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Query: UMLS:C1835664 (TOC)
 2,763 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Water samples were collected from 384 waterworks that supply 70.9% of the Norwegian population. The samples were collected after water treatment and were analysed for 30 constituents. Although most constituents show wide concentration ranges, Norwegian drinking water is generally soft. The median values obtained are: 0.88 mg Si l-1, 0.06 mg Al l-1, 47 micrograms Fe l-1, 0.69 mg Mg l-1, 2.9 mg Ca l-1, 3.8 mg Na l-1, 6 micrograms Mn l-1, 12 micrograms Cu l-1, 14 micrograms Zn l-1, 9 micrograms Ba l-1, 15 micrograms Sr l-1, 0.14 mg K l-1, 58 micrograms F- l-1, 6.4 mg Cl- l-1, 11 micrograms Br- l-1, 0.46 mg NO3- l-1, 5.3 mg SO4(2-) l-1, 2.4 mg TOC l-1, 6.8 (pH), 5) microseconds cm-1 (conductivity) and 11 mg Pt l-1 (colour). Titanium, Pb, Ni, Co, V, Mo, Cd, Be and Li were seldom or never quantified, due to insufficient sensitivity of the ICP (inductively coupled plasma) method. Norwegian quality criteria, which exist for 17 of the constituents examined, are generally fulfilled, indicating that the chemical quality of drinking water, by and large, is good in Norway. For Fe, Ca, Mn, Cu, pH, TOC and colour, however, the norms for good drinking water are exceeded in more than 9% of the samples, reflecting two of the major problems associated with Norwegian drinking water supplies: (i) many water sources contain high concentrations of humic substances; (ii) in large parts of the country, the waters are soft and acidic, and therefore corrosive towards pipes, plumbing and other installations. Most constituents show marked regional distribution patterns, which are discussed in the light of different mechanisms contributing to the chemical composition of drinking water, namely: chemical weathering of mineral matter; atmospheric supply of salt particles from the sea; anthropogenic pollution (including acid precipitation); corrosion of water pipes and plumbing; water treatment; decomposition of organic matter; and hydrological differences.
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PMID:A nation-wide survey of the chemical composition of drinking water in Norway. 203 65

The combination of TiO2-assisted photocatalysis and ozonation in the degradation of nitrogen-containing substrates such as alkylamines, alkanolamines, heterocyclic and aromatic N-compounds has been investigated. A laboratory set-up was designed and the influence of the structure of the N-compound, the TiO2 and ozone concentration on the formation of breakdown products were examined. The experimental results showed that a considerable increase in the degradation efficiency of the N-compounds is obtained by a combination of photocatalysis and ozonation as compared to either ozonation or photocatalysis only. The mineralization of the model substances was monitored by measurements of the TOC and ion-chromatographic determinations of the formed NO2- and NO3-. The temporal changes of concentrations of breakdown products, such as NH4+, short chain alkyl- and alkanolamines were determined by single column ion chromatography (SCIC) and as well as by electrospray mass spectrometry (EI-MS).
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PMID:Degradation of nitrogen containing organic compounds by combined photocatalysis and ozonation. 1010 56

A laboratory scale two-stage sequencing batch reactor (TSSBR) was used to study the effectiveness of pH as a real-time control parameter in swine wastewater treatment. A Ringlace media was inserted into the A/O (Anoxic/Oxic) reactor for bacteria immobilization. The TSSBR was subjected to three levels of organic loading. The pH and ORP (Oxidation Reduction Potential) patterns obtained were consistent with distinct features, enabling the real-time control strategy to effectively set a flexible aeration time pending on influent concentration, hence resulting in flexible cycle time and HRT (Hydraulic Retention Time) for the system. The real-time process ensured a removal efficiency of over 99% and 95%, respectively, for ammonia and TOC (Total Organic Carbon). For NO3(-)-N and PO4(-3), the run with influent TOC = 4,000 mg/L yielded the most efficient removal of 61% and 95%, respectively. Test results suggest that pH can be a viable tool for on-line real-time control of a biological treatment process.
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PMID:Swine wastewater treatment in a two stage sequencing batch reactor using real-time control. 1080

