Cometabolic degradation of acifluorfen by a mixed microbial culture

Abstract

Laboratory experiments were conducted to study the degradation of acifluorfen 5‐[2‐chloro‐4‐ (trifluoromethyl)‐phenoxy]‐2‐nitrobenzoic acid by a mixed microbial population.

Concentrations of acifluorfen up to 100 mg/1 had no inhibitory effect on the growth of microbial culture.

The microorganisms degraded acifluorfen through a cometabolic process in presence of 2‐nitrobenzoate.

The degradation rate of acifluorfen, determined by liquid chromatography analysis in batch cultures incubated under oxygen and oxygen‐limited conditions were compared. The degradation was slower under oxygen than oxygen‐limited conditions. Aminoacifluorfen was produced in both conditions.     

Sorption and Biodegradation of Vapor-Phase Organic Compounds with Wastewater Sludge and Food Waste Compost

ABSTRACT

To test the possible use of composted food waste and wastewater sludge as biofilters to treat gas-phase volatile organic compounds (VOCs), batch experiments were conducted with an isolated strain that could degrade aromatic compounds under aerobic conditions. A benzene and trichloroethylene (TCE) mixture was used as the gas-phase pollutant in experiments with composted food waste, sludge, and soil. Under aerobic conditions, benzene was degraded as a primary substrate and TCE was degraded cometabolically, with water contents varying from 6 to 60% (volume of water added/volume of solid). Optimal water content for VOC removal was 12% for the soil, 36% for the composted food waste, and 48% for the sludge.

The extent of VOC sorption and biodegradation at the optimal water content was different for each material. With the same initial VOC concentration, more VOCs were removed by sorption onto the composted food waste and the sludge, while less VOCs were biodegraded in comparison with the results using soil. The reason the biodegradation in the soil was greater may be partly attributed to the fact that, due to less sorption, the aqueous-phase concentration of VOCs, which microorganisms could utilize as a carbon source or cometabolize, was higher. We also speculate that the distribution of microorganisms in each medium affects the rate of biodegradation. A large number of microorganisms were attached to the composted food waste and sludge. Mass transfer of VOCs and oxygen to these microorganisms, which appear to have been heterogeneously distributed in clusters, may have been limited, resulting in hindered biodegradation.     

Hydroxyquinol Pathway for Microbial Degradation of Halogenated Aromatic Compounds

Several peripheral metabolic pathways can be used by microorganisms to degrade toxic aromatic compounds that are known to pollute the environment. Hydroxyquinol (1,2,4-trihydroxybenzene) is one of the central intermediates in the degradative pathway of a large variety of aromatic compounds. The present review describes the microorganisms involved in the degradative pathway, the key enzymes involved in the formation and splitting of the aromatic ring of (chloro)hydroxyquinol as well as the central intermediates formed. An attempt was also made to provide some estimation for genetic basis of the hydroxyquinol pathway.     

Estimating the Lower Heating Values of Hazardous and Solid Wastes

ABSTRACT

A new equation is proposed to predict the lower heating value of hazardous and non-hazardous materials. The equation was developed by a statistical correlation of heating value and composition data for a variety of materials as reported in a number of sources. The model takes into account the carbon, hydrogen, oxygen, chlorine, and sulfur content of the material being combusted.     

The Fate of Hydrogen Peroxide as an Oxygen Source for Bioremediation Activities within Saturated Aquifer Systems

ABSTRACT

In situ bioremediation is an innovative technique for the remediation of contaminated aquifers that involves the use of microorganisms to remediate soils and groundwaters polluted by hazardous substances. During its application, this process may require the addition of nutrients and/or electron acceptors to stimulate appropriate biological activity. Hydrogen peroxide has been commonly used as an oxygen source because of the limited concentrations of oxygen that can be transferred into the groundwater using above-ground aeration followed by reinjection of the oxygenated groundwater into the aquifer or subsurface air sparging of the aquifer. Because of several potential interactions of H₂O₂ with various aquifer material constituents, its decomposition may be too rapid, making effective introduction of the H₂O₂ into targeted treatment zones extremely difficult and costly. Therefore, a bench-scale study was conducted to determine the fate of H₂O₂ within subsurface aquifer environments. The purpose of this investigation was to identify those aquifer constituents, both biotic and abiotic, that are most active in controlling the fate of H₂O₂. The decomposition rates of H₂O₂ were determined using both equilibrated water samples and soil slurries. Results showed H₂O₂ decomposition to be effected by several commonly found inorganic soil components; however, biologically mediated catalytic reactions were determined to be the most substantial.     

