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ABSTRACT: This work presents the effect of ammonia nitrogen concentration and zeolite addition on the specific methanogenic activity (SMA) of different anaerobic sludges with various physical structures (granular and flocculent), operating in batch conditions. Piggery, malting production and urban sludges derived from full-scale anaerobic reactors were tested in the experiment as the source of inoculum in batch digesters. It was found that piggery sludge was the most affected by the increase of ammonia nitrogen concentration while malting producing and municipal sludges were less affected. In general, the addition of zeolite at doses in the range of 0.01-0.1 g/g VSS reduced the inhibitory effect of N-NH(4)(+) for piggery sludge (P.S.). For this sludge, the propionic:acetic ratio increased when the concentration of N-NH(4)(+) increased, indicating that methanogenesis was affected. Finally, a study of the microbial population involved in this study for P.S. by using 16S rRNA based molecular techniques revealed a presence of microorganisms following the order: Methanococcaceae > Methanosarcina > Methanosaeta.
Journal of Environmental Science and Health Part A Toxic/Hazardous Substances & Environmental Engineering 06/2010; 45(7):883-9.
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ABSTRACT: Ultrasound in a liquid phase cause mass and heat transfer across the liquid through cavitational processes which act as nanoreactors to generate unstable mechanical equilibrium. The effect of 1 MHz ultrasound on the inactivation of Cryptosporidium parvum was investigated. Continuous irradiation of ultrasound (20 min) increased temperature due to cavitational phenomena. Ultrasound irradiation of liquid containing C. parvum showed significant quantitative changes in pH, temperature and inactivation of C. parvum (102.7 oocysts killed/s) with a minimum energy consumption (0.05 oocysts/s).
Bioresource Technology 05/2008; 99(6):2046-9. · 4.98 Impact Factor
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ABSTRACT: The effect of natural and modified zeolites on the anaerobic degradation of acetate and methanol was evaluated by the determination of specific methane productivity (SMP) in batch minidigesters of 50 mL at doses of 0.01, 0.05 and 0.1 g of zeolite/g of VSS. The effects of the different zeolite concentrations were determined by the results of the SMP. A kinetic characterization with data of accumulated methane gas volume was also carried out. In the second phase of the study, the effects of natural and nickel zeolite concentrations were tested with piggery waste in laboratory scale digesters of 2.5 L operating at semi continuous mode, by increasing the organic load applied from 0.2 to 22.0 g TCOD/d corresponding to organic loading rates (OLR) of 0.1-8.8 g TCOD/l x d. A greater effect of modified zeolite on SMP was observed, with an increase of 8.5 times with magnesium zeolite, 4.4 times with cobalt zeolite and 2.8 times with nickel zeolite. Two phases were defined in the kinetic study and an increase of more than 2 times the apparent constant of digesters with modified zeolites was observed in the second phase when compared to unmodified natural zeolite. Modified natural zeolite addition to digesters can allow an increase in the potential biodegradability of piggery waste solid fraction and/or a considerable reduction of digestion volume.
Water Science & Technology 02/2003; 48(6):263-9. · 1.12 Impact Factor
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Bulletin of Environmental Contamination and Toxicology 07/2002; 68(6):862-9. · 1.02 Impact Factor
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ABSTRACT: The effect of different natural zeolite concentrations on the anaerobic digestion of piggery waste was studied. Natural zeolite doses in the range 0.2-10 g/l of wastewater were used in batch experiments, which were carried out at temperatures between 27 degrees C and 30 degrees C. Total chemical oxygen demand (COD), total and volatile solids, ammonia and organic nitrogen, pH, total volatile fatty acids (TVFA), alkalinity (Alk) and accumulative methane production were determined during 30 days of digestion. The anaerobic digestion process was favored by the addition of natural zeolite at doses between 2 and 4 g/l and increasingly inhibited at doses beyond 6 g/l. A first-order kinetic model of COD removal was used to determine the apparent kinetic constants of the process. The kinetic constant values increased with the zeolite amount up to a concentration of 4 g/l. The values of the maximum accumulative methane production (Gm) increased until zeolite concentrations of 2-4 g/l. The addition of zeolite reduced the values of the TVFA/ Alk ratio while increasing the pH values, and these facts could contribute to the process failure at zeolite doses of 10 g/l.
