Exploration of the performance of iron-based superhydrophilic meshes for oil-water separation.

This study investigates the oil-water separation capability of iron-based superhydrophilic meshes. It also intends to provide an optimistic view of their potential for industrial application. Oil-water separation performance of the 150 mesh, 300 mesh, and 400 mesh is primarily examined by analyzing the efficiency and speediness of separation as well as the limit of oil intrusion using petroleum based oils. The superhydrophilic meshes are further applied for oil-water separation of locomotive wash effluent. The superhydrophilic meshes showed good oil-water separation behavior. The 300 mesh is observed to have superior separation performance. It is also tested to have good reusability and resistance in harsh conditions. The separation effectiveness of 94.7%, reduced turbidity of 21.8 NTU, and chemical oxygen demand of around 70 ppm, along with reasonable flux and intrusion pressure values of 73.28 Lm-2min-1 and 0.848 kPa, respectively, are noticed for the separation study conducted for locomotive wash effluent using the designated superhydrophilic mesh. This study hence as well demonstrates a prospective future of superhydrophilic mesh for practical utility.

Effective degradation of azo dye from textile wastewater by electro-peroxone process.

Color-producing chemicals emitted from many sources, such as textile or dye manufacturing industries, are a significant concern worldwide. The present study focuses on the electro-peroxone (EP) process for decolorizing a synthetic azo dye, C.I. Reactive Black 5 (RB5). Findings suggest that the EP process is more effective for dye degradation than ozonation and electrolysis. The EP process resulted in 100% decolorization after 60 min of contact time under optimum testing conditions such as pH 7, applied current 300 mA, and sulfate concentration 3.55 g L-1. Based on the findings of the primary investigation, EP treatment of real textile effluent was carried out and 2 h of EP treatment resulted in 99% decolorization and 74%total organic carbon (TOC) removal. As an outcome, the EP process can treat textile wastewater in a cost-effective and environmentally friendly manner.

Stabilized landfill leachate treatment by zero valent aluminium-acid system combined with hydrogen peroxide and persulfate based advanced oxidation process.

The toxic leachate generated from landfills is becoming a major nuisance to the environment and has vital role in groundwater contamination. This study evaluated the potential of zero valent aluminium (ZVAl) based advanced oxidation processes (AOPs) for stabilized landfill leachate treatment. Hydrogen peroxide (HP) and persulfate (PS) were used to generate additional radicals in aerated ZVAl acid process. ZVAl-acid system achieved 83% COD removal efficiency under optimized conditions such as acid washing time of 20 min, ZVAl dose of 10 g L-1 at initial pH 1.5. The highest exclusion efficiencies in terms of TOC, COD as well as color were 83.52%, 96% and 63.71% respectively in treatment systems showing the following order: ZVAl/H+/Air/HP/PS > ZVAl/H+/Air/PS > ZVAl/H+/Air/HP > ZVAl/H+/Air > ZVAl/H+. The involvement of other metals such as Fe and Cu in the process has been found. The reusability study revealed that ZVAl powder can be effectively used up to three cycles. The 28.48 mg/l of Al3+ residue was observed in this process which has to be removed before discharge of effluent. The study indicated that the ZVAl based AOPs is stable and active for the degradation of organic pollutants present in landfill leachate and a promising solution except for the aluminium discharge which has to be given special care.

Flyash augmented Fe3O4 as a heterogeneous catalyst for degradation of stabilized landfill leachate in Fenton process.

In this study magnetite (Fe3O4) was augmented over coal flyash and analyzed for the effectiveness as a catalyst in heterogeneous Fenton process for the degradation of persistent organic pollutant present in stabilized landfill leachate. Fe3O4 and flyash augmented Fe3O4 was prepared by simple chemical precipitation method and both had magnetic nature. XRD, FTIR and SEM with EDX characterization were consummated for both catalysts. The Fenton experiments were performed in batch mode and to identify the optimal operating condition for effective COD removal the leachate pH, catalysts and H2O2 dosages were varied. The reusability of the catalysts was studied. To understand the degradation mechanism adsorption study, Fenton oxidation of benzoic acid and scavenging experiments with KI and NaF were performed. It was witnessed that flyash augmented Fe3O4 exhibited 84.7% of COD degradation which was 12.3% of higher removal efficiency than Fe3O4 at optimum pH 3, 0.05 M H2O2 and 1000 mg/L of catalyst dosage in 100 min reaction time. This flyash augmented Fe3O4 showed 68% of TOC removal and good increment in biodegradability. Poor NH3-N removal was observed in the Fenton treatment process. Decrease in aromaticity was found based on SUVA254 value and also indicated the removal of organic matter. Similarly, reusability and stability were higher than Fe3O4. The results indicate that flyash augmented Fe3O4 is a competent catalyst in heterogeneous Fenton process for treatment of mature leachate. The usage of waste material flyash with Fe3O4 decreases the co-aggregation of Fe3O4 and improves the catalytic performance.

