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•SPAC had up to s480 times higher adsorption mass loading of PFAAs than GAC.•SPAC and GAC adsorption efficiency depends on PFAS chain length.•The ceramic MF membrane had minimal ...fouling during long-term filtration.•PFASs were effectively removed by the combined SPAC/MF system.
Contamination of drinking water sources with per- and polyfluoroalkyl substances (PFASs) is a major challenge for environmental engineers. While granular activated carbon (GAC) is an effective adsorbent-based treatment technology for long-chained PFASs, GAC is less effective for removal of short-chained compounds, necessitating a more complete treatment strategy. Super-fine powder activated carbon (SPAC; particle diameter <1 um) is potentially a superior adsorbent to GAC due to high specific surface area and faster adsorption kinetics. This study served to evaluate SPAC coupled with ceramic microfiltration (CMF) for PFAS removal in a continuous flow system. Comparison of PFAS mass loading rates onto SPAC and GAC to 10% breakthrough of PFASs using contaminated groundwater indicates that SPAC has nearly double the adsorption potential of GAC. Limitations reaching breakthrough for the SPAC system led to additional higher mass loading experiments where PFAS adsorption onto SPAC reached 2990 μg/g (for quantifiable PFASs), 480x greater than GAC and is thought to be a function of adsorbent size, pore content and PFAS chain length. Additional analysis of system performance through the application of liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QToF-MS) revealed the presence of additional PFASs in influent samples that were removed by the SPAC/CMF system.
•PFAA removal from wastewater effluent by GAC, AER, and SMC was investigated.•AER outperformed GAC and SMC for the removal of PFAAs from wastewater effluent.•Pretreatments significantly improved PFAA ...removal for all investigated adsorbents.•Molecular-level interference of EfOM with PFAA adsorption was investigated by SEC.•EfOM transformation/removal by pretreatments led to improved PFAA removal.
Occurrence of perfluoroalkyl acids (PFAAs) in wastewater effluent coupled with increasingly stringent regulations has increased the need for more effective sorption-based PFAA treatment approaches. This study investigated the impact of ozone (O3)- biologically active filtration (BAF) as integral components of non-reverse osmosis (RO)-based potable reuse treatment trains and as a potential pretreatment option to improve adsorptive PFAA removal from wastewater effluent by nonselective (e.g., granular activated carbon (GAC) and selective (e.g., anionic exchange resins (AER) and surface-modified clay (SMC)) adsorbents. For nonselective GAC, O3 and BAF resulted in similar PFAA removal improvements, while BAF alone performed better than O3 for AER and SMC. O3-BAF in tandem resulted in the highest PFAA removal performance improvement among pretreatments investigated for selective and nonselective adsorbents. Side by side evaluation of the dissolved organic carbon (DOC) breakthrough curves and size exclusion chromatography (SEC) for each pretreatment scenario suggested that despite the higher affinity of selective adsorbents towards PFAAs, the competition between PFAA and effluent organic matter (EfOM) (molecular weights (MWs): 100–1000 Da) negatively impacts the performance of these adsorbents. The SEC results also demonstrated that transformation of hydrophobic EfOM to more hydrophilic molecules during O3 and biotransformation of EfOM during BAF were the dominant mechanisms responsible for alleviating the competition between PFAA and EfOM, resulting in PFAA removal improvement.
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•Pre-ozonation is an effective method for enhancing purification technologies in potable reuse applications.•Pre-ozonation of wastewater effluent with relatively low specific ozone ...dose mitigated nanofiltration membrane fouling.•Increasing the specific ozone dose did not provide a significant benefit in fouling reduction.•The removal of dissolved organic carbon by nanofiltration did not show a substantial change when pre-ozonation was applied.
The selection of appropriate purification technologies for the potable reuse of municipal wastewater effluent is an important component of water resource management. In this study, a fully automated high-pressure bench-scale membrane system was used to investigate the impact of pre-ozonation of wastewater effluent on nanofiltration (NF) fouling during reuse applications. A commercial polyamide NF membrane was employed to evaluate the impact of pre-ozonation on fouling and determine an effective specific ozone dose. The results indicated that pre-ozonation of sequencing batch reactor membrane bioreactor (SBMBR) effluent with a relatively low specific ozone dose (0.2 mg O3/mg DOC) could effectively mitigate a significant portion of fouling on the membrane compared to filtration without pre-ozonation. However, increasing the specific ozone dose to 0.4 mg O3/mg DOC did not provide a significant additional benefit. The dissolved organic carbon removal performance of the NF membrane did not show a substantial change when pre-ozonation was applied and remained relatively constant which may be due to the relatively low applied specific ozone dose. Organic fouling was suspected to be the main fouling mechanism during SBMBR filtration with NF membrane.
