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1.
Health Aff (Millwood) ; 42(2): 227-236, 2023 02.
Article in English | MEDLINE | ID: mdl-36652633

ABSTRACT

The No Surprises Act prohibits most surprise billing but notably does not apply to ground ambulance services. In this study we created a novel data set that identifies the ownership structure of ground ambulance organizations to compare pricing and billing between private- and public-sector ambulances, with a specific focus on organizations owned by private equity or publicly traded companies. Overall, we found that 28 percent of commercially insured emergency ground ambulance transports during the period 2014-17 resulted in a potential surprise bill. Our analysis illustrates that being transported by a private-sector ambulance in an emergency comes with substantially higher allowed amounts, patient cost sharing, and potential surprise bills compared with being transported by a public-sector ambulance. Further, allowed amounts and cost sharing tended to be higher for private equity- or publicly traded company-owned ambulances than other private-sector ambulances. These findings highlight substantial patient liability and important differences in pricing and billing patterns between public- and private-sector ground ambulance organizations.


Subject(s)
Ambulances , Ownership , Humans , Private Sector , Public Sector , Cost Sharing
2.
Sci Total Environ ; 858(Pt 2): 159869, 2023 Feb 01.
Article in English | MEDLINE | ID: mdl-36328252

ABSTRACT

Ultrafine particles (UFPs or PM0.1; aerodynamic diameter ≤ 0.1 µm) were monitored at a roadside site (RS) in a populated area of Hanoi, Vietnam. Meanwhile, UFPs and fine particles (FPs or PM2.5, aerodynamic diameter ≤ 2.5 µm) were monitored at an ambient site (AS), located at an on-campus a university, approximately 200 m away from the RS. Sampling was conducted in different seasons-summer, winter, and the transitional periods of summer-to-winter and winter-to-summer (STP and WTP, respectively). Carbonaceous and ionic species in UFPs and FPs-rarely investigated in the study area-were analyzed to observe the seasonal variations, characteristics of UFPs near the roadway, and spatial differences between the sites. The UFPs concentration at the AS was in the order of winter > STP > WTP > summer, whereas that of the FPs was winter > WTP > STP > summer. This seasonal variation of particle concentration was possibly affected by the meteorological conditions, which contribute to the highest concentration in winter. The higher FPs concentration in WTP than in STP resulted from the substantial increase in ionic concentrations, particularly sulfate, nitrate, and ammonium. This result indicates the effect of secondary formation processes under drizzle-like weather, which is typical during WTP in northern Vietnam. Compared with UFPs at the AS, traffic-related emissions were more noticeable in UFPs at the RS, including a higher EC concentration and lower OC/EC ratio. The possibility of particle growth under favorable conditions, including the presence of gas-phase pollutants and the availability of surface areas owing to high UFPs concentration in Hanoi, may explain the low correlation of the chemical components between UFPs and FPs in the sites. This study serves as a reference for further investigation of the relationship between UFPs and FPs under highly polluted conditions in big cities in Vietnam in future studies.


Subject(s)
Air Pollutants , Humans , Air Pollutants/analysis , Environmental Monitoring/methods , Vietnam , Particulate Matter/analysis , Cities , Seasons , Particle Size , Vehicle Emissions/analysis
3.
Health Aff (Millwood) ; 41(8): 1107-1116, 2022 08.
Article in English | MEDLINE | ID: mdl-35914212

ABSTRACT

The 21st Century Cures Act of 2016 lifted regulations prohibiting Medicare Advantage (MA) enrollment after patients initiate dialysis, starting in 2021, and early reports indicate increased MA enrollment among such patients. Large shifts into Medicare Advantage could disrupt the market because the consolidated dialysis industry can negotiate payment from MA plans that is higher than that for fee-for-service Medicare. For three large insurers representing 48 percent of the 2016-17 MA market, we found that MA plans paid 27 percent more than fee-for-service Medicare. Larger dialysis center chains commanded higher markups. Virtually all facilities of the two largest chains were in network, suggesting that they leverage their market power into all-or-nothing negotiations with plans. Policy makers should consider regulations that limit market consolidation among dialysis providers, as well as their ability to exercise that power in the MA market.


