Activated Graphene Oxide-Calcium Alginate Beads for Adsorption of Methylene Blue and Pharmaceuticals.

The remarkable adsorption capacity of graphene-derived materials has prompted their examination in composite materials suitable for deployment in treatment of contaminated waters. In this study, crosslinked calcium alginate-graphene oxide beads were prepared and activated by exposure to pH 4 by using 0.1M HCl. The activated beads were investigated as novel adsorbents for the removal of organic pollutants (methylene blue dye and the pharmaceuticals famotidine and diclofenac) with a range of physicochemical properties. The effects of initial pollutant concentration, temperature, pH, and adsorbent dose were investigated, and kinetic models were examined for fit to the data. The maximum adsorption capacities qmax obtained were 1334, 35.50 and 36.35 mg g-1 for the uptake of methylene blue, famotidine and diclofenac, respectively. The equilibrium adsorption had an alignment with Langmuir isotherms, while the kinetics were most accurately modelled using pseudo- first-order and second order models according to the regression analysis. Thermodynamic parameters such as ΔG°, ΔH° and ΔS° were calculated and the adsorption process was determined to be exothermic and spontaneous.

Enhancing solar disinfection (SODIS) with the photo-Fenton or the Fe2+/peroxymonosulfate-activation process in large-scale plastic bottles leads to toxicologically safe drinking water.

Solar disinfection (SODIS) in 2-L bottles is a well-established drinking water treatment technique, suitable for rural, peri­urban, or isolated communities in tropical or sub-tropical climates. In this work, we assess the enlargement of the treatment volume by using cheap, large scale plastic vessels. The bactericidal performance of SODIS and two solar-Fe2+ based enhancements, namely photo-Fenton (light/H2O2/Fe2+) and peroxymonosulfate activation (light/PMS/Fe2+) were assessed in 19-L polycarbonate (PC) and 25-L polyethylene terephthalate (PET) bottles, in ultrapure and real water matrices (tap water, lake Geneva water). Although SODIS always reached total (5-logU) inactivation, under solar light, enhancement by or both Fe2+/H2O2 or Fe2+/PMS was always beneficial and led to an increase in bacterial elimination kinetics, as high as 2-fold in PC and PET bottles with tap water for light/H2O2/Fe2+, and 8-fold in PET bottles with Lake Geneva water. The toxicological safety of the enhancements and their effects on the plastic container materials was assessed using the E-screen assay and the Ames test, after 1-day or 1-week exposure to SODIS, photo-Fenton and persulfate activation. Although the production of estrogenic compounds was observed, we report that no treatment method, duration of exposure or material resulted in estrogenicity risk for humans, and similarly, no mutagenicity risk was measured. In summary, we suggest that SODIS enhancement by either HO•- or SO4•--based advanced oxidation process is a suitable enhancement of bacterial inactivation in large scale plastic bottles, without any associated toxicity risks.

Pilot Scale Study: First Demonstration of Hydrophobic Membranes for the Removal of Ammonia Molecules from Rendering Condensate Wastewater.

Hydrophobic membrane contactors represent a promising solution to the problem of recycling ammoniacal nitrogen (N-NH4) molecules from waste, water or wastewater resources. The process has been shown to work best with wastewater streams that present high N-NH4 concentrations, low buffering capacities and low total suspended solids. The removal of N-NH4 from rendering condensate, produced during heat treatment of waste animal tissue, was assessed in this research using a hydrophobic membrane contactor. This study investigates how the molecular composition of rendering condensate wastewater undergo changes in its chemistry in order to achieve suitability to be treated using hydrophobic membranes and form a suitable product. The main objective was to test the ammonia stripping technology using two types of hydrophobic membrane materials, polypropylene (PP) and polytetrafluoroethylene (PTFE) at pilot scale and carry out: (i) Process modification for NH3 molecule removal and (ii) product characterization from the process. The results demonstrate that PP membranes are not compatible with the condensate waste as it caused wetting. The PTFE membranes showed potential and had a longer lifetime than the PP membranes and removed up to 64% of NH3 molecules from the condensate waste. The product formed contained a 30% concentrated ammonium sulphate salt which has a potential application as a fertilizer. This is the first demonstration of hydrophobic membrane contactors for treatment of condensate wastewater.

