Direct degradation of Bisphenol A from aqueous solution by active red mud in aerobic environment

As industrial waste from aluminum production, red mud (RM) poses a severe threat to the local environment that needs to be appropriately utilized. The activation of iron oxide, which is abundant in RM, improves its effectiveness as a catalytic material for the degradation of organic pollutants. This study developed a novel activation approach by adding dithionite citrate bicarbonate (DCB) for Bisphenol A (BPA) degradation under aeration conditions. Electrochemical experiments and reactive oxygen species (ROSs) trapping experiments showed that DCB treatment enhanced the redox cycle of Fe(II)/Fe(III), which promoted free radical generation. The optimized condition for the RM activation was achieved at 21 mmol/L dithionites, 84 mmol/L citrates, and 34 mmol/L bicarbonate, and the degradation of BPA by activated RM reached 410 µg BPA per gram of RM. This work provided a feasible way to utilize RM resources as an efficient, low-cost catalyst for organic pollutants treatment.

Evaluation of aerobic biodegradation of phenanthrene using Pseudomonas turukhanskensis: an optimized study

The ability of Pseudomonas turukhanskensis GEEL-01 to degrade the phenanthrene (PHE) was optimized by response surface methodology (RSM). Three factors as independent variables (including temperature, pH, and inoculum) were studied at 600 mg/L PHE where the highest growth of P. turukhanskensis GEEL-01 was observed. The optimum operating conditions were evaluated through the fit summary analysis, model summary statistics, fit statistics, ANOVA analysis, and model graphs. The degradation of PHE was monitored by high-performance liquid chromatography (HPLC) and the metabolites were identified by gas chromatography-mass spectrometry (GC-MS). The results showed that the correlation among independent variables with experimental and predicted responses was significant (p < 0.0001). The optimal temperature, pH, and inoculum were 30 ℃, 8, and 6 mL respectively. The HPLC peaks exhibited a reduction in PHE concentration from 600 mg/L to 4.97 mg/L with 99% degradation efficiency. The GC-MS peaks indicated that the major end products of PHE degradation were 1-Hydroxy-2-naphthoic acid, salicylic acid, phthalic acid, and catechol. This study demonstrated that the optimized parameters by RSM for P. turukhanskensis GEEL-01 could degrade PHE by phthalic and salicylic acid pathways.

Superabsorbent hydrogel as a formulation to promote mineralization and accelerate degradation of acetochlor in soils

The excessive use of herbicides had caused serious environmental pollution and ecological problems. Therefore, it is imperative to explore an effective method to reduce herbicide residues and pollution. In the present study, we used superabsorbent hydrogels coated ¹⁴C-acetochlor (SH-ACE) to investigate its behavior in different soils under oxic conditions. After 100 days, the mineralization by SH-ACE was increased by 2.3%, 2.5% and 3.3% in the red clay soils, fluvio-marine yellow loamy soils and coastal saline soils, respectively, compared to the control group. This result indicated that the SH-ACE treatment resulted in more complete degradation and detoxification of acetochlor. In addition, the dissipation rates of acetochlor were significantly faster in the SH-ACE treatment, which reduced the persistence of acetochlor. The probable degradation pathways of acetochlor involved dechlorination, hydroxylation, deethoxymethylation, and the formation of thioacetic acid derivatives in the two treatments, but the contents of transformation products were completely different. These findings suggest that the SH-ACE treatment has a significant effect to accelerate the degradation of acetochlor. When developing green pesticides, we emphasize that superabsorbent hydrogel coating treatment should be considered as a promising method for ecological safety in the environment.

Transcriptome profiling reveals upregulation of benzoate degradation and related genes in Pseudomonas aeruginosa D6 during textile dye degradation