Monitoring the toxicity of phenolic chemicals to activated sludge using a novel optical scanning respirometer.

This paper reports the development of optical scanning respirometer for determining the toxicity of chemicals to activated sludge. The respirometer is used to measure the dissolved oxygen concentration by monitoring the luminescence intensity of ruthenium dye immobilized in a polymer film in contact with the wastewater sample. The intensity is related to the extent of oxygen quenching of luminescence. The toxicity of chemicals can be evaluated by measuring the inhibition on respiration rate of microorganism using the scanning respirometer. The IC50 values (concentration of a chemical that exhibits 50% respiration inhibition) of various phenolic chemicals in activated sludge were determined. The performance of this method is compared with other toxicity methods. The experimental results indicate that the reproducibility and sensitivity of this respirometer are reasonably good.     

Anaerobic Mesophilic Treatment of Cattle Manure in an Upflow Anaerobic Sludge Blanket Reactor with Prior Pasteurization

Abstract

Different autonomous communities located in northern Spain have large populations of dairy cattle. In the case of Asturias, the greatest concentration of dairy farms is found in the areas near the coast, where the elimination of cattle manure by means of its use as a fertilizer may lead to environmental problems. The aim of the present research work was to study the anaerobic treatment of the liquid fraction of cattle manure at mesophilic temperature using an upflow anaerobic sludge blanket (UASB) reactor combined with a settler after a pasteurization process at 70 °C for 2 hr. The manure used in this study came from two different farms, with 40 and 200 cows, respectively. The manure from the smaller farm was pretreated in the laboratory by filtration through a 1-mm mesh, and the manure from the other farm was pretreated on the farm by filtration through a separator screw press (0.5-mm mesh). The pasteurization process removed the pathogenic microorganisms lacking spores, such as Enterococcus, Yersinia, Pseudomonas, and coliforms, but bacterial spores are only reduced by this treatment, not removed. The combination of a UASB reactor and a settler proved to be effective for the treatment of cattle manure. In spite of the variation in the organic loading rate and total solids in the influent during the experiment, the chemical oxygen demand (COD) of the effluent from the settler remained relatively constant, obtaining reductions in the COD of ～85%.     

Size Distribution of Particles That May Contribute to Soiling of Material Surfaces

ABSTRACT

This study investigated the effect of adding vanadium (V) to natural manganese oxide (NMO) in ammonia (NH₃) selective catalytic reduction (SCR). The addition of V to NMO decreased the catalytic activity at low temperatures by blocking the active site. However, the enhancement of catalytic activity was achieved by controlling NH₃ oxidation at high temperatures. From the NH₃ temperature programmed desorption and oxygen on/off test, it was confirmed that the amount of Lewis acid site and active lattice oxygen of the catalyst affects the catalytic performance at low temperature

IMPLICATIONS Recently, NMO and manganese oxide have been reported as SCR catalysts. They usually have only reported the reaction characteristics and catalytic activity on the NH₃ SCR over NMO or manganese/metal oxide catalysts. There are no studies about the effect of addition of V to NMO. Therefore, this study investigates the catalytic activity and reaction characteristics on the NH₃ SCR over NMO and V/NMO, and a new application is proposed based on the conclusions of this study.     

Advanced Oxidation Processes in the Treatment of Trifluraline Effluent

The treatment of an effluent from the production of trifluraline was studied using a 1-L, semi-batch, tank-stirred glass reactor for performing three different advanced oxidation processes (photoperoxidation, Fenton, photo-Fenton). A commercial, medium-pressure mercury lamp was used for sample irradiation. The degradation was monitored by measurements of absorptiometric color reduction, UV-visible absorption spectra, and chemical oxygen demand (COD). The obtained results showed that the photo-Fenton process was the most effective treatment for the trifluraline effluent.     

Antimicrobial effects of clofibrate on the wheat pathogen Fusarium culmorum

Abstract

The biological effects of clofibrate (ethyl p‐chlorophenoxy‐isobutyric acid) on the growth and metabolism of the soil‐borne wheat pathogen Fusarium culmorum, were examined.

In mid log phase (16 hr) cultures both phenylalanine uptake and secondary spore production were stimulated at 0.1 μM concentration; the net sterol content was reduced 50% at 0.35 μM; oxygen uptake was stimulated at 0.1 mM; growth was inhibited 50% at 0.1 mM concentration. Both phenylalanine and oxygen uptake were inhibited at 1.0 mM and pyruvate dehydrogenase activity was reduced 50% at 50 mM concentration of clofibrate.