Subject(s)
Medicare Part C , Aged , Fee-for-Service Plans , Humans , Renal Dialysis , Salaries and Fringe Benefits , United States
4.
Am J Manag Care ; 27(6): e195-e200, 2021 06 01.
Article in English | MEDLINE | ID: mdl-34156223

ABSTRACT

OBJECTIVES: Anesthesiology services are a focal point of policy making to address surprise medical billing. However, allowed amounts and charges for anesthesiology services have been understudied due to the specialty's unique conversion factor (CF) unit of payment and complex provider structures involving anesthesiologists and certified registered nurse anesthetists (CRNAs). This study compares payments for common outpatient anesthesiology services by commercial health plans, Medicare Advantage (MA), and traditional Medicare. STUDY DESIGN: Analysis of 2016-2017 claims from Health Care Cost Institute. METHODS: We derived allowed amount and charge CFs for commercial and MA claims using the base units assigned to each procedure code, time units, and modifiers. We computed the ratio of the allowed amount and charge CFs relative to the traditional Medicare CF. We described these payment measures by provider structure and network status. RESULTS: Mean in-network commercial allowed amount CFs for anesthesiology services ($70) are 314% of the traditional Medicare rate ($22), whereas mean commercial charge CFs ($148) are 659% of the Medicare rate. Commercial payments vary widely and are higher to anesthesiologists than to CRNAs and higher out of network than in network. MA plan payments align with traditional Medicare with payment parity between anesthesiologists and CRNAs, both in network and out of network. CONCLUSIONS: Common payment measures for anesthesia services-commercial allowed amounts, charges, or traditional Medicare-are highly divergent. MA plans' relatively low payments likely reflect the cost-containing influence of competition with traditional Medicare and MA's prohibition on balance billing. Out-of-network benchmarks for anesthesia services, such as the "qualifying payment amount" used in the No Surprises Act as a guidepost for arbitrators, may benefit from considering commercial payment differences across independent anesthesiologist, independent CRNA, or anesthesiologist-CRNA dyad provider structures.


Subject(s)
Anesthesiology , Medicare Part C , Aged , Anesthesiologists , Female , Health Care Costs , Humans , Nurse Anesthetists , Pregnancy , United States
5.
J Anal Methods Chem ; 2021: 6661955, 2021.
Article in English | MEDLINE | ID: mdl-33552612

ABSTRACT

In this work, twelve heavy metals and arsenic, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, and Zn, in a rice sample collected from some areas of Vietnam have been quantified and implemented by using multiple analytical platforms such as ICP-MS, AAS, and mercury analyser. Seventy rice samples collected from the Red River Delta and mining zone activity were analysed. Concentration of heavy metals and arsenic in rice was analysed after appropriated sample digestion using internal or external calibration curves. The mean concentration (mg kg-1 dried weight) of the analysed elements in rice samples decreased on the order of Mn (19.268) > Fe (13.624) > Zn (8.163) > Cu (3.138) > Ni (0.384) > Cr (0.296) > Co (0.279) > As (0.115) > Cd (0.111) > Pb (0.075) > Hg (0.007) > Se (

