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

A novel water quality index, the mutagen formation potential (MFP) is proposed for use in evaluation of the quality of drinking water which may contain pollutants capable of forming mutagens when chlorinated under the conditions used in water purification processes. A method for measuring MFP was established as follows. The water sample to be tested is diluted until the TOC reaches 3-4 mg l-1, the pH is adjusted to 7.0 +/- 0.2, sodium hypochlorite is added to obtain conditions where Cl/TOC = 3-4 mg Cl (mg C)-1, and the water sample is left standing for 24 +/- 2 h at room temperature. Thereafter, 21 of the chlorinated water sample at pH 2.0 +/- 0.1 is passed through a Sep-Pak Plus CSP-800 cartridge to adsorb any mutagens formed, and DMSO is applied to the cartridge to desorb the mutagens. Then, a 2 ml sample of the eluate is collected after the DMSO had begun to flow out of the cartridge and evaluated by the Ames Salmonella mutagenicity assay (preincubation method).
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PMID:Method for measuring mutagen formation potential (MFP) on chlorination as a new water quality index. 1132 63

Photolytic and photocatalytic interactions of hypochlorite ion and humic acid are investigated under various conditions. Humic acid oxidation by aqueous chlorine under dark conditions are expressed in terms of first order reaction kinetics. Upon irradiation (300 nm < lambda < 400 nm), photolysis of aqueous chlorine affect the removal efficiency of humic acid via oxidation. TiO2 sensitised photocatalytic oxidation conditions reveal an increase in the TOC removal rate of humic acid in the presence of aqueous chlorine. Under the specified conditions, increasing the photocatalyst loading up to 1.0 mg/mL markedly increase the TOC removal rate.
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PMID:Interactions of hypochlorite ion and humic acid: photolytic and photocatalytic pathways. 1169 60

One of the major problems encountered in the textile industry is production of highly colored large volumes of wastewater. It is often not possible to predict the characteristics of textile wastewaters by using reported values in the literature because every textile industry is unique with respect to the type of production and the technology and chemicals used in production. Furthermore, the concentrations of pollutants in textile wastewaters vary according to the wastewater management practices and amount of water used in the production. In the first part of this study, wastewater characteristics of a cotton mill textile industry were determined by using the normal and log-normal II distribution functions for flow, COD, TOC, pH and colour. These parameters were measured in the effluent of the equalization tank and the statistical fits were evaluated by using the chi-Square test. It was found that flow and TOC values fitted normal distribution; COD values fitted log-normal II distribution. On the other hand, pH and colour did not fit in to aforementioned distributions. In the second part of this study, the treatment of textile wastewater by coagulation/flocculation/precipitation (CFP) was investigated. Lime, iron and aluminum salts with anionic polielectrolite combination were used as coagulants. Aluminum salts and the combination FeSO4 + lime + polielectrolite were used to remove the colour from mixed textile wastewaters, successfully. On the other hand, FeSO4 + lime + polielectrolite was more effective than aluminum salts to remove the colour from wastewater of indigo dyeing process. In the third part of this work, the removal of sulfide arising from indigo dyeing was investigated. Sulfide removal was accomplished by chemical oxidation and catalyzed air oxidation and removal efficiencies up to ninety percent were found. Chemical oxidation using sodium hypochlorite resulted in color removal too; however, dosages of hypochlorite have to be carefully monitored in order to avoid toxic effects of excess chlorine in water.
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PMID:Chemical treatment of textile wastewaters: statistical characterization, colour and sulfide removal. 1239 14

The electrochemical degradation of acid red B (ARB) with hydrogen peroxide and hypochlorite ion electrogenerated by paired electrooxidation technology was investigated. High performance liquid chromatography (HPLC) was used to inspect the degradation process of ARB. Through analyzing chromatographic survey and UV-Vis spectra, as well as the removal of CODCr, TOC and color in the anode and cathode cells, the degradation processes of ARB in different cells were different. The color removal in the cathode cell was slower than in the anode cell, but the CODCr and TOC removal, which were 71.70% and 56.40% respectively, was higher than the removal in the anode cell, which were 25.15% and 27.57%. It maybe result from the different oxidation capabilities of the electrogenerated substances in the anode and cathode cells.
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PMID:[Study on electrochemical degradation of acid red B(ARB)]. 1280 Jun 69

