Effect of Biofuels on Biodegradation of Benzene and Toluene at Gasoline Spill Sites

The risk that benzene and toluene from spills of gasoline will impact drinking water wells is largely controlled by the natural anaerobic biodegradation of benzene and toluene. Benzene and toluene, as well as ethanol and other biofuels, are degraded under anaerobic conditions to the same pool of degradation products. Biodegradation of biofuels may produce concentrations of degradation products that make the thermodynamics for degradation of benzene and toluene infeasible under methanogenic conditions and produce larger plumes of benzene and toluene. This study evaluated the concentrations of fuel alcohols that are necessary to inhibit the anaerobic degradation of benzene and toluene under methanogenic conditions. At two ethanol spill sites, concentrations of ethanol greater ≥42 mg/L inhibited the anaerobic degradation of toluene. The pH and concentrations of acetate, dissolved inorganic carbon, and molecular hydrogen were used to calculate the Gibbs free energy for the biodegradation of toluene. In general, the anaerobic biodegradation of toluene was not thermodynamically feasible in water with ≥42 mg/L ethanol. In a microcosm study, when the concentrations of ethanol were ≥14 mg/L or the concentrations of n‐butanol were ≥16 mg/L, the biodegradation of the alcohols consistently produced concentrations of hydrogen, dissolved inorganic carbon, and acetate that would preclude natural anaerobic biodegradation of benzene and toluene by syntrophic organisms. In contrast, iso‐butanol and n‐propanol only occasionally produced conditions that would preclude the biodegradation of benzene and toluene.     

Natural Attenuation of Aromatic Hydrocarbons in a Shallow Sand Aquifer

Inadvertent release of petroleum products such as gasoline into the subsurface can initiate ground water contamination, particularly by the toxic, water-soluble and mobile gasoline components: benzene, toluene and xylenes (BTX). This study was undertaken to examine the processes controlling the rate of movement and the persistence of dissolved BTX in ground water in a shallow, unconfined sand aquifer.
Water containing about 7.6 mg/ L total BTX was introduced below the water table and the migration of contaminants through a sandy aquifer was monitored using a dense sampling network. BTX components migrated slightly slower than the ground water due to sorptive retardation. Essentially all the injected mass of BTX was lost within 434 days due to biodegradation. Rates of mass loss were similar for all monoaromatics; benzene was the only component to persist beyond 270 days. Laboratory biodegradation experiments produced similar rates, even when the initial BTX concentration varied.
A dominant control over BTX biodegradation was the availability of dissolved oxygen. BTX persisted at the field site in layers low in dissolved oxygen. Decreasing mass loss rates over time observed in the field experiment are not likely due to first-order deeradation rates, but rather to the persistence of small fractions of BTX mass in anoxic layers.     

Generation of Power by Microbial Fuel Cell with Ferricyanide in Biodegradation of Benzene

The power generation potential of a microbial fuel cell (MFC) during the process of benzene biodegradation with potassium ferricyanide (0–200 mM) as the terminal electron acceptor was evaluated. Experimental results demonstrate that benzene was used as the sole carbon source in generating electricity by a mixed culture. The power density increased from 0.0276 to 2.1 mW m^?2 as the concentration of potassium ferricyanide in the cathode chamber was increased from 0 to 200 mM. With a benzene concentration of 10.87 mg L^?1 and a potassium ferricyanide concentration of between 0 and 150 mM, complete degradation of benzene was achieved in 22–24.5 h. However, when the concentration of potassium ferricyanide was raised to 200 mM, the time required for complete benzene degradation was prolonged to 35 h. The results of this investigation can be used as a basis for future assessments of the power generation capacity of MFCs that are used to treat benzene‐contaminated wastewater.     