In column experiments of Mexican wastewater irrigated soils the effects of changing water quality (untreated = UT, primary = PT and tertiary treated = TT wastewater) on carbon, nitrogen and heavy metal dynamics were investigated. In the column effluents the nitrate concentrations varied between 141-683 mg l-1. The total amount of leached TOC decreased in the order UT > PT > TT. Outflow concentrations of Pb ranged from 31.6-166.5 micrograms l-1 and of Cu from 31.2-146.8 micrograms l-1. Irrigation water quality influenced the Pb but not the Cu efflux. Cu seemed to be co-transported with TOC by preferential flow whereas there was no correlation of Pb and TOC concentrations in the effluents. The possibility of Pb transport through preferential flow paths is discussed.
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PMID:Carbon, nitrogen and heavy metal dynamics in long-term wastewater irrigated Mexican soils. 1084 23

The photooxidation of C2H5NH2, (C2H5)2NH, HOC2H4NH2, (HOC2H4)2NH and (HOC2H4)3N using TiO2 and Pt/TiO2 as photocatalysts has been investigated. A laboratory set up was designed and a study on the influence of the concentration of the photocatalyst, the pH-value and the structure of the amine performed. The photocatalytic process was optimized with respect to the concentrations of the model substances during degradation. The decrease of the amine concentrations was found to be maximum at a pH of 10. The time-dependence of the formation of cationic breakdown products, such as NH3/NH4 and short-chain alkyl- and alkanolamines was studied by analyses with single column ion chromatography. The experimental data show that the photodegradation follows a Langmuir-Hinshelwood kinetic. The mineralization of the model substances also was monitored by measurements of the decrease of the TOC and of the formation of NO2 and NO3. The different mineralization efficiencies for the model substances studied are discussed with regard to their structure and adsorption behaviour on the photocatalyst. A possible breakdown mechanism involving the electrophilic attack of the hydroxyl radical is given. The applicability of the TiO2-assisted photocatalytic degradation of C2H5NH2 and (C2H5)2NH was tested at the pilot plant-scale with real solar radiation. The degradation rates and products obtained were similar to those found in the laboratory experiments.
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PMID:Degradation of short-chain alkyl- and alkanolamines by TiO2- and Pt/TiO2-assisted photocatalysis. 1105 97

A lab-scale hybrid upflow sludge bed-filter (USBF) reactor was employed to carry out methanogenesis and denitrification of the effluent from an anaerobic industrial reactor (EAIR) in a fish canning industry. The reactor was initially inoculated with methanogenic sludge and there were two different operational steps. During the first step (Step I: days 1-61), the methanogenic process was carried out at organic loading rates (OLR) of 1.0-1.25 g COD l-1 d-1 reaching COD removal percentages of 80%. During the second step (Step II: days 62-109) nitrate was added as KNO3 to the industrial effluent and the OLR was varied between 1.0 and 1.25 g COD l-1 d-1. Two different nitrogen loads of 0.10 and 0.22 g NO3(-)-N l-1 d-1 were applied and these led to nitrogen removal percentages of around 100% in both cases and COD removal percentages of around 80%. Carbon to nitrogen ratio (C:N) in the influent was maintained at 2.0 and eventually it was increased to 3.0, by means of glucose addition, to control the denitrification process. From these results it is possible to establish that wastewater produced in a fish canning industry can be used as a carbon source for denitrification and that denitrifying microorganisms were present in the initially methanogenic sludge. Biomass productions of 0.23 and 0.61 g VSS:g TOC fed for Steps I and II, respectively, were calculated from carbon global balances, showing an increase in biomass growth due to denitrification.
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PMID:Simultaneous methanogenesis and denitrification of pretreated effluents from a fish canning industry. 1122 93

