Cobalt toxicity in anaerobic granular sludge: influence of chemical speciation

The influence of cobalt speciation on the toxicity of cobalt to methylotrophic methanogenesis in anaerobic granular sludge was investigated. The cobalt speciation was studied with three different media that contained varying concentrations of complexing ligands [carbonates, phosphates and ethylenediaminetetraacetic acid (EDTA)]. Three fractions (nominal added, dissolved and free) of cobalt were determined in the liquid media and were correlated with data from batch toxicity experiments. The average concentration of cobalt that was required for 50% inhibition of methanogenic activity (IC50) for free Co2+ in the three sets of measurements was 13 mu mol/L with a standard deviation of 22% and a similarity of 72% between the data obtained in the three different media for the range of cobalt concentrations investigated. The standard deviation of the IC50 for the other two fractions was much higher, i.e. 85 and 144% for the added cobalt and dissolved cobalt, respectively, and the similarity was almost 0% for both fractions. Complexation (and precipitation) with EDTA, phosphates and carbonates was shown to decrease the toxicity of cobalt on methylotrophic methanogenesis. The free cobalt concentration is proposed to be the key parameter to correlate with cobalt toxicity. Thus, the toxicity of cobalt to granular sludge can be estimated based on the equilibrium-free cobalt concentration

Idoneidad del agua de lavado de aceites de oliva como donador de electrones en un sistema alimentado por lotes bioelectroquímico

Olive oil washing water derived from the two-phase manufacturing process was assessed as an electron donor in a bio-electrochemical system (BES) operating at 35 ºC. Start-up was carried out by using acetate as a substrate for the BES, reaching a potential of around +680 mV. After day 54, BES was fed with olive oil washing water. The degradation of olive oil washing water in the BES generated a maximum voltage potential of around +520 mV and a Chemical Oxygen Demand (COD) removal efficiency of 41%. However, subsequent loads produced a decrease in the COD removal, while current and power density diminished greatly. The deterioration of these parameters could be a consequence of the accumulation of recalcitrant or inhibitory compounds, such as phenols. These results demonstrated that the use of olive oil washing water as an electron donor in a BES is feasible, although it has to be further investigated in order to make it more suitable for a real application.El agua de lavado del aceite de oliva procedente del proceso de elaboración en dos fases fue utilizada como donador de electrones en un Sistema Bioelectroquímico (BES) operado a 35ºC. Se realizó una etapa de arranque del sistema mediante alimentación con acetato, alcanzando un potencial de referencia de +680 mV. Tras 54 días, el sistema se alimentó con agua de lavado de aceite, generando un potencial máximo de +520 mV y una eliminación de materia del 41%, en demanda química de oxígeno. Sin embargo, cargas subsecuentes conllevaron una bajada en la eliminación de materia, mientras que la densidad de corriente y de potencia disminuyeron ostensiblemente. El empeoramiento de estos parámetros puede deberse a la acumulación de compuestos recalcitrantes o inhibidores, como fenoles. Por tanto, el uso del agua de lavado de aceite de oliva en un BES es factible, aunque es necesario llevar a cabo nuevas investigaciones que hagan más atractiva su aplicación a escala real

Role of nickel in high rate methanol degradation in anaerobic granular sludge bioreactors

The effect of nickel deprivation from the influent of a mesophilic (30°C) methanol fed upflow anaerobic sludge bed (UASB) reactor was investigated by coupling the reactor performance to the evolution of the Methanosarcina population of the bioreactor sludge. The reactor was operated at pH 7.0 and an organic loading rate (OLR) of 5–15 g COD l−1 day−1 for 191 days. A clear limitation of the specific methanogenic activity (SMA) on methanol due to the absence of nickel was observed after 129 days of bioreactor operation: the SMA of the sludge in medium with the complete trace metal solution except nickel amounted to 1.164 (±0.167) g CH4-COD g VSS−1 day−1 compared to 2.027 (±0.111) g CH4-COD g VSS−1 day−1 in a medium with the complete (including nickel) trace metal solution. The methanol removal efficiency during these 129 days was 99%, no volatile fatty acid (VFA) accumulation was observed and the size of the Methanosarcina population increased compared to the seed sludge. Continuation of the UASB reactor operation with the nickel limited sludge lead to incomplete methanol removal, and thus methanol accumulation in the reactor effluent from day 142 onwards. This methanol accumulation subsequently induced an increase of the acetogenic activity in the UASB reactor on day 160. On day 165, 77% of the methanol fed to the system was converted to acetate and the Methanosarcina population size had substantially decreased. Inclusion of 0.5 μM Ni (dosed as NiCl2) to the influent from day 165 onwards lead to the recovery of the methanol removal efficiency to 99% without VFA accumulation within 2 days of bioreactor operation