Sulfate Land Application Enhances Biodegradation in a Petroleum Hydrocarbon Smear Zone

Delivery of sulfate to petroleum hydrocarbons (PHCs) source zones and groundwater plumes is desirable to enhance biodegradation rates when treatment has become limited due to depletion of sulfate. Sulfate land application involves spreading sulfate salts on ground surface and allowing their dissolution and infiltration of sulfate into subsurface. The objectives of this pilot-scale investigation were to capture the vertical transport of sulfate beneath an application area, confirm that sulfate reduction was occurring, and explore how the added sulfate affected biodegradation of benzene and toluene. Approximately 4000 kg of gypsum was spread over a 30 m × 30 m study area above a smear zone located approximately 2 m below-ground surface. Precipitation was augmented by two irrigation events. Groundwater samples, collected over 1058 days from multilevel wells and a conventional long-screened monitoring well, were analyzed for benzene, toluene, ethylbenzene, and xylenes (BTEX), sulfate, bromide, dissolved inorganic carbon (DIC) and methane. Compound-specific isotope analyses (CSIA) for benzene and toluene, and isotope analyses of ¹³C-DIC and ³⁴S-SO₄²⁻ were performed. Following application, an increase in sulfate concentration was noted in the smear zone. ³⁴S-SO₄²⁻ enrichment and ¹³C-DIC depletion indicated that sulfate reduction and mineralization of PHCs were enhanced. CSIA results provided unequivocal evidence of anaerobic biodegradation of benzene and toluene. After 1058 days when sulfate was depleted, methane concentrations were about three times greater than baseline conditions suggesting syntrophic benefit of the delivered sulfate. Observations from this investigation support the viability of sulfate land application to enhance biodegradation rates in shallow PHC smear zones.     

Inhibition Concentration of Phenolic Substances under Different Cultivation Conditions. Part I: Phenol Oxidation by Mixed Microbial Population in a Model System

The effects of oxygen supply rate and the presence or absence of nutrients on the kinetics of phenol degradation and oxygen consumption by a mixed microbial population were tested in a model system. The values for the maximum specific rate of phenol degradation (q_Smax), the saturation constant (K_S), and the inhibition concentration (S_CR) were determined for unlimited growth (K_La = 340 h^?1, growth medium) with 1.7 mmol g^?1 h^?1, 65 mg L^?1, and 190 mg L^?1. Under limitation conditions, alterations occur depending on the type of limitation. Nutrient limitations lead to values of 0.8 mmol g^?1 h^?1, 45 mg L^?1, and 160 mg L^?1, and oxygen limitations lead to 1.2 mmol g^?1 h^?1. 30 mg L^?1, and 120 mg L^?1, respectively. The results suggest that with excess oxygen, the rate of phenol degradation was higher and the inhibition effect of phenol was suppressed to some extent. Under the same high oxygen supply rate, the presence of nutrients in the model water significantly supported the phenol degradation rate.     

Efficiency of Pleurotus florida Laccase on Decolorization and Detoxification of the Reactive Dye Remazol Brilliant Blue R (RBBR) under Optimized Conditions

Laccase from the white‐rot fungus Pleurotus florida, produced under solid‐state fermentation conditions, was used for the decolorization of reactive dye Remazol Brilliant Blue R (RBBR). RBBR was decolorized up to 46% by P. florida laccase alone in 10 min. In the presence of N‐hydroxybenzotriazole (HBT), the rate of decolorization was enhanced 1.56‐fold. Central composite design of response surface methodology with four variables namely, dye, enzyme, redox mediator concentrations, and time at five levels was applied to optimize the RBBR decolorization. The predicted optimum level of variables for maximum RBBR decolorization (87%) was found to be 52.90 mg L^?1 (RBBR), 1.87 U mL^?1 (laccase), 0.85 mM (HBT), and 7.17 min (time), respectively. The validation results showed that the experimental value of RBBR decolorization (82%) was close to the predicted one. The disappearance of C–N and C–X groups, and a small shift in N–H groups in Fourier‐transform infra red (FTIR) spectroscopy confirms the degradation of RBBR chromophore by laccase enzyme. The phytotoxicity of RBBR was considerably reduced after the treatment with laccase. RBBR decolorization kinetics; K_m and V_max were calculated to be 145.82 mg L^?1 and 24.86 mg L^?1 min, respectively.     

