Paula Alexandra Marques

Removal efficiency of Cu2+, Cd2+ and Pb2+ by waste brewery biomass : pH and cation association effects

In this work two distinct (flocculent and non-flocculent) yeast wastes from Portuguese breweries were used for the selective removal of Cu 2÷, Cd 2+ and Pb 2+ from aqueous solutions. One of the goals was to establish both the pH profiles for the removal of each metal ion (1.0 mM) and the effect on the biomass biosorption capacity ofpH adjustment during the process. The effect of the presence of multiple metal ions, in the 0.1-1.0 mM range, on metal removal efficiency was also studied. The results showed that, in the absence ofpH adjustment, the optimum initial pH for the removal of three cations was in the 4.5-5.5 range for both types ofbiomass. However, a gradual pH increase was observed during the removal process, up to a final equilibrium value of 7.0-8.0. Regarding the biomass efficiency for metal removal in multi-cation systems, it was verified that only Cu 2÷ was significantly affected by the presence of the other metals in solution and only when the non-flocculent yeast biomass was used as biosorbent. Cd 2÷ was only slightly affected by the presence of both Cu 2+ and Pb 2÷, and Pb 2÷ removal was not affected by the presence of any or both of the interferent metals for the two biosorbents used in this work. The highest and lowest metal removal yields were obtained for Pb 2+ and Cu 2÷, respectively.

Combining biotechnology with circular bioeconomy: From poultry, swine, cattle, brewery, dairy and urban wastewaters to biohydrogen

&NA; The ability of microalgae to grow in nutrient‐rich environments and to accumulate nutrients from wastewaters (WW) makes them attractive for the sustainable and low‐cost treatment of WW. The valuable biomass produced can be further used for the generation of bioenergy, animal feed, fertilizers, and biopolymers, among others. In this study, Scenedesmus obliquus was able to remove nutrients from different wastewaters (poultry, swine and cattle breeding, brewery and dairy industries, and urban) with removal ranges of 95–100% for nitrogen, 63–99% for phosphorus and 48–70% for chemical oxygen demand. The biomass productivity using wastewaters was higher (except for poultry) than in synthetic medium (Bristol), the highest value being obtained in brewery wastewater (1025 mg/(L.day) of freeze‐dried biomass). The produced biomass contained 31–53% of proteins, 12–36% of sugars and 8–23% of lipids, regardless of the type of wastewater. The potential of the produced Scenedesmus obliquus biomass for the generation of BioH2 through batch dark fermentation processes with Enterobacter aerogenes was evaluated. The obtained yields ranged, in mL H2/g Volatile Solids (VS), from 50.1 for biomass from anaerobically digested cattle WW to 390 for swine WW, whereas the yield with biomass cultivated in Bristol medium was 57.6 mL H2/gVS. Graphical abstract Figure. No Caption available. HighlightsPoultry, swine, cattle, brewery, dairy and urban WWs could be microalga‐based treated.Removal efficiency ranges were 95–100% for N, 63–99% for P and 48–70% for COD.Higher biohydrogen production yield was obtained using poultry and swine wastewaters.

CO2 utilization in the production of biomass and biocompounds by three different microalgae

The atmospheric CO2 increase is considered the main cause of global warming. Microalgae are photosynthetic microorganisms that can help in CO2 mitigation and at the same time produce value‐added compounds. In this study, Scenedesmus obliquus, Chlorella vulgaris, and Chlorella protothecoides were cultivated under 0.035 (air), 5 and 10% (v/v) of CO2 concentrations in air to evaluate the performance of the microalgae in terms of kinetic growth parameters, theoretical CO2 biofixation rate, and biomass composition. Among the microalgae studied, S. obliquus presented the highest values of specific growth rate (μ = 1.28 d−1), maximum productivities (Pmax = 0.28 g L−1d−1), and theoretical CO2 biofixation rates (0.56 g L−1d−1) at 10% CO2. The highest oil content was found at 5% CO2, and the fatty acid profile was not influenced by the concentration of CO2 in the inflow gas mixture and was in compliance with EN 14214, being suitable for biodiesel purposes. The impact of the CO2 on S. obliquus cells’ viability/cell membrane integrity evaluated by the in‐line flow cytometry is quite innovative and fast, and revealed that 86.4% of the cells were damaged/permeabilized in cultures without the addition of CO2.