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

The release performances of an organic and mineral activated sludge matrix were studied for a wide range of disintegration treatments like mechanical, thermal, thermal-chemical and oxidative disintegration techniques. The maximal COD release was 35% of total COD after 24 hours contact time at 95 degrees C. A limiting value of 60% COD release was obtained for 500 and 700 bars after 10 passes. Concerning theoxidative disintegration techniques (O3 and H2O2), a limiting value of around 60-65% of TOC release was observed. Therefore, it was hypothesised that thermal and mechanical treatments allow mainly for breaking apart the micro-organisms while the oxidative treatment destroys the sludge flocs and disrupts the micro-organisms. A release effect of the mineral fraction is observed only oxidative disintegration techniques.
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PMID:A comparative study between mechanical, thermal and oxidative disintegration techniques of waste activated sludge. 1247 56

This paper evaluated the COD, TOC removal and molecular frontier energies in the ozonation of naphthalene sulfonic acids (NSAs). It was found that both COD and TOC degradation of the 11 compounds followed the pseudo-first-order kinetic and the reaction rate constants with ozone varied widely. A linear relationship between logarithm of global COD degradation rate constant and the energy of the highest occupied molecular orbit, E(homo), was obtained for these NSAs with a regression coefficient of 0.88 and a slope of 0.4672 eV(-1). TOC degradation kinetics also reached similar results with a regression coefficient of 0.90 and a slope of 0.9336 eV(-1). The results of correlation analysis suggested that TOC and COD removal in ozonation of NSAs follow the frontier orbital theory and can be predicted by E(homo), which indicated that electrophilic effect was the main factor in the ozonation of NSAs. Therefore, it is possible to improve the biodegradability of dyestuff wastewater bearing mainly NSAs by ozonation at an accepted cost and evaluate the economy of ozonation process.
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PMID:Ozonation of naphthalene sulfonic acids in aqueous solutions: part II--relationships of their COD, TOC removal and the frontier orbital energies. 1255 95

The dynamic membrane forming on the surface of 0.1 mm Dacron mesh was utilized instead of static membrane, e.g. hollow fiber membrane, to develop a submerged dynamic membrane bioreactor (DMBR). The DMBR had high quality effluents when treating domestic wastewater at HRT = 3.5 h. The dynamic membrane could work steadily at a pressure no more than several centimeters water head drop. The highest SS concentration in the effluents was 4.05 mg/L, whereas the measured SS concentrations were zero in most circumstances. At condition of MLSS = 7000-8000 mg/L, the effluent head drop was only 5.8 mm when flux = 14.9 L/(m2.h), and it had little change during a continuous run for 27 days. The dynamic membrane averagely removed 28.74% of COD and 36.9% of TOC in the supernatant of the mixed liquor. The DMBR could remove NH3-N more than 96% when DO in the mixed liquor was no less than 2-3 mg/L.
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PMID:[A submerged dynamic membrane bioreactor for domestic wastewater treatment]. 1261 78

Color removal from biologically pre-treated molasses wastewater by means of chemical oxidation with ozone has been investigated. Batch experiments have been performed in order to analyze the influence of ozone dosage and reaction time on color removal, molecular weight distribution and decolorization kinetics. Depending on the applied ozone dosage, color removal from 71% to 93% and COD reduction from 15% to 25% were reached after 30 min reaction time. TOC values remained constant throughout ozonation. Gel permeation chromatography corroborated that high molecular weight compounds, responsible for the brown color, were present in raw wastewater. UV spectral studies confirmed that these colored compounds were melanoidins. As a result of ozonation the concentration of chromophore groups decreased. Ozonation of synthetic melanoidin under the same experimental conditions provided similar color removal efficiencies. Pseudo-first order kinetics with respect to colored compounds were found.
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PMID:Chemical oxidation of wastewater from molasses fermentation with ozone. 1269 80