Two two-stage sequencing batch reactors (TSSBR), one attached-growth and one suspended-growth, were operated under three levels of wastewater concentration (approximately 4,000, 2,000 and 500 TOC mg/L), respectively, to compare the pH and ORP (oxidation-reduction potential) patterns and system performance. In both TSSBR systems, the pH and ORP profiles varied with organic loading yet exhibited consistent patterns with distinctive features suitable for real-time control. For all runs at the three levels of influent, both systems achieved similar levels of treatment for BOD5, TOC and TSS of over 97.5, 93.4, and 97.3%, respectively. The attached-growth system out performed the suspended-growth system in achieving the same levels of treatment at much shorter aeration cycle times. The treatment efficiency for NO3(-)-N and PO4(-3) was greatly affected by the carbon content in the wastewater, and the best treatment was achieved during the TOC approximately 4,000 mg/L runs with final effluent at 4.0 and 21.3 mg/L, respectively.
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PMID:Swine wastewater treatment using attached-growth and suspended-growth two stage sequencing batch reactors with real-time control. 1140 98

Based on a rational and simple chemical approach, a field-investigation aimed to assess the role played by a natural channel "lama" on the quality of underlying groundwater and neighbouring soils has been carried out. The results have demonstrated that: (a) the stream flowing through the "lama" is mainly made up of treated effluent from a nearby municipal wastewater treatment plant; (b) the occurrence of nitrates in the "lama" is due to rain-washing of nitrogen fertilized agricultural soils bordering on the "lama"; (c) hydraulic connections exist between the lama and the underlying groundwater causing contaminants flowing through the "lama" to reach groundwater within less than one week; (d) compared with the values measured in the "lama", the concentrations of TOC, N-NH4 and N-NO3 in groundwater result: lower, far lower and greater, respectively; (e) agricultural soils bordering on the "lama" result significantly contaminated by halogenated organics.
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PMID:Role played by a natural channel on the quality of bordering environment: a chemical assessment. 1150 33

The photocatalytic oxidation of the non-biodegradable p-nitrotoluene-o-sulfonic acid (p-NTS) in homogeneous (photo-Fenton reactions) and heterogeneous (with TiO2) solutions has been studied at a pilot-scale under solar irradiation at the Plataforma Solar de Almeria (PSA). In this study two different reactors were tested: a medium concentrating radiation system (Heliomans, HM) and a non-concentrating radiation system (CPC). Their advantages and disadvantages for p-NTS degradation have been compared and discussed. The degradation rates obtained in the CPC collector are around three times more efficient than in the HM collectors. However, in both systems, 100% of the initial concentration of p-NTS was removed. Kinetic experiments were performed in both systems using TiO2 suspensions. During the photodegradation, the disappearance of p-NTS was followed by HPLC, the mineralization of the solution by the TOC technique, the evolution of NO3-, NO2-, and SO4(2-) concentration by ionic chromatography, the toxicity by the standard Microtox test, and the biodegradability by BOD5 and COD measurements. The obtained results demonstrated the utility of the heterogeneous catalysis (using TiO2 as catalyst) as a pretreatment method that can be followed by a biological process.
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PMID:Concentrating versus non-concentrating reactors for solar photocatalytic degradation of p-nitrotoluene-o-sulfonic acid. 1169 62

Nutrients and other pollutant runoffs from streams in artificial forest areas in central Hyogo Prefecture in southwest Japan have been investigated to estimate pollutant loads since 1995. The orthophosphate and ammonium nitrogen contents were usually low and constant during the investigation. When the flowrates of the streams were normal, the concentrations of suspended solids, COD(Mn), TOC and total phosphorus were very low, and did not change much. However, when stream flows were increased by rainstorms or other precipitation, higher concentrations of these parameters occurred. Otherwise, the average concentrations of nitrate nitrogen and total nitrogen were 0.26 mg/l and 0.31 mg/l, respectively, and they were often increased by precipitation events. They changed at the same time because the ratio of nitrate nitrogen per total nitrogen was high, about 80%. The fluctuation of concentrations of total phosphorus was similar to SS concentrations, which suggested that phosphorus was discharged in the types of suspended solids from forest areas. The specific loads of the nutrients and some other pollutants did not differ among the three watersheds investigated. However, the difference among them between fine days and rainy days was fairly large. It was presumed that pollutant runoff from forest areas is strongly dependent on precipitation events.
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PMID:Runoff characteristics of nutrients in the forest streams in Hyogo Prefecture, Japan. 1172 81


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