Synchronous COD removal and nitrogen recovery from high concentrated pharmaceutical wastewater by an integrated chemo-biocatalytic reactor systems

Present report, an investigation of highly concentrated and low bio-degradable pharmaceutical wastewater (HCPWW) treatment; simultaneously ammoniacal nitrogen recovery for struvite fertilizer. The use of multiple solvents and many formulation processes in HCPWW, resulting highly refractory chemicals. Here, in this study focused on evaluation of chemo-biocatalysts for the removal of refractory organics, nitrogen recovery from HCPWW. The initial organics, and nitrogen content in HCPWW was 20,753 ± 4606 mg/L; BOD, 6550 ± 1500 mg/L and NH₄⁺-N, 1057.9 ± 185.8 mg/L. Initially, the biodegradability (BOD₅: COD ratio from 0.32 to 0.45) of HCPWW, which was improved by heterogeneous Fenton oxidation (HFO) processes, and porous carbon (PCC, 30 g/L), along with FeSO₄.7H₂O, 200 mg/L and H₂O₂ (30% v/v), 0.4 ml/L were used as a catalyst in a weakly acidic medium. For the biocatalytic processes, the microbial culture cultivated from sewage and incorporated into a Fluidized Immobilized Carbon Catalytic Oxidation reactor (FICCO), and dominant species are Pseudomonas Putida sp., Pseudomonas Kilionesis sp., and Pseudomonas Japonica sp., which is identified by using 16 S rDNA sequencing analysis. The COD and BOD₅ removal efficiency of 65-93% and 70-82%, and follow the pseudo-second-order kinetic model with the rate constants of 1.0 × 10^-4 L COD^-1 h^-1, 1.5 × 10^-3 L COD^-1 h^-1 and 3.0 × 10^-3 L COD^-1 h^-1 in the HFO-FICCO-CAACO catalytic processes. The optimized hydraulic retention time (HRT) of FICCO reactor was 24 h, and 1 h for the Chemo-Autotrophic Activated Carbon Oxidation (CAACO) reactor for maximum organics removal. MAP (Magnesium Ammonium Phosphate precipitation) process showed 90% of NH₄⁺-N elimination and recovered it as a struvite fertilizer at an optimum molar ratio of 1:1.3:1.3 (NH₄⁺-N: Na₂HPO₄.2H₂O: MgO). FT-IR, UV-visible, and UV-fluorescence data confirm the effective elimination of organics. Hence, this integrated treatment system is appropriate for the management of pharmaceutical wastewater especially elimination of complex organic molecules and the recovery of nitrogen in the wastewater.

Biocatalytic lipoprotein bioamphiphile induced treatment of recalcitrant hydrocarbons in petroleum refinery oil sludge through transposon technology

The present investigation employed transposon technology to enhance the degradation of recalcitrant petroleum hydrocarbons present in petroleum oil sludge by using biosurfactant hyper-producing strain Enterobacter xiangfangensis STP-3. Out of 2500 transposon induced mutants, mutants M_{257E.xiangfangensis} and M_{916E.xiangfangensis} hyper-produce biocatalytic lipoprotein biosurfactant by1.98 and 2.34 fold higher than wild-type strain. Transposon induced mutation also modified the amino acid composition which improved the hydrophobicity and thermal stability of the biosurfactants produced by mutants, compared to the wild-type biosurfactant. GC-MS and LC-MS-MS revealed that biosurfactants have pentameric lipid moiety and esterase as protein moiety. Increased biosurfactant hydrophobicity and yield by the mutants resulted in the enhanced bioavailability of petroleum hydrocarbons, thereby mutants M_{257E.xiangfangensis} and M_{916E.xiangfangensis} demonstrated better petroleum oil sludge degradation by 82% and 88% respectively, than wild-type (72%). Disrupted genes vgr G and pgm M in M257_{E.xiangfangensis} and M916_{E.xiangfangensis} respectively hyper-produce biosurfactant by competitive pathway inhibition and increased precursor availability mechanism. Hyper-production of biosurfactant was also validated by comparing the expression of biosynthetic genes ent E, ent F and est using qPCR. This is the first report on the application of transposon technology to hyper-produce biosurfactant for the effective bioremediation of hydrocarbon contaminated environments.

