Use and impact of a novel nurse-led consultation model in a palliative care consultation service for terminally ill cancer patients in Taiwan: an 11-year observational study.

PURPOSE: The early integration of palliative care for terminally ill cancer patients improves quality of life. We have developed a new nurse-led consultation model for use in a palliative care consultation service (PCCS) to initiate early palliative care for cancer patients. METHODS: In this 11-year observational study, data were collected from the Hospice-Palliative Clinical Database (HPCD) of Taichung Veterans General Hospital (TCVGH). Terminally ill cancer patients who had received PCCS during the years 2011 to 2021 were enrolled. Trend analysis was performed in order to evaluate differences in outcomes seen within the categories of either a nurse-led consultation model or ordinary consultation model throughout the study period. Analysis included studying the duration of PCCS and DNR declaration, as well as awareness of disease by both patients and families before and after PCCS. RESULTS: In total, 6923 cancer patients with an average age of 64.1 years received PCCS from 2011 to 2021, with the average duration of PCCS being 11.1 days. Three thousand four hundred twenty-one patients (49.4%) received both a nurse consultation and doctor consultation during PCCS. Being admitted to the Department of Hematology, a longer duration of hospitalization, a DNR declaration after PCCS, and having had a PCCS consultation by a nurse only or both with a nurse and a doctor were significant determinants of a PCCS duration of more than 7 days. CONCLUSION: This 11-year observational study shows that the number of terminal cancer patients receiving a novel nurse-led consultation during PCCS has increased significantly during the past decade, while a nurse-led consultation model during PCCS was effective in improving the duration of PCCS among terminally ill cancer patients.

Land use, hydrology, and climate influence water quality of China's largest river.

Influences of multiple environmental factors on water quality patterns is less studied in large rivers. Landscape analysis, multiple statistical methods, and the water quality index (WQI) were used to detect water quality patterns and influencing factors in China's largest river, the Yangtze River. Compared with the dry season, the wet season had significantly higher total phosphorus (TP), chemical oxygen demand (COD), total suspended solids (TSS), and turbidity (TUR). The WQI indicated "Moderate" and "Good" water quality in the wet and dry seasons, respectively. Compared with other sites, the upper reach sites that immediately downstream of the Three Gorges Dam had lower TP, TN, TSS and TUR in both seasons, and had lower and higher water temperature in the wet and dry seasons, respectively. Water quality patterns were mainly driven by heterogeneity in land use (i.e., wetland, cropland, and urban land), hydrology (i.e., water flow, water level), and climate (i.e., rainfall, air temperature). Water quality in the wet season was primarily driven by land use while the joint effect of land use and hydrology primarily drove in the dry season. Decision-makers and regulators of large river basin management may need to develop programs that consider influences from both human and natural drivers for water quality conservation.

Attenuation of organics contamination in polymers processing effluent using iron-based sludge: process optimization and oxidation mechanism.

The feasibility of using iron extracted from acid mine drainage (AMD) as Fenton's reagent for removal of organics pollutants from polymer and plastics manufacturing effluent was investigated in this study. AMD iron dose, H2O2 concentration and pH were evaluated as the treatment factors for their effects on organics oxidation. Optimum treatment conditions were identified using response surface methodological analysis (RSM), and of the ranges of the treatment factors examined, an optimal treatment combination was found to be AMD iron concentration: 40 mg/L and H2O2: 500 mg/L at pH 2.2, organics removal efficiency as high as 98% for TOC removal was achieved. The removal efficiency increased with temperature up to 40°C and further temperature increases resulted in lower removal efficiencies. The organics oxidation was characterized well by investigating the kinetic order and the process is following the second-order reaction kinetics. The thermodynamic parameters showed that the oxidation reaction was endothermic and non-spontaneous in nature.

Trend analysis of palliative care consultation service for terminally ill non-cancer patients in Taiwan: a 9-year observational study.

