Biodegradability Enhancement Research Articles

Organics removal in high strength petrochemical wastewater with combined microbubble-catalytic ozonation process

Ozonation is a well-known and widely applied advanced oxidation process (AOP) for industrial wastewater treatment, while the ozonation efficiency might be limited by low mass transfer, poor solubility, and rapid decomposition rate of ozone molecules in the aqueous phase. The present study aims to investigate the feasibility of combined microbubble-catalytic ozonation process (M-O3/Fe/GAC) for improving the ozonation efficiency during treatment of petrochemical wastewater (PCW). M-O3/Fe/GAC process optimization was carried out with different pH conditions, ozone dosages and catalyst loadings. The optimum operating conditions were identified as 50 mg L−1 ozone dosage, real PCW pH (7.0–7.5) and 4 g L−1 catalyst loading. Among different ozonation processes, M-O3/Fe/GAC process achieved the highest chemical oxidation demand (COD) removal efficiency of 88%, which is 18% and 43% higher than those achieved by the microbubble and macrobubble ozonation processes, respectively. Phenolic compounds presented in PCW could be reduced by 63% within 15 min in M-O3/Fe/GAC treatment process. Long-term continuous flow studies suggested M-O3/Fe/GAC process to be the most cost-effective technology for PCW treatment with an operating cost of S$0.18 kg−1 COD and S$0.4 m-3 with good catalyst stability. Liquid size exclusion chromatography with organic carbon detection (LC-OCD) data suggested humic substances to be the dominant organic species in PCW, M-O3/Fe/GAC could achieve significant humic substances removal and biodegradability enhancement in PCW. Kinetics and mechanism studies revealed that organics removal in M-O3/Fe/GAC was 1.8 times higher than that in microbubble ozonation process, and hydroxyl radical (●OH) was the dominant oxidant specie for organics removal in M-O3/Fe/GAC process.

Enhancement of phenol biodegradation: Metabolic division of labor in co-culture of Stenotrophomonas sp. N5 and Advenella sp. B9

The aim of this work is to study the synergistic effect of Stenotrophomonas sp. N5 and Advenella sp. B9 co-culture (COC) on enhancement of phenol biodegradation. These two strains utilizing phenol as sole carbon and energy source were isolated from phenol-containing coking wastewater. The results of biodegradation experiment showed the COC of N5 and B9 has stronger capability to degrade phenol than either of mono-culture (MOC). Growth kinetics studies indicated inhibitory effect of phenol on COC was reduced by the interaction of N5 and B9 in COC. The RNA-Seq results demonstrated that phenol biodegradation was enhanced by metabolic division of labor (DOL) in COC based on the expression of key genes for phenol degradation. GO enrichment analysis of differentially expressed genes (DEGs) indicated DEGs between COC and MOC degradation systems are mainly concentrated in the synthesis of cell components, microbial growth and metabolism, and catalytic activity. The expression of 3 transcriptional factors (LysR, Two-component system response regulator, and TetR families) which can regulate degradation of aromatic compounds, was identified beneficial to phenol degradation.

Enhancement of hydrophilicity, biocompatibility and biodegradability of poly(ε-caprolactone) electrospun nanofiber scaffolds using poly(ethylene glycol) and poly(L-lactide-co-ε-caprolactone-co-glycolide) as additives for soft tissue engineering

