of disinfection byproducts (DBPs) in finished drinking water is an ongoing challenge for public health agencies and water utilities. The Fourth Unregulated Contaminant Monitoring Rule data were used to assess the prevalence and drivers of haloacetic acids (HAAs)—a class of DBPs—in New York State's (NYS) public water systems, with a focus on total measured (HAA9), regulated (HAA5), brominated (HAA6Br), and unregulated (HAA4) HAAs. The concentrations of all HAA groups in NYS are found to be similar to those nationally, with HAA4 composing approximately 20% of HAA9. Concentrations of all HAA groups are lowest in groundwater and highest in surface waters across NYS systems. Higher total organic carbon (TOC) concentrations lead to elevated HAA9 and HAA5, while higher bromide concentrations favor more HAA4 and HAA6Br. HAA4 concentrations are well predicted with pre-oxidation/disinfection types, HAA5, TOC, and bromide concentrations, with an adjusted R² of 70%.

Hydraulic performance issues in drinking-water biofilters have sometimes been associated with phosphorus limitation and increased production of extracellular polymeric substances in previous bench-scale studies. However, field studies utilizing phosphorus supplementation to improve biofilter hydraulic performance have produced mixed results. Here, we determined the ratio of activities for phosphatase to glycosidase (PHO:GLY), which are enzymes involved in acquiring orthophosphate and biodegradable organic carbon from complex organic substrates, to assess phosphorus limitation in 21 pilot- and full-scale biofilters. Supplementation of the pilot-scale biofilter influents with 37 μg/L orthophosphate-P reduced the PHO:GLY from 1.8–40.3 (mean 14.8) to 0.3–15.9 (mean 5.3), demonstrating that increased orthophosphate availability decreases PHO:GLY. In the absence of phosphorus supplementation, the PHO:GLY of the pilot- and full-scale biofilters ranged from 0.3 to 40.3 (mean 10.1), and no hydraulic performance issues were noted. Thus, severe phosphorus limitation appears uncommon in the field, suggesting that phosphorus supplementation is unlikely to improve hydraulic performance in typical drinking water biofilters.

Reduction coagulation filtration using ferrous iron (Fe(II)-RCF), or reduction filtration using stannous tin (Sn(II)-RF), for the removal of hexavalent chromium (Cr(VI)) from drinking water represent attractive alternatives to ion exchange or reverse osmosis. With a new maximum contaminant level for Cr(VI) anticipated in California, this study sought to expand on previous research by applying Fe(II)-RCF and Sn(II)-RF to multiple groundwaters under a variety of reductant dose and reduction time scenarios. Four different granular filter media were also tested for removal of total chromium (Cr(T)) following Cr(VI) reduction to trivalent chromium (Cr(III)). Sodium hypochlorite, instead of aeration, was used to oxidize excess Fe(II) to Fe(III) prior to filtration, with minimal Cr(III) to Cr(VI) reoxidation. Sn(II)-RF was also able to achieve Cr(T) and Cr(VI) treatment goals without dedicated reduction time prior to filtration. Results of this study were used to develop more up-to-date, feasibility-level, 20-year annualized cost estimates.

Commercial and institutional buildings now experience weeks and even months with below-normal occupancy due to remote work/learning, which results in reduced water use and has the potential to adversely impact water quality. This study monitored the variations in water quality in multiple university buildings during several months of below-normal occupancy followed by several months of normal occupancy. The levels of free chlorine, copper, and cellular ATP in water varied within buildings and between buildings. Using Wi-Fi activity as a surrogate for building occupancy, the free chlorine concentration in water increased as Wi-Fi counts increased. The copper concentration in building water was higher when the occupancy was below-normal compared with normal occupancy, and the copper concentration decreased as Wi-Fi counts increased. Throughout the study, flushing a fixture at the time of use decreased the concentrations of copper and cellular ATP and increased the concentration of free chlorine.

Alameda County Water District has observed increased biofilter effluent manganese concentrations during winter operations. To investigate manganese removal across surface water biofilters during cold-water conditions, trends were analyzed between water temperature and manganese removal across multiple testing scales, multiple biofilter influent water qualities, and both anthracite and GAC media. During acclimation of new biofilters, 100% removal of manganese was observed sooner across both anthracite and GAC biofilters brought online at 20°C compared to 12°C. Acclimation at 12°C required 18 extra days for the GAC biofilters and 48 additional days for the anthracite biofilters. For fully acclimated biofilters, a decrease in manganese removal across both GAC and anthracite biofilters at temperatures below 15°C was observed. However, greater and more consistent manganese removal was observed across GAC compared to anthracite biofilters. Performance differences between locations also suggest that operational and water quality conditions also likely affect manganese removal.