Biological Oxidation Process Research Articles

Remediation of polluted river water by biological contact oxidation process using two types of carriers

Biological contact oxidation technology was used to remediate the polluted river water in Hanyang, China. The purification effect of the polluted river water in three simulated rivers was investigated using two different carriers, i.e., AquaMats made in USA and semi flexible supports made in China. The results showed that when the hydraulic loading rate increased, purification effect in terms of CODMn decreased. Moreover, the removal efficiency of total nitrogen (TN) increased when AquaMats support was used, however it decreased when semi flexible support was used, in comparison with the control experiment. The removal ability of total phosphorus (TP) was strengthened by using different carriers.

Investigation on laboratory and pilot-scale airlift sulfide oxidation reactor under varying sulfide loading rate

Airlift bioreactor was established for recovering sulfur from synthetic sulfide wastewater under controlled dissolved oxygen condition. The maximum recovered sulfur was 14.49 g/day when sulfide loading rate, dissolved oxygen (DO) and pH values were 2.97 kgHS−/m3-day, 0.2–1.0 mg/L and 7.2–7.8, respectively. On the other hand, the increase in recovered sulfur reduced the contact surface of sulfide oxidizing bacteria which affects the recovery process. This effect caused to reduce the conversion of sulfide to sulfur. More recovered sulfur was produced at high sulfide loading rate due to the change of metabolic pathway of sulfide-oxidizing bacteria which prevented the toxicity of sulfide in the culture. The maximum activity in this system was recorded to be about 3.28 kgS/kgVSS-day. The recovered sulfur contained organic compounds which were confirmed by the results from XRD and CHN analyzer. Afterwards, by annealing the recovered sulfur at 120°C for 24 hrs under ambient Argon, the percentage of carbon reduced from 4.44% to 0.30%. Furthermore, the percentage of nitrogen and hydrogen decreased from 0.79% and 0.48% to 0.00% and 0.14%, respectively. This result showed the success in increasing the purity of recovered sulfur by using the annealing technique. The pilot-scale biological sulfide oxidation process was carried out using real wastewater from Thai Rayon Industry in Thailand. The airlift reactor successfully removed sulfide more than 90% of the influent sulfide at DO concentration of less than 0.1 mg/L, whereas the elementary sulfur production was 2.37 kgS/m3-day at sulfide loading rate of 2.14 kgHS−/m3-day. The sulfur production was still increasing as the reactor had not yet reached its maximum sulfide loading rate.

A unified model of ammonium oxidation rate at various initial ammonium strength and active ammonium oxidizer concentrations

This paper attempts to provide insight into the biological ammonium oxidation process applied to high-strength ammonium wastewater treatment. The ammonium oxidation process has been investigated at various ammonium and biomass concentrations. Using the oxygen uptake rate (OUR) method, a proportion of both active ammonium oxidizers (AAO) and nitrite oxidizers to the total suspended solids were separately estimated, and then tested to normalize the ammonium oxidation rate at various ammonium strengths and AAO concentrations. High-ammonium strength showed no significant inhibition to ammonium oxidation due to high-AAO concentration. It was demonstrated that the key factor deciding the specific ammonium oxidation rate was the ratio of ammonium concentration to the active nitrifiers (AN) concentration, but not the sole-variable such as initial ammonium concentration and AN concentration. Contois model was screened to suitably fit the ammonium oxidation kinetics under the high-ammonium loading condition, resulting in a half-saturation constant of 0.028 mg N mg −1 AAO and a maximum specific ammonium oxidation rate of 3.56 g N g −1 AAO d −1.

Theoretical study of the hydroxylation of phenols mediated by an end-on bound superoxo–copper(II) complex

Peptidylglycine alpha-amidating monooxygenase and dopamine beta-monooxygenase are copper-containing proteins which catalyze essential hydroxylation reactions in biological systems. There are several possible mechanisms for the reductive O(2)-activation at their mononuclear copper active site. Recently, Karlin and coworkers reported on the reactivity of a copper(II)-superoxo complex which is capable of inducing the hydroxylation of phenols with incorporated oxygen atoms derived from the Cu(II)-O(2) (.-) moiety. In the present work the reaction mechanism for the abovementioned superoxo complex with phenols is studied. The pathways found are analyzed with the aim of providing some insight into the nature of the chemical and biological copper-promoted oxidative processes with 1:1 Cu(I)/O(2)-derived species.