The data indicate that clofibrate affects a number of biological and enzyme systems. The inhibitory effect on the growth of the pathogen suggest a potential use of hypolipidemic agents like clofibrate as an antifungal agent for seed protection.     

Nitrogen Dioxide Absorption and Sulfide Oxidation in Aqueous Sulfide

ABSTRACT

Rates of nitrogen dioxide (NO₂) absorption and sulfide oxidation were measured in a highly characterized stirred cell contactor at 55 °C, with O₂ present in the gas phase. The rate constant of the reaction between NO₂ and sul-fide at 55 °C was determined to be 26.4 x10⁵ M^-1sec^-1. A reaction mechanism was proposed that is consistent with the kinetic data. NO₂ absorption initiates sulfide oxidation in the presence of oxygen. The rate of sulfide oxidation increased with sulfide and oxygen concentration and with the rate of NO₂ absorption. Furthermore, thiosulfate was an effective inhibitor of sulfide oxidation.     

Multicriteria Aided Design of Integrated Heating-Cooling Energy Systems in Buildings

Abstract

This paper presents an analysis of the possible application of integrated heating-cooling systems in buildings. The general algorithm of integrated heating-cooling system design aid was formulated. The evaluation criteria of technically acceptable variants were defined. Fossil fuel energy consumption, carbon dioxide emission, investment, and total exploitation cost were identified as the most important factors describing the considered decision problem. The multicriteria decision aid method ELECTRE III was proposed as the decision tool for the choice of the most compromised variant. The proposed method was used for a case study calculation—the choice of an integrated heating-cooling system for an office building.     

Factors affecting oxygen-transfer rates in headspace-gas respirometers.

Satisfactory measures of the biological-oxygen-uptake rate in headspace-gas respirometers can only be achieved if the rate of oxygen transfer from the headspace gas to liquid is greater than the rate of oxygen uptake by microorganisms. In the authors' study, factors potentially affecting oxygen-transfer limitations in headspace-gas respirometers were evaluated quantitatively. Tests were conducted to measure maximum-oxygen-uptake rates by operating a respirometer under various test conditions. Analysis of respirometric data indicated that limiting oxygen-transfer rates were related to mixing intensity, length of magnetic stirring bar, volume of sample, and oxygen content in the headspace gas. A multivariable model was developed to describe the overall contribution of these factors to the limiting oxygen-transfer rate. This model should be useful for estimating maximum-oxygen-transfer rates for essentially all headspace-gas respirometers.     

Effects of some insecticides on microbial activities in sandy soil

Abstract

Laboratory tests were conducted with 14 insecticides applied to a sandy loam to determine whether these materials caused any effects on microbial activities related to soil fertility. The ammonification of soil native organic nitrogen was not inhibited by any of the insecticide treatments. Some insecticides showed an effect on nitrification during the second week of incubation which subsequently recovered to levels similar to those obtained in the controls. There was a significant effect on denitrification in a number of treated samples. However, recovery of denitrifying capacity was rapid. This recovery indicated that the indigenous soil microorganisms can tolerate the chemicals used for control of insect pests. No significant inhibition of sulfur oxidation was observed. Results indicated that the insecticide treatments at the level tested were not drastic enough to be considered deleterious to soil microbial activities important to soil fertility.     

Bioaerosol Concentration at an Outdoor Composting Center

ABSTRACT

Compost centers are one of many environments that produce airborne microorganisms. The objective of this study was to compare the bacterial, fungal, and acti-nomycete concentrations at the Norman, OK, compost center to background concentration of these same microorganisms. For this comparison, a modified Andersen Microbial Sampler was used. Sampling was performed at three sites at the outdoor compost center and at two background sites. The concentration of each microorganism was measured as total colony forming units per cubic meter (CFU/m³). The predominantly downwind compost center site had a 10-fold increase in all the microorganisms in comparison with the other sites (p < 0.05). The median concentrations (95% confidence interval) of total viable bacteria, Gram-negative bacteria, fungi, and actinomycetes at this site were 5059 (CI₉₅= 4952-9600) CFU/m³, 2023 (CI₉₅= 2586-6806) CFU/m³, 972 (CI₉₅= 964-1943) CFU/m³, and 2159 (CI₉₅= 1755-4190) CFU/m³, respectively.     