6.
Health Aff (Millwood) ; 40(1): 130-137, 2021 01.
Article in English | MEDLINE | ID: mdl-33400578

ABSTRACT

In 2018 New Jersey implemented a final-offer arbitration system to resolve payment disputes between insurers and out-of-network providers over surprise medical bills. Similar proposals are being considered by Congress and other states. In this article we examine how arbitration decisions compare with other relevant provider payment amounts by linking administrative data from New Jersey arbitration cases to Medicare and commercial insurance claims data. We find that decisions track closely with one of the metrics that arbitrators are shown-the eightieth percentile of provider charges-with the median decision being 5.7 times prevailing in-network rates for the same services. It is not a foregone conclusion that arbitrators will select winning offers based on proximity to this target, although our findings suggest that it is a strong anchor. The amount that providers can expect to receive through the arbitration process also affects their bargaining leverage with insurers, which could affect in-network negotiated rates more broadly. Therefore, basing arbitration decisions or a payment standard on unilaterally set provider-billed charges appears likely to increase health care costs relative to other surprise billing solutions and perversely incentivizes providers to inflate their charges over time.


Subject(s)
Dissent and Disputes , Negotiating , Aged , Humans , Insurance Carriers , Medicare , New Jersey , United States
7.
Am J Manag Care ; 26(9): 401-404, 2020 09.
Article in English | MEDLINE | ID: mdl-32930553

ABSTRACT

OBJECTIVES: To quantify the proportion of health plan spending on services for which surprise billing is common-provided by radiologists, anesthesiologists, pathologists, emergency physicians, emergency ground ambulances, and emergency outpatient facilities-and estimate the potential impact of proposed policies to address surprise billing on health insurance premiums. STUDY DESIGN: Analysis of 2017 commercial claims data from the Health Care Cost Institute, comprising 568.5 million claims from 44.8 million covered lives in 3 large US insurers: UnitedHealthcare, Aetna, and Humana. METHODS: We calculate the share of total health plan claims spending attributable to ancillary and emergency services. Next, we estimate the premium impact of proposed federal policies to address surprise billing, which, by removing provider leverage stemming from the ability to surprise-bill, could reduce in- and out-of-network payments for these services, in turn affecting premiums. Specifically, we model the premium impact of reducing payment for these services (1) by 15% and (2) to 150% of traditional Medicare payment rates. RESULTS: More than 10% of health plan spending is attributable to ancillary and emergency services that commonly surprise-bill. Reducing payment for these services by 15% would reduce premiums by 1.6% ($67 per member per year), and reducing average payment to 150% of traditional Medicare rates-the high end of payments to other specialists-would reduce premiums by 5.1% ($212 per member per year). These savings would reduce aggregate premiums for the nation's commercially insured population by approximately $12 billion and $38 billion, respectively. CONCLUSIONS: Addressing surprise billing could substantially affect commercial insurance premiums.


Subject(s)
Health Policy , Insurance, Health , Medicare , Aged , Health Care Costs , Humans , Insurance Carriers , Policy , United States
8.
Milbank Q ; 98(3): 747-774, 2020 09.
Article in English | MEDLINE | ID: mdl-32525223

ABSTRACT

Policy Points Out-of-network air ambulance bills are a type of surprise medical bill and are driven by many of the same market failures behind other surprise medical bills, including patients' inability to choose in-network providers in an emergency or to avoid potential balance billing by out-of-network providers. The financial risk to consumers is high because more than three-quarters of air ambulances are out-of-network and their prices are high and rising. Consumers facing out-of-network air ambulance bills have few legal protections owing to the Airline Deregulation Act's federal preemption of state laws. Any federal policies for surprise medical bills should also address surprise air ambulance bills and should incorporate substantive consumer protections-not just billing transparency-and correct the market distortions for air ambulances. CONTEXT: Out-of-network air ambulance bills are a growing problem for consumers. Because most air ambulance transports are out-of-network and prices are rising, patients are at risk of receiving large unexpected bills. This article estimates the prevalence and magnitude of privately insured persons' out-of-network air ambulance bills, describes the legal barriers to curtailing surprise air ambulance bills, and proposes policies to protect consumers from out-of-network air ambulance bills. METHODS: We used the Health Care Cost Institute's 2014-2017 data from three large national insurers to evaluate the share of air ambulance claims that are out-of-network and the prevalence and magnitude of potential surprise balance bills, focusing on rotary-wing transports. We estimated the magnitude of potential balance bills for out-of-network air ambulance services by calculating the difference between the provider's billed charges and the insurer's out-of-network allowed amount, including the patient's cost-sharing. For in-network air ambulance transports, we calculated the average charges and allowed amounts, both in absolute magnitude and as a multiple of the rate that Medicare pays for the same service. FINDINGS: We found that less than one-quarter of air ambulance transports of commercially insured patients were in-network. Two-in-five transports resulted in a potential balance bill, averaging $19,851. In the latter years of our data, in-network rates for transports by independent (non-hospital-based) carriers averaged $20,822, or 369% of the Medicare rate for the same service. CONCLUSIONS: Because the states' efforts to curtail air ambulance balance billing have been preempted by the Airline Deregulation Act, a federal solution is needed. Owing to the failure of market forces to discipline either prices or supply, out-of-network air ambulance rates should be benchmarked to a multiple of Medicare rates or, alternatively, air ambulance services could be delivered and financed through an approach that combines competitive bidding and public utility regulation.


