Aerobic Batch Research Articles

Method to estimate the required oxygen amount and aeration period for the completion of landfill aeration

To reliably predict field operation performance derived from lab-based tests, it is very important to observe and consider all the specific landfill-site properties. The purpose of this study was to suggest and discuss the availability of batch and lysimeter tests to estimate the oxygen amount and the aeration period. To achieve this purpose, a comparison between lab test (batch and lysimeter tests) and full-scale applications was conducted. This study showed that aerobic batch and lysimeter tests could be used to estimate the amount of oxygen (mg-O2/g-DM) required to bio-stabilize landfilled wastes within a short period of time. In addition, aeration periods necessary to reach the target value can be calculated by a first-order kinetic depending on moisture content. Therefore, this study suggests that when applying in situ aeration processes to field-scale landfills, the amount of aeration required to bio-stabilize landfilled wastes has to be determined by the aerobic batch test, and then the aeration period required to reach the target value can be calculated by a reliable monitoring of the oxygen concentration in a landfill site in combination with the first-order kinetic.

Mapping atrazine and phenol degradation genes in Pseudomonas sp. EGD-AKN5

Bacterial isolates with multi-substrate degradation capacities are good candidates for bioremediation of environmental niches. Lab isolate Pseudomonas sp. EGD-AKN5 was found to degrade atrazine, benzoate, phenol, toluene and catechol at the rate of 1.88±0.01, 16.5±1.37, 9.08±2.20, 3.86±0.11, and 3.3±0.29mgL−1h−1, respectively. Draft genome sequence analysis demonstrated the presence of the complete degradation pathway for atrazine and phenol. Gene annotation results indicated that atrazine was degraded via the chlorohydrolase route with atzA/B/C/D/E/F genes, while phenol was converted to catechol via a multicomponent phenol hydroxylase from the phc pathway. Genes from the ortho pathway were responsible for the further biodegradation of catechol; a result that was confirmed by enzyme assays. A model to describe the growth and biodegradation of atrazine, phenol and related compounds was applied and fit to a series of aerobic batch degradation experiments. Kinetic studies revealed that EGD-AKN5 showed potential to degrade both phenol and atrazine simultaneously using phenol as the carbon source and atrazine as nitrogen source. Gene expression studies indicated a longer lag phase for expression of genes from the atrazine degradation pathway, when compared to expression of phenol and catechol degradation.

Removal of Organics and Metal Ion Nanoparticles from Synthetic Wastewater by Activated Sludge Process (ASP)

Adsorption technique is widely used for removal of toxic organic contaminants from aqueous streams. Owing to the hazardous or otherwise undesirable characteristics of phenolic compounds in particular, their presence in wastewater from municipal and industrial discharge is one of the most important environmental issue. The discharge of poor quality effluents by the chemical-based laboratories and refineries in India is posing a serious threat to water sources and wastewater treatment installations alike. Our study was set up in the Indo-French Unit for Water and Wastewater Technologies (IFUWWT), IIT Delhi. The main objective of this study was to assess the efficiency of a laboratory-scale activated sludge treatment process in producing a final effluent conforming to regulatory standards of Central Pollution Control Board, India (CPCB norms) with regards to COD and metal ion loads. The study was conducted in three principal stages: characterization of wastewater containing nanoparticles; treatability studies of laboratory generated discards and investigations of heavy metal ions before and after treatment. The various raw effluent parameters analyzed were COD, BOD, F/M ratio, Sludge Value Index, Total Solids and concentrations of Cu, Ag and Zn. Studies were conducted using two aerobic Sequencing Batch Reactors (SBR). MLSS of the aeration basin was calculated to be 7180 ± 261.3 mg/L while the F/M ratio was kept down to 0.1560 ± .0149; besides, an SVI of 107.24 mL/g complied with the state of bioreactor’s sludge. These set of values suggested to set an extended aeration processes for the reactors. Accordingly, the detention time in aeration basin was 24 hours. The results showed over 98% influent COD reduction and nearly 100% removal of metal ions. The sample used was operated on sludge collected from Vasant Kunj Wastewater Treatment plant. Based on the results from waste characterization and treatability studies, it was decided that the mixed liquor discharged in the activation tank should have glucose solution and laboratory discarded sample in 1:1 ratio. The reactor was operated on a glucose fed batch basis for 30 days. For the sake of metal analysis, the digested water samples were analyzed for the presence of copper, silver and zinc using the Element AS AAS4141 atomic adsorption spectrophotometer (by Electronics Corporation of India Ltd). The Biosorption capacities were found to be over 95% in all the cases with the minimum correlation coefficient for calibration curve being 0.9811. Such a high sludge yield is suggestive of the fact that heavy metals are in very low concentrations in the considered carboy sample. Because of these insignificant values, the amount of metal ions introduced to the system gets adsorbed almost completely, hence leaving behind no metal ion within the supernatant. Well-treated wastewater has enormous potential as a source of water for crops, households and industry.