An upsurge in textile dye pollution has demanded immediate efforts to develop an optimum technology for their bioremediation. However, the molecular mechanism underpinning aerobic decolorization of dyes is still in its infancy. Thus, in the current work, the intricacies of aerobic remediation of textile dyes by Pseudomonas aeruginosa D6 were understood via a transcriptomic approach. The bacterium isolated from the sludge sample of a common effluent treatment plant was able to decolorize 54.42, 57.66, 50.84 and 65.86% of 100 mg L^-1 of four different dyes i.e., TD01, TD04, TD05, and TD06, respectively. The maximum decolorization was achieved within six days and thus, the first and sixth day of incubation were selected for transcriptome analysis at the early and late phase of the decolorization, respectively. The expression profiles of all samples were compared to gain insight into the dye-specific response of bacterium and it was found that it behaved most uniquely in the presence of the dye TD01. Several genes critical to core metabolic processes like the TCA cycle, glycolysis, pentose phosphate pathway, translation, cell motility etc. Were found to be overexpressed in the presence of dyes. Interestingly, in response to dyes, the benzoate degradation pathway was significantly upregulated in the bacterium as compared to control (i.e., bacterium without dye). Thus, seven genes contributing to the induction of the same were further studied by RT-qPCR analysis. Overall, the involvement of the benzoate pathway implies the appearance of aromatic intermediates during decolorization, which in turn infers dye degradation.

Biochemical-thermal-hydro-mechanical coupling model for aerobic degradation of landfilled municipal solid waste

Ventilating solid waste landfills with an oxygen supply can effectively accelerate the degradation of waste, achieve rapid stabilization, and realize the sustainable utilization of landfills. Aiming to understand and verify the aerobic degradation process in landfills, this paper proposed a biochemical-thermal-hydro-mechanical coupling model. The model considers aerobic biochemical reactions, dissolved solute migration, heat transport, two-phase flow, and skeleton deformation. The model was verified by comparison with an in-situ experiment at Jinkou landfill. The results showed the model could accurately represent the observed degradation phenomena during the experiment. The modelling results indicated that the rate of temperature increase and peak temperature of the upper layer, which were lower than those of the middle layer, were affected by heat exchange at the landfill surface. The lowest temperatures occurred near the bottom because of high water content and low oxygen concentrations. The high temperature zone migrated out from the injection well during degradation, reflecting the degradation of degradable organic matter associated with oxygen diffusion rates and aerobic degradation reactions. The initial accumulated settlement value was fast, but slowed and finally stabilized. The surface subsidence also developed from the center around the injection well to the surrounding area, and 70% of the total subsidence occurred within 150 days. This newly developed model provides a theoretical framework for analyzing the multi-field coupling of aerobic degradation of landfilled municipal solid waste (MSW).

Hydrolyzed urine for enhanced valorization and toxicant degradation of wet coffee processing wastes: Implications for soil contamination and health risk reductions

Coffee pulp (CP) and wastewater, from wet coffee processing plants, pollute water and soil ecosystems unless a greener management system is employed. The aim was to evaluate the effect of hydrolyzed human urine (HU) on the dynamics of total phenol, caffeine, and heavy metals during CP and coffee processing wastewater (CPWW) co-composting. The associated health risks reduction after application for cabbage production was also estimated. For the purpose, five treatments were prepared as C₀ (CP, control), C₁ (CP + CPWW), C₂ (CP + 1:1 CPWW:HU), C₃ (CP + 1:2 CPWW:HU) and C₄ (CP + 1:3 CPWW:HU). The optimum compost was applied for cabbage cultivation in comparison with mineral fertilizer and without fertilization in a greenhouse. The total phenol reduction was in the order of C₁ (77.71%) < C₀ (78.66%) < C₄ (79.89%) < C₃ (91.20%) < C₂ (91.48%), and maximum significant reduction of caffeine was also observed in C₃ (81.34%) and C₂ (82.66%). Pb and Cd were significantly reduced in C₂, and Cr in C₃ with a reduction of 4.38-15.13%, 12.50-33.00%, and 2.94-19.57%, respectively. The bio-concentration factor decreased in the order of Cd > Cr > Ni > Pb with concentrations, hazard quotient, hazard index (along with phenol) < 1, and cancer risk values below 1.00E-04, indicating very little risk. Thus, supplementing HU enhanced degradation of the anti-nutrient factors, and provide compost that enrich soil nutrients with little health risks of application.