Subject(s)
Air Ambulances/economics , Financing, Personal/statistics & numerical data , Health Policy , Air Ambulances/organization & administration , Air Ambulances/statistics & numerical data , Fees and Charges/statistics & numerical data , Financing, Personal/economics , Health Care Costs/statistics & numerical data , Humans , Insurance Coverage/economics , Insurance Coverage/statistics & numerical data , Insurance, Health/economics , Insurance, Health/organization & administration , Insurance, Health/statistics & numerical data , Prevalence , United States
9.
Environ Sci Pollut Res Int ; 27(24): 30661-30672, 2020 Aug.
Article in English | MEDLINE | ID: mdl-32472507

ABSTRACT

PM0.1 has been believed to have adverse short- and long-term effects on human health. However, the information of PM0.1 that is needed to fully evaluate its influence on human health and environment is still scarce in many developing countries. This is a comprehensive study on the levels, chemical compositions, and source apportionment of PM0.1 conducted in Hanoi, Vietnam. Twenty-four-hour samples of PM0.1 were collected during the dry season (November to December 2015) at a mixed site to get the information on mass concentrations and chemical compositions. Multiple linear regression analysis was utilized to investigate the simultaneous influence of meteorological factors on fluctuations in the daily levels of PM0.1. Multiple linear regression models could explain about 50% of the variations of PM0.1 concentrations, in which wind speed is the most important variable. The average concentrations of organic carbon (OC), elemental carbon (EC), water-soluble ions (Ca2+, K+, Mg2+, Na+, NH4+, Cl-, NO3-, SO42-, C2O42-), and elements (Be, Al, V, Cr, Mn, Co, Ni, Cu, Zn, As, Se, Mo, Cd, Sb, Ba, Tl, Pb, Na, Fe, Mg, K, and Ca) were 2.77 ± 0.90 µg m-3, 0.63 ± 0.28 µg m-3, 0.88 ± 0.39 µg m-3, and 0.05 ± 0.02 µg m-3, accounting for 51.23 ± 9.32%, 11.22 ± 2.10%, 16.28 ± 2.67%, and 1.11 ± 0.94%, respectively. A positive matrix factorization model revealed the contributions of five major sources to the PM0.1 mass including traffic (gasoline and diesel emissions, 46.28%), secondary emissions (31.18%), resident/commerce (12.23%), industry (6.05%), and road/construction (2.92%).