Lipid Production by <i>Rhodotorula glutinis</i> from Pulp and Paper Wastewater for Biodiesel Production

This study investigated the potential of oleaginous yeast Rhodotorula glutinis utilizing pulp and paper wastewater effluents as cultivation media for the sustainable production of microbial lipids as biodiesel feedstock. R. glutinis is oleaginous yeast, which has the ability to produce significant quantities of intercellular lipids in the form of triacylglycerols. Yeast lipids are a promising potential feedstock for biodiesel production due to similar fatty acid composition to plant oils. The effect of various carbon sources on biomass production, lipid accumulation, substrate utilization, and fatty acid composition using R. glutinis in the pulp and paper wastewater media was studied. The pulp and paper wastewater was supplemented with glucose, xylose, and glycerol as carbon sources under nitrogen-limited conditions. The maximum lipid productions of 1.3 - 2.9 g•L–1, which corresponded to the intracellular lipid contents of 8% - 15% cell dry weight (CDW), were obtained under various carbon substrates. A kinetic study of the batch fermentation was performed in a 3 L aerobic batch fermenter to describe the cell growth, lipid accumulation, and substrate utilization process, and the kinetic parameter was estimated. The fatty acid profile of oleaginous yeast was rich in palmitic, oleic, and linoleic acids and comparable to vegetable oils. Thus, the results of this study indicated that pulp and paper wastewater could be used to produce lipids as biodiesel feedstock.

Design, development and comparison of ethanol production from free and immobilizedsaccharomyces cerevisiaeunder stationary culture

Background: The aim of the present study is to design, develop and compare the production capacity and the difference in the yield of the ethanol by fermentation technology. The utility of the alcohol per annum is increasing day by day as the number of industries using ethanol as a solvent, pharmaceutical aid. Hence the production of ethanol by fermentation technology has triggered us to investigate the best way and method to produce ethanol of benefit of Pharmaceutical Industry. Method: The conventional method of production of alcohol was performed by aerobic batch type of fermentation: the yield was noted. The same production was performed by using immobilized yeast cells by gel entrapment technique. We produced ethanol by free and immobilized 'saccharomyces cerevisiae' under stationary culture. Cane molasses was used as a sugar source for about (12 - 21%), medium pH (4-5.5). incubation temperature (25 degreesc-30 degreesc), volume of fermentation medium (200 - 350ml) and reuse of immobilized yeast cells. Result: Rate of ethanol production was maximal with immobilized yeast cells. The results indicate that 2gm vegetative cells of yeast on utilizing molasses at 15% sugar concentration with medium pH 4.5 at 30oC. Conclusion: Hence we conclude that the fermentation optimization and the yield value of popular organic solvent (ethanol) was studied and reported. The specific gravity of the distillated alcohol by free and immobilized yeast cells were found to be 0.9730, 0.9705 at room temperature and the alcohol content was found to be 85%, 93.52% as per International Pharmacopeia respectively. To conclude the immobilized yeast cells were found to yield more ethanol than free yeast cells.

