Biomimetically Generated Nanoparticles in Boosting the Performance of Microbial Fuel Cells

Studies are presented in the context of the past attempts at finding nanocatalysts that can boost the performance of microbial fuel cells (MFCs) ? in terms of waste treatment and energy generation. Given the great potential of biomimetically synthesized nanoparticles (BMNPs) in providing less expensive and more environmentally friendly alternatives to NPs synthesized by physical and chemical methods, as well as a near-total lack of previous work in this area, the current research was undertaken. Effect of gold and silver nanoparticles (NPs), synthesized biomimetically using five freely available weeds, was assessed as catalysts in the MFCs. In all cases, the nanoparticles were seen to enhance the coulombic efficiency (reflective of the reduction in the waste’s organic carbon load), maximum attainable power density, and overall energy yield of the MFCs by >200% relative to the uncatalyzed MFCs. Gold nanoparticles were more effective than silver nanoparticles by ? 20%. The results reveal that biomimetically synthesized NPs can be highly effective in reducing the operational costs as well as ecological footprints of MFCs and further work should be focused on NPs of non-precious metals.

Performance of a Woodchip Bioreactor for the Treatment of Nitrate-Laden Agricultural Drainage Water in Northeastern Germany

Reactive barriers, such as denitrifying bioreactors, have been identified as a clean-up option for nutrient-laden agriculture runoff. Here we tested a 20 m long, 3.75 m wide and 2.2 m deep woodchip bioreactor receiving tile drainage water from a 5.2 ha field site, aiming at testing the hydraulic functioning of a dual-inlet system and quantifying its impact on nutrient loads (nitrogen, reactive phosphorus, organic carbon) in a region with a drainage season taking place in the hydrological winter (November to April). The hydraulic conditions in the dual-inlet bioreactor system developed differently than expected; asymmetric flow rates led to long average hydraulic retention times and a highly dispersed residence time distribution, which was revealed by a bromide tracer test. With a nitrate load reduction of 51 to 90% over three drainage seasons, the woodchip bioreactor proved at the same time to be very effective under the winter conditions of northeastern Germany. The bioreactor turned from an orthophosphate source in the first year of operation into an orthophosphate sink in the second and third year, which was not expected because of anoxic conditions (favorable for denitrification) prevailing within the woodchips. Besides an efficient nutrient retention, the woodchip bioreactor contributed to the total organic carbon load of receiving waters, which impairs the overall positive role of bioreactors within intensively agriculturally used landscapes. We consider this promising low-maintenance biotechnology particularly suitable for single drainage pipes with high discharge and high nitrate concentrations.

Summer–winter contrast in carbon isotope and elemental composition of total suspended particulate matter in the urban atmosphere of Krakow, Southern Poland

The city of Krakow located in southern Poland ranks among the most polluted urban agglomerations in Europe. There are persisting controversies with respect to impact of different pollution sources operating in Krakow agglomeration on air quality within the city. The presented pilot study was aimed at exploring the possibilities offered by elemental and carbon isotope composition of total suspended particulate matter (TSPM) for better characterization of its sources in Krakow atmosphere. The analyses of carbon isotope composition of total carbon in the investigated TSPM samples were supplemented by parallel analyses of radiocarbon content in atmospheric carbon dioxide (CO2). This study revealed large seasonal variability of carbon isotope composition in the analysed TSPM samples. This large variability reflects seasonally varying contribution of different sources of fossil and modern carbon to the TSPM pool. The elemental composition of TSPM also reveals distinct seasonal variability of the analysed elements, reflecting varying mixture of natural and anthropogenic sources of those elements. A linear relationship between the fossil carbon load in the TSPM samples and the fossil carbon load in the atmospheric CO2 was found, pointing to the presence of additional source of anthropogenic carbonaceous particles not associated with burning of fossil fuels. Wearing of tyres and asphalt pavement is most probably the main source of such particles.