Bioresource Technology 11/2001; 80(1):37-43. · 4.98 Impact Factor
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ABSTRACT: The removal effect of natural and modified zeolites containing different heavy metals (Ni2+, Zn2+, Fe3+ and Cu2+) on pure cultures of Escherichia coli and Staphylococcus aureus in a solid medium was evaluated in this work. These experiments were carried out in a continuous mode treating municipal wastewater. Faecal coliform species and Pseudomonas aeruginosa were identified. The rate constants of heavy metal lixiviation were determined using a first order kinetic model. The removal effect of modified natural zeolites in both a solid medium and in continuous mode showed an increased elimination of the bacterial population. The results established a decreasing order of the removal effect as follows: Cu2+ > Fe3+ > Zn2+ > Ni2+. The best performance of columns was obtained for inlet bacterial concentrations below 10(6) cells/100 ml. Most of the identified bacterial species were affected by copper modified zeolites, although Serratia marcescens presented the highest sensitivity and Klebsiella pneumoniae the greatest resistance.
Journal of Environmental Science and Health Part A 02/2001; 36(6):1073-87. · 1.19 Impact Factor
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Bulletin of Environmental Contamination and Toxicology 03/1999; 62(2):138-43. · 1.02 Impact Factor
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Bulletin of Environmental Contamination and Toxicology 07/1998; 60(6):936-43. · 1.02 Impact Factor
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Bulletin of Environmental Contamination and Toxicology 07/1996; 56(6):1000-7. · 1.02 Impact Factor
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ABSTRACT: Root and shoot tolerance indices and photosynthesis characteristics (CO2-dependent-O2 evolution; H2O→MV electron transport; whole-leaf photosynthesis by infrared gas analyzer) indicated that ADT-36 and CR-1009 rice varieties
were more tolerant than other varieties (IR-50, IR-20, and Ponni). Vigna varieties (T-9 and Krishna) were most susceptible
to aqueous oil pollution. Since the oil-polluted soil contained a potentially toxic concentration of cadmium, tolerant (ADT-36)
and susceptible (IR-50) varieties of Oryza were further analyzed for cadmium-binding components. Higher accumulations of cadmium
were found in the roots than in the leaves of both rice varieties. Cadmium is associated with proteins of about 50,000 and
33,000-dalton in molecular mass, of which the 33-kdalton protein was significantly induced only in ADT-36. It is suggested
by the present study that the ADT-36 rice variety is most tolerant to aqueous oil pollution, as evidenced by higher STI (shoot
tolerance index) and RTI (root tolerance index) values, induction of Cd-binding proteins, and comparatively normal photosynthesis
rates.
Applied Biochemistry and Biotechnology 04/1990; 26(1):11-22. · 1.94 Impact Factor
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Bulletin of Environmental Contamination and Toxicology 03/1989; 42(2):187-94. · 1.02 Impact Factor
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Bulletin of Environmental Contamination and Toxicology 01/1989; 42(2):187-194. · 1.02 Impact Factor
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ABSTRACT: As a result of continuous aqueous oil effluent irrigation in about 25 acres of crop field, oil compounds infiltrated up to 50 cm depth of the soil. In an oil-polluted soil, respiration was always higher than the uncontaminated soil. Total hydrocarbon content of the polluted soil was quantified by infrared spectrophotometric technique. A significant correlation was observed between oil concentration (total hydrocarbons) in the upper layer of the soil (0–25 cm) and air temperature. Seed germination, percentage of seedling emergence, number of root nodules/plant, leghaemoglobin content in root nodules, total soluble sugars, total soluble proteins, free amino acids, total chlorophyll and carotenoids and nucleic acids of the leaves of Vigna mungo (L.) Hepper grown in the polluted soil decreased significantly due to persistence of hydrocarbon. Total phenolic content of the leaves in the polluted plant increased significantly.
Science of The Total Environment.
