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At least 1,135 records · Page 63Linked to original sources

PubMed2006

The possibility of useful usage of biodegradation products of sunflower plants.

Heads of sunflower (Helianthus annuus L.) were first biodegraded at 55 degrees C by their microflora. Biodegradation products of sunflower heads (BPSH) were analyzed. They were found to contain 9.77% dry matter, 3.98% total ash, 3.18% crude protein and 5.75% total organic matter. BOD load was determined as 4.80 g/100 g. Subsequently, the effects of BPSH at various concentrations (1.0%, 2.5%, 10% and 100%) on the seed germination and some growth parameters of Phaseolus vulgaris L., Cicer arietinum L. and Triticum vulgare L. were investigated. The percentages of seed germination and germination index of seeds were similar between the control and 1.0% and 2.5% BPSH groups, but these values decreased at higher concentrations. On the other hand, growth of the seedlings gradually increased up to a concentration of 10% BPSH and decreased at 100% concentration. As a result, at concentrations up to 10% the product was found to be beneficial for growth of plants.

Agriculture↗

PubMed2005

Biodegradation of pyridine in a completely mixed activated sludge process.

A potential bacterial culture (P1), isolated from garden soil and identified as Pseudomonas pseudoalcaligenes-KPN, was used as a starter seed to develop the biomass in a completely mixed activated sludge (CMAS) reactor and the system was evaluated for treatment of wastewater containing pyridine. The results of this study indicate that pyridine could be degraded efficiently at a loading of 0.251 kg pyridine kg MLSS(-1) d(-1) (0.156 kg TOC kg MLSS(-1) d(-1)) and at an optimal hydraulic retention time (HRT) of 24 h. Pyridine was used as the sole source of carbon and nitrogen by the biomass. Ammonia-nitrogen (NH3-N) was formed due to the metabolism of the pyridine ring. In the present investigation, the performance of CMAS with reference to pyridine biodegradation and the bio-kinetic constants for the biodegradation of pyridine, in a continuous system, were computed. The results indicate that a CMAS system inoculated with P. pseudoalcaligenes-KPN, under optimum conditions of HRT and pyridine loading, gives a yield coefficient of (Y) 0.29, decay coefficient (Kd) 0.0011 d(-1), maximum growth rate constant (mumax) 0.108 d(-1) and saturation rate constant (Ks) 5.37 mg L(-1) for pyridine.

Biodegradation, Environmental↗

PubMed2005

Biodegradation of high concentrations of hexadecane by Aspergillus niger in a solid-state system: kinetic analysis.

Solid-state microcosms were used to assess the influence of constant and variable C/N ratios on the biodegradation efficiency by Aspergillus niger at high hexadecane (HXD) concentrations (180-717 mg g-1). With a constant C/N ratio, 100% biodegradation (33-44% mineralization) was achieved after 15 days, at rates increasing as the HXD concentration increased. Biomass yields (YX/S) remained almost independent (approximately 0.77) of the carbon-source amount, while the specific growth rates (mu) decreased with increasing concentrations of HXD. With C/N ratios ranging from 29 to 115, complete degradation was only attained at 180 mg g-1, corresponding to 46% mineralization. YX/S diminished (approximately 0.50 units) as the C/N ratio increased. The highest values of mu (1.08 day-1) were obtained at low C/N values. Our results demonstrate that, under balanced nutritional conditions, high HXD concentrations can be completely degraded in solid-state microcosms, with a negligible (<10%) formation of by-products.

Alkanes↗

PubMed2005

Biodegradation of tannery wastewater using sequencing batch reactor--respirometric assessment.