Biodegradation and transport of benzene,toluene, and xylenes in a simulated aquifer: comparison of modelled and experimental results

Both laboratory experiments and numerical modelling were conducted to study the biodegradation and transport of benzene–toluene–xylenes (BTX) in a simulated semi‐confined aquifer. The factors incorporated into the numerical model include advection, hydrodynamic dispersion, adsorption, and biodegradation. The various physico‐chemical parameters required by the numerical model were measured experimentally. In the experimental portion of the study, BTX compounds were introduced into the aquifer sand. After the contaminants had been transported through the system, BTX concentrations were measured at 12 equally spaced wells. Subsequently, microorganisms obtained from the activated sludge of a sewage treatment plant and cultured in BTX mixtures were introduced into the aquifer through the 12 sampling wells. The distribution data for BTX adsorption by the aquifer sand form a nonlinear isotherm. The degree of adsorption by the sand varies, depending on the composition of the solute. The degradation time, measured from the time since the bacteria were added to the aquifer until a specific contaminant was no longer detectable, was 35–42 h for BTX. The dissolved oxygen, after degradation by BTX compounds and bacteria, was consumed by about 40–60% in the entire simulated aquifer; thus the aerobic conditions were maintained. This study provides insights for the biodegradation and transport of BTX in aquifers by numerical modelling and laboratory experiments. Experimental and numerical comparisons indicate that the results by Monod degradation kinetics are more accurate than those by the first‐order degradation kinetics. Copyright © 2002 John Wiley & Sons, Ltd.     

Groundwater Defluoridation with Raw Bauxite,Gypsum, Magnesite,and Their Composites

Breakthrough characteristics, kinetics, and dose‐effect in defluoridation with bauxite, gypsum, magnesite, and their composites were determined. The aim was to identify optimum filter and configuration viable for groundwater defluoridation. Bed depth service time (BDST) design model and empty bed residence time (EBRT) optimization model were employed to characterize breakthrough. Higher doses obtained lower loading capacities but higher sorption percentages and breakthrough times. Breakthrough times obtained were 50 400, 32 400, 25 200, and 19 800 s for 150, 120, 75, and 45 g, respectively. The equation ? = 1.0 × 10^?4 δ² ?0.022 δ + 1.5053 defined the operating line with ?, adsorbent exhaustion rate, in g L^?1 and δ, EBRT, in seconds. A critical bed depth (Z_o) of 6.56 cm was obtained. Second order kinetic rate constants were 0.73, 1.17, and 1.81 g mg^?1 s^?1 for magnesite, gypsum, and bauxite, respectively. The composite, gypsum and bauxite decreased water pH but magnesite increased pH in water defluoridation. Experimental data did not fit the two‐parameter logistics model; model values were significantly different from experimental values. Optimum defluoridation characteristics were obtained in fixed bed. Despite high residual sulphates and apparent color, fixed‐bed defluoridation with raw composites of these materials, treated in this manner, is viable.     

Effects of Short‐term and Long‐term Aluminium Stress on Photosynthesis,Respiration, and Reproductive Capacity in a Unicellular Green Flagellate (Euglena gracilis)