Organic removal and synthesis of biopolymer from synthetic oily bilge water using the novel mixed bacterial consortium.

Synthetic oily bilge water (OBW) treatment and subsequent production of biopolymer were studied by using a sequential batch reactor (SBR). The effect of various influencing parameters such as solids retention time (SRT), cycle time (CT), substrate concentration, pH level on the organic removal and synthesis of polyhydroxyalkanoates (PHA) was examined by novel soil bacteria isolated from hydrocarbon contaminated site near Karaikal port, India. The isolates were identified as Pseudomonas tuomuerensis and Pseudomonas nitroreducens using 16S rRNA. Sudan Black B staining was performed to visualize the presence of PHA. The experimental results showed that a decrease in substrate concentration to 5000 mg/L of soluble COD (CODs) showed maximum organic removal (81%) and maximum PHA yields of its cell dry mass (81%). The PHA yield was maximum at SRT of 5 d, pH = 7 and CT of 24 h. The produced PHA was characterized by using FTIR, XRD and SEM analysis.

Stabilized landfill leachate treatment using heterogeneous Fenton and electro-Fenton processes.

In the present study, stabilized landfill leachate treatment by heterogeneous Fenton and electro-Fenton (EF) was carried out. Iron-manganese binary oxide loaded zeolite (IMZ) was used as a catalyst for generating hydroxyl radicals in the acidic medium. Heterogeneous Fenton process was capable of removing 88.6% COD from landfill leachate at the optimal conditions, while 87.5% COD removal was observed at optimal EF treatment conditions. Biodegradability of landfill leachate was increased significantly from 0.03 to 0.52 after Fenton treatment. The prepared heterogeneous catalyst was found reusable with a reduction in COD removal rate. Even though, both the processes are efficient for leachate treatment, the low catalyst dosage requirement in case of EF process justifies that it is more feasible than Fenton process.

Surface plasmon resonance induced enhancement of photoluminescence and Raman line intensity in SnS quantum dot-Sn nanoparticle hybrid structure.

In this article, we report on enhancement in photoluminescence and Raman line intensity of SnS quantum dots embedded in a mesh of Sn nanostructures. SnS nanoparticles synthesized by homogenous precipitation method show strong quantum confinement with a band gap of ∼2.7 eV (blue shift of ∼1 eV compared to bulk SnS particles). The optical band gap of SnS quantum dots is controlled by varying the pH (∼0 to 2.25), ageing time (24 to 144 h) and molarity (0 to 2 M) of the precursors. These SnS nanoparticles are embedded in a mesh of Sn nanostructures which are synthesized from tin chloride by using sodium borohydride as reducing agent. The Sn nanostructures have a morphology dependent, tunable surface plasmon resonance (SPR), ranging from UV (∼295 nm) to visible region (∼400 nm) of the electromagnetic spectrum. In the SnS-Sn nanohybrids, the excitons are strongly coupled with plasmons leading to a shift in the excitonic binding energy (∼400 meV). The pure SnS quantum dots have a very weak photoluminescence peak at ∼560 nm and Raman shift of low intensity at 853.08 cm-1, 1078.17 cm-1, 1255.60 cm-1, 1466.91 cm-1. The coupling of SnS nanoparticles with Sn nanoparticles results in strong exciton-plasmon interactions leading to enhanced photoluminescence and Raman line intensity. The nanohybrids formed using Sn nanosheets whose SPR matches with absorption onset of the SnS nanoparticles shows an enhancement of ∼104 times higher than pure SnS nanoparticles. Thus, Sn nanosheet with surface plasmon resonance in visible region (400 nm) like Au and Ag is a promising material for surface enhanced Raman spectroscopy, plasmon assisted fluorescence imaging and for enhancing the emission intensity of semiconductors with weak emission intensity.