In this study, poly(ε-caprolactone) (PCL) has been blended with a more hydrophilic poly(ethylene glycol) (PEG) and with a biocompatible block-co-polymer: poly(L-lactide-co-ε-caprolactone-co-glycolide) (PLCG) in order to improve hydrophilicity, biocompatibility and biodegradability of PCL. PCL and the blend solutions were subjected to electrospinning to produce nanofiber scaffolds by the addition of only 1 wt% of PEG and PLCG either singly or in combination in PCL to retain the mechanical properties of the scaffolds. PCL-PEG-PLCG ternary and two binary (PCL-PEG and PCL-PLCG) blend nanofiber scaffolds have been prepared for comparison. The resulting nanofibers showed a smooth and flaw-free surface and the diameter of the nanofibers displayed a normal distribution. The PCL-PEG nanofiber scaffold showed improved hydrophilicity [water contact angle (WCA) ∼84°] over pristine PCL (WCA ∼127°); while PCL-PLCG and PCL-PEG-PLCG scaffolds exhibited absolute wetting by water, likely due to high porosity. In vitro biocompatibility studies using gingival mesenchymal stem cells (gMSCs) suggested that, both the PCL and the blend scaffolds were biocompatible supporting cell-viability and growth of gMSCs following their seeding on these scaffolds. Biodegradation studies in phosphate buffer solution showed that the addition of PEG and PLCG in PCL increased the weight loss of scaffolds with time, indicating higher extent of biodegradation in the blend scaffolds and the weight loss followed the power law curve with time.

Low-current electro-oxidation enhanced the biodegradation of the recalcitrant naphthenic acids in oil sands process water

Combining electro-oxidation (EO) with biodegradation for real oil sands process water (OSPW) treatment was evaluated in terms of naphthenic acid (NA) biodegradation enhancement. Ion mobility spectrometry (IMS) qualitative analysis showed that EO by graphite was able to degrade the different NA clusters in OSPW including: classical, oxidized and heteroatomic NAs. Applying EO even at current density as low as 0.2 mA/cm2 was still able to reduce classical NAs and acid extractable fraction (AEF) by 19% and 7%, respectively. EO pretreatment preferentially broke long carbon chains and highly cyclic carboxylic fractions of NAs in OSPW to improve the biodegradation of NAs. Aerobic biodegradation for 40 days reduced NAs by up to 30.9% when the samples were pre-treated with EO. Applying EO at current densities below 2 mA/cm2 maintained current efficiency as high as 48% and resulted in improvement in the biodegradation rate of remaining NAs by up to 2.7 folds. It was further revealed that applying EO before biodegradation could reduce the biodegradation half-life of classical NAs by up to 4.4 folds. 16S amplicon sequencing analysis showed that the samples subjected to biodegradation had increased abundances of Sphingomonadales and Rhodocyclales with increasing applied current density for EO pre-treatments.

Electro-Fenton treatment of a complex pharmaceutical mixture: Mineralization efficiency and biodegradability enhancement

Combination of the electro-Fenton process with a post-biological treatment could represent a cost-effective solution for application of electrochemical advanced oxidation processes. The objective of this study was to assess this treatment strategy in the case of a complex pharmaceutical mixture. First, main operating parameters ([Fe2+] and current) of the electro-Fenton process were optimized. An optimal concentration of 0.2 mM of Fe2+ was obtained for mineralization of the pharmaceutical mixture. An optimal current of 400 mA was also obtained for degradation of caffeine and 5-fluorouracil in the mixture. However, mineralization of the effluent was continuously improved when increasing the current owing to the promotion of mineralization of organic compounds at the BDD anode. Besides, energy efficiency was decreased at prolonged treatment time because of mass transport limitation. Interestingly, it was observed a strong biodegradability enhancement of the solution after short treatment times (<3 h) at 500 and 1000 mA, which can be related to the degradation of parent compounds into more biodegradable by-products. The need for an acclimation time of the biomass to the pre-treated effluent was also emphasized, most probably because of the formation of some toxic by-products as observed during acute toxicity tests. Therefore, a biological post-treatment could represent a cost-effective solution for the removal of biodegradable residual organic compounds as well as for the removal of nitrogen released from mineralization of organic compounds under the form of NO3− and NH4+ during electro-Fenton pre-treatment.