Degradation of terbutryn in sediments and water under various redox conditions

Abstract

A laboratory study was conducted to examine the degradation of terbutryn [2‐(t‐butylamino)‐4‐(ethylamino)‐6‐(methylthio)‐s‐triazine] in sediment and water under different redox conditions. Terbutryn degraded slowly in static aerobic systems (loosely capped flask, 25°C) with half‐lives of 240 and 180 days in pond and river sediment, respectively. Degradation products, identified by co‐chromatography on TLC and HPLC systems, included hydroxy‐terbutryn, terbutryn‐sulfoxide and N‐deethyl terbutryn. Hydroxyterbutryn was the major degradation product in sediments and water representing 60–70% of the extractable radioactivity after 515 days incubation. Under nitrogen aeration in respirometer flasks (redox potential ‐46 to +210 mv) degradation of terbutryn was very slow with half lives greater than 650 days.     

A Novel Design for Anaerobic Chemical Oxygen Demand and Nitrogen Removal from Leachate in a Semiaerobic Landfill

Abstract

The removal capacity of carbon and nitrogen from an artificial leachate was evaluated by using laboratory-scale columns, and a design was proposed to remove nitrogen more efficiently from a semiaerobic landfill. Five columns (i.e., two artificial municipal waste columns under anaerobic and semiaerobic conditions, an artificial construction waste column under semiaerobic conditions, and two crushed stone columns under anaerobic and semiaerobic conditions) were used. The influent load rates of organics [g chemical oxygen demand (COD)/m³ ·day], NH₄ ⁺, NO₃ ^?, and aeration conditions for the columns were varied, and the removal capacities of the columns for COD, NH₄ ⁺-N, and NO₃ ^?-N were measured.

Among the packed column materials, crushed stone was shown to be most effective in removing COD, NH₄ ⁺-N, and NO₃ ^?-N from artificial leachate. Average removal rates of crushed column under the semiaerobic condition (column D) for COD and NH₄ ⁺-N were estimated at about 150 g COD/m³·day and 20 g COD/m³ ·day, while those of crushed column under anaerobic condition (column E) for COD and NO₃ ^?-N at about 400 and 150 g COD/m³ ·day, respectively. It also was found that denitrification and nitrification reactions in column D occurred at the same time, and the ratio of denitrification to nitrification was estimated to be about 80%. Therefore, an anaerobic structure, which could be attached to the bottom of a main pipe in a semiaerobic landfill, is suggested to remove nitrogen and organic substances more effectively.     

Bioventing Feasibility Assessment and System Design Using Subsurface Oxygen Sensors

Abstract

Vadose zone oxygen sensors can be effectively used to improve bioventing remediation design and monitoring. The capacity of the oxygen sensors for continuously monitoring oxygen concentrations unattended offers an improved approach for bioventing feasibility evaluation and respiration measurements. A new in-situ technique has been developed using these sensors for evaluating respiration rate at the startup of air injection or vapor extraction. This dynamic method imposes little restriction on the flowrate and soil conditions when the oxygen sensors are within the radius of influence, whereas a traditional in-situ oxygen uptake respiration test assumes a static condition. Oxygen uptake respiration tests measure a localized respiration rate. The dynamic method determines a spatially averaged respiration rate in the air flow path between injection point and a sensing point in air injection setup, or within the capture zone of a vapor extraction setup. Because respiration measurements can be made using the new technique at the startup of a remediation process, whether it is air injection or vapor extraction, it allows the process to run without interruption. Using the subsurface oxygen sensor, the dynamic method also allows the respiration rate to be continuously monitored. A case study at a site in Palm Springs, California is used to document the application of this new technique and its advantages. In addition to directly monitoring the radius of influence, the subsurface oxygen sensor can also provide necessary parameters to calculate a radius of influence for a given air injection rate. The Palm Springs case study demonstrates the application, as well as the limitation, of the radius of influence calculation.     

83rd Annual Meeting & Exhibition

Abstract

The estimation of odor production and dispersion from landfill sites is a very complicated task because of the different chemical species that exist in biogas. To site a new landfill, it is necessary to know the distance that odors can travel around the landfill under atmospheric conditions that increase the concentration of pollutants. Although CH₄ is an odorless gas, it can be used as an index to determine the dispersion of low-reactivity odorous species around a landfill site. Methane production rates, estimated by biogas production models, were used by an air dispersion model to determine the spatial distribution of CH₄ around landfill sites. By utilizing dispersion models under extreme atmospheric conditions, a maximum CH₄ concentration around the landfills was determined. Based on the ratio between CH₄ and odorous chemical species, the spatial distribution of the concentration of an odorous species was determined for those species with low reactivity in the atmosphere. For odorous species with high reactivity in the atmosphere, a dispersion-reaction model must be used. In this way, the acceptable distance between new landfills and residential areas can be determined. The proposed methodology could be used as a design tool for those who are interested in landfill siting.