This investigation proved that respirometry combined with sequencing batch reactor (SBR) could be an effective way for the removal of COD in tannery wastewater. Measurement of oxygen uptake rates (OUR) and corresponding COD uptake rates showed that a 12-h operating cycle was optimum for tannery wastewater. The removal of COD by degradation was stoichiometric with oxygen usage. A plot of OUR values provided a good indication of the biological activity in the reactor. A high OUR value corresponded to the feed period; at the end of the cycle, when the substrate was depleted, the OUR value was low. At a 12-h SBR cycle with a loading rate of 1.9-2.1 kgm(-3) d(-1), removal of 80-82% COD, 78-80% TKN and 83-99% NH(3)-N were achieved. These removal efficiencies were much higher than the conventional aerobic systems. A simple method of COD fractionation was performed from the OUR and COD uptake rate data of the SBR cycle. About 66-70% of the influent COD was found to be readily biodegradable, 10-14% was slowly degradable and 17-21% was non-biodegradable. The oxygen mass transfer coefficient, K(L)a (19 +/- 1.7 h(-1)) was derived from respirometry. It was observed that with the exception of high organic load at the initial feed the oxygen transfer capacity was in excess of the OUR, and aerobic condition was generally maintained. Simultaneous nitrification-denitrification was observed in the SBR during the feed period as proved by mass balance.

Biodegradation, Environmental↗

PubMed2006

Comparative studies on crosslinked and uncrosslinked natural rubber biodegradation by Pseudomonas sp.

A comparative study on biodegradation of di-cumyl peroxide (DCP) crosslinked and uncrosslinked natural rubber by Pseudomonas sp. was carried out. Decrease in organic carbon content along with the changes in tensile strength of the treated rubber, both DCP crosslinked and uncrosslinked natural rubber, indicated rubber hydrocarbon utilization by the Pseudomonas sp. A decrease in 60.88% MPa and 41.66% MPa was observed after five month's old treated uncrosslinked natural rubber and DCP crosslinked rubber, respectively. Biodegradation was more pronounced in natural uncrosslinked rubber, which was further confirmed by the formation of aldehydic compounds with decrease in CH2 stretching frequencies.

Benzyl Compounds↗

PubMed2006

Aerobic biodegradation of alkylphenol ethoxylates.

Primary aerobic biodegradation of alkylphenol ethoxylates (APEOs) was studied using a new simple and fast porphyrin method, which did not require the extraction step. Extent of primary biodegradation of a nonylphenol ethoxylates (NP-10) was excess of 92% after 1.5 days, and reached 99% after 2 days, which was similar to the results obtained using modified CTAS (thiocyanate active substances) method. Degradation of benzene ring of NP-10 was studied using UV-absorbance at 277 nm in chloroform. Results showed that only little of benzene ring was degraded.

Bacteria, Aerobic↗

PubMed2006

Anaerobic biodegradation tests and gas emissions from subsurface flow constructed wetlands.

Anaerobic tests with gravel from horizontal subsurface flow constructed wetlands (SSF) used for the treatment of urban wastewater were developed in order to evaluate the anaerobic biodegradability of their effluents. Two types of assays were conducted. The reactors used for the first type were glass vials of 45 mL, that were used for only one measurement, requiring starting experiments with a number of reactors equal to the measurements to be made. For the second type of experiments multiple measurements were done in the same reactors, by using flasks of 2.2L. The COD of the SSF effluents used for the tests ranged from 60 to 130 mg/L. The evolution of CO(2) in the headspace of the reactors was used as indicator of anaerobic biodegradation rates. CO(2) mass emission rates ranged from 0.005 to 0.015 micromol/mL day. CH(4) generation was not detected in the tests in relation with the refractory properties of the effluent organic matter of the studied SSF. In situ measurement of CO(2) and CH(4) emissions from the gravel of the SSF ranged from 0.106 to 0.464 and from 0.039 to 0.107 mmol/m(2)h, respectively. Several CO(2) fluxes measured in the field were quite consistent with the emissions observed in the laboratory. The developed tests can help to understand the performance of SSF and improve their operation.

Anaerobiosis↗

PubMed2004

Acclimation of anaerobic sludge degrading chlorophenols and the biodegradation kinetics during acclimation period.