Effects of short‐term (1 h exposure) and long‐term (7 d exposure) aluminium stress on photosynthesis and reproductive capacity have been studied in Euglena gracilis strain Z. Following concentrations of Al_tot (added as AlCl₃) were tested: 0.5 mg L^‐1, 1.0 mg L^‐1, 1.5 mg L^‐1, 2.5 mg L^‐1, 5.0 mg L^‐1, 7.5 mg L^‐1, 10.0 mg L^‐1, and 15.0 mg L^‐1 Al, respectively. Growth rates at different aluminium concentrations did not show significant differences, except at 15.0 mg L^‐1Al. Initial respiration was higher in long‐term than in the short‐term experiments. It is supposed that an energy‐dependent mechanism of excretion of aluminium ions has been active in the stressed cells. Consequently, the cells of E. gracilis after long‐term exposure to aluminium are believed to be more acclimatised to the aluminium stress. Photosynthetic efficiency (PE) has been negatively affected by aluminium in all experiments performed. Differences between control algae and those treated with aluminium were significant in all cases. PE in long‐term experiments was in general significantly higher at all concentrations of aluminium studied, compared to the short‐term experiments. The aluminium concentrations tested led only to a general decrease in PE while the level of decrease was not especially concentration‐dependent. In general, aluminium tolerance of E. gracilis can be estimated as low, especially by short‐term exposure. However, good acclimatisation capacity of this green flagellate to aluminium doses by long‐term exposure can be supposed.     

Quantification of Diclofenac in Hospital Effluent and Identification of Metabolites and Degradation Products

In this study the occurrence of diclofenac and sub‐products in effluent emerging from the University Hospital at the Federal University of Santa Maria was investigated. One metabolite was identified and, in aqueous solution, three degradation products. The quantification was conducted by means of HPLC‐DAD, and the determination of metabolite and degradation products by LC–ESI–MS/MS–QTrap. For the HPLC‐DAD method, a 70:30 mixture of methanol/sodium phosphate was used in isocratic mode. For the LC–ESI–MS/MS–QTrap determinations, a mobile phase, where phase A was an ammonium acetate solution 5 × 10^?3 mol L^?1, and phase B was methanol (5 × 10^?3 mol L^?1)/ammonium acetate (9:1, v/v), on gradient mode. The LDs for the HPLC and LC–MS/MS methods, respectively, were 2.5 and 0.02 µg L^?1, the LQs, 8.3 and 0.05 µg L^?1, and the linear range from 10 up to 2000 µg L^?1 and 0.05 up to 10 µg L^?1. As expected, the LC–ESI–MS/MS–QTrap method was more sensitive and less laborious. The metabolite 4′‐hydroxy‐diclofenac was identified. Photolysis was used for the degradation studies and three products of diclofenac were identified (m/z of 214, 286 and 303) in aqueous solution. These results notwithstanding, no degradation products of diclofenac were found in the hospital effluent.     

A Preliminary Study of Chromophoric Dissolved Organic Matter (CDOM) in Lake Taihu,a Shallow Subtropical Lake in China

The optical properties and spatial distribution of chromophoric dissolved organic matter (CDOM) in Meiliang Bay of Lake Taihu were evaluated and compared to the results in literature. Concentrations of dissolved organic carbon (DOC) ranged from 8.75 to 20.19 mg L^?1 with an average of (13.10 ± 3.51) mg L^?1. CDOM absorption coefficients a(λ) at 280 nm, 355 nm, and 440 nm were in the range 11.28...33.46 m^?1 (average (20.95 ± 5.52) m^?1), 2.42...7.90 m^?1 (average (4.92 ± 1.29) m^?1), and 0.65...2.44 m^?1 (average (1.46 ± 0.44) m^?1), respectively. In general, CDOM absorption coefficient and DOC concentration were found to decrease away from the river inflow to Meiliang Bay towards the lake center. The values of the DOC‐specific absorption coefficients a*(λ), given as absorption coefficient related to mass concentration of organic carbon (C) ranged from 0.28 to 0.47 L mg^?1 m^?1 at 355 nm. The determination coefficients between CDOM absorption and DOC concentration decreased with the increase of wavelength from 280 to 550 nm. The linear regression relationship between CDOM absorption at 280 nm and DOC concentration was following: a(280 nm) = 1.507 L mg^?1 m^?1 · DOC + 1.215 m^?1. The spectral slope S values were dependent on the wavelength range used in the regression. The estimated S values decreased with increasing wavelength range used. A significant negative linear relationship was found between CDOM absorption coefficients, DOC‐specific absorption coefficients and estimated S values especially in longer wavelength range. The linear regression relationship between DOC‐specific absorption coefficients at 440 nm and estimated S values during the wavelength range from 280 to 500 nm was following: a*(440 nm) = (–0.021 μm · S + 0.424) L mg^?1 m^?1.     