Enhancement of biodegradability and tensile characteristics of composite plastic film with spirulina algal biomass

This paper presents the possibility of blending the Spirulina Algae with Poly-Vinyl Alcohol (PVA) in producing composite plastic film with higher biodegradability. In this paper, the tensile characteristics and biodegradation rate of the plastic films with different blending ratio of algae with PVA was investigated. By using solvent casting technique, the composite films with 0%, 5%, 10% and 20% (wt/wt) of algae/PVA were fabricated. The soil degradation results show that the degradation increased as the algal percentage increased. The composite plastic film gave up to ∼50% of weight loss after 1 week of degradation process. Besides, by comparing with other study, the soil degradation results of this study suggested that Spirulina Algae can be act as a better blender with PVA in producing plastic film as compared to corn starch. Moreover, the plastic film demonstrated an excellent tensile characteristic with the increment of algal proportional. The ultimate tensile strength, however, remained constant at around 165 MPa for 10% and 20% algae/PVA plastic films, which was higher than the other previous study. With this high ultimate tensile strength, it was suggested that the algae/PVA composite film are more applicable towards heavy-duty plastics manufacturing sectors that requires tough and durable plastic films. In short, the optimal proportion of Spirulina Algae to PVA for the production of composite plastic film is 20 (wt/wt)% as it gave high ultimate tensile strength and at the same time has the highest biodegradability.

Integrated anaerobic digestion and photodegradation of slaughterhouse wastewater: Energy analysis and degradation of aromatic compounds

Combined anaerobic digestion (AD) and photodegradation of slaughterhouse wastewater (SWW) was carried out to remove biodegradable chemical oxygen demand (COD) and biorecalcitrant aromatic compounds which were mainly p-cresol and dibutyl phthalate (DBP). The synergy between the two processes was analyzed through biodegradability enhancement by photodegradation and supply of bioenergy through AD to supplement the energy requirement of the photodegradation process. Degradation products of each process were determined using gas chromatography coupled with a mass spectrometer (GC–MS). Anaerobic digestion as a stand-alone process removed up to 80% COD, while it could only remove about 35% of the aromatic compounds. Photodegradation, as a post-treatment to the AD, removed 92% of the aromatic compounds and enhanced the biodegradability of the digester effluent by 50%, which could be recycled to the AD unit. The aromatic compounds were photodegraded via phthalic acid and hydroquinone. Also, AD as an initial step removed fats, oils, and grease which otherwise would have hindered catalytic activity during photodegradation post-treatment. The biomethane produced could supplement up to 20% of the electricity requirement by the energy-intensive photodegradation process to achieve total pollutants removal, making the integrated process to be a viable option for SWW management.

Ozone-driven processes for mature urban landfill leachate treatment: Organic matter degradation, biodegradability enhancement and treatment costs for different reactors configuration

In this work, the application of ozone-driven processes for the treatment of mature landfill leachate was investigated by testing different system setups. As a first approach, ozonation (O3-only) was tested, using a porous ceramic diffuser combined with a bubble column (BC), and the best operational conditions were established for leachate treatment (initial pH = 9.0; inlet ozone dose = 18 mg O3/min). Then, a novel photoreactor (FluHelik) was coupled in series with the bubble column, using a diffuser or a Venturi to inject ozone into the fluid stream. The FluHelik/BC-Venturi setup led to the highest efficiency, treating 50% more leachate than BC-alone using the same ozone dose and reaction time (3 h). Following, the oxidation ability of ozone combined with H2O2 and/or UVC for leachate treatment was assessed. The highest synergistic effect was obtained for the O3/UVC process, with pseudo-first-order rate constant for DOC and COD removal, 2.0 and 1.4 times higher than for the O3-only, respectively. Ozone-driven processes considerably enhanced the leachate biodegradability from 17% to 79% (O3/H2O2), 81% (O3-only), 85% (O3/H2O2/UVC) and 91% (O3/UVC), after a 3 h reaction period. With FluHelik/BC-Venturi system, the O3/UVC process stands out as the most efficient and cost-effective (6.0 €/m3), ensuring an effluent that meets discharge legal limit for COD (150 mg/L) after further biological oxidation.