Review of zero-valent aluminium based water and wastewater treatment methods.

Zero-valent metals (ZVM) are widely used to remove heavy metals, contaminants, toxicity, etc. from water and wastewater. Zero-valent aluminium (ZVAl) has large surface area and high surface reactivity. It has enormous flexibility for the in-situ application. ZVAl can be applied as either a single or a bimetallic system as well as advanced oxidation processes (AOPs). It is observed that ZVAl is capable of generating hydroxyl and sulfate radicals in water medium, which remove non-biodegradable pollutants from aqueous solution. ZVAl-based processes can remove non-biodegradable organic contaminants from water medium within a short duration. ZVAl is also used as a reducing agent. It is efficient to reduce toxic hexavalent chromium to less toxic trivalent chromium. ZVAl, in various combinations in bimetallic system (Fe/Al, Pd/Al, Cu/Al), is able to remove various contaminants from aqueous medium. Overall, it can be concluded that ZVAl-based methods for water and wastewater treatment are promising environmental technologies.

Removal of rhodamine B dye from aqueous solution by electro-Fenton process using iron-doped mesoporous silica as a heterogeneous catalyst.

In the current study, Rhodamine B (RhB) dye was removed by electro-Fenton (EF) process using iron-doped SBA-15 (Fe-SBA-15; SBA: Santa Barbara Amorphous) mesoporous silica as a heterogeneous catalyst. This catalyst was prepared with the help of ferric nitrate nonahydrate as a forerunner by wet impregnation method. Various techniques of characterization such as XRD and N2 adsorption-desorption isotherms were performed to confirm the presence of iron particles in the pores of the catalyst. These characterization methods were also used to examine the morphological properties and textural arrangement of the synthesized material. In the batch study of EF process, 750 mL working volume of RhB dye was taken. Anode and cathode used in the process were graphite electrodes respectively with effective area of 25 cm2 each. To maximise the process efficiency, the effect of initial pH, applied voltage, electrode spacing, the concentration of supporting electrolyte and Fe-SBA-15 dosage were investigated and optimized. The optimum conditions obtained were pH of 2, voltage of 8 V, an electrode spacing of 3 cm and Fe-SBA-15 dosage of 15 mg L-1. At the end of 3 h electrolysis, maximum RhB removal of 97.7% and TOC removal of 35.1% were achieved for 10 mg L-1 RhB concentration. In a batch study with real wastewater, 97% of color and 39% of TOC were removed at optimum conditions. Utilization of EF heterogeneous catalyst Fe-SBA-15 is an alternative technique for the elimination of dyes from solution.

Combined heterogeneous Electro-Fenton and biological process for the treatment of stabilized landfill leachate.

Treatment of stabilized landfill leachate is a great challenge due to its poor biodegradability. Present study made an attempt to treat this wastewater by combining electro-Fenton (E-Fenton) and biological process. E-Fenton treatment was applied prior to biological process to enhance the biodegradability of leachate, which will be beneficial for the subsequent biological process. This study also investigates the efficiency of iron molybdophosphate (FeMoPO) nanoparticles as a heterogeneous catalyst in E-Fenton process. The effects of initial pH, catalyst dosage, applied voltage and electrode spacing on Chemical Oxygen Demand (COD) removal efficiency were analyzed to determine the optimum conditions. Heterogeneous E-Fenton process gave 82% COD removal at pH 2, catalyst dosage of 50 mg/L, voltage 5 V, electrode spacing 3 cm and electrode area 25 cm2. Combined E-Fenton and biological treatment resulted an overall COD removal of 97%, bringing down the final COD to 192 mg/L.

Optimization and production of pyrrolidone antimicrobial agent from marine sponge-associated Streptomyces sp. MAPS15.