Subject(s)
Air Pollutants/analysis , Nanoparticles , Environmental Monitoring , Humans , Particulate Matter/analysis , Vehicle Emissions/analysis , Vietnam
10.
Chemosphere ; 254: 126749, 2020 Sep.
Article in English | MEDLINE | ID: mdl-32339797

ABSTRACT

Volatile organic compounds (VOCs) are important air pollution issues because of their potential health effects, and the contribution to ground ozone and secondary particulate matter. In this study, 53 VOC species near nine roads in Hanoi were monitored by sampling and analyzed by GC-FID four times per day on weekdays and in the morning on the weekend, from December 2014 to January 2015. In parallel with VOC sampling, vehicle number was counted, and meteorological conditions were recorded. A large share of motorbikes was found, accounted for 82% of overall for all period, and 88% in rush hours. The average TVOC concentration was 305.1 ppb; while those of BTEX were 12.8/27.4/4.8/15.9/6.0 ppb for benzene/toluene/ethylbenzene/m,p-xylenes/o-xylene, respectively. Isopentane was the most abundant species of VOCs. A significant carcinogenic risk of benzene species was found. Ozone formation potential (OFP) of VOCs was of 1752.7 ppb. Levels of VOC species reflected well the transportation volume. Strong correlations between motorbike number related parameters and ethylbenzene were found. High correlations were also found among ethylbenzene and almost all other VOC species. It implied that the majority of VOCs near road emitted from the same source, which is motorbikes. The calculation using emission factors from COPERT 5 model with conditions of fleets in Hanoi showed that VOCs from motorbikes contributed to more than 90% of the VOC level.


Subject(s)
Air Pollutants/analysis , Environmental Monitoring , Volatile Organic Compounds/analysis , Air Pollution , Benzene/analysis , Gasoline/analysis , Ozone/analysis , Particulate Matter/analysis , Pentanes , Toluene/analysis , Vietnam , Xylenes
11.
J Anal Methods Chem ; 2019: 5924942, 2019.
Article in English | MEDLINE | ID: mdl-31183246

ABSTRACT

In this work, high-performance liquid chromatography in combination with inductively coupled plasma dynamic reaction cell quadrupole mass spectrometry was introduced and optimized for speciation analysis of five major arsenic species including arsenobetain (AsB), arsenite (As(III)), monomethylarsonic (MMA), dimethylarsenonic acid (DMA), and arsenate (As(V)) in rice samples. Five arsenic compounds were separated on a Hamilton PRP X100 strong anion-exchange column employed with the mobile phase that is compatible with mass spectrometry, containing ammonium carbonate, methanol, and disodium ethylenediaminetetraacetic acid. Arsenic compounds were detected online by inductively coupled plasma dynamic reaction cell quadrupole mass spectrometry utilizing oxygen as the reaction gas at a flow rate of 0.7 mL·min-1. Five selected arsenic species were baseline separated at the optimum experimental conditions. The excellent LOD and LOQ values of the developed method were achieved in the range of 0.5 to 2.9 µg·kg-1 and 1.7 to 9.6 µg·kg-1 for all species of arsenic, respectively. The ionization effect in plasma during chromatographic gradient elution was systematically investigated by using postcolumn injector. Arsenic compounds in rice samples were extracted by diluted nitric acid at elevated temperature. The extraction efficiency and the interconversion of target compounds during sample preparation were also assessed. The full validation of the developed method was performed by using certified reference material, BRC 211, from European Institute of Reference and Standard for speciation analysis. The recovery of all selected arsenic species was in the range of 70 to 135.5%. The validated method was also applied to analyze rice samples collected from some contaminated rice fields. The results showed that As(III), DMA, and As(V) were found in all rice samples. Average concentration (range) of inorganic arsenic and DMA in all rice samples were 130.3 (65.5-228.1) and 32 (8.2-133.01) µg·kg-1, respectively. However, total concentration of inorganic arsenic in most of investigated rice samples was below the maximum residual level according to US-FDA and European Union standards.