Aerobic Conversion of Glycerol to 2,3-Butanediol by a Novel Klebsiella variicola SRP3 Strain

The manufacture of biodiesel generates about 10% crude glycerol as a core by- product. This research is to identify novel bacterial strains which are capable of efficiently converting glycerol aerobically, and improve the strains for large scale production of value-added products. The production of a major product 2,3-butanediol (2,3- BD) from glycerol as a sole carbon source by the newly isolated Klebsiella variicola SRP3 are reported in a series of batch processes under aerobic condition. This study also compares the bacterial cell biomass, bio-products and glycerol dehydrogenase (GDH) enzyme production of K. variicola SRP3 isolated from paper mill waste when grown in aerobic condition. The incubation temperature, pH, glycerol concentration and nitrogen sources are the most important factors ruling the glycerol dehydrogenase. Acidic initial pH (pH 5.0) led to enhanced GDH activity (558.2 μmol/min/mg protein), yielding 25.33 g/L 2,3-BD, 7.6 g/L 1,3-PDO and 2.2 g/L acetoin from 50.0 g/L glycerol. In our aerobic batch culture the mutated strain K. variicola SRM3 exhibited 1.3 fold increased GDH activity of 721.5 units/mg protein from 558.2 units/mg protein, yielding 29.87 g/L 2,3-BD, 7.08 g/L 1,3-PDO and 2.02 g/L acetoin from 50.0 g/L glycerol. In our report, the optimal conditions for maximal GDH enzyme activity were defined, and 0.79 g/g product yield was achieved by the muted strain K. variicola SRM3, which is the highest amount obtained from glycerol as a sole carbon source until now. The research has for the first time proved that this K. variicola species can efficiently convert glycerol.

Biodegradation kinetics of tetrahydrofuran, benzene, toluene, and ethylbenzene as multi-substrate by Pseudomonas oleovorans DT4.

The biodegradation kinetics of tetrahydrofuran, benzene (B), toluene (T), and ethylbenzene (E) were systematically investigated individually and as mixtures by a series of aerobic batch degradation experiments initiated by Pseudomonas oleovorans DT4. The Andrews model parameters, e.g., maximum specific growth rates (μmax), half saturation, and substrate inhibition constant, were obtained from single-substrate experiments. The interaction parameters in the sum kinetics model (SKIP) were obtained from the dual substrates. The μmax value of 1.01 for tetrahydrofuran indicated that cell growth using tetrahydrofuran as carbon source was faster than the growth on B (μmax, B = 0.39) or T (μmax, T = 0.39). The interactions in the dual-substrate experiments, including genhancement, inhibition, and co-metabolism, in the mixtures of tetrahydrofuran with B or T or E were identified. The degradation of the four compounds existing simultaneously could be predicted by the combination of SKIP and co-metabolism models. This study is the first to quantify the interactions between tetrahydrofuran and BTE.

Application of a New Type of Dispersed Particles-Stabilized Biomass in Aerobic Sequencing Batch Reactor (SBR) for Treating Starchy Wastewater

In this study, we present the advance in the performance of a sequencing batch reactor (SBR) by adding rubber particles to grow a new type of dispersed particles-stabilized biomass. The moving beds were tiny particles of casting rubber with density of 1.15 ± 0.03 g · cm−3. A conventional SBR was used as control, to compare the results between moving-bed SBR (MB-SBR) and SBR, hence received no moving bed. It was found that MB-SBR had acceptable resistance against the phenomena that caused rapid changes in settlement properties in comparison with SBR. The results showed that by decreasing the hydraulic retention time, the performance of MB-SBR was not influenced considerably in comparison with SBR. The performance of MB-SBR was approximately 26% and 88% higher than that of SBR for influent chemical oxygen demand of 1000 and 2000 mg · L−1, respectively. Improved resistant against organic loading shocks was observed in MB-SBR.