Tertiary treatability of molasses secondary effluents for color and organics: performance and limits of ozonation and adsorption

Molasses wastewaters (MWWs) such as baker’s yeast and distilleries effluents are usually pretreated by anaerobic, followed by aerobic biodegradation. This removes almost all the BOD, enough for meeting the current discharge standards in many low- and middle-income countries. However, as shown in the present work, the biotreated effluent still contains high levels of recalcitrant COD, color (melanoidins) and inorganic salts that end up in rivers (approx. 1000 mg/L COD, 2850 Pt–Co color units, 5000 mg/L TDS and 5400 μS/cm conductivity). To address this global problematics, and given the lack of proven cost-effective advanced treatment trains for MWW, this study assessed the performance and limits of ozonation and activated carbon (AC) adsorption (contrasting with O3 applications on raw MWW). The applied versus the reacted O3 doses were quantified, allowing also to estimate the ozone uptake rate as a new tool for characterizing the reactivity of the wastewaters. The effects of the treatments on different key parameters were studied: COD, color, aromaticity (UV254 nm), toxicity (Microtox) and biodegradability (by respirometry). O3 reduced the color (> 95%), but causing low COD mineralization (< 35%) and biodegradability enhancement (only 8% more). Meanwhile, adsorption was efficient on both COD and color (97–91%), but needing high AC dosage. In consequence, a more sustainable treatment train was suggested, i.e., upgrading the activated sludge with aerobic granular sludge technology and transforming the granules into AC.

Carbon mineralization, biological indicators, and phytotoxicity to assess the impact of urban sewage sludge on two light-textured soils in a microcosm.

The agricultural reuse of urban sewage sludge (USS) modifies soil properties depending on sludge quality, management, and pedo-environmental conditions. The aim of this microcosm study was to assess C mineralization and subsequent changes in soil properties after USS addition to two typical Mediterranean soils: sandy (Soil S) and sandy loam (Soil A) at equivalent field rates of 40 t ha-1 (USS-40) and 120 t ha-1 (USS-120). Outcomes proved the biodegradability of USS through immediate CO2 release inside incubation bottles in a dose-dependent manner. Accordingly, the highest rates of daily C emission were recorded with USS-120 (3.7 and 3.9mg kg-1 d-1 for Soils S and A, respectively) after 84 d of incubation at 25 °C. The addition of USS also improved soil fertility by enhancing soil macronutrients, microbial proliferation, and protease activity. Protease showed significant correlation with N, total organic C, and heterotrophic bacteria, reflecting the biostimulation and bioaugmentation effects of sludge. Soil indices like C/N/P stoichiometry and metabolic quotient (qCO2 ) varied mostly with mineralization rates of C and P in both soils. Despite a significant increase of soil salinity and total heavy metal content (lead, nickel, zinc, and copper) with USS dose, wheat germination was not affected by these changes. Both experimental soils showed intrinsic (Soil A) and incubation-induced (Soil S) phytotoxicities that were alleviated by USS addition. This was likely due to the enhancement of biodegradation and/or retention of phytotoxicants originating from previous land uses. Urban sewage sludge amendments could have applications in soil remediation by reducing the negative effects of allelopathic and/or anthropogenic phytoinhibitors.

Highly biodegradable fluoroquinolone derivatives designed using the 3D-QSAR model and biodegradation pathways analysis.

