Effect of Zinc and Copper on Anaerobic Stabilization of Sewage Sludge

The most frequently found metals in municipal sewage sludge are copper and zinc. The aim of this study was to the evaluate effect of these metals on anaerobic microorganisms during sewage sludge stabilization. Anaerobic fermentation tests were carried out in 24 batch fermenters with hydraulic retention time 21 days at mesophilic temperature conditions 38 oC +- 0.2 oC. Five different concentrations of metal ionts (100-1000 mg.l-1) were tested. Cumulative biogas and methane production were used as the comparative parameters of inhibition. Hypothesis, which predicted presence of inhibitory effect of zinc and copper on anaerobic microorganisms, mainly on methanogenic Archaea, was confirmed. The lowest concentration of zinc and copper which cause significant inhibition of biogas production was 400 mg Zn2+.l- and 1000 mg Cu2+.l- 1, which cause reduction of 10.3 +- 2.0 % and 82.8 +- 1.1 %, respectively. The lowest concentration of zinc and copper which lead to significant inhibition of methane production is 400 mg Zn2+.l- and 600 mg Cu2+.l- 1, which caused to reduction of 16.1 +- 3.2 % and 17.4 +- 2.2 %, respectively. The reduction in methane production is higher than in biogas production.O

Bioelectrochemical systems using microalgae − A concise research update

Excess consumption of energy by humans is compounded by environmental pollution, the greenhouse effect and climate change impacts. Current developments in the use of algae for bioenergy production offer several advantages. Algal biomass is hence considered a new bio−material which holds the promise to fulfil the rising demand for energy. Microalgae are used in effluents treatment, bioenergy production, high value added products synthesis and CO2 capture. This review summarizes the potential applications of algae in bioelectrochemically mediated oxidation reactions in fully biotic microbial fuel cells for power generation and removal of unwanted nutrients. In addition, this review highlights the recent developments directed towards developing different types of microalgae MFCs. The different process factors affecting the performance of microalgae MFC system and some technological bottlenecks are also addressed

Triphenylarsonium-functionalised gold nanoparticles: potential nanocarriers for intracellular therapeutics.

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.Two new triphenylarsonium alkylthiolate precursors, a thiosulfate zwitterion and a thioacetate salt, have been structurally characterised and their cytotoxicity evaluated against PC3 cells. The arsonium compounds have been used to prepare gold nanoparticles decorated with triphenylarsonium groups.Sheffield Hallam University and Indian Institute of Science (NL)

Potential of the filamentous fungus Aspergillus niger AN 400 to degrade Atrazine in wastewaters

This research aims to evaluate the ability of the fungal specie Aspergillus niger AN 400 to metabolize atrazine (ATZ) in model wastewaters, as most of the research with this worldwide used herbicide is focused on bacteria and on soil bioremediation. Firstly, the tolerance of A. niger for ATZ was evaluated in petri dishes. A. niger growth in all the tested ATZ concentrations, up to 30 mg L1. Biodegradation of ATZ was then conducted in batch reactors of 3 L, with dispersed fungal biomass. Reactors were operated for 8 days at different conditions: without glucose (RG0) and glucose at concentrations of 0.5; 1.0; 2.0; 3.0; 4.0 and 5.0 g L1 - RG0.5; RG1; RG2; RG3; RG4 and RG5, respectively. Control (RC) includes a reactor in the absence of fungal spores. The highest ATZ removal, 72%, occurred in RG3. At higher glucose concentration, substrate competition kinetics may be the responsible for the decrease of biodegradation rate constants. Only 50% of Chemical Oxygen Demand (COD) removal was obtained due to the presence of methanol used to dissolve ATZ, which has contributed for most of the COD in reactors. Detoxification of the ATZ solution by the biological treatment was observed by the Allium test.The authors thank CAPES for the PhD scholarships and wich and CNPQ there search productivity grantPQ2(311203/2012-4) and the bagPDE (200444/2014-0). Acknowledges also to the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE01-0145-FEDER-000004) funded by European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. Luciana Pereira a post-doc fellowship (SFRH/BPD/110235/ 2015) from FCT