The acclimation of sludge from Hangzhou citrate factory and Hangzhou municipal wastewater treatment plant for degradation dechlorination of chlorophenols (CPs) compounds, and its biodegradation kinetics were studied in batch process with or without addition of sucrose. Three monochlorophenols (2-CP; 3-CP; 4-CP) and pentachlorophenol (PCP) were concurrently fed to different bioreactors. The parameters that were monitored included biogas production, biogas composition and chemical oxygen demand (COD). The results showed that acclimation with chlorophenol can increase the degradation activity of anaerobic sludge and degradation rate of chlorophenolic compounds, and reduce the lag time. Degradation dechlorination activity of the acclimated sludge strongly depended on sludge source, microorganism population and chlorophenol congener. 2-CP was more easily acclimated than 3-CP and 4-CP. Among the four tested compounds, 4-CP was the most difficult to be acclimated. The observed degradation rate with presence of sucrose was higher than that with absence of sucrose, suggesting that addition of the external carbon source can stimulate the formation of acclimated sludge which could effectively degrade chlorophenols. Kinetic equations of biodegradation of chlorophenols were also presented in this paper.

Anaerobiosis↗

PubMed2004

Identification and molecular characterization of a Bacillus subtilis IS13 strain involved in the biodegradation of 4,5,6-trichloroguaiacol.

4,5,6-Trichloroguaiacol (4,5,6-TCG) is a recalcitrant organochlorine compound produced during pulp bleaching and a potential environmental hazard in paper mill effluents. We report here the identification by biochemical tests and molecular biological analysis, using 16S ribotyping, of a 4,5,6-TCG-degrading bacterium, identified as a strain of Bacillus subtilis that is most closely related according to the phylogenetic analysis to B. subtilis strain Lactipan (alignment score 99%). Biodegradation of 4,5,6-TCG by this organism in a mineral salts medium was shown to occur only when the inoculum was composed of cells in the stationary phase of growth and to be accelerated by an additional carbon source, such as glucose, sucrose, glycerol or molasses. An additional nitrogen source (as ammonium sulfate) did not affect the rate of 4,5,6-TGC removal. No plasmids were detected in the bacterial cells. This is the first strain of B. subtilis which degrades chlorophenols and shows that 4,5,6-TCG is not degraded by cometabolism and that the gene encoding this characteristic is probably located on the chromosome. The lack of requirement for additional nitrogen source, the ability to enhance biodegradation by adding cheap carbon sources such as molasses, and the fact the trait is likely to be stable since it is encoded on the cell chromosome, are all characteristics that make the organism an attractive possibility for treatment of wastes and environments polluted with organochlorine compounds.

Bacillus subtilis↗

PubMed2004

Fate of biodegradable dissolved organic carbon produced by ozonation on biological activated carbon.

The adsorption and desorption characteristics of BDOC produced by ozonation and the replacement of BDOC by non-BDOC on BAC was studied. The fate of BDOC produced by ozonation in the BAC column was also evaluated by comparative experiment between the BAC supplied with the mixture of BDOC and non-BDOC and the BAC supplied only with non-BDOC. Fulvic acids extracted from two river sediments and one forest soil were used. BDOC produced by ozonation showed the same or lower adsorption capacity than non-BDOC after biodegradation. The adsorption rate of BDOC on GAC was lower than that of non-BDOC. BDOC produced by ozonation had low desorbability and majority of BDOC produced were not replaced by non-BDOC. BDOC in the ozonated fulvic acid did not affect the breakthrough of the ozonated fulvic acid on GAC in the early stage of adsorption, suggesting that most of BDOC were biodegraded on the surface of GAC before adsorption. Therefore, the production of BDOC by ozonation before the GAC treatment is very effective for the extension of GAC service life and the reduction of DOC loading to GAC.

Adsorption↗

PubMed2005

Anaerobic biodegradability and methanogenic toxicity of key constituents in copper chemical mechanical planarization effluents of the semiconductor industry.