A three-dimensional quantitative structure-activity relationship (3D-QSAR) model was established based on molecular structures and docking scores (representing the biodegradability); the scores were obtained for 23 fluoroquinolones (FQs) and the oxidoreductase (PDB ID: 1YZP) of Phanerochaete chrysosporium in the aerobic process of municipal wastewater treatment plants. In the Comparative Molecular Field Analysis (CoMFA) model, q2 was 0.516 and r2pred was 0.727, which showed that the model was reliable and robust. The modification information obtained by the contour maps showed that introducing electronegative, bulky or electropositive groups at different active sites could increase the biodegradability of fluoroquinolone derivatives. Using levofloxacin (LEV) as a modified molecule, 35 fluoroquinolone derivatives with higher biodegradability than LEV were designed. After the evaluation of genotoxicity, bioconcentration and photodegradation, Derivative-15, with higher biodegradability (increased by 27.85%), higher genotoxicity, higher photodegradation and lower bioconcentration, was identified as the most environmentally friendly fluoroquinolone derivative. The 2D-QSAR model of FQ biodegradability was established through the quantization parameters, and q+ was identified as the main parameter affecting the biodegradability of FQs through sensitivity analysis. In addition, the docking results of LEV and Derivative-15 with the oxidoreductase in P. chrysosporium showed that the electrostatic field force between Derivative-15 and the amino acid residues promoted the binding of the donor to the receptor protein, thereby increasing the biodegradability of Derivative-15. Additionally, molecular dynamics simulations revealed that the enhancement of the electrostatic field force with Derivative-15 could promote the binding of the ligand to the receptor, which was basically consistent with the conclusion of molecular docking. Finally, the three microbial degradation pathways of LEV and Derivative-15 were also proposed. The total energy barrier value of the pathway with the lowest total energy barrier of biodegradation was reduced by 32.07%, which was basically consistent with the enhancement of biodegradability of Derivative-15.

Biodegradability enhancement and pre-treatment of industrial estate wastewater by electro-Fenton process

Advanced oxidation processes have been applied as one of the main commonly treatment methods to improve the biodegradability of persistent organic materials, especially in industrial wastewaters. In this study, the chemical oxygen demand (COD) and total oxygen carbon (TOC) removal efficiency and biodegradability improvement of the industrial estate wastewater were investigated by electro-Fenton process (EFP). The influences of various parameters including pH, H2O2 concentration, electrical current density, and reaction time were evaluated on the EFP. The maximum removal efficiency of COD (88) and TOC (80.8) was achieved at optimum pH 4, H2O2 concentration 13.5 mM, current density 5 mA cm(-2), and reaction time 20 min. The optimum H2O2/Fe2+ molar ratio was found to be 2. The biodegradability of the wastewater was increased from 0.23 to 0.39 after treatment by EFP under optimum conditions. The results showed that H2O2/Fe2+ molar ratio was the most important factor in the EFP system. The findings showed that the EFP can be considered as a suitable technique for pre-treatment and biodegradability enhancement of the industrial estate wastewater. So, this wastewater can be easily post-treated by biological treatment methods.

Methane production enhancement and comparative study of biodegradation of some plants and animal wastes

This study investigated the production of methane using various substrates. Plantain peels, pig dung, poultry droppings, walnut peels/plantain peels and cow blood/wheat waste were all co-digested, charged in digesters (A-E) and allowed to ferment anaerobically for forty-five (45) days within the mesophilic temperature range of 20.0-39.0°. Digester A contained 3.9 Kg of wheat waste/cow blood and 19.5 Kg of water in the ratio of 1.5 which gave a total gas yield of 22.5 L of biogas; B contained 7.8 Kg of walnut peels/plantain peels and 15.6 Kg of water in the ratio 1:2 which gave a total gas yield of 115.0 L; C contained 8 Kg of plantain peels and 16 Kg of water which yielded 133.0 L of biogas; D contained 8 Kg of pig dung mixed thoroughly with 16 Kg of water which gave a total of 321.0 L; and E contained 8 Kg of poultry droppings mixed with 16 Kg of water which yielded 168.5 L of biogas. From the cumulative comparison of the biogas yields of the samples, pig dung gave the highest yield of 321 L and cow blood/wheat husk produced the lowest yield of 22.5 L. Pig dung (animal waste) gave the highest total viable count (TVC) of 7 × 106 cfu/mL. The sludge contains NPK which is a good biofertilizer.