Biosequestration of lignin in municipal landfill leachate by tailored cationic lipoprotein biosurfactant through Bacillus tropicus valorized tannery solid waste

Bioremediation of municipal landfill leachate (MLL) is often intricate due to presence of refractory lignin. In the present study, it was attempted to tailor the histidine rich protein moiety of cationic lipoprotein biosurfactant (CLB) to sequester the lignin from MLL. Animal fleshing (AF), the solid waste generated in tanning industry was utilized for the production of histidine rich CLB by de novo substrate dependent synthesis pathway involving Bacillus tropicus. The optimum conditions for the maximum production of CLB were determined using response surface methodology. At the optimized conditions, the maximum yield of CLB was 217.4 mg/g AF (on dry basis). The produced histidine rich CLB was purified using Immobilized metal affinity chromatography at the optimum binding and elution conditions. The histidine residues were more pronounced in the CLB, as determined by HPLC analysis. The CLB was further characterized by SDS-PAGE, Zeta potential, XRD, FT-IR, Raman, NMR, GC-MS and TG analyses. The CLB was immobilized onto functionalized nanoporous activated bio carbon (FNABC) and the optimum immobilization capacity was found to be 211.6 mg/g FNABC. The immobilization of CLB onto FNABC was confirmed using SEM, FT-IR, XRD and TG analyses. The isotherm models, kinetic and thermodynamics studies of CLB immobilization onto FNABC were performed to evaluate its field level application. Subsequently, the CLB-FNABC was then applied for the sequestration of lignin in MLL. The maximum lignin sequestration was achieved by 92.5 mg/g CLB-FNABC at the optimized sequestration time, 180 min; pH, 5; temperature, 45 °C and mass of CLB-FNABC, 1.0 g. The sequestration of lignin by CLB- FNABC was confirmed by SEM, FT-IR and UV-Vis analyses. Further, the mechanistic study revealed the anchoring of CLB onto the surface of lignin through electrostatic interaction.

Genomic characterization of Enterobacter xiangfangensis STP-3: Application to real time petroleum oil sludge bioremediation

Sustainable treatment of petroleum oil sludge still remains as a major challenge to petroleum refineries. Bioremediation is the promising technology involving bacteria for simultaneous production of biosurfactant and followed by degradation of petroleum compounds. Complete genomic knowledge on such potential microbes could accentuate its successful exploitation. The present study discusses the genomic characteristics of novel biosurfactant producing petrophilic/ petroleum hydrocarbon degrading strain, Enterobacter xiangfangensis STP-3, isolated from petroleum refinery oil sludge contaminated soil. The genome has 4,584,462 bp and 4372 protein coding sequences. Functional analysis using the RAST and KEGG databases revealed the presence of biosynthetic gene clusters linked to glycolipid and lipopeptide production and multiple key candidate genes linked with the degradation pathway of petroleum hydrocarbons. Orthology study revealed diversity in gene clusters associated to membrane transport, carbohydrate, amino acid metabolism, virulence and defence mechanisms, and nucleoside and nucleotide synthesis. The comparative analysis with 27 other genomes predicted that the core genome contributes to its inherent bioremediation potential, whereas the accessory genome influences its environmental adaptability in unconventional environmental conditions. Further, experimental results showed that E. xiangfangensis STP-3 was able to degrade PHCs by 82 % in 14 days during the bioremediation of real time petroleum oil sludge with the concomitant production of biosurfactant and metabolic enzymes, To the best of our knowledge, no comprehensive genomic study has been previously reported on the biotechnological prospective of this species.