The membrane bioreactor (MBR) system has become more and more attractive in the field of wastewater treatment. It is particularly attractive in situations where long solids retention times are required, such as nitrifying bacteria, and physical retention critical to achieving more efficiency for biological degradation of pollutant. Although it is a new technology, the MBR process has been applied for industrial wastewater treatment for only the past decade. The opto-electronic industry, developed very fast over the past decade in the world, is high technology manufacturing. The treatment of the opto-electronic industrial wastewater containing a significant quantity of organic nitrogen compounds with a ratio over 95% in organic nitrogen (Org-N) to total nitrogen (T-N) is very difficult to meet the discharge limits. This research is mainly to discuss the treatment capacity of high-strength organic nitrogen wastewater, and to investigate the capabilities of the MBR process. A 5 m3/day capacity of MBR pilot plant consisted of anoxic, aerobic and membrane bioreactor was installed for evaluation. The operation was continued for 150 days. Over the whole experimental period, a satisfactory organic removal performance was achieved. The COD could be removed with an average of over 94.5%. For TOC and BOD5 items, the average removal efficiencies were 96.3 and 97.6%, respectively. The nitrification and denitrification was also successfully achieved. Furthermore, the effluent did not contain any suspended solids. Only a small concentration of ammonia nitrogen was found in the effluent. The stable effluent quality and satisfactory removal performance mentioned above were ensured by the efficient interception performance of the membrane device incorporated within the biological reactor. The MBR system shows promise as a means of treating very high organic nitrogen wastewater without dilution. The effluent of TKN, NOx-N and COD can fall below 20 mg/L, 30 mg/L and 50 mg/L.
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PMID:High-strength nitrogen removal of opto-electronic industrial wastewater in membrane bioreactor--a pilot study. 1292 37

The quantitative fractions of conversion of organic carbon in the decomposable organic wastes with initial moisture of 70% sorted from municipal solid wastes (MSW) in lysimeters into biogas, leachate and solid residue were characterized, under temperatures of 25, 30 and 41 degrees C, respectively, and circulation of leachate generated within the lysimeter. It is found that 27% of organic carbon in the wastes are conversed into gases, 0.8% into leachate, and the other 72% remained in the decomposable solid residues, after 180 days' degradation at 41 degrees C. Higher temperature will lead to more rapid degradation and result to higher conversion of the organic carbon to biogas and lower to both solid residues and leachate, while the pollutant concentrations in leachate will be lower at a higher temperature and the values of COD are quite consistent with TOC.
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PMID:Conversion of organic carbon in the decomposable organic wastes in anaerobic lysimeters under different temperatures. 1293 79

The effect of ozonation on the biodegradability of 100-ppm aqueous solutions of 2,4-dichlorophenol has been investigated. BOD at 5, 10 and 21 days, BOD/COD and BOD/TOC ratios and the average oxidation state are presented. Biodegradability measured as BOD5/COD ratio was increased from 0 of the original solution to 0.25 at the moment of removing all the initial compound (corresponding to an ozone dose of 0.12 g L-1, 0.48 for BOD21/COD ratio). To test the effect of this pre-treatment, the biological oxidation of these pre-ozonated solutions was performed in two semi-continuous stirred tank reactors, one with non-acclimated sludge and one with acclimated-to-phenol sludge. The study showed that the TOC content of the pre-treated solution could be removed up to 68% by an aerobic biological treatment as well as co-digested with municipal wastewater (TOC removal up to 82%), with similar operating retention times to a municipal wastewater plant (12-24 h). Kinetic studies based on Monod model have also been carried out. Pseudo-first-order kinetic constants were found to be in the range of 0.5-0.8 L g TVSS-1 h-1.
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PMID:Contribution of the ozonation pre-treatment to the biodegradation of aqueous solutions of 2,4-dichlorophenol. 1450 3