Two types of practical electrochemical treatment systems (treatment capacities of 4 and 0.5 m3/h) were constructed. These systems generate radical species for effective oxidation of organic pollutants in wastewater, providing a novel treatment system for treating various kinds of wastewater. A series of experiments was performed using effluents from an anaerobic digester (EAD) of cattle wastewater, supernatants from primary sedimentation in a sewage plant (SPS), and domestic wastewater to evaluate the systems' treatment abilities. As a result, for both EAD and SPS, the 4 m3/h system was found to remove 87-91% of T-P, 74-96% of T-N, 70-94% of NH4-N, 88-91% of TOC, 75-87% of COD. Similarly, for wastewater, the 0.5 m3/h system was able to remove 62-90% of T-P, 83-92% of T-N, 90-100% of NH4-N, 75-83% of TOC, 80-100% of COD. It was further demonstrated that the high-voltage pulses and ultrasonic treatment effectively decomposed NH4-N and TOC due to the formation of radical species such as hydroxyl radicals and hypochlorite, T-P was removed by the electrocoagulation.
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PMID:Performance of two new electrochemical treatment systems for wastewaters. 1547 42

Activated carbon adsorption and chemical oxidation followed by activated carbon adsorption of resorcinol in water has been studied. Three chemical oxidants have been used: hypochlorite, permanganate and Fenton's reagent. The influence of concentrations of resorcinol and activated carbon on adsorption removal rates has been investigated. Both isotherm and adsorption kinetics have been studied. Results are fit well by Freundlich isotherms and adsorption rates of resorcinol were found to follow a pseudo-second-order kinetic model. However, pyrogallol, an intermediate of resorcinol oxidation with permanganate and Fenton's reagent, showed an unfavourable isotherm type. At the conditions investigated, chemical oxidation allows slight reductions of TOC and intermediates formed were found to inhibit the adsorption rate of TOC in the case of permanganate and Fenton's reagent oxidation, likely due to formation of some polymer pyrogallol product. The adsorption process was found to be controlled by pore internal diffusion, which justifies the poor affinity of oxidation intermediates toward activated carbon since molecules of larger size should diffuse rapidly for the adsorption to be effective.
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PMID:Influence of resorcinol chemical oxidation on the removal of resulting organic carbon by activated carbon adsorption. 1797 75

Composite ferrate(VI) solution (CFS) with improved stability was successfully prepared in this study. The stability of Fe(VI) increased from hours for potassium ferrate at pH 9-10 to 16d for 1 mmol L(-1) Fe(VI) in CFS at 25 degrees C, decomposing 24%. The Fe(VI) was more stable at low concentration (1 mmol L(-1)) than that at high concentration (10 mmol L(-1)). The degradation of the azo dye reactive brilliant red X-3B (X-3B) by CFS was investigated. The results showed that pH, initial dye concentration and CFS dosage affected the degradation efficiency. For 0.08 mmol L(-1) X-3B simulate wastewater, the optimal pH and CFS dosage were 8.4 and 25 mg L(-1) (as K(2)FeO(4)), and about 99% X-3B was decolorized after 20 min under this conditions. The color decay was considerably faster than the decrease in COD and TOC, which was attributed to the ease of chromophore destruction. Compared with the decolorization, the removal percentage of COD and TOC were 42% and 9% after 60 min, respectively. The Fe(VI) and ClO(-) were contained in CFS, which have synergetic effect for the degradation of X-3B. Additionally, phthalic acid and muconic acid were identified as intermediates by GC/MS, which was in accordance with the lowered pH with the reaction time. The complete mineralization of X-3B cannot be achieved under the oxidation by CFS. And a tentative pathway for the oxidative degradation of X-3B was postulated.
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PMID:Degradation of azo dye active brilliant red X-3B by composite ferrate solution. 1855 98