Biodegradation of petroleum refining industry oil sludge by microbial-assisted biocarrier matrix: process optimization using response surface methodology

Safe disposal of petroleum oil sludge generated from crude oil storage tank bottom is a major challenge for petroleum refineries across the globe. The presence of long chain hydrocarbons in petroleum oil sludge are known to have effects on the environment through bioaccumulation or biosorption. The present study was focused to develop a modified bioremediation process using hydrocarbonoclastic microbial-assisted biocarrier matrix (MABC) mediated through biosurfactants and biocatalysts for the efficient treatment of petroleum industrial oily sludge. The development of hydrocarbonoclastic microbial-assisted biocarrier matrix was confirmed by scanning electron microscopy analysis. The biocatalysts such as lipase, laccase, esterase and biosurfactant produced by MABC system were found to be 40 U/mg, 18 U/mg, 36 U/mg and 220 mg/g of oil sludge respectively using one variable at a time approach. Further, the response surface methodology was used to determine the optimum treatment conditions (Time, pH, Mass of biocarrier matrix and Amount of oil sludge) for the enhanced removal of total petroleum hydrocarbons (TPH) present in the oil sludge and TPH was degraded by 88.78% at Hydraulic Retention Time of 7 days. The biodegradation of oil sludge was confirmed using Gas Chromatography-Mass Spectrometry analysis.

Nano fibrous carbon produced from chromium bearing tannery solid waste as the bitumen modifier

Bitumen binders play a major role in reducing the aging and oxidation property of bitumen. Carbon nanomaterials act as an effective bitumen modifier due to its stiffness and strength. Thus, nano fibrous carbon (NFC) was prepared from Chrome Tanned Buffing Dust (a solidwaste generated from leather industries) with proper care of avoiding oxidation of Cr(III) to Cr(VI) through pulse pyrolysis system. Morphology analysis using TEM confirmed the nano fibrous structure of NFC. XRD pattern of NFC depicts the graphitic phases of carbon along with the Cr₂O₃. Prepared NFC has been used as bitumen modifier and the blending of NFC with bitumen were done using both conventional and microwave heating methods to study the proper blending methods to enhance the bitumen properties. Thermogram of the modified bitumen showed that the decomposition temperature increases by increasing the percentage of NFC (5-25%) in both the heating methods, but comparatively the thermal stability is more in microwave mixing than in conventional mixing. The morphology analysis of the modified bitumen showed that non-uniform blending in conventional type of heating and homogeneously blended mixture in microwave type of heating. The penetration value and ductility decreases while softening point and kinematic viscosity increases by increasing the quantity of NFC from 5 to 25% in modified bitumen. Microwave heat mixing method yielded better modified bitumen with NFC than conventional heating method in terms of stability, uniform blending and physical properties. The non-leachability of the Cr(III) in the NFC modified bitumen was confirmed through total chromium analysis in the leachate. But, chromium analysis in leachate of NFC immersed in acetate buffer for one month showed leaching of Cr(III) 5.5 μg/L in the 25% NFC modified bitumen block mixed using conventional heating method.

Antioxidant and antimicrobial activity of bioactive prodigiosin produces from Serratia marcescens using agricultural waste as a substrate

The objective of this investigation was to explore the antioxidant and antimicrobial property of bioactive prodigiosin produced from Serratia marcescens using rice bran. The antioxidant potential of prodigiosin was examined by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and 2, 2'-azino-bis 3-ethylbenzthiazoline-6-sulfonic acid (ABTS) radical scavenging method via UV-visible, electron spin resonance spectrum (ESR), cyclic voltammetry and excitation emission spectrum. The antimicrobial activity of prodigiosin was examined against foodborne pathogens. The shelf life extending capacity of prodigiosin was evaluated with meat extract powder (MEP) as a model food material. The DPPH and ABTS radicals were completely scavenged by prodigiosin at the concentration of 10 mg/L. The food spoilage was inhibited by the addition of prodigiosin with MEP and it was compared with conventional preservative. The prodigiosin has prohibited the growth of foodborne pathogens effectively and the shelf life of the food was also extended significantly. The antimicrobial edible preservative developed in this study inhibited the growth of the microbial populations that produced through storage of the MEP and free radical scavenging activity. The results reveal that the bioactive prodigiosin effectively scavenged the free radical and inhibited the bacterial growth in food stuff.