12.
Environ Health Prev Med ; 23(1): 9, 2018 Feb 23.
Article in English | MEDLINE | ID: mdl-29471789

ABSTRACT

BACKGROUND: Currently, it is recognized that water polluted with toxic heavy metal ions may cause serious effects on human health. Therefore, the development of new materials for effective removal of heavy metal ions from water is still a widely important area. Melanin is being considered as a potential material for removal of heavy metal from water. METHODS: In this study, we synthesized two melanin-embedded beads from two different melanin powder sources and named IMB (Isolated Melanin Bead originated from squid ink sac) and CMB (Commercial Melanin Bead originated from sesame seeds). These beads were of globular shape and 2-3 mm in diameter. We investigated and compared the sorption abilities of these two bead materials toward hexavalent-chromium (CrVI) in water. The isotherm sorption curves were established using Langmuir and Freundlich models in the optimized conditions of pH, sorption time, solid/liquid ratio, and initial concentration of CrVI. The FITR analysis was also carried out to show the differences in surface properties of these two beads. RESULTS: The optimized conditions for isotherm sorption of CrVI on IMB/CMB were set at pH values of 2/2, sorption times of 90/300 min, and solid-liquid ratios of 10/20 mg/mL. The maximum sorption capacities calculated based on the Langmuir model were 19.60 and 6.24 for IMB and CMB, respectively. However, the adsorption kinetic of CrVI on the beads fitted the Freundlich model with R2 values of 0.992 for IMB and 0.989 for CMB. The deduced Freundlich constant, 1/n, in the range of 0.2-0.8 indicated that these beads are good adsorption materials. In addition, structure analysis data revealed great differences in physical and chemical properties between IMB and CMB. Interestingly, FTIR analysis results showed strong signals of -OH (3295.35 cm- 1) and -C=O (1608.63 cm- 1) groups harboring on the IMB but not CMB. Moreover, loading of CrVI on the IMB caused a shift of broad peaks from 3295.35 cm- 1 and 1608.63 cm- 1 to 3354.21 cm- 1 and 1597.06 cm- 1, respectively, due to -OH and -C=O stretching. CONCLUSIONS: Taken together, our study suggests that IMB has great potential as a bead material for the elimination of CrVI from aqueous solutions and may be highly useful for water treatment applications.


Subject(s)
Chromium/chemistry , Melanins/chemistry , Waste Disposal, Fluid/methods , Water Pollutants, Chemical/chemistry , Water Pollution, Chemical/prevention & control , Water Purification/methods , Adsorption , Kinetics
13.
Article in English | WPRIM (Western Pacific) | ID: wpr-775190

ABSTRACT

BACKGROUND@#Currently, it is recognized that water polluted with toxic heavy metal ions may cause serious effects on human health. Therefore, the development of new materials for effective removal of heavy metal ions from water is still a widely important area. Melanin is being considered as a potential material for removal of heavy metal from water.@*METHODS@#In this study, we synthesized two melanin-embedded beads from two different melanin powder sources and named IMB (Isolated Melanin Bead originated from squid ink sac) and CMB (Commercial Melanin Bead originated from sesame seeds). These beads were of globular shape and 2-3 mm in diameter. We investigated and compared the sorption abilities of these two bead materials toward hexavalent-chromium (Cr) in water. The isotherm sorption curves were established using Langmuir and Freundlich models in the optimized conditions of pH, sorption time, solid/liquid ratio, and initial concentration of Cr. The FITR analysis was also carried out to show the differences in surface properties of these two beads.@*RESULTS@#The optimized conditions for isotherm sorption of Cr on IMB/CMB were set at pH values of 2/2, sorption times of 90/300 min, and solid-liquid ratios of 10/20 mg/mL. The maximum sorption capacities calculated based on the Langmuir model were 19.60 and 6.24 for IMB and CMB, respectively. However, the adsorption kinetic of Cr on the beads fitted the Freundlich model with R values of 0.992 for IMB and 0.989 for CMB. The deduced Freundlich constant, 1/n, in the range of 0.2-0.8 indicated that these beads are good adsorption materials. In addition, structure analysis data revealed great differences in physical and chemical properties between IMB and CMB. Interestingly, FTIR analysis results showed strong signals of -OH (3295.35 cm) and -C=O (1608.63 cm) groups harboring on the IMB but not CMB. Moreover, loading of Cr on the IMB caused a shift of broad peaks from 3295.35 cm and 1608.63 cm to 3354.21 cm and 1597.06 cm, respectively, due to -OH and -C=O stretching.@*CONCLUSIONS@#Taken together, our study suggests that IMB has great potential as a bead material for the elimination of Cr from aqueous solutions and may be highly useful for water treatment applications.