BACKGROUNDS: Early integration of palliative care for terminally ill non-cancer patients improves quality of life. However, there are scanty data on Palliative Care Consultation Service (PCCS) among non-cancer patients. METHODS: In this 9-year observational study Data were collected from the Hospice-Palliative Clinical Database (HPCD) of Taichung Veterans General Hospital (TCVGH). Terminally ill non-cancer patients with 9 categories of diagnoses who received PCCS during 2011 to 2019 were enrolled. Trend analysis was performed to evaluate differences in categories of diagnosis throughout study period, duration of PCCS, patient outcomes, DNR declaration, awareness of disease by patients and families before and after PCCS. RESULTS: In total, 536 non-cancer patients received PCCS from 2011 to 2019 with an average age of 70.7 years. The average duration of PCCS was 18.4 days. The distributions of age, gender, patient outcomes, family's awareness of disease before PCCS, and patient's awareness of disease after PCCS were significantly different among the diagnoses. Organic brain disease and Chronic kidney disease (CKD) were the most prevalent diagnoses in patients receiving PCCS in 2019. For DNR declaration, the percentage of patients signing DNR before PCCS remained high throughout the study period (92.8% in 2019). Patient outcomes varied according to the disease diagnoses. CONCLUSION: This 9-year observational study showed that the trend of PCCS among non-cancer patients had changed over the duration of the study. An increasing number of terminally ill non-cancer patients received PCCS during late life, thereby increasing the awareness of disease for both patients and families, which would tend to better prepare terminally ill patients for end-of-life as they may consider DNR consent. Early integration of PCCS into ordinary care for terminally non-cancer patients is essential for better quality of life.

Palliative Care Consultation Services on Terminally Ill Cancer Patients and Non-Cancer Patients: Trend Analysis from a 9-Year-Long Observational Study in Taiwan.

Early integration of palliative care for terminally ill cancer and non-cancer patients improves quality of life. However, there are sparse data on results of palliative care consultation services (PCCS) between cancer and non-cancer patients. In this 9-year observational study, data were collected from the Hospice-Palliative Clinical Database (HPCD) of Taichung Veterans General Hospital (TCVGH). Terminally ill cancer and non-cancer patients who received PCCS during 2011 to 2019 were enrolled. Trend analysis was performed to evaluate differences in outcomes of PCCS, including duration of PCCS, the awareness of disease of patients and families before and after PCCS, status of PCCS termination, and DNR declaration before and after PCCS among cancer and non-cancer patients throughout study period. In total, 5223 cancer patients and 536 non-cancer patients received PCCS from 2011 to 2019. The number of people who received PCCS increased stably over the decade, both for cancer and non-cancer patients. The average duration of PCCS for cancer and non-cancer patients was 21.4 days and 18.4 days, respectively. Compared with non-cancer patients, cancer patients had longer duration of PCCS, less DNR declaration (82% vs. 98%, respectively), and more transfers to the palliative care unit (17% vs. 11%, respectively), or for palliative home care (12% vs.8%, respectively). Determinants of late referral to PCCS includes age (OR 0.992, 95% CI 0.987-0.996), DNR declaration after PCCS (OR 1.967, 95% CI 1.574-2.458), patients' awareness after PCCS (OR 0.754, 95% CI 0.635-0.895), and status of PCCS termination. This 9-year observational study showed that the trend of PCCS among cancer and non-cancer patients had changed over the duration of the study, and early integration of PCCS to all patients is essential for both cancer and non-cancer patients.

Functional Interrelationships of Microorganisms in Iron-Based Anaerobic Wastewater Treatment.

This study explicated the functional activities of microorganisms and their interrelationships under four previously reported iron reducing conditions to identify critical factors that governed the performance of these novel iron-dosed anaerobic biological wastewater treatment processes. Various iron-reducing bacteria (FeRB) and sulfate reducing bacteria (SRB) were identified as the predominant species that concurrently facilitated organics oxidation and the main contributors to removal of organics. The high organic contents of wastewater provided sufficient electron donors for active growth of both FeRB and SRB. In addition to the organic content, Fe (III) and sulfate concentrations (expressed by Fe/S ratio) were found to play a significant role in regulating the microbial abundance and functional activities. Various fermentative bacteria contributed to this FeRB-SRB synergy by fermenting larger organic compounds to smaller compounds, which were subsequently used by FeRB and SRB. Feammox (ferric reduction coupled to ammonium oxidation) bacterium was identified in the bioreactor fed with wastewater containing ammonium. Organic substrate level was a critical factor that regulated the competitive relationship between heterotrophic FeRB and Feammox bacteria. There were evidences that suggested a synergistic relationship between FeRB and nitrogen-fixing bacteria (NFB), where ferric iron and organics concentrations both promoted microbial activities of FeRB and NFB. A concept model was developed to illustrate the identified functional interrelationships and their governing factors for further development of the iron-based wastewater treatment systems.

Magnetic sludge byproducts for adsorptive phosphorus removal: Resource recovery from iron-based anaerobic sewage sludge.