Colour removal and biodegradability enhancement of biomethanated spent wash from distillery using wet oxidation treatment

In India, high strength spent wash (SW) produced from alcohol distilleries is preferably treated by biomethanation process. However, biomethanated SW (BMSW) still contains intensified dark brown colour, high chemical oxygen demand (COD) and poor biodegradability which requires further treatment before disposal. Wet oxidation (WO) is considered an effective treatment for high strength non-biodegradable wastewaters (COD > 10 g/L). Hence, the present study explored WO of BMSW (pH = 5.7, COD = 65.5 g/L, and total organic carbon (TOC) = 23.5 g/L) in a high pressure batch reactor (0.7 L capacity) at temperatures ranging from 160-220°C and oxygen pressure of 1.1 MPa. At 220°C temperature, TOC, COD and color removals of 39%, 59% and 90%, respectively, were observed after 3 h of reaction period. Meanwhile, biodegradability index (BI) was enhanced from 0.27 to 0.81. Carbon balance calculations showed that the oxidation reaction contribution in TOC removal was enhanced with increase in temperature (64 – 92% of total carbon removal). Fourier transform infrared (FTIR) analysis suggested the precipitation of carbonyl group and nitrogen containing compounds. During the reaction, volatile fatty acids (oxalic acid, malonic acid and acetic acid) formation was also confirmed in the treated wastewater.

Study of biodegradability of the vegetable oil modified epoxy coatings

АBSTRACT&#x0D; Introduction. For solving environment protection problems and reducing the volume of ‘polymer waste’, the study of biodegradability of polymer materials by means of their modification without impairing main performance is of practical importance. This is achievable by application of biodegradable natural additives. The radical solution is the development of polymer materials that are capable of retaining their performance throughout their service life only.&#x0D; Materials and methods. To modify compositions, APh-2 aminoalkylphenol-cured ED-20 epoxy diane resin was used. Liquid fraction of rubber tree oil (RTO) and Vietnam-produced soybean oil (SO) were used as the modifiers. Biodegradability of the materials was evaluated by Sturm’s method checking respirometric activity of soil in their presence. Resistance of the epoxy materials to microbiological putrefaction in soil was investigated by mass loss value. Thermal stability of the epoxy coatings was tested by simultaneous thermal analysis on Netzch-Gerätebau GmbH apparatus at the heating rate 10 °C/min when the temperature varying within the range of 25 °C to 600 °C. Water absorption was evaluated as per GOST 4650-2014 standard. Sol-gel analysis was implemented in boiling acetone in the Soxhlet apparatus. Abrasion hardness of epoxy materials was carried out on the IZV-1 vertical optical caliper. Hardness was checked by Barcol impressor. Frictional factor was determined by means of the CSM Instruments Tribometer automated friction machine.&#x0D; Results. Applying vegetable oils governs a significant growth of the abrasion resistance and enhancement of antifriction characteristics of epoxy materials. The vegetable oils exercise a plasticizing effect on epoxy compositions, accelerate processes of epoxy material biodegradation in soil and reduce their resistance to micromyces. Epoxy resin is characterized with high funginertness and its modification by the RTO results in enhancement of biodegradability when exposed to mouldy fungi.&#x0D; Conclusions. Applying the RTO as a modifier of the epoxy materials accelerates processes of their biodegradation in soil and decreases their resistance to micromyces. The higher biodegradation of vegetable oil-modified epoxy films takes place at complex exposure to bacteria and mycelian fungi as a part of soil microbiocenosis.