Copper chemical mechanical planarization (CMP) effluents can account for 30-40% of the water discharge in semiconductor manufacturing. CMP effluents contain high concentrations of soluble copper and a complex mixture of organic constituents. The aim of this study is to perform a preliminary assessment of the treatability of CMP effluents in anaerobic sulfidogenic bioreactors inoculated with anaerobic granular sludge by testing individual compounds expected in the CMP effluents. Of all the compounds tested (copper (II), benzotriazoles, polyethylene glycol (M(n) 300), polyethylene glycol (M(n) 860) monooleate, perfluoro-1-octane sulfonate, citric acid, oxalic acid and isopropanol) only copper was found to be inhibitory to methanogenic activity at the concentrations tested. Most of the organic compounds tested were biodegradable with the exception of perfluoro-1-octane sulfonate and benzotriazoles under sulfate reducing conditions and with the exception of the same compounds as well as Triton X-100 under methanogenic conditions. The susceptibility of key components in CMP effluents to anaerobic biodegradation combined with their low microbial inhibition suggest that CMP effluents should be amenable to biological treatment in sulfate reducing bioreactors.

Bacteria, Anaerobic↗

PubMed2005

The effects of preozonation on the biodegradability of mixed phenolic solution using a new gas-inducing reactor.

In this study, the effects of preozonation on the biodegradability of mixed 2-chlorophenol/4-cresol solution were investigated using a new gas-inducing reactor, which can provide high ozone utilization efficiency. The decomposition rate of phenolic mixture, COD removal and TOC removal increases with increasing pH. A half-order overall kinetic model can correctly describe the decomposition of phenolic mixture. The BOD(5)/COD ratio of the preozonized solutions increases with increasing preozonation time, indicating that preozonation can enhance the biodegradability. Based on high ozone utilization rate, it is concluded that the best characteristic time can be chosen at the rapid increase of ozone gas outlet concentration. Since the ozone gas outlet concentration can be easily monitored, it is a useful real-time control parameter in preozonation.

Biodegradation, Environmental↗

PubMed2005

A review of the occurrence, analyses, toxicity, and biodegradation of naphthenic acids.

Naphthenic acids occur naturally in crude oils and in oil sands bitumens. They are toxic components in refinery wastewaters and in oil sands extraction waters. In addition, there are many industrial uses for naphthenic acids, so there is a potential for their release to the environment from a variety of activities. Studies have shown that naphthenic acids are susceptible to biodegradation, which decreases their concentration and reduces toxicity. This is a complex group of carboxylic acids with the general formula CnH(2n+Z)O2, where n indicates the carbon number and Z specifies the hydrogen deficiency resulting from ring formation. Measuring the concentrations of naphthenic acids in environmental samples and determining the chemical composition of a naphthenic acids mixture are huge analytical challenges. However, new analytical methods are being applied to these problems and progress is being made to better understand this mixture of chemically similar compounds. This paper reviews a variety of analytical methods and their application to assessing biodegradation of naphthenic acids.

Biodegradation, Environmental↗

PubMed2005

Effect of textile auxiliaries on the biodegradation of dyehouse effluent in activated sludge.

The textile industry is confronted with serious environmental problems associated with its immense wastewater discharge, substantial pollution load, extremely high salinity, and alkaline, heavily coloured effluent. Particular sources of recalcitrance and toxicity in dyehouse effluent are two frequently used textile auxiliaries; i.e. dye carriers and biocidal finishing agents. The present experimental work reports the observation of scientific and practical significance related with the effect of two commercially important textile dye carriers and two biocidal finishing agents on biological activated sludge treatment at a textile preparation, dyeing and finishing plant in Istanbul. Respirometric measurements of the dyehouse effluent spiked with the selected textile chemicals were carried out for the assessment of the "readily biodegradable COD fraction" of the wastewater. The respirometric data obtained to visualize the effect of the selected textile auxiliaries on biomass activity was evaluated by an adopted activated sludge model. Results have indicated that the tested biocides did not exert any significant inhibitory effect on the treatment performance of the activated sludge reactor at the concentrations usually encountered in the final, total dyehouse effluent. The situation with the dye carriers was inherently different; one dye carrier appeared to be highly toxic and caused serious inhibition of the microbial respirometric activity, whereas the other dye carrier, also known as the more ecological alternative, i.e. the "Eco-Carrier", appeared to be biodegradable. Finally, the respirometric profile obtained for the Eco-Carrier was described by a simplified respirometric model.

