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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 Microtox assay and various parameters (growth, ATP concentration and electrochemical detection) of Escherichia coli were used to assess the toxicity of various levels of granular activated carbon treated coal gasification process water. The generation time of E. coli was statistically significantly slower at the level of 50 percent treatment than any other level of treatment. No differences were seen for ATP concentration per cell or in the electrochemical detection methods for any level treatment. There was a very high correlation between total organic carbon removal by GAC treatment and reduction in toxicity as measured by the Microtox system. However, even the treated water which had 91 percent of the TOC removed was still highly toxic.
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PMID:Toxicity of granular activated carbon treated coal gasification water as determined by the Microtox test and Escherichia coli. 351 64

Swimming pool water covers made of different plastics were investigated in laboratory experiments. The possible influence on the chemical and the bacteriological water quality (test bacterium Ps. (fluorescens) was observed. Strong-PVC-plastics proved to have no respectively hardly any chemical or bacteriological influence on the water quality. PE-soft-plastics showed clearly higher chlorine consumption and TOC counts. The influence on bacterial growth was here either inhibition or of nutrient character. A direct colonisation of the plastic was not to be seen--neither in vivo nor in vitro. There are no principal objections against the use of plastics swimming pool covers from hygienical point of view. Some limitating aspects are discussed.
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PMID:[Hygienical assessment of swimming pool water covers made of plastic (author's transl)]. 734 72

A process on crystallized precipitation of ammonium by adding magnesium salt and phosphate was carried out to improve C/N ratio in swine wastewater. After completion of crystallized precipitation of ammonium, an intermittent aeration process with aeration and nonaeration periods alternated at interval of 1:1 hr day-1 is used for the improved swine wastewater (T-N/BOD = 0.14: BOD = 8200 mg/liter and T-N = 1166 mg/liter). The results obtained from the experiment show that the removal ratios of T-N and NH4-N are 91% and 99%, respectively. T-P is not removed, while the removal ratio of PO4-P is 60% as 3% of CaCl2 liquid is added. The results also indicate that dilution with water is effective to improve the removal of phosphorus even if raw swine wastewater contains high concentrations of T-N, T-P, BOD, and TOC.
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PMID:Nitrogen and phosphorus removal for swine wastewater by ammonium crystallization and intermittent aeration process. 852 33

Phenolic antioxidants of the hydroxychroman class, alpha-tocopherol (alpha-TOC) and 2,2,5,6,7-pentamethyl-6-hydroxychroman (PMHC), and the hindered phenols 2,3-dihydro-5-hydroxy-2,2,4-trimethylnaphtho[1,2-b]furan (NFUR), 2,6-di-tert-butyl-4-methoxyphenol (DBHA), and 2,6-di-tert-butyl-4-methyl phenol (BHT), were delivered into oxidizable (ACCEPTOR) liposomes of dilinoleoylphosphatidylcholine (DLPC) or 1-palmitoyl-2-linoleoyl-phosphatidylcholine (PLPC) from saturated DONOR liposomes of dimyristoylphosphatidylcholine (DMPC) by liposomal transfer. The antioxidant activities, k(inh), by the inhibited oxygen uptake method were compared with the k(inh)s determined when the antioxidants were introduced into the liposomes by coevaporation from organic solvents. The peroxidations were initiated using either thermal initiators, water-soluble azo-bis-amidinopropane hydrochloride (ABAP), lipid-soluble azo-bis-2,4-dimethylvaleronitrile (ADVN) and di-tert-butylhyponitrite (DBHN), or the photoinitiator benzophenone. The antioxidants PMHC, NFUR, DBHA, and BHT transferred rapidly between liposomes, but several hours of incubation were needed to transfer alpha-TOC. The average k(inh)s in liposomes, in the relative order NFUR approximately DBHA > PMHC > BHT approximately alpha-TOC, were markedly lower than known values in organic solvent. k(inh) values in liposomes appear to be controlled by effects of hydrogen bonding with water and by restricted diffusion of antioxidants, especially in the case of alpha-TOC. Product studies of the hydroperoxides formed during inhibited oxygen consumption were carried out. The cis,trans/trans,trans (c,t/t,t) product ratios of the 9- and 13-hydroperoxides formed from PLPC during inhibited peroxidation by PMHC were similar for both the coevaporated and liposomal transfer procedures. The c,t/t,t ratio for the same concentration of alpha-TOC, 1.52, compares to a value of 1.69 for PMHC at the start of the inhibition period. The higher c,t/t,t ratio observed for NFUR in DLPC, which varied between values of 7.0 at the start of the inhibition to about 1.8 after the break in the induction period, is a reflection of the increased hydrogen atom donating ability of the antioxidant plus the increased concentration of oxidizable lipid provided by DLPC.
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PMID:The efficiency of antioxidants delivered by liposomal transfer. 929 40