Enhanced fat degradation following the addition of a Pseudomonas species to a bioaugmentation product used in grease traps.

The presence of fats, oils and greases (FOGs) in wastewater can lead to many problems including blockages. Investigation of a bioaugmentation product, consisting of Bacillus spp., to degrade butter (1%, W/V) and olive oil (1%, V/V) was performed in aerobic batch cultures for 13-day incubation. Gravimetric analysis of the remaining substrates showed slowly degradation of the oil after a 2-day lag, but no degradation of the butter. Addition of a Pseudomonas putida strain CP1 to the Bacillus spp. population promoted rapidly degradation of both fats after 7 days of incubation. High fat accumulation revealed the potential use of the new bacterial mixture for production of added-value compounds. Lipase production only by the Bacillus spp. along with the analysis of the remaining lipids with thin layer chromatography and gas chromatography, suggested that the Bacillus spp. mainly only hydrolyzed the fat. The breakdown products were metabolized by the Pseudomonas putida CP1 performing preferential utilization of unsaturated fatty acids. Investigation of population dynamics using selective plating and a labeled Pseudomonas putida CP1::Tn7-gfp showed domination of the latter. The new mixture performed a successful cooperation with good potential for FOG treatment and an aggregative response desirable to fat degradation in grease traps.

Waste fat biodegradation and biomodification by Yarrowia lipolytica and a bacterial consortium composed of Bacillus spp. and Pseudomonas putida.

Fats, oils, and greases (FOGs) are a particular environmental threat. Biodegradation of FOGs is a challenge and in this study the biodegradation of waste cooking fats, namely butter and olive oil, was studied using a non-conventional yeast, Yarrowia lipolytica strain LFMB 20, and a bioaugmentation product consisting of Bacillus spp. and Pseudomonas putida CP1 strain. The microorganisms were grown aerobically in shake-flask experiments in an enriched medium supplemented with ca 0.85% w/v of waste fat. Analysis of the remaining substrate showed a removal of ca 90% of the fat by the yeast at the end of the incubation, while the bacteria removed ca 95% of both fats. Growth rate, biomass production and biomass yield per unit of fat consumed were all higher for the yeast compared to the bacterial consortium. The bacterial consortium exhibited autolysis and a significant decrease in its DCW value at the late growth phases of both fat substrate cultures. The main fatty acids (FAs) present in both fats were linoleic (Δ9,12C18:2), oleic (Δ9C18:1), palmitic (C16:0), palmitoleic (Δ9C16:1) and stearic (C18:0) acid. Both the bacterial consortium and Y. lipolytica preferentially removed Δ9C18:1 from the medium, while a negative selectivity against C18:0 was reported. Both inocula produced microbial mass that contained intra-cellular lipid quantities, but the bacterial consortium gave significantly higher lipid in DCW values compared with the yeast (maximum values up to ca 63% w/w for the butter and ca 42% w/w for the olive oil while the respective values for both lipids were 22% ± 2% w/w for Y. lipolytica). In all cases, intra-cellular lipids in DCW values decreased during the late growth phases, while their FA composition differed with those of the substrate fat.

Antibacterial properties of F-doped ZnO visible light photocatalyst.

Nanocrystalline ZnO photocatalysts were prepared by a sol-gel method and modified with fluorine to improve their photocatalytic anti-bacterial activity in visible light. Pathogenic bacteria such as Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) were employed to evaluate the antimicrobial properties of synthesized materials. The interaction with biological systems was assessed by analysis of the antibacterial properties of bacteria suspended in 2% (w/w) powder solutions. The F-doping was found to be effective against S. aureus (99.99% antibacterial activity) and E. coli (99.87% antibacterial activity) when irradiated with visible light. Production of reactive oxygen species is one of the major factors that negatively impact bacterial growth. In addition, the nanosize of the ZnO particles can also be toxic to microorganisms. The small size and high surface-to-volume ratio of the ZnO nanoparticles are believed to play a role in enhancing antimicrobial activity.