Biodegradability of DOC and DON for UV/H 2O 2 pre-treated melanoidin based wastewater

The aim of this study was to determine if preliminary treatment of melanoidin based wastewater by an advanced oxidation process (AOP) made the associated DOC and DON more biodegradable. UV-C irradiation of H 2O 2 was used to create the hydroxyl radical for chemical oxidation, while aerobic batch bioassays were used to assess the subsequent biodegradability of the DOC and DON associated with melanoidin. State-of-the-art natural organic matter identification techniques were used to identify melanoidin and study the subsequent degradation products throughout the chemical and biological oxidation processes. Melanoidins are large (50–70 kDa), coloured, nitrogenous organic compounds that are refractory to sewage treatment plant (STP) biodegradation, but are susceptible to degradation by sunlight in receiving environments. This study showed that over an extended chemical oxidation period (72 h, which was sufficient to reach maximum chemical degradability) DOC and DON removal from a synthetic melanoidin wastewater were 92% and 48%, respectively. In comparison, the DOC and DON removal after 4 h of chemical oxidation followed by 7 days of aerobic biodegradation were 82% and 86%, respectively. Thus, the removal of organic bound nitrogen was drastically improved by using a combination of chemical and biological oxidation in place of the hydroxyl radical AOP alone. Molecular weight fractionation results showed that the cleavage of the large nitrogenous melanoidin molecules, during chemical oxidation, produced small DON molecular weight compounds (<1 kDa) and ammonia, which were readily biodegradable. It was apparent that the small molecular weight DOC formed during the hydroxyl radical oxidation of melanoidin was biodegradable, but unlike the DON could also be chemically oxidised given sufficient exposure time to the hydroxyl radical.

Helmut Beinert (1913–2007)

Helmut Beinert (1913–2007)

Aerobic Bio-oxidation with Ozonation for Recalcitrant Wastewater Treatment

AbstractThe aim of the present research was to find a combination of biological and chemical oxidation processes that improves the purification efficiency of recalcitrant wastewater treatment at reduced ozone consumption. The following wastewater treatment processes were experimentally studied: conventional aerobic biooxidation, post-ozonation of biologically treated wastewater, a combined process - aerobic bio-oxidation with ozonation in a re-circulation system - and aerobic bio-oxidation with direct introduction of ozone-containing water into a bioreactor. A synthetic landfill leachate corresponding in its composition to leachate of young landfills, thermo-mechanical pulping water, and phenolic effluent from the Estonian oil shale industry were used as wastewaters. It was established that compared with conventional aerobic bio-oxidation, the combined process enables an improvement in purification efficiency even at relatively low ozone doses (10 to 60 mgO

The Last Month of Szent-Györgyi in Groningen

Albert (von) Szent-Gyorgyi started his studies on biological oxidation processes – which also resulted in the discovery of vitamin C, for which he received the Nobel Price in 1937 – in the Laboratory of Physiology of the University in Groningen in 1922–1926. These studies were later continued in Cambridge (UK) and Szeged (Hungary). When he had already received the invitation as well as the financial means to come and work in Cambridge, he still did experiments in Groningen to find out whether the adrenal extract, isolated by him and later found to be a major source of vitamin C, contained the hormone essential for the survival of cats whose adrenals were removed. He was rather upset by the negative results of this experiment, judging by the recollections of a former student of his. This history constitutes an interesting example of the difference between serendipitous discovery and planned invention.

Phylogenetic distribution of catalase-peroxidases: Are there patches of order in chaos?