Twenty-nine actinobacterial strains were isolated from marine sponge Spongia officinalis and screened for antagonistic activity against various bacterial and fungal pathogens. The active antibiotic producer MAPS15 was identified as Streptomyces sp. using 16S rRNA phylogenetic analysis. The critical control factors were selected from Plackett-Burman (PB) factorial design and the bioprocess medium was optimized by central composite design (CCD) for the production of bioactive metabolite from Streptomyces sp. MAPS15. The maximum biomass and active compound production obtained with optimized medium was 6.13 g/L and 62.41 mg/L, respectively. The economical carbon source, paddy straw was applied for the enhanced production of bioactive compound. The purified active fraction was characterized and predicted as pyrrolidone derivative which showed broad spectrum of bioactivity towards indicator organisms. The predicted antimicrobial spectra suggested that the Streptomyces sp. MAPS15 can produce a suite of novel antimicrobial drugs.

Modeling of crystal violet adsorption by bottom ash column.

The removal of crystal violet from wastewater, by means of bottom ash, was investigated in a packed bed down-flow column. The bed depth service time (BDST) model was used to analyze the experimental data up to breakthrough time (corresponding to C(t)/C(0) = 0.1). A mass transfer model was used to analyze the mass transfer zone. The breakthrough curve was analyzed by the Thomas, Yoon-Nelson, and Clark models. All models fit well with the experimental data. Results showed that as the flow rate increases, at a constant concentration and bed depth, the value of the adsorption capacity of bottom ash decreases. The adsorption capacity of bottom ash decreases with an increase in depth and initial crystal violet concentration. Error analyses were performed for the Thomas, Yoon-Nelson, and Clark models. Water

Fixed bed column study for Cu (II) removal from aqueous solution using water hyacinth (Eichornia crassipes) biomass.

This paper reports the results of the study on the performance of low-cost biosorbent water hyacinth (WH) in removing Cu (II) from aqueous solution. The adsorbent material adopted was found to be an efficient media for the removal of Cu (II) in continuous mode using fixed bed column. The column studies were conducted with 10 mg/L metal solution with a flow rate of 10 mL/min with different bed depths such as 10, 20 and 30 cm. The column design parameters like adsorption rate constant, adsorption capacity and minimum bed depth were calculated. It was found that, the adsorption capacity of copper ions by water hyacinth increased by increasing the bed depth and the contact time.

Optimization and production of a biosurfactant from the sponge-associated marine fungus Aspergillus ustus MSF3.

Marine endosymbiotic fungi Aspergillus ustus (MSF3) which produce high yield of biosurfactant was isolated from the marine sponge Fasciospongia cavernosa collected from the peninsular coast of India. Maximum production of biosurfactant was obtained in Sabouraud dextrose broth. The optimized bioprocess conditions for the maximum production was pH 7.0, temperature 20 degrees C, salt concentration 3%, glucose and yeast extract as carbon source and nitrogen sources respectively. The response surface methodology based analysis of carbon and nitrogen ratio revealed that the carbon source can increase the biosurfactant yield. The biosurfactant produced by MSF3 was partially characterized as glycolipoprotein based on the estimation of macromolecules and TLC analysis. The partially purified biosurfactant showed broad spectrum of antimicrobial activity. The strain MSF3 can be used for the microbially enhanced oil recovery process.

Removal of heavy metal ions from municipal solid waste leachate using coal fly ash as an adsorbent.

The purpose of this study was to investigate the possibility of the utilization of coal fly ash as a low cost adsorbent material for the adsorption of heavy metal ions (Zn, Pb, Cd, Mn and Cu) present in the municipal solid waste leachate. Batch experiments were conducted to determine the effect of contact time and fly ash dosage on adsorption of heavy metals. Experimental data were evaluated to find out kinetic characteristics of the adsorption process. The isothermal data could be well described by the Freundlich adsorption model. Kinetic parameters of adsorption such as the pseudo first-order constant, pseudo second-order constant and the intraparticle diffusion rate constant were determined. The fly ash concentration required to achieve maximum heavy metal removal was found to be 2g/L with the removal efficiencies of 39%, 28%, 74%, 42% and 71% for Cu, Mn, Pb, Zn and Cd respectively. The results of the study demonstrated that the fly ash could be used as an effective low cost adsorbent for the removal of heavy metal ions from municipal solid waste leachate.

