Aerobic Biological Degradation Research Articles

Aerobic biological treatment of black table olive washing wastewaters: effect of an ozonation stage

The present work is a study of oxidative degradation of the organic matter present in the washing waters from the black table olive industry. Pollutant organic matter reduction was studied by an aerobic biological process and by the combination of two successive steps: ozonation pretreatment followed by aerobic biological degradation. In the single aerobic biological process, the evolution of biomass and organic matter contents was followed during each experiment. Contaminant removal was followed by means of global parameters directly related to the concentration of organic compounds in those effluents: chemical oxygen demand (COD) and total phenolic content (TP). A kinetic study was performed using the Contois model, which applied to the experimental data, provides the specific kinetic parameters of this model: 4.81×10 −2 h −1 for the kinetic substrate removal rate constant, 0.279 g VSS g COD −1 for the cellular yield coefficient and 1.92×10 −2 h −1 for the kinetic constant for endogenous metabolism. In the combined process, an ozonation pretreatment is conducted with experiments where an important reduction in the phenolic compounds is achieved. The kinetic parameters of the following aerobic degradation stage are also evaluated, being 5.42×10 −2 h −1 for the kinetic substrate removal rate constant, 0.280 g VSS g COD −1 for the cellular yield coefficient and 9.1×10 −3 h −1 for the kinetic constant for the endogenous metabolism.

Ozonation of black‐table‐olive industrial wastewaters: effect of an aerobic biological pretreatment

The present work is a study of oxidative degradation of the organic matter present in the washing waters from the black-table-olive industry. This oxidation is performed by an ozonation process, by an aerobic biological degradation process, and by another ozonation of biologically pretreated washing waters. In the ozonation process, a second-order kinetic reaction with respect to ozone and COD or aromaticity has been deduced. The kinetic rate constants were correlated as a function of temperature by Arrhenius-type equations. In the aerobic biological treatment, a kinetic study was performed using the Contois model, giving a value of 4.8 10−2 h−1 for the kinetic bioreaction constant. Likewise, a cell yield coefficient of 0.30 g VSS g COD−1 and a kinetic constant for the endogenous metabolisme of 1.2 10−2 h−1 were deduced. Finally, in the ozonation of biologically pretreated wash-waters, the deduced kinetic rate constants for COD and aromaticity were, respectively, 4.5 and 2.4 times higher that those corresponding to the ozonation of wash-waters without biological pretreatment. © 2000 Society of Chemical Industry

Natural attenuation of chlorinated ethene compounds: model development and field-scale application at the Dover site

A multi-dimensional and multi-species reactive transport model was developed to aid in the analysis of natural attenuation design at chlorinated solvent sites. The model can simulate several simultaneously occurring attenuation processes including aerobic and anaerobic biological degradation processes. The developed model was applied to analyze field-scale transport and biodegradation processes occurring at the Area-6 site in Dover Air Force Base, Delaware. The model was calibrated to field data collected at this site. The calibrated model reproduced the general groundwater flow patterns, and also, it successfully recreated the observed distribution of tetrachloroethene (PCE), trichloroethene (TCE), dichloroethylene (DCE), vinyl chloride (VC) and chloride plumes. Field-scale decay rates of these contaminant plumes were also estimated. The decay rates are within the range of values that were previously estimated based on lab-scale microcosm and field-scale transect analyses. Model simulation results indicated that the anaerobic degradation rate of TCE, source loading rate, and groundwater transport rate are the important model parameters. Sensitivity analysis of the model indicated that the shape and extent of the predicted TCE plume is most sensitive to transmissivity values. The total mass of the predicted TCE plume is most sensitive to TCE anaerobic degradation rates. The numerical model developed in this study is a useful engineering tool for integrating field-scale natural attenuation data within a rational modeling framework. The model results can be used for quantifying the relative importance of various simultaneously occurring natural attenuation processes.

Ozonation of black-table-olive industrial wastewaters: effect of an aerobic biological pretreatment

The present work is a study of oxidative degradation of the organic matter present in the washing waters from the black-table-olive industry. This oxidation is performed by an ozonation process, by an aerobic biological degradation process, and by another ozonation of biologically pretreated washing waters. In the ozonation process, a second-order kinetic reaction with respect to ozone and COD or aromaticity has been deduced. The kinetic rate constants were correlated as a function of temperature by Arrhenius-type equations. In the aerobic biological treatment, a kinetic study was performed using the Contois model, giving a value of 4.8 10−2 h−1 for the kinetic bioreaction constant. Likewise, a cell yield coefficient of 0.30 g VSS g COD−1 and a kinetic constant for the endogenous metabolisme of 1.2 10−2 h−1 were deduced. Finally, in the ozonation of biologically pretreated wash-waters, the deduced kinetic rate constants for COD and aromaticity were, respectively, 4.5 and 2.4 times higher that those corresponding to the ozonation of wash-waters without biological pretreatment. © 2000 Society of Chemical Industry