Aerobic degradation of nonhalogenated organophosphate flame esters (OPEs) by enriched cultures from sludge: Kinetics, pathways, bacterial community evolution, and toxicity evaluation

The degradation by bacteria has been considered the main process for eliminating nonhalogenated organophosphate esters (OPEs) from wastewater treatment plants (WWTPs), but limited research has reported the biodegradation processes and clarified the microbial-mediated mechanisms for nonhalogenated OPE degradation in WWTPs. The aim of this study was to monitor the biodegradation of the most common nonhalogenated OPEs, namely, tris(2-butoxyethyl) phosphate (TBOEP), tris (n-butyl) phosphate (TNBP) and trisphenyl phosphate (TPHP), under aerobic conditions by sludge cultures from a conventional sewage plant. The microbial cultures were enriched separately with each OPE from activated sludge cultures, and the presence of glucose significantly enhanced degradation of the OPEs during the enrichment. The removal ratios for the three OPEs reached 29.3-89.9% after 5 cycles (25 days) of cultivation, and the first-order degradation kinetics followed the order of TPHP > TBOEP > TNBP, with their half-lives ranging between 12.8 and 99.0 h. Pathways of hydrolysis, hydroxylation, methoxylation, and substitution were confirmed for the aerobic biodegradation of these nonhalogenated OPEs, but only di-alkyl phosphates (DAPs) largely accumulated in culture medium as the most predominant transformation products. Phylotypes in Klebsiella were significantly more abundant during OPE biodegradation than in the initial sludge, which indicated that these microorganisms are associated with the biodegradation of nonhalogenated OPEs in sludge culture. Biodegradation of all investigated nonhalogenated OPEs was associated with a significant reduction in the residual toxicity to Vibrio fischeri, indicating a rather positive ecotoxicological outcome of the aerobic biotransformation processes achieved by the enriched sludge culture.

Long-term evaluation of the effect of peracetic acid on a mixed aerobic culture: Organic matter degradation, nitrification, and microbial community structure

Peracetic acid (PAA) has been widely used as a disinfectant in many industries; its use in poultry processing is steadily increasing. However, information related to the potential inhibitory effect of PAA solutions (PAA and H₂O₂) on biological wastewater treatment processes used by the poultry processing industry is extremely limited. The work reported here assessed the long-term effect of PAA solution on aerobic degradation and nitrification in three bioreactors fed with poultry processing wastewater by quantifying the extent of COD removal and nitrification rates. Changes in culture viability, intracellular reactive oxygen species (ROS), and microbial community structure were also evaluated. COD removal and nitrification were not affected by H₂O₂ and PAA solutions added to the wastewater before feeding (indirect addition). However, both processes were significantly affected by high levels of H₂O₂ (i.e., 27 mg/L) and PAA solution (i.e., 60/8.4 mg/L PAA/H₂O₂) directly added to the reactors. Directly added PAA/H₂O₂ at 40/5.6 mg/L was the lowest dose resulting in nitrification inhibition. Fast recovery of COD removal and nitrification was observed when direct addition of H₂O₂ and PAA solution ended. Cell viability measurements revealed that the negative impact on nitrification was predominantly attributed to enzyme inhibition rather than to loss of cell viability. The impact on nitrification was not related to intracellular ROS levels. Microbiome analysis showed major shifts in community composition during the long-term addition of H₂O₂ and even more with PAA addition. No significant time-trend change in the relative abundance of ammonia-oxidizing bacteria or nitrite-oxidizing bacteria was observed, further supporting the conclusion that the negative impact on nitrification was attributed mainly to enzyme inhibition.

Degradation strategies and associated regulatory mechanisms/features for aromatic compound metabolism in bacteria

As a result of anthropogenic activity, large number of recalcitrant aromatic compounds have been released into the environment. Consequently, microbial communities have adapted and evolved to utilize these compounds as sole carbon source, under both aerobic and anaerobic conditions. The constitutive expression of enzymes necessary for metabolism imposes a heavy energy load on the microbe which is overcome by arrangement of degradative genes as operons which are induced by specific inducers. The segmentation of pathways into upper, middle and/or lower operons has allowed microbes to funnel multiple compounds into common key aromatic intermediates which are further metabolized through central carbon pathway. Various proteins belonging to diverse families have evolved to regulate the transcription of individual operons participating in aromatic catabolism. These proteins, complemented with global regulatory mechanisms, carry out the regulation of aromatic compound metabolic pathways in a concerted manner. Additionally, characteristics like chemotaxis, preferential utilization, pathway compartmentalization and biosurfactant production confer an advantage to the microbe, thus making bioremediation of the aromatic pollutants more efficient and effective.