Anaerobic digestion of sulphate-rich post-tanning wastewater at different COD/sulphate and F/M ratios

Anaerobic digestion of post-tanning wastewater was performed in batch anaerobic digester to evaluate the effect of COD/sulphate ratio [0.62, 0.69, and 1.20 (w/w) %] and F/M ratio [0.2, 0.3, 0.5, 0.7, 0.9, 1.1, 1.3, and 1.5 (w/w) %)] on the removal efficiency of COD. The F/M ratio of 0.3 was found to be the optimum ratio for the removal of COD by 53, 57, and 65%, respectively at COD/sulphate ratio of 0.62, 0.69, and 1.20. The maximum sulphate removal was observed at F/M ratio of 0.2 and the removal efficiency was 48, 50, and 58% at COD/sulphate ratio of 0.62, 0.69, and 1.20, respectively. The removal efficiency of COD and sulphate was increased with increase in COD/sulphate ratio from 0.62 to 1.20 and decreased with increase in F/M ratio from 0.2 to 1.5 in anaerobic digestion of post-tanning wastewater. The maximum concentration of sulphide formation was 784 mg/L at COD/sulphate ratio of 0.62 in anaerobic digestion process and the process was inhibited at this sulphide concentration. The microbial activity in the sludge was evaluated through live and dead cell assay using fluorescent microscopy. The maximum amount of dead microbes was observed in the anaerobic digester, which was operated at COD/sulphate ratio of 0.62 than other studied ratio.

Hydroxyl radical generation by cactus-like copper oxide nanoporous carbon catalysts for microcystin-LR environmental remediation

Copper oxide supported on nanoporous activated carbon (CuO-NPAC) is reported for the aqueous phase catalytic degradation of cyanotoxin microcystin-LR (MC-LR).

A novel mariner-based transposon system for the enhanced removal of high strength ammoniacal nitrogen in pharmaceutical effluents

High strength NH₃–N in the effluent is the major issue in the pharmaceutical industry. A novel mariner-transposan based system could be the better solution for the treatment of high strength NH₃–N in the pharmaceutical effluent.

Simultaneous removal of NH4+-N and refractory organics through sequential heterogeneous Fenton oxidation process and struvite precipitation: kinetic study

Graphical representation of integrated HFO and MAP processes.

Influence of fermented tannery solid waste on morphological, biochemical, yield and nutritional responses of tomato plants

The non-tanned proteinaceous tannery solid waste animal fleshing (ANFL), containing high nutritive value, was hydrolyzed using bacteria Selenomonas ruminantium HM000123 through submerged (SmF) and solid-state (SSF) fermentation processes. In addition, the effects of ANFL fermentative hydrolysate on growth, yield and biochemical properties of tomato plants were investigated. The treatments included T1 (SmF-ANFL), T2 (SSF-ANFL), T3 (recommended dose of NPK fertilizers) and a control without any amendment. Hydrolysates of both SmF-ANFL and SSF-ANFL treatments increased the biomass and yield as evidenced by plant height, stem girth, number of leaves and fruit yield when compared with both NPK and control plants. In this 90-day study, significant (p ≤ 0.05) changes were observed in SSF-ANFL treated plants compared to the other treatments. Protein profile analyzed through SDS-PAGE indicates the expression of a high molecular weight protein (205 kDa) and other proteins in the leaves of the SSF-ANFL treated plants. Overall results revealed that SSF-ANFL can be successfully utilized as a fertilizer particularly for cultivating tomato plants.

Biosequestration of chromium(iii) in an aqueous solution using cationic and anionic biosurfactants produced from two different Bacillus sp. – a comparative study

Interaction of cationic biosurfactant with chromium(iii) in an aqueous solution.

Immobilization of thermotolerant intracellular enzymes on functionalized nanoporous activated carbon and application to degradation of an endocrine disruptor: kinetics, isotherm and thermodynamics studies

Degradation of 2-nitro phloroglucinol using mixed intracellular enzymes immobilized FNAC matrix

Bioactive prodigiosin-impregnated cellulose matrix for the removal of pathogenic bacteria from aqueous solution

The prodigiosin impregnated column reactor (PICCR) was developed for the removal of pathogenic bacteria from water/wastewater. The impregnation of prodigiosin on cellulose matrix significantly improved the activity and stability.