Electricity generation from tetrathionate in microbial fuel cells by acidophiles

Inorganic sulfur compounds, such as tetrathionate, are often present in mining process and waste waters. The biodegradation of tetrathionate was studied under acidic conditions in aerobic batch cultivations and in anaerobic anodes of two-chamber flow-through microbial fuel cells (MFCs). All four cultures originating from biohydrometallurgical process waters from multimetal ore heap bioleaching oxidized tetrathionate aerobically at pH below 3 with sulfate as the main soluble metabolite. In addition, all cultures generated electricity from tetrathionate in MFCs at pH below 2.5 with ferric iron as the terminal cathodic electron acceptor. The maximum current and power densities during MFC operation and in the performance analysis were 79.6mAm−2 and 13.9mWm−2 and 433mAm−2 and 17.6mWm−2, respectively. However, the low coulombic efficiency (below 5%) indicates that most of the electrons were directed to other processes, such as aerobic oxidation of tetrathionate and unmeasured intermediates. The microbial community analysis revealed that the dominant species both in the anolyte and on the anode electrode surface of the MFCs were Acidithiobacillus spp. and Ferroplasma spp. This study provides a proof of concept that tetrathionate serves as electron donor for biological electricity production in the pH range of 1.2–2.5.

Mobilisation of arsenic from bauxite residue (red mud) affected soils: Effect of pH and redox conditions

The tailings dam breach at the Ajka alumina plant, western Hungary in 2010 introduced ∼1millionm3 of red mud suspension into the surrounding area. Red mud (fine fraction bauxite residue) has a characteristically alkaline pH and contains several potentially toxic elements, including arsenic. Aerobic and anaerobic batch experiments were prepared using soils from near Ajka in order to investigate the effects of red mud addition on soil biogeochemistry and arsenic mobility in soil–water experiments representative of land affected by the red mud spill. XAS analysis showed that As was present in the red mud as As(V) in the form of arsenate. The remobilisation of red mud associated arsenate was highly pH dependent and the addition of phosphate to red mud suspensions greatly enhanced As release to solution. In aerobic batch experiments, where red mud was mixed with soils, As release to solution was highly dependent on pH. Carbonation of these alkaline solutions by dissolution of atmospheric CO2 reduced pH, which resulted in a decrease of aqueous As concentrations over time. However, this did not result in complete removal of aqueous As in any of the experiments. Carbonation did not occur in anaerobic experiments and pH remained high. Aqueous As concentrations initially increased in all the anaerobic red mud amended experiments, and then remained relatively constant as the systems became more reducing, both XANES and HPLC–ICP-MS showed that no As reduction processes occurred and that only As(V) species were present. These experiments show that there is the potential for increased As mobility in soil–water systems affected by red mud addition under both aerobic and anaerobic conditions.

Removal performance of nitrogen and endocrine-disrupting pesticides simultaneously in the enhanced biofilm system for polluted source water pretreatment

The removal performances of nitrogen and trace levels of endocrine-disrupting pesticides (cypermethrin and chlorpyrifos) were studied in the enhanced biofilm pretreatment system at various substrates concentrations and dissolve oxygen (DO) niches. No significant change of EDPs removal occurred with the increased feed of ammonia nitrogen in aerobic batch tests or nitrate in anaerobic batch reactors, but significantly enhanced via reed addition both in aerobic and anaerobic conditions. Simultaneously enhanced denitrification and EDPs removal were achieved in the anoxic niche with reed addition. The results of denaturing gradient gel electrophoresis (DGGE) indicated that new bands appeared, and some bands became more intense with the reed addition. Sequences analysis showed that the dominant species belonged to Methylophilaceae, Hyphomicrobium, Bacillus and Thauera, which were related to the nitrogen or EDPs removals. In addition, the growth of functional heterotrophic microbes may be promoted via reed addition.