The objective of this pilot study was to investigate the operational conditions of newly developed MBR modules for water reclamation under tropical conditions. MUDC-620A MBR modules with hollow fibre PVDF membranes from Asahi-Kasei Chemicals were used in the study. The pilot plant with capacity of 50 m(3)/d was operated continuously (24-hour) over four months on site of Ulu Pandan Water Reclamation Plant (UPWRP) in Singapore. During the study, the MLSS in membrane tank was in the range of 6,840 approximately 9,540 mg/L. Filtration operation mode of the membrane unit was 9 minutes on production and 1 minute backwash. The air scouring for the membranes was 0.18-0.30 Nm(3)/h per m(2) membrane area all of the time. Trials on different membrane fluxes were conducted to obtain the sustainable flux. The analytical results showed that COD, TOC, T-N and NH4-N of the treated water were <30 mg/L, 5-7 mg/L, <13 mg/L and <0.1 mg/L, respectively, which met the requirement of Industrial Water for reuse. TMP was in the range of 12-40 kPa and could be recovered after cleaning with 2,000 mg/L sodium hypochlorite solution. Sludge clogging could be a challenge for long-term operation with the current module design. It was concluded that it was feasible for MUDC-620A MBR to operate at a net flux of 25-29 LMH (or 0.6-0.7 m/d) for treating the municipal wastewater at UPWRP.
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PMID:Pilot study of a submerged membrane bioreactor for water reclamation. 1995 52

In this study, two electrochemical oxidation processes were utilized to mineralize oxalic acid which was a major intermediate compound in the oxidation of phenols and other aromatic compounds. The anode rod and cathode net were made of a titanium coated with RuO(2)/IrO(2) (Ti-DSA) and stainless steel (S.S. net, SUS304), respectively. First, the Fered-Fenton process, which used H(2)O(2) and Fe(2+) as additive reagents, achieved 85% of TOC removal. It proceeded with ligand-to-metal charge-transfer (LMCT), which was evidenced by the accumulation of metallic foil on the selected cathode. However, in the absence of H(2)O(2)/Fe(2+), it showed a higher TOC removal efficiency while using Cl(-) only as an additive reagent due to the formation of hypochlorite on the anode. It was also found that the mineralization of oxalic acid by electrolysis generated hypochlorite better than the dosage of commercial hypochlorite without electricity. Also, pH value was a major factor that affected the mineralization efficiency of the oxalic acid due to the chlorine chemistry. 99% TOC removal could be obtained by Cl(-) electrolysis in an acidic environment.
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PMID:Oxalic acid mineralization by electrochemical oxidation processes. 2132 Jul 49

This paper provides the information on the optimum conditions of the treatment process of the boat pressure washing wastewater (BPWW) by the combination of the ozonation and electrochemical (EC) methods developed on the laboratory and pilot plant scale. The initial effluent was highly enriched in heavy metals and elevated levels of organic contaminants. The concentrations of V, Cr, Fe, Cu, Zn, TOC, and COD exceeded the upper permissible limits of 22, 20, 6, 112, 17, 4, and 2 times, respectively. The main mechanisms of the organic matter destruction were the ozone oxidation and the indirect oxidation with chlorine/hypochlorite formed by the anodic oxidation of chloride already present in the wastewater. The heavy metal removal was forced by the coagulation/flocculation using Fe(2+), Fe(3+), and Al(3+) ions released into the treated solution by electrochemical corrosion of the sacrificial stainless steel and aluminum electrodes. At the optimum conditions obtained with the pilot plant, the removal efficiencies of the parameters V, Cr, Fe, Ni, Cu, Zn, Pb, TOC, and COD were 100.00 %, 99.35 %, 99.51 %, 87.31 %, 99.83 %, 99.65 %, 100.00 %, 88.46 %, and 76.28 %, respectively. All the parameters in the final effluent were in agreement with regulated values. The advantages of this system compared to its physico-chemical counterparts are as follows: (1) no need for the external addition of flocculating agents since they are electrochemically generated inside the treatment tank; (2) minimal pH changes during the treatment process not requiring pH adjustment by acids/basis; (3) a significantly lower amount of sludge since only Fe and Al ions were released in the solution; (4) flocs formed by the electrocoagulation can be easily separated by the filtration due to their higher stability, lower content of the bound water and larger surface compared to chemical flocs; (5) the final EC effluent is clear, colourless and odourless, containing the less total dissolved solids and organics, thence more suitable for the reuse compared to the one obtained by the standard chemical treatment.
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PMID:The application of the ozonation/electrocoagulation treatment process of the boat pressure washing wastewater. 2192 69


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