A hybrid anaerobic solid-liquid (HASL) bioreactor was developed to enhance food waste conversion. The HASL bioreactor is a modified two-phase anaerobic digestion system with a solid waste reactor and a high-rate anaerobic wastewater reactor, which was a UASB reactor. In this study, the methanogenesis in the UASB reactor was investigated under a semi-continuous operation of the food waste digestion system. The HASL process, including 7 days of start-up and 23 days of semi-continuous operation followed by 6 days of batch operation, was commenced by loading 2.8 kg of shredded food waste. During the semi-continuous operation, 0.2 kg of the same waste was loaded daily. The leachate from acidification phase, i.e., solid waste reactor, remained acidic (pH 4.9-5.5) and high in total VFA (TVFA), 9,500-11,500 mg/L, and COD (8,000-11,800 mg/L) levels. In the methanogenesis phase, i.e., UASB reactor, effective TVFA and COD removals (88 +/- 5% and 85 +/- 7%, respectively) were obtained, while the methane content was 71%. At the end of operation, about 78% of VS added in the HASL bioreactor was removed, while TOC and total COD reductions were 78% and 79%, respectively. The results showed that the use of UASB reactor in the semi-continuous HASL system can enhance the methanogenesis process and increase the methane content in biogas production.
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PMID:Semi-continuous anaerobic digestion of food waste using a hybrid anaerobic solid-liquid bioreactor. 1453 36

Anaerobic treatment has seldom been used for wastewaters from the pulp and paper industry and other branches of the chemical industry. Escape of volatile pollutants to the atmosphere, which always occurs during aerobic treatment, is avoided, and much less sludge is being produced than in an aerobic process. The greatest obstacle for using anaerobic treatment in the pulp and paper industry is the large wastewater volume, which necessitates short hydraulic detention times, because the treatment is to occur in an enclosed space. We used solid carrier particles to prevent wash-out of biomass from the reactor at high hydraulic loading, and an up-flow system in order to be able to use very small carrier particles, maximizing the surface area for biomass attachment. In this paper we describe and discuss the results obtained with this type of anaerobic reactor (fluidised bed) at bench and semitechnical scale for wastewaters from pressurized ground wood pulping and paper manufacture, sulphite pulp evaporator condensate and bleach waste. Earlier work with Kraft pulp bleaching effluent and thermomechanical pulping wastewater and evaporator condensates using anaerobic reactors is also discussed. The results obtained thus far show that there are several wastewater streams from the pulping industry, where 60 to 90% of the dissolved organic pollutants (measured as COD(Cr) or TOC) was biodegraded within 4 to 24 h. The high strength waste streams (COD(Cr) >2000 mg O(2) 1(-1)) allowed organic space load of 4 to 10 kg COD(Cr) m(-3) reactor volume d(-1). With low strength wastes the hydraulic loading was the limiting factor.
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PMID:Anaerobic fluidised bed for the purification of effluents from chemical and mechanical pulping. 1454 5

Response Surface Methodology (RSM) was employed to investigate the effect of TOC ratio of high molecular weight organic matter (HMWOM) to low molecular weight organic matter (LMWOM), the LMWOM concentration and hydrogen peroxide to ferrous ion molar ratio on COD removal during the treatment of sanitary landfill leachate with Fenton reagents. The high and low levels of HMWOM/LMWOM, the LMWOM concentration and H2O2/Fe2+ were from 14 to 38, 975 to 3000 mg/L, and 1.75 to 4.00 respectively. Using the software of Design--Expert 5, a response surface quadratic model in terms of actual factors was obtained based on the experimental data, and COD removal contour plots were derived from the model accordingly. It showed that COD removal increased with the increase of HMWOM to LMWOM ratio, but decreased with increasing LMWOM concentration. There existed an optimal hydrogen peroxide to ferrous ion molar ratio so that the highest COD removal efficiency could be achieved.
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PMID:[Evaluation of Fenton process for the treatment of sanitary landfill leachate with Response Surface Methodology]. 1455 75


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