Per- and polyfluoroalkyl substance (PFAS) contamination in aqueous matrices has intensified the search for PFAS adsorbents with elevated capacity, selectivity, and cost effectiveness. A novel surface ...modified organoclay (SMC) adsorbent was evaluated for PFAS removal performance in parallel with granular activated carbon (GAC) and ion exchange resin (IX) for the treatment of five distinct PFAS impaired waters including groundwater, landfill leachate, membrane concentrate and wastewater effluent. Rapid small scale column tests (RSSCTs) and breakthrough modeling were coupled to provide insight on adsorbent performance and cost for multiple PFAS and water types. IX exhibited the best performance with respect to adsorbent use rates in treatment of all tested waters. IX was nearly four times more effective than GAC and two times more effective than SMC in the treatment of PFOA from water types excluding groundwater. Employed modeling strengthened the comparison of adsorbent performance and water quality to infer adsorption feasibility. Further, evaluation of adsorption was extended beyond PFAS breakthrough with the inclusion of unit adsorbent cost as a decision metric influencing adsorbent selection. An analysis of levelized media cost indicated treatment of landfill leachate and membrane concentrate was at least three times more expensive than groundwaters or wastewaters evaluated.
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•RSSCT evaluation of GAC, IX, and surface modified clay for PFAS removal.•PFAS concentration, DOC, anions impacted PFAS adsorbent use rates.•Lower levelized media cost guided adsorbent selection.
•Combination of NF and UV-sulfite more cost effective PFAS degradation method.•NF effective technology to concentrate (> 10x) and reject PFASs (∼95%).•Faster UV-sulfite degradation in alkaline pH ...11.2.•UV-sulfite degradation of all PFCAs < 2 h and PFOS < 4 h in NF reject.•Treatment train EE/O ≤ 13.1 kWh/m3 for all PFCAs and 14.1 kWh/m3 for PFOS.
Previous laboratory scale studies indicate nanofiltration (NF) and UV-sulfite photochemical treatments as promising technologies for the removal and destruction, respectively, of per- and polyfluoroalkyl substances (PFASs) from contaminated water. This study reports on a field demonstration of a pilot-scale hybrid NF and UV-sulfite treatment train for the remediation of 12 PFASs detected in groundwater impacted by aqueous film-forming foam (AFFF) at a U.S. Department of Defense installation. For most of the detected PFASs, NF rejection was consistently ≥ 95% over a 30-day field trial when operating at 90% total permeate recovery. Rejection of short-chain perfluorosulfonic acids (PFSAs) by NF decreased when recoveries increased from 90 to 97%; tests with a reverse osmosis (RO) membrane showed ≥ 99% rejection of all PFASs regardless of increasing recovery. UV treatment of the NF reject following 90% permeate recovery resulted in variable destruction of individual PFASs, with rates also being dependent on pH and the identity and concentration of UV photosensitizer. Rates of perfluorocarboxylic acid (PFCA) degradation were greater than those measured for PFSAs and perfluoroalkyl acid (PFAA) precursors and were independent of perfluoroalkyl chain length. In contrast, rates of PFSA degradation increased with increasing chain length. Consistent levels of PFAS degradation by UV-sulfite were observed during a 30-day demonstration experiment in NF reject water amended with 10 mM sulfite and adjusted to pH 11.2. Collectively, > 75% of the detected PFAS mass in the NF reject was destroyed after 4 h of UV treatment, increasing to > 90% after 8 h of treatment. An analysis of electrical energy inputs for the hybrid NF/UV-sulfite treatment train showed energy per order magnitude (EE/O) requirements ranging from ≤ 13.1 kWh/m3 for PFCAs and 14.1 kWh/m3 for PFOS to values > 100 kWh/m3 for more recalcitrant short-chain PFSA analogues. The UV reactor and water-cooling system were the major contributors to overall energy requirements and represent the greatest opportunities for improving efficiency of the technology.
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While drinking water treatment plants (DWTPs) are not considered a source of per‐ and polyfluoroalkyl substances (PFAS), PFAS concentrate in treatment residuals relative to their source water ...concentrations. Regulatory actions considered for PFAS‐impacted residuals could affect the cost and viability of conventional residual management practices. This study estimated the annual quantity of residuals generated in the United States and presents a framework for understanding how PFAS may concentrate in these residual streams. Findings of this work indicate that PFAS may substantially impact DWTP residuals management, especially coagulation and softening solids, at concentration factors greater than 100 and spent adsorbents at PFAS concentration factors greater than 10,000. If potential regulatory actions were to apply to coagulation and softening residuals, those regulations must consider impacts on disposal of more than 420,000,000 wet tons of at‐risk DWTP residuals which are generated annually.