Subject(s)
Adsorption , Chromium , Chemistry , Kinetics , Melanins , Chemistry , Waste Disposal, Fluid , Methods , Water Pollutants, Chemical , Chemistry , Water Pollution, Chemical , Water Purification , Methods
14.
Environ Monit Assess ; 185(2): 1427-36, 2013 Feb.
Article in English | MEDLINE | ID: mdl-22527469

ABSTRACT

There is considerable interest in minimizing the chlorine residual in Japan because of increasing complaints about a chlorinous odor in drinking water. However, minimizing the chlorine residual causes the microbiological water quality to deteriorate, and stricter control of biodegradable organics in finished water is thus needed to maintain biological stability during water distribution. In this investigation, an acceptable level of assimilable organic carbon (AOC) for biologically stable water with minimized chlorine residual was determined based on the relationship between AOC, the chlorine residual, and bacterial regrowth. In order to prepare water samples containing lower AOC, the fractions of AOC and biodegradable organic matter (BOM) in tap water samples were reduced by converting into biomass after thermal hydrolysis of BOM at alkaline conditions. The batch-mode incubations at different conditions of AOC and chlorine residual were carried out at 20 °C, and the presence or absence of bacterial regrowth was determined. The determined curve for biologically stable water indicated that the acceptable AOC was 10.9 µg C/L at a minimized chlorine residual (0.05 mg Cl(2)/L). This result indicated that AOC removal during current water treatment processes in Japan should be significantly enhanced prior to minimization of the chlorine residual in water distribution.


Subject(s)
Carbon/analysis , Chlorine/analysis , Drinking Water/chemistry , Water Pollutants, Chemical/analysis , Water Purification/methods , Water Quality/standards , Bacteria/growth & development , Drinking Water/standards , Hydrogen-Ion Concentration , Japan , Water Pollutants, Chemical/standards , Water Purification/standards
15.
Environ Technol ; 32(13-14): 1605-13, 2011 Oct.
Article in English | MEDLINE | ID: mdl-22329152

ABSTRACT

In Japan, customers' concerns about chlorinous odour in drinking water have been increasing. One promising approach for reducing chlorinous odour is the minimization of residual chlorine in water distribution, which requires stricter control of organics to maintain biological stability in water supply systems. In this investigation, the levels and seasonal changes of assimilable organic carbon (AOC) and its precursors in drinking water were surveyed to accumulate information on organics in terms of biological stability. In tap water samples purified through rapid sand filtration processes, the average AOC concentration was 174 microgC/L in winter and 60 microgC/L in summer. This difference seemed to reflect the seasonal changes of AOC in the natural aquatic environment. On the other hand, very little or no AOC could be removed after use of an ozonation-biological activated carbon (BAC) process. Especially in winter, waterworks should pay attention to BAC operating conditions to improve AOC removal. The storage of BAC effluent with residual chlorine at 0.05-0.15 mgCl2/L increased AOC drastically. This result indicated the possibility that abundant AOC precursors remaining in the finished water could contribute to newly AOC formation during water distribution with minimized residual chlorine. Combined amino acids, which remained at roughly equivalent to AOC in finished water, were identified as major AOC precursors. Prior to minimization of residual chlorine, enhancement of the removal abilities for both AOC and its precursors would be necessary.


Subject(s)
Drinking Water/analysis , Drinking Water/chemistry , Environmental Monitoring/methods , Organic Chemicals/analysis , Seasons , Water Pollutants, Chemical/analysis , Japan
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