The Seashell Wastes as Biosorbent for Reactive Dye Removal from Textile Effluents

This study investigates structural and adsorption properties of the powdered waste shells of Rapana gastropod and their use as a new cheap adsorbent to remove reactive dye Brilliant Red HE‐3B from aqueous solutions under batch conditions. For the powder shells characterization, solubility tests in acidic solutions and X‐ray diffraction (XRD), scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDX), Fourier transform IR spectroscopy (FT‐IR) and thermogravimetric analyses were performed. The results revealed that the adsorbent surface is heterogeneous consisting mainly from calcium carbonate layers (either calcite or aragonite) and a small amount of organic macromolecules (proteins and polysaccharides). The dye adsorptive potential of gastropod shells powder was evaluated as function of initial solution pH (1–5), adsorbent dose (6–40 g L^?1), dye concentration (50–300 mg L^?1), temperature (5–60°C), and contact time (0–24 h). It was observed that the maximum values of dye percentage removal were obtained at the initial pH of solution 1.2, shells dose of 40 g L^?1, dye initial concentration of 50–50 mg L^?1 and higher temperatures; the equilibrium time decreases with increasing of dye concentration. It is proved that the waste seashell powder can be used as low cost bioinorganic adsorbent for dyes removal from textile wastewaters.     

Surfactant Enhance DLLME/FO‐LADS: Assay of Malachite Green Level in Aquatic Environment of Trout Fish

Malachite green (MG), a traditional agent used in aquaculture although is not approved; its low cost and high efficacy make illicit use likely. We developed a small‐scale, simple, and sensitive dispersive liquid–liquid microextraction procedure for the assay of trace amounts of MG in aquatic environment of Trout fish. Fiber optic‐linear array detection spectrophotometry with charge‐coupled device detector benefiting from a microcell was used for this purpose. The method is based on enhancement effect of an anionic surfactant on the extraction of MG in to very fine multidroplets of microextraction solvent which made assisted by disperser solvent. Under the optimum conditions, the enrichment factor 77.5 was obtained from a 5‐mL water sample. The calibration graph was linear up to 5 × 10^?7 mol L^?1 with detection limit of 1 × 10^?8 mol L^?1. The relative standard deviation for seven replicate measurements of 4 × 10^?7 and 5 × 10^?8 mol L^?1 of MG were 3.3 and 4.5%, respectively.     

Nitrate content and potential microbial signature of rock glacier outflow,Colorado Front Range

Here we characterize the nutrient content in the outflow of the Green Lake 5 rock glacier, located in the Green Lakes Valley of the Colorado Front Range. Dissolved organic carbon (DOC) was present in all samples with a mean concentration of 0·85 mg L^?1 . A one‐way analysis of variance test shows no statistical difference in DOC amounts among surface waters (p = 0·42). Average nitrate concentrations were 69 µmoles L^?1 in the outflow of the rock glacier, compared to 7 µmoles L^?1 in snow and 25 µmoles L^?1 in rain. Nitrate concentrations from the rock glacier generally increased with time, with maximum concentrations of 135 µmoles L^?1 in October, among the highest nitrate concentrations reported for high‐elevation surface waters. These high nitrate concentrations appear to be characteristic of rock glacier outflow in the Rocky Mountains, as a paired‐difference t‐test shows that nitrate concentrations from the outflow of 7 additional rock glaciers were significantly greater compared to their reference streams (p = 0·003). End‐member mixing analysis suggest that snow was the dominant source of nitrate in June, ‘soil’ solution was the dominant nitrate source in July, and base flow was the dominant source in September. Fluoresence index values and PARAFAC analyses of dissolved organic matter (DOM) are also consistent with a switch from terrestrial DOM in the summer time period to an increasing aquatic‐like microbial source during the autumn months. Copyright © 2006 John Wiley & Sons, Ltd.     