Separation of sodium chloride from the evaporated residue of the reverse osmosis reject generated in the leather industry--optimization by response surface methodology

Reverse osmosis (RO) concentrate is being evaporated by solar/thermal evaporators to meet zero liquid discharge standards. The resulted evaporated residue (ER) is contaminated with both organic and inorganic mixture of salts. The generation of ER is exceedingly huge in the leather industry, which is being collected and stored under the shelter to avoid groundwater contamination by the leachate. In the present investigation, a novel process for the separation of sodium chloride from ER was developed, to reduce the environmental impact on RO concentrate discharge. The sodium chloride was selectively separated by the reactive precipitation method using hydrogen chloride gas. The selected process variables were optimized for maximum yield ofNaCl from the ER (optimum conditions were pH, 8.0; temperature, 35 degrees C; concentration of ER, 600 g/L and HCl purging time, 3 min). The recovered NaCl purity was verified using a cyclic voltagramm.

Dietary inclusion of protease producing novel Pontibacter spp. and Bacillus megaterium as a probiotic enhances immune responses in Labeo rohita

Abstract: This study stresses the key role which can be played by Tannery Fleshing (TF) hydrolyzing probiotic Pontibacter spp. in aqua feed formulation and identifies the probiotic strains in the fish gut capable of enhancing the overall growth and immune responses. Probiotics included are Pontibacter species (Pb) and Bacillus megaterium (BM) wherein Lactobacillus (LB) served as control. Experimental diets includes tannery fleshing (TF1), TF+LB strain (TF2), TF+BM strain (TF3), TF+Pb strain (TF4), Fishmeal+BM(TF5), Fishmeal+Pb and Control fish meal based diet (TF6). Compared with control, total weight gain (TWG), Specific Growth Rate (SGR), Feed Conversion Ratio (FCR) and Protein Efficiency Ratio (PER) in fish fed with diets supplemented with probiotics were significantly increased (p < 0.05). NBT, lysozyme activity, total protein and globulin content were highest in TF4 diet. After challenge with Aeromonas hydrophila, TF4 recorded highest survival and TF1 lowest survival in comparison with the control. Growth and related parameters reveals the effective utilization potential of tannery fleshing probiotic as a feed source. Comparative studies with standard fish meal diets reveals that the fish fed with Pontibacter spp. and Bacillus megaterium included feeds enhanced both assimilating capacity and immunological responses in Labeo rohita.

Lipase production from a novel thermo-tolerant and extreme acidophile Bacillus pumilus using palm oil as the substrate and treatment of palm oil-containing wastewater

The thermo-tolerant and extreme acidophilic microorganism Bacillus pumilus was isolated from the soil collected from a commercial edible-oil extraction industry. Optimisation of conditions for the lipase production was conducted using response surface methodology. The optimum conditions for obtaining the maximum activity (1,100 U/mL) of extremely acidic thermostable lipase were fermentation time, 96 h; pH, 1; temperature, 50 °C; and concentration of palm oil, 50 g/L. After purification, a 7.1-fold purity of lipase with specific activity of 5,173 U/mg protein was obtained. The molecular weight of the thermo-tolerant acidophilic lipase (TAL) was 55 kDa. The predominant amino acid in the TAL was glycine. The functional groups of lipase were determined by Fourier transform infrared spectroscopy. TAL exhibited enhanced activity (114 %) with dimethyl sulphoxide (20 %, v/v), and it showed a moderate activity with methanol, hexane and benzene. The optimum conditions for the treatment of palm oil in wastewater using the TAL were found to be time, 3 h; pH, 1; temperature, 50 °C with pseudo second-order kinetic constant of 1.88 × 10(-3) L mol(-1) min(-1). The Michaelis-Menten enzyme kinetic model and the nonlinear kinetic model were evaluated for the TAL. TAL established hydrolysis efficiency of 96 % for palm oil in wastewater at 50 °C.