Application of Natural Carbon Isotopes for Emission Source Apportionment of Carbonaceous Particulate Matter in Urban Atmosphere: A Case Study from Krakow, Southern Poland

Successful mitigation of air pollution in large cities requires information about the structure of emission sources and their contribution to total atmospheric load. The presented research demonstrates a possibility of application of isotope tracers for the estimation of contribution of different sources to the carbonaceous fraction of PM2.5 (Particulate Matter containing fraction below 2.5 μm) collected in the urban atmosphere of Krakow, Poland during the summer and winter seasons. Isotope mass balance approach was used to perform source apportionment analysis for those two seasons. The analysis showed that the dominant source of the carbonaceous fraction of PM2.5 in Krakow is coal burning during the winter season and biogenic emissions during the summer season. Sensitivity analysis revealed that the uncertainty of the percentage contribution of different sources to the overall carbon load of the analyzed PM2.5 fraction is in order of a few percent.

Features of the Species and Spatial Structure of Macrobenthos in the Green Cape Lagoon (Kandalaksha Bay, White Sea)

Features of the species and spatial structure of macrobenthic sublittoral communities in a lagoon ecosystem on the Green Cape (the White Sea) were studied. 31 invertebrate species and 3 species of sea grasses and algae (Zostera marina, Cladophora sericea, and Fucus vesiculosus) were found in the sublittoral of the surveyed lagoon. The data on the species composition, diversity and spatial structure of macrobenthos communities indicate the predominance of littoral brackish-water and marine euryhaline macrobenthos species (Hydrobia ulvae, Tubificoides benedii, Chironomus salinarius, and Macoma balthica) in the coastal region of the lagoon, marine euryhaline littoral and sublittoral species (mainly polychaetes Heteromastus filiformis, Polydora ciliata, and Capitella capitata) in the central deeper region, and marine sublittoral less euryhaline species (Pontoporeia femorata, Anonyx nugans, Nereimyra punctata, Terebellides stroemi, Astarte montagui, Micronephthys minuta, and Atylus carinatus) at the exit from the lagoon. The ecosystem of the Green Cape lagoon belongs to lagoons significantly fenced off from the sea with depleted specific fauna (many littoral species) and largely influenced by carbon load and salinity. The reduced connection of the lagoon with the sea due to the continued rise of the White Sea coast (4 mm per year in this area) will contribute to a decrease in the species diversity and the predominance of few small eurytopic invertebrate species resistant to organic load, oxygen deficiency, and desalination.

Selective recovery of polyphenols from MDF process waters by adsorption on a macroporous, cross-linked pyrrolidone-based resin

A scalable, fixed-bed adsorption system for the removal and selective recovery of polyphenols (lignans and stilbenes) from medium-density fiberboard (MDF) process waters was developed. Before adsorption, fibers and non-colloidal substances were removed from process water by centrifugation, while colloidal fatty and resin acids were removed by filtration through a 30-kDa cut-off membrane. Polyphenols were then isothermally adsorbed on a medium-pressure liquid chromatography (MPLC) column packed with Divergan® RS, a regenerable macroporous, cross-linked pyrrolidone-based [polyvinylpolypyrrolidone (PVPP)] resin. Loading at acidic pH and subsequent gradient elution of polyphenols with methanol were monitored at 280 nm, and elution conditions for selective polyphenol recovery were optimized based on gas chromatography/mass spectrometry (GC/MS) analyses of the obtained fractions. Lignans were eluted in successive fractions containing the individual lignans in different proportions, followed by pinosylvin in a separate fraction. The capacity of the PVPP for hydroxymatairesinol (HMR) as a model lignan was determined to be 37.4 mg g−1 at 1% breakthrough. Highly polar substances such as sugars and sugar alcohols, however, were not retained on the column and remained in the flow-through. The results revealed the benefits of PVPP for the recovery of potentially valuable polyphenols from MDF process waters while reducing carbon load and toxicity for subsequent biological treatment.