Fate and degradation kinetics of nonylphenol compounds in aerobic batch digesters

Nonylphenol (NP) compounds are toxic and persistent chemicals that are not fully degraded either in natural or engineered systems. Current knowledge indicates that these compounds concentrate in sewage sludge. Therefore, investigating the degradation patterns and types of metabolites formed during sludge treatment are important for land application of sewage sludge. Unfortunately, the information on the fate of nonylphenol compounds in sludge treatment is very limited. This study aims to investigate the biodegradation patterns of nonylphenol diethoxylate (NP2EO) in aerobic batch digesters. For this purpose, two NP2EO spiked and two control laboratory aerobic batch digesters were operated. The spiked digester contained 3 mg/L NP2EO in the whole reactor content. The compounds of interest (parent compound and expected metabolites) were extracted with sonication and analyzed by gas chromatography-mass spectrometry (GC–MS) as a function of time. Results showed that, following the day of spike, NP2EO degraded rapidly. The metabolites observed were nonylphenol monoethoxylate (NP1EO), NP and dominantly, nonylphenoxy acetic acid (NP1EC). The mass balance over the reactors indicated that the total mass spiked was highly accounted for by the products analyzed. The time dependent analysis indicated that the parent compound degradation and daughter product formation followed first order kinetics. The digester performance parameters analyzed (VS and COD reduction) indicated that the spike of NP2EO did not affect the digester performance.

Selection and characterization of indigenous hydrocarbon-degrading bacteria from tourist ports in the Mediterranean Sea Basin

Pollution by petroleum hydrocarbons is one of the major environmental problems in ports and it is mainly associated with ship/boat traffic and related facilities. Ports are not closed systems and their pollution may impact adjacent coastal areas. Hydrocarbon degraders and particularly the obligate hydrocarbonoclastic bacteria carry out a fundamental and global activity in biological removal of hydrocarbons in marine habitats. This studywas carried out withinMAPMED, amultidisciplinary project aimed to improve the environmental sustainability of tourist ports in the Mediterranean Sea with regard to monitoring and reduction of hydrocarbon pollution. Three tourist ports were selected as case study sites: Cagliari (Italy), El Kantaoui (Tunisia), and Heraklion (Greece). The degradation potential of the autochthonous bacterial communities was evaluated enumerating heterotrophs and hydrocarbon degraders by MPN in the surface seawater. Heterotrophs were significantly more abundant in seawater from Cagliari port as compared to El Kantaoui and Heraklion ports. On the contrary, higher viable titles of dieseland phenanthrene-degraders were found in seawater from El Kantaoui port compared to the other two areas. Hydrocarbon-degrading bacteria were isolated and characterized regarding their phylogenetic position and catabolic abilities. The hydrocarbon degradation activities were evaluated by GC-MS in aerobic batch reactors on diesel as carbon source. The majority of degraders from Cagliari were assigned to Pseudomonas whereas strains from El Kantaoui and Heraklion were assigned to Alcanivorax and Marinobacter. The selection of the most appropriate methodologies for the eco-efficient remediation of petroleum-hydrocarbon contamination of selected sites is currently in progress.

Effect of C/N ratio on extracellular polymeric substances of activated sludge from an anoxic–aerobic sequencing batch reactor treating saline wastewater