Hydrogen peroxide features in many biological oxidative processes and must be continuously degraded enzymatically either via a catalatic or a peroxidatic mechanism. For this purpose ancestral bacteria evolved a battery of different heme and non-heme enzymes, among which heme-containing catalase-peroxidases (CP) are one of the most widespread representatives. They are unique since they can follow both H 2O 2-degrading mechanisms, the catalase activity being clearly dominant. With the fast increasing amount of genomic data available, we were able to perform an extensive search for CP and found almost 300 sequences covering a large range of microorganisms. Most of them were encoded by bacterial genomes, but we could also find some in eukaryotic organisms other than fungi, which has never been shown until now. Our screen also reveals that approximately 60% of the bacteria do not possess CP genes. Chaotic distribution among species and incongruous phylogenetic reconstruction indicated existence of numerous lateral gene transfers in addition to duplication events and regular speciation. The results obtained show an impressively complex gene transmission pattern, and give some new insights about the role of CP and the origin of life on earth. Finally, we propose for the first time bacterial candidates that may have participated in the transfer of CP from bacteria to eukaryotes.

Peroxy‐Radical‐Mediated Chemiluminescence: Mechanistic Diversity and Fundamentals for Antioxidant Assay

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Quantum chemical simulation of cytochrome P450 catalyzed aromatic oxidation: Metabolism, toxicity, and biodegradation of benzene derivatives

AbstractThe dependences of biological oxidation and toxicity of the mono‐ and multi‐substituted benzene derivatives on the nature of substituents are studied using an oxenoid model and the quantum chemical calculations. According to this model, the P450 enzyme breaks the dioxygen molecules and generates the active atomic oxygen species (oxens); these species readily react with substrates. Using MO LCAO MNDO approach, we calculated the differences ΔE of the total energies of aromatic compounds and corresponding arene oxides containing tetrahedrally coordinated carbon atoms. We obtained that the ΔE values determine the positions of the enzyme mediated oxidation, rate of substrate biotransformation, and toxicity of the benzene derivatives. In addition to the “dynamic” reactivity index ΔE related to the enzyme‐mediated substrate biotransformation, we calculated many standard “static” reactivity indices, corresponding to the substrate molecules in the starting equilibrium geometry (the energies of the occupied and unoccupied MOs, the effective atomic charges, the free valence indices, and the superdelocalizabilities). The arene oxide stability ΔE parameter is shown to be the most adequate characteristic of both the biological oxidation process and toxicity of benzenes. The ΔE parameters were also used successfully to describe the features of di‐ and tri‐chlorinated biphenyls bacterial metabolism. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007

Peroxy-radical-mediated chemiluminescence: mechanistic diversity and fundamentals for antioxidant assay

Herein, we give a retrospective overview and analyze recent developments in the field of chemiluminescence derived from organic oxidation processes (so called oxychemiluminescence), most prominently, mediated by peroxy radicals. As evidenced from the presented analysis, the diversities of the reaction and the excited-state-generation mechanisms are governed mainly by a diverse chemical nature of substrates being oxidized. The notable oxychemiluminescence cases, which involve peroxy radicals as key reactive species, refer to oxidation of saturated and unsaturated hydrocarbons, polymers, lipids and proteins. The general feature of the considered chemiluminescence processes pertains to a formation of high-energy cyclic intermediates (tetroxides and/or dioxetanes), whose cleavage yields electronically excited products. The considered modes of the chemiluminescence enhancement encompass the energytransfer and the electron-transfer mechanisms. Most prominent application of the discussed oxychemiluminescence phenomenon resides in a versatile chemiluminescent assay to monitor antioxidants (both their concentration and reactivity) in chemical and biological media.

Treatment of High H2S Concentrations by Chemical Absorption and Biological Oxidation Process

The feasibility of a chemical absorption and a biological oxidation process to remove high H2S concentrations (500–1500 ppm) was evaluated. The experiment included the effects of gas retention time (GRT) and H2S concentration on H2S removal efficiency, Fe3+ oxidation rate, and Fe2+ production rate in the chemical absorption reactor. The effects of carbon source and liquid flow rate on pH value, Fe2+ oxidation rate, Fe3+ production rate, total iron concentration, and growth of Thiobacillus ferrooxidans CP9 in the biological oxidation reactor were also examined. The optimal operating conditions for the individual process and design guidelines for the serial processes were established. The results of this study indicated that a long GRT could elevate H2S removal efficiency under all operating conditions. However, a high H2S concentration (e.g., 1,500 ppm) resulted in a significant difference. H2S removal efficiency stayed above 99.5% for the first 10 h of reaction, but it then decreased because of the decrea...