Treatment of pharmaceutical industrial wastewater by nano-catalyzed ozonation in a semi-batch reactor for improved biodegradability

The study reports the biodegradability enhancement of pharmaceutical wastewater along with COD (Chemical Oxygen Demand) color and toxicity removal via O₃, O₃/Fe²⁺, O₃/nZVI (nano zero valent iron) processes. Nano catalytic ozonation process (O₃/nZVI) showed the highest biodegradability (BI = BOD₅/COD) enhancement of pharmaceutical wastewater up to 0.63 from 0.18 of control with a COD, color and toxicity removal of 62.3%, 93% and 82% respectively. The disappearance of the corresponding Fourier transform infrared (FTIR) and gas chromatography-mass spectrometry (GC-MS) peaks after pretreatment indicated the degradation or transformation of the refractory organic compounds to more biodegradable organic compounds. The subsequent aerobic degradation study of pretreated pharmaceutical wastewater resulted in biodegradation rate enhancement of 5.31, 2.97, and 1.22 times for O₃/nZVI O₃/Fe²⁺ and O₃ processes respectively. Seed germination test using spinach (Spinacia oleracea) seeds established the toxicity removal of pretreated pharmaceutical wastewater.

Elucidating the biodegradation mechanism of tributyl phosphate (TBP) by Sphingomonas sp. isolated from TBP-contaminated mine tailings

Tributyl phosphate (TBP) is recognised as a global environmental contaminant because of its wide use in floatation reagents, nuclear fuel reprocessing and plasticisers. This contaminant is hardly degraded by hydrolysis in the environment due to its special physicochemical properties. In this study, one TBP-degrading strain was isolated from TBP-contaminated abandoned mine tailings, and 16S rRNA identification revealed that the strain belonged to the genus Sphingomonas. Results validated that the strain could utilise TBP as the sole carbon source, and vitamin was not the essential factor for its growth. Liquid chromatography time-of-flight mass spectrometry analysis identified di-n-butyl phosphate (DnBP) and mono-n-butyl phosphate (MnBP) as the intermediate metabolites for TBP biodegradation. No obvious change in carbon and hydrogen isotope composition was observed in biodegradation processes (cell suspension and crude extract degradation), which indicated that the first irreversible bond cleavage did not involve carbon or hydrogen. Hence, the TBP degradation scheme by Sphingomonas sp. proposed that the first irreversible step of TBP transferred to DnBP would lead to PO bond cleavage. This study combined the identification of products and isotope fractionation in substrates to investigate the transformation mechanism, thereby providing an eco-friendly and cost-effective way for the in situ bioremediation of TBP-contaminated sites by the isolated TBP degradation strain.

Catalytic ozone pretreatment of complex textile effluent using Fe2+ and zero valent iron nanoparticles

The study investigates the effect of catalytic ozone pretreatment via Fe²⁺ and nZVI on biodegradability enhancement of complex textile effluent. The nZVI particles were synthesized and characterized by XRD, TEM and SEM analyses. Results showed that nano catalytic ozone pretreatment led to higher biodegradability index (BOD₅/COD = BI) enhancement up to 0.61 (134.6%) along with COD, color and toxicity removal up to 73.5%, 87%, and 92% respectively. The disappearance of the corresponding GCMS & FTIR spectral peaks during catalyzed ozonation process indicated the cleavage of chromophore group and degradation of organic compounds present in the textile effluent. Subsequent aerobic biodegradation of nZVI pretreated textile effluent resulted in maximum COD and color reduction of 78% and 98.5% respectively, whereas the untreated effluent (BI = 0.26) indicated poor COD and color reduction of only 31% and 33% respectively. Bio-kinetic parameters also confirmed the increased rate of bio-oxidation at enhanced BIs. Seed germination test using seeds of Spinach (Spinacia oleracea), indicated the effectiveness of nano catalyzed ozone pretreatment in removing toxicity from contaminated textile effluent.