The effect of C/N ratio on extracellular polymeric substances (EPS) of activated sludge was investigated in an anoxic–aerobic sequencing batch reactor (SBR) treating saline wastewater. The protein (PN) and protein/polysaccharide (PN/PS) ratio in the loosely bound EPS (LB-EPS) increased with the decrease of C/N ratio, whereas the PS in the LB-EPS decreased. The PS, PN and PN/PS ratio in the tightly bound EPS (TB-EPS) were independent of C/N ratio. Two fluorescence peaks in the LB-EPS and TB-EPS were identified at excitation/emission (Ex/Em) wavelengths of 275–280/335–340 nm and 220–225/330–340 nm by three-dimensional excitation–emission matrix (3D-EEM) fluorescence spectroscopy, respectively. These peaks in LB-EPS and TB-EPS were, respectively, associated with tryptophan protein-like substances and aromatic protein-like substances. The tryptophan protein-like fluorescence peaks in LB-EPS showed blue shift along the Ex axis and red shift along the Em axis with the decrease of C/N ratio. Fourier transform infrared spectra suggested that the variation of C/N ratio had more distinct effect on the functional groups of protein in the LB-EPS than those in the TB-EPS. The sludge volume index value decreased with the increase of LB-EPS, but there was no correlation between SVI and TB-EPS.

Optimization of the production of extracellular α-amylase by Kluyveromyces marxianus IF0 0288 by response surface methodology

The aim of this work was to study the production of extracellular α-amylase by Kluyveromyces marxianus IF0 0288 using optimized nutritional and cultural conditions in a complex yeast medium under aerobic batch fermentation. By applying the conventional "one-variable-at-a-time" approach and the response surface methodology, the effect of four fermentation parameters (type of carbon source, initial culture pH, temperature, and incubation time) on the growth and α-amylase production was evaluated. The production of α-amylase during 60 h of fermentation increased 13-fold under optimized conditions (1% starch, pH 6.0, 30ºC) in comparison to the conventional optimization method. The initial pH value of 6.13 and temperature of 30.3ºC were optimal conditions by the response surface methodology, leading to further improvement (up to 13-fold) in the production of extracellular α-amylase. These results constituted first evidence that K. marxianus could be potentially used as an effective source of extracellular α-amylase.

Central treatment of different emulsion wastewaters by an integrated process of physicochemically enhanced ultrafiltration and anaerobic–aerobic biofilm reactor

The feasibility of an integrated process of ultrafiltration (UF) enhanced by combined chemical emulsion breaking with vibratory shear and anaerobic/aerobic biofilm reactor for central treatment of different emulsion wastewaters was investigated. Firstly, it was found that calcium chloride exhibited better performance in oil removal than other inorganic salts. Chemical demulsification pretreatment could efficiently improve oil removal and membrane filtration in emulsion wastewater treatment by VSEP. According to aerobic batch bioassay, UF permeate exhibited good biodegradability and could be further treated with biological process. Additionally, pilot test indicated that anaerobic-aerobic biofilm exhibited an excellent ability against rise in organic loading and overall chemical oxygen demand (COD) removal efficiency of biological system was more than 93% of which 82% corresponded to the anaerobic process and 11% to the aerobic degradation. The final effluent of integrated process could meet the "water quality standards for discharge to municipal sewers" in China.

Transformation of Biocides Irgarol and Terbutryn in the Biological Wastewater Treatment

The biocides irgarol and terbutryn enter the wastewater treatment plant (WWTP) via combined sewer systems after leaching from coatings and paints of materials. In this study, the biotransformation of irgarol and terbutryn was examined in aerobic batch experiments with activated sludge taken from the nitrification zone of a conventional WWTP, since currently there is no information about the fate of irgarol and terbutryn in biological wastewater treatment. Both, irgarol and terbutryn were transformed into one main transformation product (TP) following pseudo first-order kinetics. The TPs were tentatively identified by high-resolution mass spectrometry (HR-MS) to be irgarol sulfoxide and terbutryn sulfoxide. The final confirmation of the proposed chemical structures of the TPs was achieved by a comparison of mass spectra and nuclear magnetic resonance (NMR) spectra with those of authentic reference standards (e.g., synthesized). An analytical method for the sensitive quantification of irgarol, terbutryn and their TPs in environmental samples was developed based on solid phase extraction (SPE) and LC tandem MS detection. Irgarol sulfoxide and terbutryn sulfoxide were detected in the effluents (average concentrations up to 22 ng L(-1) and 65 ng L(-1)) of all four investigated WWTPs as well as in streams and small rivers (up to 14 ng L(-1) and 34 ng L(-1)). Luminescent bacteria inhibition test with Vibrio fischeri exhibited that the TPs irgarol sulfoxide and terbutryn sulfoxide feature a similar bacterial toxicity than the parent compounds.