The response of aggregated Pseudomonas putida CP1 cells to UV-C and UV-A/B disinfection.

UV radiation is a spread method used worldwide for the disinfection of water. However, much of the research on the disinfection of bacterial cells by UV has focused on planktonic cells. Many bacterial cells in nature are present in clumps or aggregates, and these aggregates, which are more resistant to disinfection than their planktonic counterparts, can be problematic in engineered water systems. The current research used Pseudomonas putida (P. putida) CP1, an environmental and non-pathogenic microorganism which autoaggregates when grown under certain conditions, as a model organism to simulate aggregated cells. The study investigated the response of both the planktonic and the aggregated forms of the bacterium to UV-C (λ = 253.7 nm) and UV-A/B (λ > 300 nm) disinfection at laboratory scale in a minimal medium. The planktonic cells of P. putida CP1 were inactivated within 60 s by UV-C and in 60 min by UV-A/B; however, the aggregated cells required 120 min of UV-C treatment and 240 min of UV-A/B radiation to become inactive. The size of the aggregate was reduced following UV treatment. Although all the cells had lost culturability, viability as measured by the LIVE/DEAD® stain and epifluorescence microscopy was not completely lost and the cells all demonstrated regrowth after overnight incubation in the dark.

Highly Efficient F, Cu doped TiO2 anti-bacterial visible light active photocatalytic coatings to combat hospital-acquired infections.

Bacterial infections are a major threat to the health of patients in healthcare facilities including hospitals. One of the major causes of patient morbidity is infection with Staphylococcus aureus. One of the the most dominant nosocomial bacteria, Methicillin Resistant Staphylococcus aureus (MRSA) have been reported to survive on hospital surfaces (e.g. privacy window glasses) for up to 5 months. None of the current anti-bacterial technology is efficient in eliminating Staphylococcus aureus. A novel transparent, immobilised and superhydrophilic coating of titanium dioxide, co-doped with fluorine and copper has been prepared on float glass substrates. Antibacterial activity has demonstrated (by using Staphylococcus aureus), resulting from a combination of visible light activated (VLA) photocatalysis and copper ion toxicity. Co-doping with copper and fluorine has been shown to improve the performance of the coating, relative to a purely fluorine-doped VLA photocatalyst. Reductions in bacterial population of log10 = 4.2 under visible light irradiation and log10 = 1.8 in darkness have been achieved, compared with log10 = 1.8 under visible light irradiation and no activity, for a purely fluorine-doped titania. Generation of reactive oxygen species from the photocatalytic coatings is the major factor that significantly reduces the bacterial growth on the glass surfaces.

Influence of selenium supplementation on fatty acids profile and biological activity of four edible amaranth sprouts as new kind of functional food.

Suitability assessment of amaranth sprouts as a new functional food was carried out. The optimisation of sprouting process and the influence of selenium supplementation, in doses 10, 15, and 30 mg/l of selenium as sodium selenite, on amaranth growth and fatty acid profile were examined. Methods such as FRAP, DPPH, polyphenols content and GPX activity were applied to characterize antioxidant potential of seeds and sprouts of four different edible amaranth genera. E. coli, S. aureus, C. albicans were used to evaluate amaranth sprouts antimicrobial properties. Interaction between amaranth sprouts and biological systems was assessed by analysing antibacterial and antifungal properties with a disc diffusion test. The studies proved amaranth sprouts to be potentially attractive as functional food. As confirmed by all the data amaranth sprouts are suitable as a moderate selenium accumulator and are rich in essential fatty acids, especially linoleic and alpha-linolenic acids, which are precursors of long chain polyunsaturated fatty acids. Thus, it opens dietary opportunities for amaranth sprouts. They can also serve as a moderate source of antioxidant compounds. Nevertheless, the experiments revealed neither antibacterial, nor antifungal properties of sprouts. In general, amaranth sprouts biological activity under evaluation has failed to prove to be significantly impacted by selenium fertilization.