Continuous ozonation of polycyclic aromatic hydrocarbons in oil/water-emulsions and biodegradation of oxidation products

The continuous ozonation of polycyclic aromatic hydrocarbons (PAH) was studied in a two stage ozonation system followed by aerobic biological degradation. The highly condensed PAH benzo(e)pyrene and benzo(k)iluoranthene were oxidized selectively in synthetic oil/water-emulsions. The influence of the ozone mass transfer gas-liquid on the reaction rate of benzo(k)fluoranthcne was studied for process optimization. The dissolved ozone concentration is influenced by temperature to a higher degree than the reaction rate of PAH. In dependence on pH, PAH oxidation occurs by a direct reaction with ozone inside the oil droplets. Two main ozonation products of benzo(e)pyrene were quantified at different retention times during ozonation and their transformation could be shown in the biological treatment step.

Degradation efficiency and molecular size alteration during the aerobic microbial treatment of lignite pyrolysis deposit water.

Investigation into aerobic biological degradation were carried out as part of an extensive programme designed to facilitate the cheap remediation of a pyrolysis waste-water deposit. Attention was focused on the processes of carbon conversion by different populations. The susceptibility of a body of lignite-processing deposit water to microbiological degradation was examined in batch investigations in a Sapromat system and in continuous bench-scale fermenter cultivations, with respect to nutrient supply, inoculation culture and molecular size distribution. It was found that degradation best occurs with an adapted mixed culture. The autochthonous culture removes 30% less dissolved organic carbon (DOC) and has a 40% higher specific oxygen demand. A shortage of phosphorus, investigated with a view to avoiding additional eutrophication problems in the open water in the case of in situ remediation, causes reduced DOC degradation and significantly higher specific oxygen demand. The biological process is overlapped by abiotic oxidation. During aerobic treatment, a concentration of colour-giving aromatic substances of between 0.5 kDa and 5 kDa was observed. This phenomenon is caused by the oxidation of low- and high-molecular-mass compounds. The removal of DOC is limited to 65% and mainly occurs in the range below 0.5 kDa (30%) and in the 0.5-1 kDa range (12%); the removal is negligible in the ranges 1-3 kDa (0.8%) and 3-5 kDa (2%) and a little higher in the ranges 5 kDa-0.3 micron (5%) and above 0.3 micron (6%). In the investigations it was discovered that DOC removal causes in the ranges below 0.5 kDa, 0.5-1 kDa and 5 kDa-0.3 micron mainly as a result of degradation, but the range above 0.3 micron is chiefly caused by bioadsorption. Aerobic microbiological treatment is able to remove most low-molecular-mass substances. In order to remove the macromolecular and colour-giving part of the deposit water, an additional treatment stage, e.g. flocculation, is required.

Biodegradation kinetics of chlorinated aliphatic hydrocarbons with methane oxidizing bacteria in an aerobic fixed biofilm reactor

This paper describes the kinetics of aerobic biological degradation of chlorinated aliphatic hydrocarbons, specifically trichloroethene (TCE), 1,1,1-trichloroethane (TCA), cis-1,2-dichloroethene (c-1,2-DCE) and trans-1,2-dichloroethene (t-1,2-DCE). The kinetics were determined by using a completely mixed laboratory biofilm reactor seeded with methane-oxidizing (methanotrophic) bacteria originally obtained from an aquifer contaminated with chlorinated hydrocarbons. The contaminant degradation followed first order kinetics in the concentration range 0–1 mg/l. TCA was degraded with the same reaction rate as TCE. In other studies with methanotrophic bacteria TCA appear to be non-biodegradable. In general, the degradation of TCE, TCA and c-1,2-DCE was relatively slow at 20–24°C, whereas t-1,2-DCE was transformed relatively fast. The growth of methane oxidizing bacteria in the biofilm was studied. The biofilm thickness increased linearly for a constant loading of methane. The formation of c-1,2-DCE epoxide was presumably an intermediate from c-1,2-DCE degradation, and t-1,2-DCE epoxide was probably formed from t-1,2-DCE. This work indicates that in order to make the aerobic degradation of the chlorinated hydrocarbons practically feasible methods are required for increasing the biodegradation rate of TCE, TCA and c-1,2-DCE.

Aerobic two-stage biological degradation of organic carbon compounds and ammonium

In a two-stage pilot plant biological processes effect substantial degradation of organic carbon compounds and the ammonium contained in highly contaminated waste waters at extremely short mean residence time in the bioreactor. This achievement is mainly due to employment of a newly-developed type of bioreactor — the reciprocating jet bioreactor.