The effect of chemical oxidation on the biological sulfide oxidation by an alkaliphilic sulfoxidizing bacterial consortium

Higher solubility at alkaline conditions is very significant for an efficient treatment process of gaseous H 2S (g) by reducing the gas–liquid transfer limitations. Nevertheless, the alkaline biodegradation process of H 2S can be limited when sulfide concentrations are inhibitory. At alkaline conditions (pH > 9), the abiotic chemical sulfide oxidation can attain relatively high rates. A series of abiotic and biotic kinetic experiments of oxygen consumption were performed at pH 10. For the biological oxidation, an alkaliphilic sulfide oxidizing consortium (ASBC) isolated from a soda lake was used. The intermediates from the chemical sulfide oxidation in alkaline and aerobic conditions did not inhibit the activity of ASBC at six-fold concentration of that where H 2S inhibition was detected (1.19 mM). Stoichiometries and kinetic expressions for the chemical sulfide oxidation to pentasulfide (S 5 2−) and its further oxidation to thiosulfate (S 2O 3 2−) are proposed and validated with experimental data. The faster oxic chemical sulfide oxidation under alkaline conditions could be advantageous for the biological oxidation to sulfate by reducing the concentration of the inhibiting sulfide. These results suggest that the chemical and the biological oxidation processes can be segregated, allowing higher sulfide loading rates.

Acidophilic microbial communities catalyzing sludge bioleaching monitored by fluorescent in situ hybridization

Biological autotrophic sulfur oxidation processes have been proposed to remove heavy metals from wastewater treatment sludge by bioleaching. We made a characterization of the microbial population in batch and continuous sludge bioleaching reactors using fluorescent in situ hybridization of fluorescently-labeled oligonucleotidic probes targeting rRNA in a 'top to bottom approach'. Batch incubations of sludge with 0.2% (w/v) elemental sulfur resulted in a pH value of 5. Alpha-Proteobacteria hybridizing with probe ALF1b were dominant in this incubation. Members of the Acidophilium-group (hybridizing with probe Acdp821) of Nitrospira/Leptospirillum phylum (Ntspa712 probe) and from the archaeal domain (ARCH915) were also detected. When sludge was incubated with 1% elemental sulfur in batch or continuous reactor experiments, final pH values were always below 2. Active microbial communities consisted almost exclusively of gamma-Proteobacteria (hybridizing with probe GAM42a). However, further hybridization experiments with probe Thio820 targeting Acidithiobacillus ferroxidans and Acidithiobacillus thioxidans gave negative results. A new probe, named THIO181, encompassing all known members of the genus was designed. Hybridization perfomed with THIO181 and GAM42a showed a perfect co-localization of the hybridization signals. Further hybridization experiments with probe THIO181 and THC642, specific for the species Acidithiobacillus caldus, confirmed that this bacteria was largely responsible for the sulfur oxidation reaction in our acidophilic sludge bioleaching reactors.

A new bacterial strain mediating As oxidation in the Fe-rich biofilm naturally growing in a groundwater Fe treatment pilot unit

A bacterial strain B2 that oxidizes arsenite into arsenate was isolated from the biofilm growing in a biological groundwater treatment process used for Fe removal. This strain is phylogenetically and morphologically different from the genus Leptothrix commonly encountered in biological iron oxidation processes. T-RFLP fingerprint of the biofilm revealed that this isolated strain B2 corresponds to the major population of the bacterial community in the biofilm. Therefore, it is probably one of the major contributors to arsenic removal in the treatment process.