Removal of organic compounds from shale gas flowback water

Ozonation, sorption to granular activated carbon and aerobic degradation were compared as potential treatment methods for removal of dissolved organic carbon (DOC) fractions and selected organic compounds from shale gas flowback water after pre-treatment in dissolved air flotation unit. Flowback water was characterised by high chemical oxygen demand and DOC. Low molecular weight (LMW) acids and neutral compounds were the most abundant organic fractions, corresponding to 47% and 35% of DOC respectively. Ozonation did not change distribution of organic carbon fractions and concentrations of detected individual organic compounds significantly. Sorption to activated carbon targeted removal of individual organic compounds with molecular weight >115 Da, whereas LMW compounds remained largely unaffected. Aerobic degradation was responsible for removal of LMW compounds and partial ammonium removal, whereas formation of intermediates with molecular weight of 200-350 Da was observed. Combination of aerobic degradation for LMW organics removal with adsorption to activated carbon for removal of non-biodegradable organics is proposed to be implemented between pre-treatment (dissolved air floatation) and desalination (thermal or membrane desalination) steps.

Methodology to determine the extent of anaerobic digestion, composting and CH4 oxidation in a landfill environment

An examination of the processes contributing to the production of landfill greenhouse gas (GHG) emissions is required, as the actual level to which waste degrades anaerobically and aerobically beneath covers has not been differentiated. This paper presents a methodology to distinguish between the rate of anaerobic digestion (r_AD), composting (r_COM) and CH₄ oxidation (r_OX) in a landfill environment, by means of a system of mass balances developed for molecular species (CH₄, CO₂) and stable carbon isotopes (δ¹³C-CO₂ and δ¹³C-CH₄). The technique was applied at two sampling locations on a sloped area of landfill. Four sampling rounds were performed over an 18 month period after a 1.0 m layer of fresh waste and 30-50 cm of silty clay loam had been placed over the area. Static chambers were used to measure the flux of the molecular and isotope species at the surface and soil gas probes were used to collect gas samples at depths of approximately 0.5, 1.0 and 1.5 m. Mass balances were based on the surface flux and the concentration of the molecular and isotopic species at the deepest sampling depth. The sensitivity of calculated rates was considered by randomly varying stoichiometric and isotopic parameters by ±5% to generate at least 500 calculations of r_OX, r_AD and r_COM for each location in each sampling round. The resulting average value of r_AD and r_COM indicated anaerobic digestion and composting were equally dominant at both locations. Average values of r_COM: ranged from 9.8 to 44.5 g CO₂ m^-2 d^-1 over the four sampling rounds, declining monotonically at one site and rising then falling at the other. Average values of r_AD: ranged from 10.6 to 45.3 g CO₂ m^-2 d^-1. Although the highest average r_AD value occurred in the initial sampling round, all subsequent r_AD values fell between 10 and 20 g CO₂ m^-2 d^-1. r_OX had the smallest activity contribution at both sites, with averages ranging from 1.6 to 8.6 g CO₂ m^-2 d^-1. This study has demonstrated that for an interim cover, composting and anaerobic digestion of shallow landfill waste can occur simultaneously.

Effects of environmental conditions on aerobic degradation of a commercial naphthenic acid

Naphthenic acids (NAs) are problematic constituents in energy-derived waters, and aerobic degradation may provide a strategy for mitigating risks to aquatic organisms. The overall objective of this study was to determine the influence of concentrations of N (as ammonia) and P (as phosphate), and DO, as well as pH and temperatures on degradation of a commercial NA in bench-scale reactors. Commercial NAs provided replicable compounds necessary to compare influences of environmental conditions on degradation. NAs were quantified using high performance liquid chromatography. Microbial diversity and relative abundance were measured in treatments as explanatory parameters for potential effects of environmental conditions on microbial populations to support analytically measured NA degradation. Environmental conditions that positively influenced degradation rates of Fluka NAs included nutrients (C:N 10:1-500:1, C:P 100:1-5000:1), DO (4.76-8.43 mg L(-1)), pH (6-8), and temperature (5-25 °C). Approximately 50% removal of 61 ± 8 mg L(-1) was achieved in less than 2 d after NA introduction, achieving the method detection limit (5 mg L(-1)) by day 6 of the experiment in treatments with a C:N:P ratio of 100:10:1, DO > 8 mg L(-1), pH ∼8-9, and temperatures >23 °C. Microbial diversity was lowest in lower temperature treatments (6-16 °C), which may have resulted in observed slower NA degradation. Based on results from this study, when macro- and micronutrients were available, DO, pH, and temperature (within environmentally relevant ranges) influenced rates of aerobic degradation of Fluka NAs. This study could serve as a model for systematically evaluating environmental factors that influence NA degradation in field scenarios.