This study evaluated feasibility of resource recovery from iron-based sewage sludge from a novel Fe(III)-dosed anaerobic bioreactor used for wastewater treatment. Sludge samples were calcined at five different temperatures (300, 350, 400, 450, and 500 °C) to investigate the transformation of the sludge into different magnetic phases of iron oxide particles. The material phase analysis revealed the presence of 14 to 39 wt% magnetite and 8 to 19 wt% maghemite for different temperature treatments, which indicate the successful conversion of sludge materials into magnetic particles. This magnetic conversion was further confirmed by magnetization measurements of the sludge byproducts that found a 6.3 to 10.9 emu/g saturation magnetization and a 0.7 to 2.0 emu/g remanent magnetization. Due to surface effects phenomenon of nanocrystals, the magnetization values were observed to increase with calcination temperature along with the crystallinity and crystallite size of the thermally-treated sludge materials. This indicates the crystallinity of the samples played a significant role in determining the magnetization properties of the sludge byproducts. Phosphate adsorption capacity and kinetics of the sludge byproducts were evaluated for the samples calcined at 350 and 500 °C. Both samples showed a high phosphate adsorption capacity, but the sample treated at 350 °C showed relatively higher capacity presumably due to smaller crystallite size and reduced crystallinity of the particles in the sample. This study demonstrated that a simple thermal treatment of the sludge can render dual benefits of recovering magnetic particles and further utilizing them for beneficial applications.

A holistic assessment of water quality condition and spatiotemporal patterns in impounded lakes along the eastern route of China's South-to-North water diversion project.

Water quality is one of the key determinants for assessing effectiveness and success of water diversions, but rarely studied at a spatial scale that crosses large river basins. Multiple statistical methods and the water quality index (WQI) were used to assess overall condition and detect spatiotemporal patterns of water quality in a series of impounded lakes along the Eastern Route of China's South-to-North Water Diversion Project. Principal components analysis and analysis of variances identified three groups with distinct water quality characteristics: upstream Gaoyou Lake and Hongze Lake showing relatively higher nutrients, turbidity, and total suspended solids; downstream Dongping lake and Donghu Lake showing higher conductivity, total hardness, and chloride; and Luoma Lake and Nansi Lake intermediate between the two former groups. The WQI indicated overall "Good" water quality with an improving trend from upstream to downstream lakes. The upstream Gaoyou Lake had over 55% of the monitoring sites with "Moderate" water quality in all the seasons. Management should focus on preventing high nitrogen, phosphorus, turbidity, and total suspended solids in upstream lakes, high chloride in downstream lakes, high nitrogen during water diversion seasons, and high phosphorus during non-water diversion seasons. These findings greatly improved our understanding of the spatiotemporal water quality patterns of the impounded lakes, and can be used to develop water quality management strategies. This study exemplifies a methodology for investigating and securing water quality for inter-basin water transfer projects.

Eutrophication and heavy metal pollution patterns in the water suppling lakes of China's south-to-north water diversion project.

This study used non-supervised machine learning self-organizing maps (SOM) in conjunction with traditional multivariate statistical techniques (e.g., hierarchical cluster analysis, principle component analysis, Pearson's correlation analysis) to investigate spatio-temporal patterns of eutrophication and heavy metal pollution in the water supplying lakes (i.e., the Gao-Bao-Shaobo Lake, GBSL) of the eastern route of China's South-to-North Water Diversion Project (SNWDP-ER). A total of 28 water quality parameters were seasonally monitored at 33 sampling sites in the GBSL during 2016 to 2017 (i.e., 132 water samples were collected in four seasons). The results indicated that: 1) spatially, the western and south-western GBSL was relatively more eutrophic and polluted with heavy metals; and 2) temporally, the lakes suffered from high risks of heavy metal contamination in spring, but eutrophication in summer while water quality in winter was the best among the four seasons. Two main potential sources of pollution and transport routes were identified and discussed based on the pollution patterns. These findings contributed considerably to providing in-depth understanding of water pollution patterns, as well as potential pollution sources in the water-supplying region. Such understanding is crucial for developing pollution control and management strategies for this mega inter-basin water transfer project.

Effects of Fe/S ratio on the kinetics and microbial ecology of an Fe(III)-dosed anaerobic wastewater treatment system.