Destabilization of Aqueous Colloidal C60 Nanoparticles in the Presence of Various Organic Matter

The extractable fraction of aqueous colloidal C₆₀ nanoparticles (nC₆₀) was quantified using a liquid–liquid extraction method in the presence of five types of dissolved organic matter (DOM): Aldrich humic acid (AHA), Suwannee River fulvic acid (SFA), sodium dodecyl sulfate (SDS) micelle, liposomes composed of 1‐palmitoyl‐2‐oleoyl‐sn‐glycero‐3‐phosphocholine (POPC), and bovine serum albumin (BSA). The changes in toluene extractable fraction highly depended on the type and dose of DOM. Whereas an environmentally relevant concentration of AHA, 2–20 mg L^?1, was sufficient to reduce the nC₆₀ fraction easily destabilized, much higher dose of fulvic acid was needed to result in the similar degree of stabilization. A big contrast between two types of self‐organized DOM, SDS micelle and POPC liposomes, was observed. Although SDS micelle significantly decreased the toluene extractable fraction of nC₆₀ at the dose greater than its critical micelle concentration, no apparent decrease in toluene extractable fraction was found in the presence of POPC liposomes up to 3000 mg L^?1. The toluene extractable fraction of nC₆₀ in the presence of BSA rapidly decreases at lower doses then gradually decreased at higher doses. An equilibrium complexation model was proposed to quantitatively describe the decrease in the extractability of nC₆₀ in the presence of DOM. The observed decrease in the extractability of nC₆₀ was well explained by the model and the complexation of nC₆₀ with DOM was thought to occur close to 1:1 molar ratio except for BSA. The association constants of nC₆₀ with DOM were in the order of BSA, AHA, SFA, and SDS micelle, showing the differences in the affinity to nC₆₀.     

Adsorption of BTEX on Surfactant Modified Granulated Natural Zeolite Nanoparticles: Parameters Optimizing by Applying Taguchi Experimental Design Method

In this paper, a novel adsorbent developed by means of granulating of natural zeolite nanoparticles (i.e., clinoptilolite) was evaluated for possible removal of the petroleum monoaromatics (i.e., benzene, toluene, ethylbenzene, and xylene, BTEX). To do this, the natural zeolite was ground to produce nanosized particulate, then modified by two cationic surfactants and granulated. The effect of various parameters including temperature, initial pH of the solution, total dissolved solids (TDS), and concentration of a competitive substance (i.e., methyl tert‐butyl ether, MTBE) were studied and optimized using a Taguchi statistical approach. The results ascertained that initial pH of the solution was the most effective parameter. However, the low pH (acidic) was favorable for BTEX adsorption onto the developed adsorbents. In this study, the experimental parameters were optimized and the best adsorption condition by determination of effective factors was chosen. Based on the S/N ratio, the optimized conditions for BTEX removal were temperature of 40°C, initial pH of 3, TDS of 0 mg/L, and MTBE concentration of 100 µg/L. At the optimized conditions, the uptake of each BTEX compounds reached to more than 1.5 mg/g of adsorbents.     

Beaver dams along an agricultural stream in southern Ontario,Canada: their impact on riparian zone hydrology and nitrogen chemistry