Consecutive anaerobic-aerobic treatment of the organic fraction of municipal solid waste and lignocellulosic materials in laboratory-scale landfill-bioreactors

The scope of this study is to evaluate the use of laboratory-scale landfill-bioreactors, operated consecutively under anaerobic and aerobic conditions, for the combined treatment of the organic fraction of municipal solid waste (OFMSW) with two different co-substrates of lignocellulosic nature, namely green waste (GW) and dried olive pomace (DOP). According to the results such a system would represent a promising option for eventual larger scale applications. Similar variation patterns among bioreactors indicate a relatively defined sequence of processes. Initially operating the systems under anaerobic conditions would allow energetic exploitation of the substrates, while the implementation of a leachate treatment system ultimately aiming at nutrient recovery, especially during the anaerobic phase, could be a profitable option for the whole system, due to the high organic load that characterizes this effluent. In order to improve the overall effectiveness of such a system, measures towards enhancing methane contents of produced biogas, such as substrate pretreatment, should be investigated. Moreover, the subsequent aerobic phase should have the goal of stabilizing the residual materials and finally obtain an end material eventually suitable for other purposes.

M7

The organochlorine insecticide γ-hexachlorocyclohexane (γ-HCH, lindane) and its non-insecticidal α- and β-isomers continue to pose serious environmental and health concerns, although their use has been restricted or completely banned for decades. In this study we report the first evidence of the growth ability of a Streptomyces strain in a mineral salt medium containing high doses of α- and β-HCH (16.6 mg l(-1)) as a carbon source. Degradation of HCH isomers by Streptomyces sp. M7 was investigated after 1, 4, and 7 days of incubation, determining chloride ion release, and residues in the supernatants by GC with µECD detection. The results show that both the α- and β-HCH isomers were effectively metabolized by Streptomyces sp. M7, with 80 and 78 % degradation respectively, after 7 days of incubation. Moreover, pentachlorocyclohexenes and tetrachlorocyclohexenes were detected as metabolites. In addition, the formation of possible persistent compounds such as chlorobenzenes and chlorophenols were studied by GC-MS, while no phenolic compounds were detected. In conclusion, we have demonstrated for the first time that Streptomyces sp. M7 can degrade α- and β-isomers individually or combined with γ-HCH and could be considered as a potential agent for bioremediation of environments contaminated by organochlorine isomers.

Transformation kinetics of trenbolone acetate metabolites and estrogens in urine and feces of implanted steers

Biotransformation of trenbolone acetate metabolites and estrogens derived from animal feeding operations in soils, waste storage systems, and in land applied manure has been well characterized. Yet recent data demonstrate potential for steroid transport into the environment directly from feedyard pens via runoff or airborne particulate matter. Therefore, the objective of this study was to determine steroid transformation rates in beef cattle excreta. Feces and urine were collected from steers recently treated with steroidal implants. Excreta were stored and periodically extracted over 112 d then analyzed for trenbolone acetate metabolites and estrogens by liquid chromatography mass spectrometry. Conjugated steroids were present primarily in urine, and conjugates quickly degraded to free steroid with a half-life of 0.6-1.0 d. The primary trenbolone acetate metabolite, 17α-trenbolone, had a half-life of 5.1-9.5 d. Likewise, 17α-estradiol was the predominant estrogen, with a half-life of 8.6-53 d. Secondary trenbolone metabolites formed from 17α-trenbolone biotransformation were observed at low concentrations less than 10% initial 17α-trenbolone concentrations. Estrone was the primary metabolite of 17α-estradiol and concentrations of estrone exceeded initial 17α-estradiol concentration in all sample types. These results suggest manure-borne steroids are more stable in excreta than in soil microcosms.

Can those organic micro-pollutants that are recalcitrant in activated sludge treatment be removed from wastewater by biofilm reactors (slow sand filters)?