Biodegradation, Environmental↗

PubMed2005

Role of cyanobacteria in the biodegradation of crude oil by a tropical cyanobacterial mat.

Cyanobacterial mats are ubiquitous in tropical petroleum-polluted environments. They form a high biodiversity microbial consortium that contains efficient hydrocarbons degraders. A cyanobacterial mat collected from a petroleum-contaminated environment located in Indonesia was studied for its biodegradation potential. In the field, the natural mat was shown to degrade efficiently the crude oil present in the environment. This natural mat demonstrated also a strong activity of degradation on model crude oil under laboratory conditions. In axenic cultures, the monospecific cyanobacterium Phormidium animale that constitute the bulk of the biomass did not exhibit any degradative capacity on hydrocarbons in the range of C13-C35 carbon atom number either in autotrophic or heterotrophic conditions. It was concluded that this cyanobacterial strain living on a heavily contaminated site had no direct effect on biodegradation of crude oil, the degradation activity being exclusively achieved by the other microorganisms present in the microbial consortium of the mat.

Biodegradation, Environmental↗

PubMed2005

Estimating biodegradation half-lives for use in chemical screening.

Biodegradation half-lives are needed for many applications in chemical screening, but these data are not available for most chemicals. To address this, in phase one of this work we correlated the much more abundant ready and inherent biodegradation test data with measured half-lives for water and soil. In phase two, we explored the utility of the BIOWIN models (in EPI Suite) and molecular fragments for predicting half-lives. BIOWIN model output was correlated directly with measured half-lives, and new models were developed by re-regressing the BIOWIN fragments against the half-lives. All of these approaches gave the best results when used for binary (fast/slow) classification of half-lives, with accuracy generally in the 70-80% range. In the last phase, we used the collected half-life data to examine the default half-lives assigned by EPI Suite and the PBT Profiler for use as input to their level III multimedia models. It is concluded that estimated half-lives should not be used for purposes other than binning or prioritizing chemicals unless accuracy improves significantly.

Biodegradation, Environmental↗

PubMed2006

Treatment of cork boiling wastewater using chemical oxidation and biodegradation.

Three cultures were enriched from cork boiling wastewater using tannic acid as the selective carbon substrate, at 25 degrees C and pH 7.2, 25 degrees C and pH 4.7 and 50 degrees C and pH 4.7. The enrichment culture obtained at neutral pH was composed of five culturable isolates, whereas from each acidic enrichment two bacterial strains were isolated. Mesophilic isolates were Gram negative bacteria belonging to the genera Klebsiella, Pseudomonas, Stenotrophomonas and Burkholderia. Thermophilic isolates were members of the genus Bacillus. Despite the capability of the enrichment cultures to use tannic acid as single carbon and energy source, those cultures were unable to reduce the total polyphenols or the total organic carbon content of cork boiling wastewater. In order to increase the bioavailability of the organic carbon in cork boiling wastewater, biodegradation was preceded by Fenton oxidation. It was demonstrated that the combined process, using small amounts of Fenton reagents and biodegradative inoculum added almost simultaneously to cork boiling wastewater, leads to TOC reductions of more than 90%.

Biodegradation, Environmental↗

PubMed2006

Biodegradation of polyethylene films with prooxidant additives.

Prooxidant additives represent a promising solution to the problem of the environment contamination with polyethylene film litter. Prooxidants accelerate photo- and thermo-oxidation and consequent polymer chain cleavage rendering the product apparently more susceptible to biodegradation. The question not fully resolved remains the biodegradation itself, its mechanism and especially the factors influencing the time-frame in which it can occur. The presented review is aimed to provide comprehensible information for both microbiologists and polymer scientists, who need participate in the research leading to an understanding of the microorganism action on the oxidized polyethylene and to design of new materials.

Biodegradation, Environmental↗