Knowledge and social capacity building for sustainable urban transformation

No abstract available

Evaluating the Impact of Nature-Based Solutions: A Handbook for Practitioners

The Handbook aims to provide decision-makers with a comprehensive NBS impact assessment framework, and a robust set of indicators and methodologies to assess impacts of nature-based solutions across 12 societal challenge areas: Climate Resilience; Water Management; Natural and Climate Hazards; Green Space Management; Biodiversity; Air Quality; Place Regeneration; Knowledge and Social Capacity Building for Sustainable Urban Transformation; Participatory Planning and Governance; Social Justice and Social Cohesion; Health and Well-being; New Economic Opportunities and Green Jobs. Indicators have been developed collaboratively by representatives of 17 individual EU-funded NBS projects and collaborating institutions such as the EEA and JRC, as part of the European Taskforce for NBS Impact Assessment, with the four-fold objective of: serving as a reference for relevant EU policies and activities; orient urban practitioners in developing robust impact evaluation frameworks for nature-based solutions at different scales; expand upon the pioneering work of the EKLIPSE framework by providing a comprehensive set of indicators and methodologies; and build the European evidence base regarding NBS impacts. They reflect the state of the art in current scientific research on impacts of nature-based solutions and valid and standardized methods of assessment, as well as the state of play in urban implementation of evaluation frameworks

Enhanced hydrogen production from thermochemical processes

To alleviate the pressing problem of greenhouse gas emissions, the development and deployment of sustainable energy technologies is necessary. One potentially viable approach for replacing fossil fuels is the development of a H2 economy. Not only can H2 be used to produce heat and electricity, it is also utilised in ammonia synthesis and hydrocracking. H2 is traditionally generated from thermochemical processes such as steam reforming of hydrocarbons and the water-gas-shift (WGS) reaction. However, these processes suffer from low H2 yields owing to their reversible nature. Removing H2 with membranes and/or extracting CO2 with solid sorbents in situ can overcome these issues by shifting the component equilibrium towards enhanced H2 production via Le Chatelier's principle. This can potentially result in reduced energy consumption, smaller reactor sizes and, therefore, lower capital costs. In light of this, a significant amount of work has been conducted over the past few decades to refine these processes through the development of novel materials and complex models. Here, we critically review the most recent developments in these studies, identify possible research gaps, and offer recommendations for future research

Photocatalytic Degradation of Toluene in Air Using a Fluidized Bed Photoreactor

The photocatalytic degradation of toluene in air was carried out on particles of TiO2 in a photocatalytic reactor that had been developed to study the treatment of organic pollutants in a gaseous phase. Hypothetically, the fluidized bed technology of this reactor could make it possible to increase the mass transfer coefficients in comparison with those of conventional photoreactors. The photocatalytic particles used were prepared by mixing TiO2 (Degussa P25) and starch in a methanol solution. The XRD and SEM results of these aggregates confirm the titanium dioxide (Degussa P25) characteristics, such as the presence of anatase on the particle surface and spongy and wrinkled morphology. Toluene concentrations varied from 0.9 to 199 ppmv, and all the experiments were carried out with a flow rate of 300 NL/h. Toluene conversions from 77% to 100% were obtained in the range studied. In this work, the regeneration processes of deactivated TiO2 photocatalysts have been investigated using FT-IR and GC/MS techniques. Benzoic acid, benzaldehyde, and benzyl alcohol were the three major intermediate products identified