The degradation of seven compounds which are usually recalcitrant in classical activated sludge treatment (e.g., diclofenac, propranolol, iopromide, iohexol, iomeprol tebuconazole and propiconazole) was studied in a biofilm reactor (slow sand filtration). This reactor was used to treat real effluent-wastewater at different flow rates (hydraulic loadings) under aerobic conditions so removal and degradation kinetics of these recalcitrant compounds were calculated. With the hydraulic loading rate of 0.012 m(3)m(2)h(-1) the reactor removed 41, 94, 58, 57 and 85% of diclofenac, propranolol, iopromide, iohexol and iomeprol respectively. For these compounds the removal efficiency was dependent on hydraulic residence-times. Only 59 and 21% of the incoming tebuconazole and propiconazole respectively were removed but their removal did not depend on hydraulic residence time. Biofilm reactors are thus efficient in removing micro-pollutants and could be considered as an option for advanced treatment in small wastewater treatment plants.

Concurrent degradation of tetrabromobisphenol A by Ochrobactrum sp. T under aerobic condition and estrogenic transition during these processes

The effect of concurrent degradation of tetrabromobisphenol A (TBBPA) by the strain Ochrobactrum sp. T under aerobic condition was investigated. The results demonstrated that four extra energy source-addition systems still followed pseudo-first order kinetics. The addition of ethanol or glucose could promote the biodegradation ability of Ochrobactrum sp. T to TBBPA, and 90.1 percent and 77.5 percent of TBBPA (5mg L(-1)) could be removed with corresponding TBBPA half-lives of 26 and 36h, respectively, after 96h reaction. Comparatively, the degradation efficiency of the sole TBBPA system was only 72.9 percent under the same condition. In contrast, two other co-substrates 2,4,6-tribromophenol (TBP) and bisphenol A (BPA) showed a negative effect on the TBBPA biodegradation, and the degradation efficiencies of TBBPA were achieved as 44.7 percent and 67.4 percent, respectively. For the TBBPA+TBP system, the competitive inhibition for the TBBPA debromination was less than the inhibition of the toxicity to the bacterium. While for the TBBPA+BPA system, the degradation of TBBPA could be promoted at the beginning of the reaction, and was then inhibited slightly with further prolonging of reaction time. This is probably due to the substrates being oxidized, and BPA can consume partial oxygen and provide the electrons during the concurrent biodegradation process. In addition, although higher estrogenic activity could be detected for the debrominated intermediates in TBBPA co-degradation process than the original TBBPA, the estrogenicity of the whole system still decreased finally after 96h degradation.

Waste degradation and gas production with enzymatic enhancement in anaerobic and aerobic landfill bioreactors

The presence of lignin is the limiting factor at later stages of biodegradation of municipal solid waste under aerobic or anaerobic conditions. Supplying enzymes into the system could facilitate lignin degradation, thereby aiding anaerobic and aerobic waste degradation processes. A comprehensive set of laboratory experiments were conducted under both anaerobic and aerobic conditions to evaluate the feasibility of using enzymes in accelerating lignin-rich waste degradation. After 30 days of anaerobic operation, MnP and LiP enzyme treated reactors produced 36 and 23 times higher cumulative methane (CH4), respectively, compared to that of the control reactor devoid of enzyme treatments. The carbon dioxide (CO2) yield of MnP enhanced aerobic reactor showed more than two-fold increase.

Wet air oxidation induced enhanced biodegradability of distillery effluent

The present study reports the feasibility of Wet Air Oxidation (WAO) as a pretreatment option for enhanced biodegradation of complex distillery effluent. Initially, the distillery effluent was pretreated by WAO at different process conditions (pressure, temperature and time) to facilitate enhancement in the biodegradability index (BI = BOD5: COD ratio). The biodegradability of WAO pretreated effluent was evaluated by subjecting it to aerobic biodegradation and anaerobic followed by aerobic biodegradation. Aerobic biodegradation of pretreated effluent with enhanced biodegradability index (BI = 0.4-0.8) showed enhanced COD reduction of up to 67.7%, whereas the untreated effluent (BI = 0.17) indicated poor COD reduction of only 22.5%. Anaerobic followed by aerobic biodegradation of pretreated effluent has shown up to 87.9% COD reduction, while the untreated effluent has shown only 43.1% COD reduction. Bio-kinetic parameters also confirmed the increased rate of bio-oxidation at enhanced BIs. The results indicate that the WAO pretreatment facilitates enhanced bio-oxidation/bio-degradation of complex effluents like the distillery spent wash.