Controlled synthesis and characterization of electron rich iron(iii) oxide doped nanoporous activated carbon for the catalytic oxidation of aqueous ortho phenylene diamine

A Fe-NPAC₄₀₀ catalyst was prepared, characterized and used as a heterogeneous Fenton catalyst to degrade and mineralize aqueous O-phenylene diamine.

Response surface modeling for optimization heterocatalytic Fenton oxidation of persistence organic pollution in high total dissolved solid containing wastewater

The rice-husk-based mesoporous activated carbon (MAC) used in this study was precarbonized and activated using phosphoric acid. N2 adsorption/desorption isotherm, X-ray powder diffraction, electron spin resonance, X-ray photoelectron spectroscopy and scanning electron microscopy, transmission electron microscopy, (29)Si-NMR spectroscopy, and diffuse reflectance spectroscopy were used to characterize the MAC. The tannery wastewater carrying high total dissolved solids (TDS) discharged from leather industry lacks biodegradability despite the presence of dissolved protein. This paper demonstrates the application of free electron-rich MAC as heterogeneous catalyst along with Fenton reagent for the oxidation of persistence organic compounds in high TDS wastewater. The heterogeneous Fenton oxidation of the pretreated wastewater at optimum pH (3.5), H2O2 (4 mmol/L), FeSO4[Symbol: see text]7H2O (0.2 mmol/L), and time (4 h) removed chemical oxygen demand, biochemical oxygen demand, total organic carbon and dissolved protein by 86, 91, 83, and 90%, respectively.

Lipoprotein biosurfactant production from an extreme acidophile using fish oil and its immobilization in nanoporous activated carbon for the removal of Ca2+and Cr3+in aqueous solution

Lipoprotein biosurfactant from extreme acidophile using fish oil and its immobilization in nanoporous activated carbon for removal of metal ions.

Nutrient and enzymatic changes of hydrolysed tannery solid waste treated with epigeic earthworm Eudrilus eugeniae and phytotoxicity assessment on selected commercial crops

Animal fleshing (ANFL) is the predominant proteinaceous solid waste generated during processing of leather and it is confronting disposal problems. The aim of this study was to assess the potential of epigeic earthworm Eudrilus eugeniae to utilize and transform the fermented ANFL in the solid state (SSF) and submerged state (SmF) into a value added product along a low residence period (25 days). A total of six treatment units containing different waste mixture compositions were established. Fifty healthy and non-clitellated earthworms were introduced in three different treatment containers: control, SSF, and SmF (+worm). Another set of treatment mixtures (control, SSF, SmF) was established without earthworms (-worm) to compare the results. The products were characterized for physico-chemical, enzymatic analysis and seedling growth parameters to compare the differences in the process with and without earthworms. The changes observed in the analytical parameters were in the following order: SSF > SmF > control mixtures (p < 0.05). The vermicompost showed a significant reduction in heavy metals, total organic carbon and an increase in total Kjeldhal nitrogen as compared to the product untreated by earthworms. The maximum enzymatic activities were observed after 21 days of vermicomposting. The relative seed germination of vermicompost extracts were in the order of tomato (Lycopersicon esculentum) > green gram (Vigna radiata) > cucumber (Cucumis sativus) > bottle gourd (Lagenaria siceraria (Mol.) Standl.) and showed no phytotoxicity effects. The results indicated that the combination of both ANFL hydrolysis through fermentation and vermicomposting is a good alternative to the management of this kind of waste.

Electrochemical treatment of evaporated residue of reverse osmosis concentrate generated from the leather industry

Proposed scheme for the separation of sodium chloride, calcium sulphate and removal of organic pollutants from ER.

Synthesis and characterization of Co-NPAC and in situ hydroxyl radical generation for the oxidation of dye laden wastewater from the leather industry

Cobalt oxide supported on nanoporous activated carbon (Co-NPAC) could be utilized as a catalyst in the heterogeneous Fenton oxidation of organic dye chemicals in tannery wastewater.