A review of research trends in the enhancement of biomass-to-hydrogen conversion

Different types of biomass are being examined for their optimum hydrogen production potentials and actual hydrogen yields in different experimental set-ups and through different chemical synthetic routes. In this review, the observations emanating from research findings on the assessment of hydrogen synthesis kinetics during fermentation and gasification of different types of biomass substrates have been concisely surveyed from selected publications. This review revisits the recent progress reported in biomass-based hydrogen synthesis in the associated disciplines of microbial cell immobilization, bioreactor design and analysis, ultrasound-assisted, microwave-assisted and ionic liquid-assisted biomass pretreatments, development of new microbial strains, integrated production schemes, applications of nanocatalysis, subcritical and supercritical water processing, use of algae-based substrates and lastly inhibitor detoxification. The main observations from this review are that cell immobilization assists in optimizing the biomass fermentation performance by enhancing bead size, providing for adequate cell loading and improving mass transfer; there are novel and more potent bacterial and fungal strains which improve the fermentation process and impact on hydrogen yields positively; application of microwave irradiation and sonication and the use of ionic liquids in biomass pretreatment bring about enhanced delignification, and that supercritical water biomass processing and dosing with metal-based nanoparticles also assist in enhancing the kinetics of hydrogen synthesis. The research areas discussed in this work and their respective impacts on hydrogen synthesis from biomass are arguably standalone. Thence, further work is still required to explore the possibilities and techno-economic implications of combining these areas for developing robust and integrated biomass-to-hydrogen synthetic schemes

Bacterially assembled biopolyester nanobeads for removing cadmium from water

Cadmium (Cd)-contaminated waterbodies are a worldwide concern for the environment, impacting human health. To address the need for efficient, sustainable and cost-effective remediation measures, we developed innovative Cd bioremediation agents by engineering Escherichia coli to assemble poly(3-hydroxybutyric acid) (PHB) beads densely coated with Cd-binding peptides. This was accomplished by translational fusion of Cd-binding peptides to the N- or C-terminus of a PHB synthase that catalyzes PHB synthesis and mediates assembly of Cd2 or Cd1 coated PHB beads, respectively. Cd1 beads showed greater Cd adsorption with 441 nmol Cd mg-1 bead mass when compared to Cd2 beads (334 nmol Cd mg-1 bead-mass) and plain beads (238 nmol Cd mg-1 bead-mass). The Cd beads were not ecotoxic and did attenuate Cd-spiked solutions toxicity. Overall, the bioengineered beads provide a means to remediate Cd-contaminated sites, can be cost-effectively produced at large scale, and offer a biodegradable and safe alternative to synthetic ecotoxic treatments.publishe

Methanogens, sulphate and heavy metals: a complex system

Anaerobic digestion (AD) is a well-established technology used for the treatment of wastes and wastewaters with high organic content. During AD organic matter is converted stepwise to methane-containing biogasa renewable energy carrier. Methane production occurs in the last AD step and relies on methanogens, which are rather sensitive to some contaminants commonly found in wastewaters (e.g. heavy metals), or easily outcompeted by other groups of microorganisms (e.g. sulphate reducing bacteria, SRB). This review gives an overview of previous research and pilot-scale studies that shed some light on the effects of sulphate and heavy metals on methanogenesis. Despite the numerous studies on this subject, comparison is not always possible due to differences in the experimental conditions used and parameters explained. An overview of the possible benefits of methanogens and SRB co-habitation is also covered. Small amounts of sulphide produced by SRB can precipitate with metals, neutralising the negative effects of sulphide accumulation and free heavy metals on methanogenesis. Knowledge on how to untangle and balance sulphate reduction and methanogenesis is crucial to take advantage of the potential for the utilisation of biogenic sulphide as a metal detoxification agent with minimal loss in methane production in anaerobic digesters.The research was financially supported by the People Program (Marie Curie Actions) of the European Union's Seventh Framework Programme FP7/2007-2013 under REA agreement 289193