ENHANCING BIOREMEDIATION OF CRUDE OIL CONTAMINATED SOIL BY COMBINING WITH PHOTOCATALYTIC PROCESS USING TiO2 AS CATALYST

One of the continuous environmental problems is hydrocarbon contamination caused by the activity of the petroleum industry. Although many contaminated sites were successfully cleaned up by bioremediation treatment, a number of field reports indicated that biological treatment was sometimes found to be very slow or incomplete mineralization occurred. Lack of bioavailability has been identified as one of the important factors that may inhibit a fast and complete degradation process. Enhancement of chemicals biodegradability during chemical oxidation gives a presumption to investigate the ability of combined photo-catalytic process using TiO2 under sunlight illumination and biodegradation. This study was expected to overcome the limitation of hydrocarbon bioavailability. The experiments were conducted in a reactor made of 25 cm x 15 cm x 10 cm glass pans microcosms by varying TiO2 concentration from 0.5, 1, 2, to 3% (w/w) and two control reactors: biostimulation and natural attenuation. During the 12-week study, several parameters were analyzed, including the main parameters: TPH gravimetric, heterotrophic bacteria, petrophylic bacteria, and other parameters, such as pH, moisture content, organic carbon, total nitrogen, and UV intensity. The results showed that the addition of photocatalyst TiO2 was adequately significant in enhancing TPH removal rates. However, the increasing concentration of TiO2 added to the reactors did not always show proportionality to the increasing of TPH degradation rates. TPH degradation rates were influenced by indigenous petrophylic bacteria activities and energy derived from UV light. The highest TPH degradation rate was found when 2% (w/w) of TiO2 added.

Comparison between Thermo-Alkaline and Electro-Fenton Disintegration Effect on Waste Activated Sludge Anaerobic Digestion.

Disintegration of municipal waste activated sludge (WAS) using thermo-alkaline (TA) and electro-Fenton (EF) methods was investigated and compared in terms of the efficiency of sludge solubilisation and enhancement of anaerobic biodegradability. Performance of organic matter solubilisation (soluble COD, proteins, polysaccharides) of sludge pretreated with EF was proved to be better than that with TA pretreatment, which resulted in the enhancement of anaerobic biodegradability. Comparison of results indicated that percentages of PN and PS release obtained after EF pretreatment (68.95 and 65.22%) were higher than those obtained by TA method (45.25 and 35.22%) respectively. An improvement of biogas potential about 2 and 1.6 times was achieved respectively by EF and TA pretreatment in comparison to raw sludge. During semi-continuous fermentation study in continuous stirred tank reactor, EF pretreated sludge gave the best biogas yield (0.6 L biogas/g COD) at an OLR of 2.5 g COD/L. d in comparison to TA pretreated sludge (0.3 L biogas/g COD), where low biogas yield about 0.1 L biogas/g COD was registered by raw sludge in the same CSTR. Therefore, the integration of EF process to anaerobic digestion might be a promising process for sludge reduction and biogas recovery.

Potential of combined advanced oxidation – Biological process for cost-effective organic matters removal in reverse osmosis concentrate produced from industrial wastewater reclamation: Screening of AOP pre-treatment technologies

While reverse osmosis (RO) technology is playing an important role in industrial wastewater reclamation, safe and cost-effective RO concentrate (ROC) disposal becomes challenging due to high levels of organic pollutants. The present study assessed the feasibility of combined advanced oxidation – biological process for organics removal in real ROC. Four advanced oxidation processes (AOPs) were evaluated for ROC pre-treatment, including UV/H2O2, UV/Persulfate (PS), Fenton and Fluidized bed reactor (FBR)-Fenton processes. Based on the results of process optimization and cost evaluation, FBR-Fenton was identified as the most cost-effective pre-treatment technology with a chemical cost of S$0.519/m3. Under the optimum operating conditions with 10 mM H2O2, 1.25 mM Fe2+, pH 3 and HRT of 1 h, continuous FBR-Fenton process increased the BOD5/COD ratios in ROC by 4.2–10.0 times, while the COD removal efficiency was in the range of 30.9–59.8%. A biological activated carbon (BAC) column with EBCT of 120 min was combined with FBR-Fenton for continuous treatment of ROC. Over the 120-day operation, the combined system performed consistent organics removal in ROC with an average COD removal efficiency of 69%. The average effluent COD level in ROC was observed to be 26 mg/L. Both LC-OCD data and fluorescence EEM spectra suggested humic substances to be the dominant organic species in ROC, FBR-Fenton could achieve significant humic substances removal and biodegradability enhancement in ROC. High-throughput sequencing demonstrated Planctomycetes to be top dominant phylum in BAC media with high salinity influent, and FBR-Fenton process promoted its proliferation for higher COD removal efficiency in ROC.