Electrochemical treatment of evaporated residue of soak liquor generated from leather industry

The organic and suspended solids present in soak liquor, generated from leather industry, demands treatment. The soak liquor is being segregated and evaporated in solar evaporation pans/multiple effect evaporator due to non availability of viable technology for its treatment. The residue left behind in the pans/evaporator does not carry any reuse value and also faces disposal threat due to the presence of high concentration of sodium chloride, organic and bacterial impurities. In the present investigation, the aqueous evaporated residue of soak liquor (ERSL) was treated by electrochemical oxidation. Graphite/graphite and SS304/graphite systems were used in electrochemical oxidation of organics in ERSL. Among these, graphite/graphite system was found to be effective over SS304/graphite system. Hence, the optimised conditions for the electrochemical oxidation of organics in ERSL using graphite/graphite system was evaluated by response surface methodology (RSM). The mass transport coefficient (km) was calculated based on pseudo-first order rate kinetics for both the electrode systems (graphite/graphite and SS304/graphite). The thermodynamic properties illustrated the electrochemical oxidation was exothermic and non-spontaneous in nature. The calculated specific energy consumption at the optimum current density of 50 mA cm(-2) was 0.41 kWh m(-3) for the removal of COD and 2.57 kWh m(-3) for the removal of TKN.

Nanoporous activated carbon fluidized bed catalytic oxidations of aqueous o, p and m-cresols: kinetic and thermodynamic studies

Nanoporous activated carbon prepared from rice husk through precarbonisation at 400 °C and phosphoric acid activation at 800 °C was used as fluidized bed in Fenton oxidation of the o, p and m-cresols in aqueous solution. The efficiencies of homogeneous Fenton oxidation, fluidized Fenton oxidation and aerobic biological oxidation systems for the removal of o, p and m-cresols in aqueous solution have been compared. The kinetic constants and the thermodynamic parameters for the homogeneous Fenton, heterogeneous Fenton and aerobic biological oxidations of o, p and m-cresols in synthetic wastewater were determined. The degradation of cresols in synthetic wastewater was confirmed using FT-IR, (1)H-NMR and UV-visible spectroscopy.

Nano-silica fabricated with silver nanoparticles: antifouling adsorbent for efficient dye removal, effective water disinfection and biofouling control

A nano-silica-AgNPs composite material is proposed as a novel antifouling adsorbent for cost-effective and ecofriendly water purification. Fabrication of well-dispersed AgNPs on the nano-silica surface, designated as NSAgNP, has been achieved through protein mediated reduction of silver ions at ambient temperature for development of sustainable nanotechnology. The coated proteins on AgNPs led to the formation of stable NSAgNP and protected the AgNPs from oxidation and other ions commonly present in water. The NSAgNP exhibited excellent dye adsorption capacity both in single and multicomponent systems, and demonstrated satisfactory tolerance against variations in pH and dye concentration. The adsorption mainly occurred through electrostatic interaction, though π-π interaction and pore diffusion also contributed to the process. Moreover, the NSAgNP showed long-term antibacterial activity against both planktonic cells and biofilms of Gram-negative Escherichia coli and Pseudomonas aeruginosa. The antibacterial activity of AgNPs retarded the initial attachment of bacteria on NSAgNP and thus significantly improved the antifouling properties of the nanomaterial, which further inhibited biofilm formation. Scanning electron and fluorescence microscopic studies revealed that cell death occurred due to irreversible damage of the cell membrane upon electrostatic interaction of positively charged NSAgNP with the negatively charged bacterial cell membrane. The high adsorption capacity, reusability, good tolerance, removal of multicomponent dyes and E. coli from the simulated contaminated water and antifouling properties of NSAgNP will provide new opportunities to develop cost-effective and ecofriendly water purification processes.