The generation of hydrophilic polypeptide-siloxane conjugates via n-carboxyanhydride polymerisation.

A novel methodology to create covalently linked polypeptide-siloxane hybrid materials by controlled n-carboxyanhydride ring opening polymerisation is disclosed. Poly-L-glutamic acid and poly-L-lysine conjugated products were formed that possessed excellent surface wettability. In addition, the poly-L-lysine-siloxane hybrids formed demonstrated bactericidal attributes against gram-positive Staphylococcus aureus and gram-negative Escherichia coli. It is anticipated that these materials may be of significance for the generation of hydrophilic siloxane-containing polymers that are commonly employed in contemporary medical devices.

Bioaugmentation of activated sludge with two Pseudomonas putida strains for the degradation of 4-chlorophenol.

The augmentation of activated sludge with two strains of Pseudomonas putida, CP1 and A(a) was investigated. Both strains of bacteria degraded 1.56 mM 4-chlorophenol. P. putida CP1 degraded the chemical using a modified ortho-cleavage pathway while P. putida A(a) used the meta-cleavage pathway. When activated sludge incapable of 4-chlorophenol degradation was augmented with either strain, substrate degradation occurred and followed the same biochemical pathways as when the bacteria were grown in pure culture. Insertion, in tandem, of the genes for gentamycin resistance and green fluorescent protein into the chromosomes of the two strains, enabled the survival and spatial location of the bacteria in the mixed microbial population to be monitored. Labelling the bacteria did not alter their degradative capabilities. P. putida CP1::Tn7-gfp survived in higher numbers than P. putida A(a)::Tn7-gfp following addition to the activated sludge. This was attributed to the ability of this strain to flocculate and become integrated in the activated sludge floc. Addition of P. putida CP1::Tn7-gfp or A(a)::Tn7-gfp to activated sludge resulted in smaller decreases in total cell numbers indicating a protective effect of the introduced P. putida strains on the overall microbial population from the harmful effects of 4-chlorophenol. The non-flocculant strain A(a) did not survive as well as CP1 in the activated sludge system and required a higher inoculum size to effect substrate degradation.

Development of a volatile amine sensor for the monitoring of fish spoilage.

A sensor with potential for the development of a "chemical barcode" for real-time monitoring of fish freshness is described. This on-package sensor contains a pH sensitive dye, bromocresol green, that responds through visible colour change to basic volatile spoilage compounds, such as trimethylamine (TMA), ammonia (NH(3)) and dimethylamine (DMA) collectively known as Total Volatile Basic Nitrogen (TVB-N). The sensor characteristics were studied as well as its response with standard ammonia gas. Trials on cod and under-utilised species have verified that the sensor response correlates with bacterial growth patterns in fish samples thus enabling the "real-time" monitoring of spoilage in various fish species. The sensor response can be interrogated with a simple, inexpensive reflectance colorimeter that we have developed based on two light emitting diodes (LEDs) and a photodetector.

The enhancement of 2-chlorophenol degradation by a mixed microbial community when augmented with Pseudomonas putida CP1.

The effect of the introduction of Pseudomonas putida CP1 to a commercial mixed microbial community for the degradation of 1.56mM 2-chlorophenol was investigated. Degradation of 2-chlorophenol by the commercial mixture was via a meta-cleavage pathway leading to incomplete degradation, while P. putida CPI was shown to be capable of the complete degradation of 2-chlorophenol via an ortho-cleavage pathway. Augmentation of the commercial mixed culture with P. putida CP1 resulted in complete degradation of 2-chlorophenol via an ortho-cleavage pathway. The augmented mixed culture displayed increased degradative capabilities, with times of degradation reduced when compared to those achieved by P. putida CP1 in isolation. The ability of P. putida CP1 to degrade 2-chlorophenol was increased with the addition of increasing concentrations of the mixed culture. Increasing the mixed culture inoculum size added to P. putida CP1 decreased lag periods and increased rates of degradation, resulting in decreased times of degradation.