Perceptions of control hold a dominant position in social cognitive theories yet there is a lack of conceptual and empirical clarity regarding what kind of control is most associated with particular ...behaviours. Three prominent types of control are perceived control (PC), perceived difficulty (PD), and perceived confidence or self‐efficacy (SE) for performing the desired behaviour. Three studies are presented with a primary goal of distinguishing PC, PD, and SE from each other, and a secondary goal of determining which of the three is the superior predictor of health‐related intentions and behaviours. The first study replicates earlier work by Trafimow et al. (2002) distinguishing the three constructs for reading 1, 30, and 100 pages, and extends it to exercising one, two, four, and six times per week and also to predicting intentions to exercise 4 days per week and behaviour 1 week later. The second study examines the predictive capability of the three constructs for intentions to floss one's teeth everyday and to eat 5–10 servings of fruits and vegetables everyday and subsequently on behaviour assessed 7 days later. The third study reports a meta‐analysis of the relative influence of PC, PD, and SE on behaviours when defined in conceptually consistent ways. The results of all three studies support the conceptual and empirical distinction of PC, PD, and SE and the superiority of SE as a predictor of health behaviours and intentions.
Since 2000, international funding for HIV has supported scaling up antiretroviral therapy (ART) in sub-Saharan Africa. However, such funding has stagnated for years, threatening the sustainability ...and reach of ART programs amid efforts to achieve universal treatment. Improving health system efficiencies, particularly at the facility level, is an increasingly critical avenue for extending limited resources for ART; nevertheless, the potential impact of increased facility efficiency on ART capacity remains largely unknown. Through the present study, we sought to quantify facility-level technical efficiency across countries, assess potential determinants of efficiency, and predict the potential for additional ART expansion.
Using nationally-representative facility datasets from Kenya, Uganda and Zambia, and measures adjusting for structural quality, we estimated facility-level technical efficiency using an ensemble approach that combined restricted versions of Data Envelopment Analysis and Stochastic Distance Function. We then conducted a series of bivariate and multivariate regression analyses to evaluate possible determinants of higher or lower technical efficiency. Finally, we predicted the potential for ART expansion across efficiency improvement scenarios, estimating how many additional ART visits could be accommodated if facilities with low efficiency thresholds reached those levels of efficiency.
In each country, national averages of efficiency fell below 50 % and facility-level efficiency markedly varied. Among facilities providing ART, average efficiency scores spanned from 50 % (95 % uncertainty interval (UI), 48-62 %) in Uganda to 59 % (95 % UI, 53-67 %) in Zambia. Of the facility determinants analyzed, few were consistently associated with higher or lower technical efficiency scores, suggesting that other factors may be more strongly related to facility-level efficiency. Based on observed facility resources and an efficiency improvement scenario where all facilities providing ART reached 80 % efficiency, we predicted a 33 % potential increase in ART visits in Kenya, 62 % in Uganda, and 33 % in Zambia. Given observed resources in facilities offering ART, we estimated that 459,000 new ART patients could be seen if facilities in these countries reached 80 % efficiency, equating to a 40 % increase in new patients.
Health facilities in Kenya, Uganda, and Zambia could notably expand ART services if the efficiency with which they operate increased. Improving how facility resources are used, and not simply increasing their quantity, has the potential to substantially elevate the impact of global health investments and reduce treatment gaps for people living with HIV.
Daily glatiramer acetate (GA) 20 mg/1.0 mL is a first-line treatment for relapsing-remitting multiple sclerosis (RRMS). To reduce the occurrence of injection pain and local injection site reactions ...(LISRs), a reduced volume formulation of GA was developed. This study compared pain and LISRs after injecting the marketed and the novel formulations. RRMS patients currently injecting GA participated in this multicenter, randomized, crossover comparative study. All patients administered once-daily subcutaneous injections of GA 20 mg/1.0 mL (marketed formulation) or GA 20 mg/0.5 mL (reduced volume formulation) for 14 days. Patients were crossed-over to the alternate treatment for an additional 14 days. Using a Visual Analog Scale (VAS), patients recorded in daily diaries the severity of injection pain immediately and 5 min post-injection, and the presence and severity of LISRs (swelling, redness, itching, lump) within 5 min and 24 h post-injection. VAS pain scores were ranked significantly lower immediately and 5 min after GA 20 mg/0.5 mL injections (
p
< 0.0001). Although LISRs were rare for both preparations, the severity of reactions ranked significantly lower and fewer symptoms occurred within 5 min and 24 h of using the reduced volume formulation (
p
< 0.0001). GA injected subcutaneously in a reduced volume formulation is a more tolerable option.
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