Integrated Bacillus sp. immobilized cell reactor and Synechocystis sp. algal reactor for the treatment of tannery wastewater

The wastewater discharged from leather industries lack biodegradability due to the presence of xenobiotic compounds. The primary clarification and aerobic treatment in Bacillus sp. immobilized Chemo Autotrophic Activated Carbon Oxidation (CAACO) reactor removed considerable amount of pollution parameters. The residual untreated organics in the wastewater was further treated in algal batch reactor inoculated with Synechocystis sp. Sodium nitrate, K(2)HPO(4), MgSO(4).7H(2)O, NH(4)Cl, CaCl(2)·2H(2)O, FeCl(3) (anhydrous), and thiamine hydrochloride, rice husk based activated carbon (RHAC), immobilization of Bacillus sp. in mesoporous activated carbon, sand filter of dimensions diameter, 6 cm and height, 30 cm; and the CAACO reactor of dimensions diameter, 5.5 cm and height, 30 cm with total volume 720 ml, and working volume of 356 ml. In the present investigation, the CAACO treated tannery wastewater was applied to Synechocystis sp. inoculated algal batch reactor of hydraulic residence time 24 h. The BOD(5), COD, and TOC of treated wastewater from algal batch reactor were 20 ± 7, 167 ± 29, and 78 ± 16 mg/l respectively. The integrated CAACO system and Algal batch reactor was operated for 30 days and they accomplished a cumulative removal of BOD(5),COD, TOC, VFA and sulphide as 98 %, 95 %, 93 %, 86 %, and 100 %, respectively. The biokinetic constants for the growth of algae in the batch reactor were specific growth rate, 0.095(day(-1)) and yield coefficient, 3.15 mg of algal biomass/mg of COD destructed. The degradation of xenobiotic compounds in the algal batch reactor was confirmed through HPLC and FT-IR techniques. The integrated CAACO-Algal reactor system established a credible reduction in pollution parameters in the tannery wastewater. The removal mechanism is mainly due to co-metabolism between algae and bacterial species and the organics were completely metabolized rather than by adsorption.

Enhanced photocatalytic activity of ZnO/CuO nanocomposite for the degradation of textile dye on visible light illumination

The photocatalytic degradation of organic dyes such as methylene blue and methyl orange in the presence of various percentages of composite catalyst under visible light irradiation was carried out. The catalyst ZnO nanorods and ZnO/CuO nanocomposites of different weight ratios were prepared by new thermal decomposition method, which is simple and cost effective. The prepared catalysts were characterized by different techniques such as X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and UV-visible absorption spectroscopy. Further, the most photocatalytically active composite material was used for degradation of real textile waste water under visible light illumination. The irradiated samples were analysed by total organic carbon and chemical oxygen demand. The efficiency of the catalyst and their photocatalytic mechanism has been discussed in detail.

Heterocatalytic Fenton oxidation process for the treatment of tannery effluent: kinetic and thermodynamic studies

BACKGROUND, AIM, SCOPE: Treatment of wastewater has become significant with the declining water resources. The presence of recalcitrant organics is the major issue in meeting the pollution control board norms in India. The theme of the present investigation was on partial or complete removal of pollutants or their transformation into less toxic and more biodegradable products by heterogeneous Fenton oxidation process using mesoporous activated carbon (MAC) as the catalyst.

MATERIALS AND METHODS

Ferrous sulfate (FeSO(4)·7H(2)O), sulfuric acid (36 N, specific gravity 1.81, 98% purity), hydrogen peroxide (50% v/v) and all other chemicals used in this study were of analytical grade (Merck). Two reactors, each of height 50 cm and diameter 6 cm, were fabricated with PVC while one reactor was packed with MAC of mass 150 g and other without MAC served as control.

RESULTS AND DISCUSSION

The oxidation process was presented with kinetic and thermodynamic constants for the removal of COD, BOD, and TOC from the wastewater. The activation energy (Ea) for homogeneous and heterogeneous Fenton oxidation processes were 44.79 and 25.89 kJ/mol, respectively. The thermodynamic parameters ΔG, ΔH, and ΔS were calculated for the oxidation processes using Van't Hoff equation. Furthermore, the degradation of organics was confirmed through FTIR and UV-visible spectroscopy, and cyclic voltammetry.

CONCLUSIONS

The heterocatalytic Fenton oxidation process efficiently increased the biodegradability index (BOD/COD) of the tannery effluent. The optimized conditions for the heterocatalytic Fenton oxidation of organics in tannery effluent were pH 3.5, reaction time-4 h, and H(2)O(2)/FeSO(4)·7H(2)O in the molar ratio of 2:1.