A Method to Estimate Practical Radial Oxygen Loss of Wetland Plant Roots

The estimation of practical radial oxygen loss (ROL) of wetland plant roots was attempted in this study. We have devised a new method to measure ROL of wetland plant roots. The whole root system was bathed in an anoxic nutrient solution. Oxygen released from the root was removed immediately by introducing oxygen-free nitrogen gas (O2 < 4 nmol L−1) to mimic natural habitats where released oxygen is consumed rapidly due to chemical and biological oxidation processes. Oxygen removed from the root-bathing chamber was simultaneously detected colorimetrically by use of the highly oxygen-sensitive anthraquinone radical anion (AQ·−) in a cell outside the root-bathing chamber, which decolorized by a rapid reaction with oxygen. An emergent macrophyte Typha latifolia L. was incubated, and its ROL was measured by both the new method and one of the conventional methods, the closed chamber/electrode method, by which the ROL of Typha latifolia L. had not yet been measured. The new method succeeded in detecting the ROL, whereas the conventional method was not able to detect oxygen, due to the level being below the detection limit of the oxygen electrode. The oxygen supply via the seedlings of Typha latifolia L. was ca. 10 times higher compared with control measurements without plant. Light illumination significantly enhanced the ROL of Typha latifolia L. (0.33 nmol O2 g−1 root dry weight s−1 under light and 0.18 nmol O2 g−1 root dry weight s−1 in the dark). Theses values fall between those previously reported by the closed chamber/titanium citrate method and the open chamber/electrode method.

Enhanced Biodegradation of Azo Dyes Using an Integrated Elemental Iron‐Activated Sludge System: II. Effects of Physical–Chemical Parameters

As part of a study to evaluate an integrated zero-valent iron (Fe(0))-biological oxidation process for treating azo dye wastewaters, we conducted batch and column experiments with the azo dye orange G to assess the effects of solution conditions on the performance of iron pretreatment. The influence of iron type and surface area, solution pH, dissolved inorganic salts, and phosphate ion on the reduction (decolorization) of orange G solution were examined. In batch experiments, increased iron surface area, decreased pH, and chloride and sulfate salts enhanced dye decolorization, whereas high pH (9.9) and phosphate concentrations (> 3 mg/L PO4-P) inhibited dye reduction. Results from batch experiments were confirmed in column experiments. An increase in temperature from 22 to 35 degrees C resulted in a near doubling of the reduction rate constant in a column study. The abiotic reduction results illustrate the feasibility and potential limitations of an integrated iron column, activated sludge treatment process for wastewaters containing azo dyes.

Highly sensitive fluorimetic determination of gluthione based inhibitory effect on multienzyme redox system

A highly sensitive spectrofluorimetric method for the determination of reduced glutathione (GSH,γ- l-glutamyl- l-cysteinylglycine) based on its inhibitory effect on hemoglobin activity was developed. Multienzyme redox system is the most important biological oxidation process in cellular respiration chain. Under the action of hemoglobin, NADH can be oxidized by hydrogen peroxide (H 2O 2) to form a dimmer that is optimally fluorescent. Under the optimum conditions, the degree of inhibitory effect was linear to the GSH concentration in the range of 5.00 × 10 −8 to 9.60 × 10 −6 mol l −1. The relative standard deviation was 3.70% for 11 determinations of 5.00 × 10 −6 mol l −1 GSH and the detection limit was 8.00 × 10 −9 mol l −1. Further experimental results revealed that the inhibition of GSH on this system was of the competitive type.

A review of ammonium attenuation in soil and groundwater

Ammonium attenuation in subsoils and groundwater is predominantly due to cation exchange and/or nitrification (biological oxidation) processes. These processes have been little studied in UK formations and this relative lack of information can result in reduced consistency and robustness in the assessment of risks posed by ammonium contamination arising from landfills, effluent soakaways, contaminated sites and other sources. A review of ammonium fate and transport in the subsurface has been completed and guidance developed on the key processes that contribute to attenuation. The amount of relevant literature is small but sufficient to provide indicative ranges of partition coefficients and biological nitrification rates for ammonium in UK subsoils and aquifers. Ammonium attenuation was found to be highly sensitive to the clay mineralogy and pore size of the strata, the availability of oxygen and the chemical composition of the contaminated fluid. The values derived may have application in the initial (screening) phases of risk assessment where the conceptual model for the site under consideration matches that from which the presented data originate.