Effects of Fe(III)/sulfate (Fe/S) ratio on organic carbon oxidation kinetics and microbial ecology of a novel Fe(III)-dosed anaerobic wastewater treatment system were investigated in this study. Fixed-film batch bioreactors under three Fe/S molar ratios (1, 2, and 3) yielded COD oxidation rates that increased with the Fe/S ratio, and estimated Michaelis-Menten model parameters Vmax ranging in 0.47-1.09 mg/L⋅min and Km in 2503-3267 mg/L. Both iron and sulfate reducing bacteria contributed to the organics oxidation, and the produced sludge materials contained both biomass (32-45 wt.%) and inorganic precipitates from biogenic ferrous iron and sulfide (68-55 wt.%). Spectroscopic and chemical elemental analyses indicated that the inorganic fraction of the sludge materials contained both FeS and FeS2, and had Fe/S stoichiometric ratios close to 1. Microbiological analyses of the biofilm samples revealed that the major putative iron- and sulfate reducers were Geobacter sp. and Desulfovibrio sp. along with noticeable N-fixing and fermentative bacteria. The COD oxidation rate had a positive correlation with the relative abundance of iron reducers, and both increased with the Fe/S ratio. A conceptual framework was proposed to illustrate the effects of Fe/S ratio on organics oxidation rate, microbial ecology and their interplays.

Background electrolytes and pH effects on selenate adsorption using iron-impregnated granular activated carbon and surface binding mechanisms.

Iron-impregnated granular activated carbon (Fe-GAC) has been shown effective for selenite adsorptive removal from aqueous solutions, but similar effectiveness was not observed with selenate. This study examined the effects of background electrolytes and pH on selenate adsorption on to Fe-GAC, and surface bindings to elucidate the selenate adsorption mechanisms. The decrease magnitude of selenate adsorption capacity under three background electrolytes followed the order: LiCl > NaCl > KCl, as ionic strength increased from 0.01 to 0.1 M. Larger adsorption capacity differences among the three electrolytes were observed under the higher ionic strengths (0.05 and 0.1 M) than those under 0.01 M. Multiplet peak fittings of high resolution X-ray photoelectron spectra for O1s and Fe2p3/2 indicated the presence of iron (III) on adsorbent surface. pH variations during the adsorbent preparation within 3-8 in NaCl solutions did not cause appreciable changes in the iron redox state and composition. Raman spectra showed the formation of both monodentate and bidentate inner sphere complexes under pHs <7 and a mixture of outer sphere and inner sphere complexes at pH 8. These results explained the lower selenate adsorption under alkaline conditions. Mechanisms for monodentate and bidentate formations and a stable six-member ring structure were proposed. Two strategies were recommended for modifying Fe-GAC preparation procedure to enhance the selenate adsorption: (1) mixed-metal oxide coatings to increase the point of zero charge (pHzpc); and (2) ferrous iron coating to initially reduce selenate followed by selenite adsorption.

Continuous sulfidogenic wastewater treatment with iron sulfide sludge oxidation and recycle.

This study evaluated the technical feasibility of packed-bed sulfidogenic bioreactors dosed with ferrous chloride for continuous wastewater treatment over a 450-day period. In phase I, the bioreactors were operated under different combinations of carbon, iron, and sulfate mass loads without sludge recycling to identify optimal treatment conditions. A COD/sulfate mass ratio of 2 and a Fe/S molar ratio of 1 yielded the best treatment performance with COD oxidation rate of 786 ± 82 mg/(L⋅d), which resulted in 84 ± 9% COD removal, 94 ± 6% sulfate reduction, and good iron retention (99 ± 1%) under favorable pH conditions (6.2-7.0). In phase II, the bioreactors were operated under this chemical load combination over a 62-day period, during which 7 events of sludge collection, oxidation, and recycling were performed. The collected sludge materials contained both inorganic and organic matter with FeS and FeS2 as the main inorganic constituents. In each event, the sludge materials were oxidized in an oxidizing basin before recycling to mix with the wastewater influent. Sludge recycling yielded enhanced COD removal (90 ± 6% vs. 75 ± 7%), and better effluent quality in terms of pH (6.8 ± 0.1 vs. 6.5 ± 0.2), iron (0.7 ± 0.5 vs. 1.9 ± 1.7 mg/L), and sulfide-S (0.3 ± 0.1 vs. 0.4 ± 0.1 mg/L) removal compared to the baseline operation without sludge recycling during phase II. This process exhibited treatment stability with reasonable variations, and fairly consistent sludge content over long periods of operation under a range of COD/sulfate and Fe/S ratios without sludge recycling. The bioreactors were found to absorb recycling-induced changes efficiently without causing elevated suspended solids in the effluents.

A case study for orphaned chemicals: 4-methylcyclohexanemethanol (MCHM) and propylene glycol phenyl ether (PPH) in riverine sediment and water treatment processes.