Balance de Flujos Metabólicos en Saccharomyces cerevisiae basado en Compartimentalización Intracelular

Flux Balance Analysis - FBA - is one of the most used techniques in prediction of microorganism bioproducts. It requires an objective function that represents biological objective of the studied microorganism. This paper presents a new kind of objective functions based on individual physical compartment objetives in the studied microorganism. These kind of functions was tested with a stoichiometric model extracted from iMM904 reconstruction of S. cerevisiae and its performance is compared with the most used objective function in literature, growth maximization, in anaerobic and aerobic batch conditions. The presented objective function outperform growth predictions in 10% and ethanol predictions in 75% compared with obtained by maximization of growth objective function, in anaerobic conditions. In aerobic batch conditions the presented objective function outperforms in 98% growth preditions and 70% ethanol predictions compared with growth maximization.

Biodegradation kinetics of Bi-substrate solution of phenol and resorcinol in an aerobic batch reactor

Phenol and resorcinol compounds are found to co-exist in real-life wastewater, especially in petrochemical, coking and coke-oven wastewater. An indigenous mixed microbial culture isolated from effluent treatment plant of a coke oven industry has been employed to investigate for its biodegradation capacity of bi-solute mixture of phenol and resorcinol under aerobic batch reactor operation. A 22 full factorial design with the two substrates at two different levels of initial concentration ranges (high and low) was explored to design the biodegradation experiments. The effect of individual substrate concentrations and their interaction on rate of phenolics biodegradation were also determined. The phenol and resorcinol as substrates were completely utilized after 22 hrs when the solutes are present at low concentrations of 100 mg/L each. But the culture has taken total 58 hrs to biodegrade completely higher initial concentrations i.e., 400 mg/L of each substrate. This study also observed that both specific growth rate of the culture and the specific substrate degradation rate have descended to lower value in presence of phenol and resorcinol as dual substrate in the solution compared to their presence as single substrate, showing the interaction and inhibition by each substrate. Sum kinetic model was used to describe the variation in the specific substrate degradation rates by the mixed culture. From the interaction parameters obtained from this model, it has been observed that resorcinol inhibits specific substrate degradation rate to a higher extent than inhibition caused by phenol (IResorcinol, Phenol = 0.5, IPhenol, Resorcinol = 0.1, RMSE = 0.04361)

Study on biodegradability of terephthalic acid in polyester fabric alkali-peeling process wastewater

Terephthalic acid (TA) and ethylene glycol (EG) are the main pollutants in polyester fabric alkali-peeling process wastewater (PAP-wastewater). The biodegradability of TA is crucial to the deep treatment of PAP-wastewater. Batch and continuous experiments were adopted to study the biodegradation of TA in synthetic wastewater. In anoxic batch experiments TA began to degrade gradually after EG was depleted completely. However, in aerobic batch experiments the biodegradation curves of TA in the presence of EG were almost identical to those of TA in the absence of EG. The combined process of anoxic hydrolysis-acidification bioreactor (HABR) and aerobic hybrid membrane bioreactor (HMBR) was employed to treat synthetic PAP-wastewater in continuous experiments. When TA was fed as sole substrate, about 6.1% was removed in the anoxic HABR and 92.1% was biodegraded in the aerobic HMBR. When TA and EG were fed as substrate, only 1.9% of TA was biodegraded in the anoxic HABR and 96.6% of TA was removed in the aerobic HMBR. By contrast, most EG was removed in the anoxic HABR. The experimental results revealed that the combined process of anoxic HABR and aerobic HMBR was an attractive alternative for the treatment of PAP-wastewater and other similar wastewater.