The hydrology and nitrogen biogeochemistry of a riparian zone were compared before and after the construction of beaver dams along an agricultural stream in southern Ontario, Canada. The beaver dams increased surface flooding and raised the riparian water table by up to 1·0 m. Increased hydraulic gradients inland from the stream limited the entry of oxic nitrate‐rich subsurface water from adjacent cropland. Permeable riparian sediments overlying dense till remained saturated during the summer and autumn months, whereas before dam construction a large area of the riparian zone was unsaturated in these seasons each year. Beaver dam construction produced significant changes in riparian groundwater chemistry. Median dissolved oxygen concentrations were lower in riparian groundwater after dam construction (0·9–2·1 mg L^?1) than in the pre‐dam period (2·3–3·9 mg L^?1). Median NO₃‐N concentrations in autumn and spring were also lower in the post‐dam (0·03–0·07 mg L^?1) versus the pre‐dam period (0·1–0·3 mg L^?1). In contrast, median NH₄‐N concentrations in autumn and spring months were higher after dam construction (0·3–0·4 mg L^?1) than before construction (0·13–0·14 mg L^?1). Results suggest that beaver dams can increase stream inflow to riparian areas that limit water table declines and increase depths of saturated riparian soils which become more anaerobic. These changes in subsurface hydrology and chemistry have the potential to affect the transport and transformation of nitrate fluxes from adjacent cropland in agricultural landscapes. Copyright © 2009 John Wiley & Sons, Ltd.     

Start‐Up Study on Biohydrogen from Palm Oil Mill Effluent in a Pilot‐Scale Reactor

A start‐up study for biohydrogen production from palm oil mill effluent (POME) is carried out in a pilot‐scale up‐flow anaerobic sludge blanket fixed‐film reactor (UASFF). A substrate with a chemical oxygen demand (COD) of 30 g L^?1 is used, starting with molasses solution for 30 days and followed by a 10% v/v increment of POME/molasses ratio. At 100% POME, a hydrogen content of 80%, hydrogen production rate of 36 L H₂ per day, and maximum COD removal of 48.7% are achieved. Bio‐kinetic coefficients of Monod, first‐order, Grau second‐order, and Stover‐Kincannon kinetic models are calculated to describe the performance of the system. The steady‐state data with 100% POME shows that Monod and Stover‐Kincannon models with bio‐kinetic coefficients of half‐velocity constant (K_s) of 6000 mg COD L^?1, microbial decay rate (K_d) of 0.0015 per day, growth yield constant (Y) of 0.786 mg volatile suspended solids (VSS)/mg COD, specific biomass growth rate (μ_max) of 0.568 per day, and substrate consumption rate of (U_max) 3.98 g/L day could be considered as superior models with correlation coefficients (R²) of 0.918 and 0.989, respectively, compared to first‐order and Grau's second‐order models with coefficients of K₁ 1.08 per day, R² 0.739, and K_2s 1.69 per day, a = 7.0 per day, b = 0.847.     

Biodegradation by Co‐inoculated Bacteria and Fungi Alleviates Adverse Effects of Red‐S3B on Growth and Nitrogen Uptake of Wheat

Textile wastewater contains huge quantities of nitrogen (N)‐containing azo‐dyes. Irrigation of crops with such wastewater adds toxic dyes into our healthy soils. One of the ways to prevent their entry to soils could be these waters after the dyes' biodegradation. Therefore, the present study was conducted to evaluate the impact of textile dyes on wheat growth, dye degradation efficiency of bacteria‐fungi consortium, and alleviation of dye toxicity in wheat by treatment with microbial consortium. Among dyes, Red‐S3B (3.19% N) was found to be the most toxic to germination and growth of seven‐day‐old wheat seedlings. Shewanella sp. NIAB‐BM15 and Aspergillus terreus NIAB‐FM10 were found to be efficient degraders of Red‐S3B. Their consortium completely decolorized 500 mg L^?1 Red‐S3B within 4 h. Irrigation with Red‐S3B‐contaminated water after treatment with developed consortium increased root length, shoot length, root biomass, and shoot biomass of 30‐day‐old wheat seedlings by 47, 18, 6, and 25%, respectively, than untreated water. Moreover, irrigation after microbial treatment of dye‐contaminated water resulted in 20 and 51% increase in shoot N content and N uptake, respectively, than untreated water. Thus, co‐inoculation of bacteria and fungi could be a useful bioremediation strategy for the treatment of azo‐dye‐polluted water.