Production and characterization of lipopeptide biosurfactant by a sponge-associated marine actinomycetes Nocardiopsis alba MSA10.

A sponge-associated marine actinomycetes Nocardiopsis alba MSA10 was screened and evaluated for the production of biosurfactant. Biosurfactant production was confirmed by conventional screening methods including hemolytic activity, drop collapsing test, oil displacement method, lipase production and emulsification index. The active compound was extracted with three solvents including ethyl acetate, diethyl ether and dichloromethane. The diethyl ether extract was fractionated by TLC and semi-preparative HPLC to isolate the pure compound. In TLC, a single discrete spot was obtained with the R (f) 0.60 and it was extrapolated as valine. Based on the chemical characterization, the active compound was partially confirmed as lipopeptide. The optimum production was attained at pH 7, temperature 30 degrees C, and 1% salinity with glucose and peptone supplementation as carbon and nitrogen sources, respectively. Considering the biosurfactant production potential of N. alba, the strain could be developed for large-scale production of lipopeptide biosurfactant.

Optimization and production of novel antimicrobial agents from sponge associated marine actinomycetes Nocardiopsis dassonvillei MAD08.

The sponge-associated actinomycetes were isolated from the marine sponge Dendrilla nigra, collected from the southwest coast of India. Eleven actinomycetes were isolated depending upon the heterogeneity and stability in subculturing. Among these, Nocardiopsis dassonvillei MAD08 showed 100% activity against the multidrug resistant pathogens tested. The culture conditions of N. dassonvillei MAD08 was optimized under submerged fermentation conditions for enhanced antimicrobial production. The unique feature of MAD08 includes extracellular amylase, cellulase, lipase, and protease production. These enzymes ultimately increase the scope of optimization using broad range of raw materials which might be efficiently utilized. The extraction of the cell free supernatant with ethyl acetate yielded bioactive crude extract that displayed activity against a panel of pathogens tested. Analysis of the active thin layer chromatography fraction by Fourier transform infrared and gas chromatography-mass spectrometry evidenced 11 compounds with antimicrobial activity. The ammonium sulfate precipitation of the culture supernatant at 80% saturation yielded an anticandidal protein of molecular weight 87.12 kDa. This is the first strain that produces both organic solvent and water soluble antimicrobial compounds. The active extract was non-hemolytic and showed surface active property envisaging its probable role in inhibiting the attachment of pathogens to host tissues, thus, blocking host-pathogen interaction at an earlier stage of pathogenesis.

Optimization of extracellular psychrophilic alkaline lipase produced by marine Pseudomonas sp. (MSI057).

An endosymbiotic Pseudomonas sp. (MSI057), which could produce high yields of lipase, was isolated from marine sponge Dendrilla nigra, collected from the peninsular coast of India. Maximum production of enzyme was obtained in minimal medium supplemented with 1% tributyrin. Catabolite repression was observed when the medium was supplemented with readily available carbon sources. The optimum temperature and pH for the enzyme production was 30 degrees C and 9.0, respectively. The enzyme exhibited maximum activity in pH range of 8-9 with an optimum pH 9.0. The activity of purified enzyme was optimum at 37 degrees C and showed 80% activity at 20 degrees C and the enzyme activity decreased dramatically above 50 degrees C. Based on the present findings, the enzyme was characterized as psychrophilic alkaline lipase, which can be developed for industrial applications.

Optimization of extracellular thermotolerant alkaline protease produced by marine Roseobacter sp. (MMD040).

Marine endosymbiontic Roseobacter sp. (MMD040), which produced high yields of protease, was isolated from marine sponge Fasciospongia cavernosa, collected from the peninsular coast of India. Maximum production of enzyme was obtained in Luria-Bertani broth. Catabolite repression was observed when the medium was supplemented with readily available carbon sources. The optimum temperature and pH for the enzyme production was 37 degrees C and 7.0, respectively. The enzyme exhibited maximum activity in pH range of 6-9 with an optimum pH of 8.0 and retained nearly 92.5% activity at pH 9.0. The enzyme was stable at 40 degrees C and showed 89% activity at 50 degrees C. Based on the present findings, the enzyme was characterized as thermotolerant alkaline protease, which can be developed for industrial applications.