The physicochemical quality of drinking and hot waters of 67 buildings in different parts of Finland was studied. Some of the buildings used processed groundwater and some processed surface water. Drinking water samples were taken from the first tap after the water was led into the building. Hot water samples were taken from taps and showers and from circulating hot water systems. Thy physicochemical quality of drinking water was affected by the origin of raw water used in the water plants. Drinking water from surface water plants contained more organic matter and less metals than water from groundwater plants. The quality goal for total organic carbon (TOC; < 2 mg l-1) was exceeded by all drinking water samples. In groundwaters, the variation in the content of non-purgeable organic carbon (NPOC) was great, probably because artificial groundwaters processed from surface waters were included in this group. Unlike in natural waters, the correlation between KMnO4-number and NPOC in the processed waters was weak. This result shows that KMnO4-number is an inaccurate estimate for organic carbon in processed waters. Corrosion of pipe materials was seen as elevated concentrations of iron and copper. In general, the physicochemical quality of drinking and hot waters in the buildings was rather similar.
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PMID:Physicochemical quality of drinking and hot waters in Finnish buildings originated from groundwater or surface water plants. 929 65

The strong mutagen, [3-chloro-4-(dichloromethyl)-5-hydroxy- 2(5H)-furanone] MX, was found to be one of the most potent mutagens in drinking water. In this study, dissolved organic matters from river water and lake water were separated into several compound classes by sorbtion on a series of resin absorbents. After chlorine treatment of the fractions, MX was determined with GC/MS in the selected ion monitoring mode. Humic substances produced more MX on a TOC-basis than other fractions and contributed more to MX formation in the chlorinated natural waters. Some phenols were detected in the oxidation products of humic substances and therefore formation of MX may occur when some phenolic precursor structures in humic substances are treated with chlorine.
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PMID:Studies on the precursors of strong mutagen [3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone]MX by chlorination of fractions from different waters. 935 5

m-Dinitrobenzene, diphenylamine and resorcinol, three aromatic compounds found inhibitory or recalcitrant to biological treatments, were chosen as model chemicals for this study on the integration of photocatalytic-biological treatments. The degradation of each of these compounds was achieved by ultraviolet photocatalytic oxidation, leading to the formation of intermediate compounds. The photocatalytic treatment was performed in a TiO2 slurry reactor containing an aqueous solution of one of the three chemicals. The biodegradability of model wastewater treated photocatalytically was measured in terms of BOD1/TOC. Intermediate compounds that appeared at early stages of the photocatalytic degradation of m-dinitrobenzene or diphenylamine seemed to be more inhibitory than the parent compounds but this was not the case for resorcinol. A substantial improvement in BOD1/TOC could be achieved, but it required the mineralization of at least 80% of the organic carbon originally in the water. Microtox toxicity results confirmed the BOD1/TOC trends for diphenylamine.
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PMID:Enhancement of the biodegradability of model wastewater containing recalcitrant or inhibitory chemical compounds by photocatalytic pre-oxidation. 952 51

A study of bacterial populations in metropolitan Adelaide domestic reticulation pipes was conducted to investigate a possible link between copper in drinking water and biofilms. Biofilm densities from cold water copper pipes at 10 sample sites were measured by viable cell counts. The range detected was from < 2 x 10(1) to 3.25 x 10(7) cfu cm-2. Five isolates were selected for further experiments as they represented a range of responses to solvated copper and relative tendency for adhesion on glass slides. Drinking water supplied to the Adelaide Hills is high in total organic carbon (TOC; 22.57 mg Cl-1) and has a negative Langelier Index (LI;-1.16), whereas Adelaide metropolitan water undergoes filtration and has both a lower TOC and LI (10.72 mg Cl-1, LI,-0.49). Copper coupons were exposed to biofilm isolates (24h), washed and resuspended in Adelaide metropolitan and Adelaide Hills water. Copper coupons not exposed to biofilm isolates were suspended in respective waters as a control. After 5 d of incubation, the copper content of Adelaide Hills water (4.71 +/- 0.87 mg Cu l-1), in which the copper coupons were suspended, consistently exceeded values obtained in the metropolitan Adelaide water (1.17 +/- 0.249 mg Cu l-1). The concentration of copper in the Adelaide Hills water was influenced by the bacterial species forming the biofilm on the coupon, with Agrobacterium sp. producing significantly higher levels of soluble copper than the control. The experiments reported here indicate that the suspended organic carbon, the aggressivity of the water and the biofilm may independently or synergistically increase the dissolution of copper from pipes into drinking water.
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PMID:Assessment of microbial involvement in the elevation of copper levels in drinking water. 975 Feb 89

The objectives of this research work was to evaluate the reduction of THM precursors by cationic p-DADMAC and determine the correlations between the chlorine demand and trihalomethane formation in the presence of electrolyte solutions and ambient light. The chlorine demand was found to be significantly reduced provided that the H2SO4 electrolyte was fed to the sample solutions. The amount of CHCl3 formation was also decreased when the Na2SO4 electrolyte was introduced in spite of the levels of light intensity. The p-DADMAC can not only effectively remove the turbidity but also reduce the formation of CHCl3. The optimum dosage of p-DADMAC for reducing the turbidity, TOC and CHCl3 in the humic acid and source water samples was determined and depended upon the nature of organics.
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PMID:Effects of polydiallyldimethyl ammonium chloride coagulant on formation of chlorinated by products in drinking water. 1046 27


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