Enhancement of solubilization and biodegradation of petroleum by biosurfactant from Rhodococcus erythropolis HX-2

The demand to repair areas contaminated with hydrocarbon products has led to the development of new technologies for the treatment of contaminants in an unconventional method, that is, no physical or chemical methods are used. Biosurfactants are amphiphilic biomolecules produced by microorganisms that can be used in environments contaminated by petroleum products due to their unexceptionable tensile properties. Petroleum degrading strain Rhodococcus erythropolis HX-2 was found to be an effective producer of biosurfactants. The resulting biosurfactant (named NK) exhibits high physicochemical properties in terms of surface activity. It is capable of reducing surface tension from 54.99 to 28.89 mN/m and critical micelle concentration (CMC) is 100 mg/L. NK was found to be a substitute for chemically synthesized surfactants because of its higher solubilization efficiency for petroleum and polycyclic aromatic hydrocarbons, superior to SDS, Tween 80, Triton X-100 and Rhamnolipid (a wide used biosurfactant). In addition, it exhibits favorable emulsion stability over a wide range of pH (3–10), temperature (20–100 °C) and salinity ranges (5–20 g/L). It was found that the addition of biosurfactant can improve the efficiency of petroleum degradation, therefore it has potential applications in bioremediation.HighlightsRhodococcus erythropolis HX-2 is an effective petroleum degrading strain.HX-2 is a potential source of biosurfactant production.The biosurfactant NK reduces surface tension and exhibits high emulsification activity.The biosurfactant NK is effective over a wide range of temperatures, pH and salinity.The biosurfactant NK shows high solubilization efficiency for petroleum as well as polycyclic aromatic hydrocarbons.

Polyaniline nanoparticles magnetically coated Ti/Sb-SnO2 electrode as a flexible and efficient electrocatalyst for boosted electrooxidation of biorefractory wastewater.

In this paper, a novel electrode named 2.5D Ti/Sb-SnO2/PANI was developed by magnetically in-situ integration of adsorbent and electrocatalyst, where the green synthetic Fe3O4/polyaniline (PANI) nanoparticles with fair adsorption capability were used as auxiliary electrodes and coated on the surface of Ti/Sb-SnO2 main electrode, to enrich the pollutants in the vicinity of anode and therefore boost the electrochemical oxidation (EO) efficiency. Since the interchangeable auxiliary electrodes can endow the anode with adjustability and versatility, the effect of auxiliary electrodes on the surface structure and electrochemical properties of 2.5D Ti/Sb-SnO2/PANI were extensively investigated. Results showed that a tiny amount of Fe3O4/PANI auxiliary electrodes changed the solid-liquid interface, brought massive less acessible active sites and kept the similar electrode impedance and same EO capability of 2D Ti/Sb-SnO2. In terms of organic elimination and solution biodegradability enhancement, 2.5D Ti/Sb-SnO2/PANI showed a boosted 30%-60% EO efficiency on two typical biorefractory targets, i.e., Acid Red G and lignosulphonate. The specific effectiveness was dependent on the loading amount of magenetic PANI nanoparticles. The operating mechanism of the assembled 2.5D Ti/Sb-SnO2/PANI electrode was further proposed based on many details, as well as a design rule for developing novel electrodes with high efficient EO performance for wastewater treatment. Moreover, the assembled 2.5D electrode was proved to have good sustainability and recyclability, which shows a great potential in the practical applications.