There are an estimated 30,000 chemicals in commerce used in quantities >1016kg per year in the US. Unfortunately there is limited information on the chemicals partitioning and reactivity properties. These orphaned or understudied chemicals are viewed as non-hazardous but can still pose serious economic, health, environmental and societal impacts as evidenced by the January 2014 spill of 37,900L of crude-MCHM (primarily 4-methylcyclohexanemethanol) and stripped-PPH (primarily dipropylene glycol phenyl ether and propylene glycol phenyl ether) into the Elk River near Charleston, WV. Using the Elk River spill as a case study of orphaned or understudied chemicals, experiments were undertaken to evaluate the adequacy of standard approaches to emergency drinking water treatment (oxidation and sorption to activated carbons). Further available sorption models for estimating the potential of these compounds to sorb to Elk River sediments and to activated carbons in drinking water systems were investigated. The results showed that powdered activated carbon (PAC) was the most effective sorbent. The trans-MCHM isomer was found to preferentially sorb compared to cis-MCHM. For MCHM concentrations ranging from 2 to 5mgL-1 in the treatment plant, PAC concentrations of 0.1-1.4mgL-1 would be required to lower both MCHM isomers to the CDC screening level. In most cases, published linear solvation energy relationships and quantitative structure activity relationships were inadequate to estimate the a priori likelihood of sorption of MCHM and PPH to sediments and GAC, but did fit the PAC results well. Permanganate and chlorine oxidation of the compounds showed limited to insignificant removal. The studies presented herein suggest that there are still inherent vulnerabilities to drinking water treatment systems that need to be addressed.

Improved COD Measurements for Organic Content in Flowback Water with High Chloride Concentrations.

An improved method was used to determine chemical oxygen demand (COD) as a measure of organic content in water samples containing high chloride content. A contour plot of COD percent error in the Cl(-)-Cl(-):COD domain showed that COD errors increased with Cl(-):COD. Substantial errors (>10%) could occur in low Cl(-):COD regions (<300) for samples with low (<10 g/L) and high chloride concentrations (>25 g/L). Applying the method to flowback water samples resulted in COD concentrations ranging in 130 to 1060 mg/L, which were substantially lower than the previously reported values for flowback water samples from Marcellus Shale (228 to 21 900 mg/L). It is likely that overestimations of COD in the previous studies occurred as result of chloride interferences. Pretreatment with mercuric sulfate, and use of a low-strength digestion solution, and the contour plot to correct COD measurements are feasible steps to significantly improve the accuracy of COD measurements.

Kinetics and microbial ecology of batch sulfidogenic bioreactors for co-treatment of municipal wastewater and acid mine drainage.

The kinetics and microbial ecology in sulfidogenic bioreactors used in a novel two-stage process for co-treatment of acid mine drainage (AMD) and municipal wastewater (MWW) were investigated. Michaelis-Menten modeling of COD oxidation by sulfate reducing bacteria (SRB) (Vmax=0.33mgL(-1)min(-1), Km=4.3mgL(-1)) suggested that the Vmax can be reasonably achieved given the typical COD values in MWW and anticipated mixing with AMD. Non-competitive inhibition modeling (Ki=6.55mgL(-1)) indicated that excessive iron level should be avoided to limit its effects on SRB. The COD oxidation rate was positively correlated to COD/sulfate ratio and SRB population, as evidenced by dsrA gene copies. Phylogenetic analysis revealed diverse microbial communities dominated by sulfate reducing delta-proteobacteria. Microbial community and relative quantities of SRB showed significant differences under different COD/sulfate ratios (0.2, 1 and 2), and the highest dsrA gene concentration and most complex microbial diversity were observed under COD/sulfate ratio 2. Major species were associated with Desulfovirga, Desulfobulbus, Desulfovibrio, and Syntrophus sp. The reported COD kinetics, SRB abundances and the phylogenetic profile provide insights into the co-treatment process and help identify the parameters of concerns for such technology development.

Two-stage combined treatment of acid mine drainage and municipal wastewater.

This study examined the feasibility of the combined treatment of field-collected acid mine drainages (AMD, pH = 4.2 ± 0.9, iron = 112 ± 118 mg/L, sulfate = 1,846 ± 594 mg/L) and municipal wastewater (MWW, avg. chemical oxygen demand (COD) = 234-333 mg/L) using a two-stage process. The process consisted of batch mixing of the two wastes to condition the mixture solutions, followed by anaerobic biological treatment. The mixings performed under a range of AMD/MWW ratios resulted in phosphate removal of 9 to ∼100%, the mixture pH of 6.2-7.9, and COD/sulfate concentration ratio of 0.05-5.4. The biological treatment consistently removed COD and sulfate by >80% from the mixture solutions for COD/sulfate ratios of 0.6-5.4. Alkalinity was produced in the biological treatment causing increased pH and further removal of metals from the solutions. Scanning electron microscopy of produced sludge with energy dispersion analysis suggested chemical precipitation and associated adsorption and co-precipitation as the mechanisms for metal removal (Fe: >99%, Al: ∼100%, Mn: 75 to ∼100%, Ca: 52-81%, Mg: 13-76%, and Na: 56-76%). The study showed promising results for the treatment method and denoted the potential of developing innovative technologies for combined management of the two wastes in mining regions.

Effect of the disinfection agents chlorine, UV irradiation, silver ions, and TiO2 nanoparticles/near-UV on DNA molecules.

Extracellular DNA in municipal wastewater and effluents from hospitals and R&D laboratories contains antimicrobial resistance and recombinant genes that are today considered as a new class of emerging contaminants. The objective of this research was to investigate the effect of disinfection agents on the integrity of DNA molecules by using real-time PCR. Escherichia coli cell suspensions and genomic DNA in aqueous solution were exposed to increasing doses of disinfection systems, including chlorination, UV irradiation, silver ions, and TiO2 nanoparticles/near-UV. The doses resulting in damage of DNA (16S rDNA) were determined using real-time PCR and compared with the doses resulting in the inactivation of bacterial cells. Our results showed that the disinfection agents chlorine, UV, and silver significantly inhibited the amplification of a fragment of 16S rDNA, but only when applied at doses much higher than the lethal doses for E. coli bacteria. The inactivation doses of TiO2 nanoparticles/near-UV were of the same order of magnitude for both DNA and living cells. Our results raise questions about the efficacy of disinfection processes to destroy and prevent the dispersion of DNA pollutants into the environment. In addition, the damage of DNA by high levels of disinfectants may have implications for the utilization of PCR-based methods for bacterial detection.

As(III) removal using an iron-impregnated chitosan sorbent.

An iron-impregnated chitosan granular adsorbent was newly developed to evaluate its ability to remove arsenic from water. Since most existing arsenic removal technologies are effective in removing As(V) (arsenate), this study focused on As(III). The adsorption behavior of As(III) onto the iron-impregnated chitosan absorbent was examined by conducting batch and column studies. Maximum adsorption capacity reached 6.48 mg g(-1) at pH=8 with initial As(III) concentration of 1007 microg L(-1). The adsorption isotherm data fit well with the Freundlich model. Seven hundred and sixty eight (768) empty bed volumes (EBV) of 308 microg L(-1) of As(III) solution were treated in column experiments. These are higher than the empty bed volumes (EBV) treated using iron-chitosan composites as reported by previous researchers. The investigation has indicated that the iron-impregnated chitosan is a very promising material for As(III) removal from water.

Fate of amoxicillin in mixed-culture bioreactors and its effects on microbial growth and resistance to silver ions.

This research focused on studying the fate of amoxicillin (AMX) in mixed-culture bioreactors and its effects on bacterial growth and bacterial resistance to silver-ion disinfection. The bioreactors were dosed with a range of AMX (10-70 mg L(-1) d(-1)) mimicking a biological treatment unit of a proposed water recovery system for long-term space missions. Aqueous-phase AMX concentrations in the bioreactors were monitored to characterize the kinetics of selected AMX fate processes. Specific growth rates and silver minimum effective concentrations (MECs) of the bacterial cultures were determined by assessing cell viability using flow cytometry. Hydrolysis, sorption, and biodegradation of AMX followed first-order kinetics with rate constants of 0.078, 0.083, and 0.13 d(-1), respectively. Specific growth rates of the AMX-dosed cultures were suppressed from 7% to 35% in order of increasing AMX dose as compared to the AMX-free control cultures. The AMX-treated cultures had higher silver MECs than the AMX-free control cultures, indicating an enhanced bacterial resistance to silver ions as a result of the AMX exposure. Biosorption experiments revealed that the AMX-treated cultures exhibited exclusion of silver ions from the cells as a potential mechanism for the enhanced resistance. This paper reports for the first time that low levels of AMX (<100 mg L(-1)) could induce bacterial cross-resistance to silver ion in an aqueous system mimicking an active biological system for wastewater treatment.