Photosynthetic membrane-less microbial fuel cells to enhance microalgal biomass concentration

The aim of this study was to quantitatively assess the net increase in microalgal biomass concentration induced by photosynthetic microbial fuel cells (PMFC). The experiment was conducted on six lab-scale PMFC constituted by an anodic chamber simulating an anaerobic digester connected to a cathodic chamber consisting of a mixed algae consortia culture. Three PMFC were operated at closed circuit (PMFC+) whereas three PMFC were left unconnected as control (PMFC-). PMFC+ produced a higher amount of carbon dioxide as a product of the organic matter oxidation that resulted in 1.5–3 times higher biomass concentration at the cathode compartment when compared to PMFC-Peer ReviewedPostprint (author's final draft

An unpublished petition from the Sorbonne collection

The GESHAEM project is a scientific research initiative which aims at enhancing the knowledge of the administration of Ptolemaic Fayyum. Its goal is also to restore and study both the cartonnages and the papyri, in Demotic and in Greek, kept in the "Fonds Jouguet Fouilles", stored at the Institut de Papyrologie of Sorbonne Université in Paris. In one cartonnage from Magdôla, a Greek petition to an official (hypomnêma) has been discovered and inventoried as Inv. Sorb. 2855, which bears a new name for a toparchês in the Fayyum: Philonautês

Anaerobic digestate as substrate for microalgae culture: the role of ammonium concentration on the microalgae productivity

In spite of the increasing interest received by microalgae as potential alternatives for biofuel production, the technology is still not industrially viable. The utilization of digestate as carbon and nutrients source can enhance microalgal growth reducing costs and environmental impacts. This work assesses microalgal growth utilizing the liquid phase of anaerobic digestate effluent as substrate. The effect of inoculum/substrate ratio on microalgal growth was studied in a laboratory batch experiment conduced in 0.5 L flasks. Results suggested that digestate may be an effective substrate for microalgal growth promoting biomass production up to 2.6 gTSS/L. Microalgal growth rate was negatively affected by a self-shading phenomenon, while biomass production was positively correlated with the inoculum and substrate concentrations. Thus, the increasing of both digestate and microalgal initial concentration may reduce the initial growth rate (µ from 0.9 to 0.04 d-1) but significantly enhances biomass production (from 0.1 to 2.6 gTSS/L).Peer ReviewedPostprint (published version

Recent achievements in the production of biogas from microalgae

The final publication is available at Springer via http://dx.doi.org/10.1007/s12649-016-9604-3Microalgae are nowadays regarded as a potential biomass feedstock to help reducing our dependence on fossil fuels for transportation, electricity and heat generation. Besides, microalgae have been widely investigated as a source of chemicals, cosmetics and health products, as well as animal and human feed. Among the cutting-edge applications of microalgae biomass, anaerobic digestion has shown promising results in terms of (bio)methane production. The interest of this process lies on its potential integration within the microalgae biorefinery concept, providing on the one hand a source of bioenergy, and on the other hand nutrients (nitrogen, phosphorus and CO2) and water for microalgae cultivation. This article reports the main findings in the field, highlighting the options to increase the (bio)methane production of microalgae (i.e. pretreatment and co-digestion) and bottlenecks of the technology. Finally, energy, economic and environmental aspects are considered.Peer ReviewedPostprint (author's final draft

Microalgae recycling improves biomass recovery from wastewater treatment high rate algal ponds

Microalgal biomass harvesting by inducing spontaneous flocculation (bioflocculation) sets an attractive approach, since neither chemicals nor energy are needed. Indeed, bioflocculation may be promoted by recycling part of the harvested microalgal biomass to the photobioreactor in order to increase the predominance of rapidly settling microalgae species. The aim of the present study was to improve the recovery of microalgal biomass produced in wastewater treatment high rate algal ponds (HRAPs) by recycling part of the harvested microalgal biomass. The recirculation of 2% and 10% (dry weight) of the HRAPs microalgal biomass was tested over one year in an experimental HRAP treating real urban wastewater. Results indicated that biomass recycling had a positive effect on the harvesting efficiency, obtaining higher biomass recovery in the HRAP with recycling (R-HRAP) (92–94%) than in the control HRAP without recycling (C-HRAP) (75–89%). Microalgal biomass production was similar in both systems, ranging between 3.3 and 25.8 g TSS/m2d, depending on the weather conditions. Concerning the microalgae species, Chlorella sp. was dominant overall the experimental period in both HRAPs (abundance >60%). However, when the recycling rate was increased to 10%, Chlorella sp. dominance decreased from 97.6 to 88.1%; while increasing the abundance of rapidly settling species such as Stigeoclonium sp. (16.8%, only present in the HRAP with biomass recycling) and diatoms (from 0.7 to 7.3%). Concerning the secondary treatment of the HRAPs, high removals of COD (80%) and N-NH4+ (97%) were found in both HRAPs. Moreover, by increasing the biomass recovery in the R-HRAP the effluent total suspended solids (TSS) concentration was decreased to less than 35 mg/L, meeting effluent quality requirements for discharge. This study shows that microalgal biomass recycling (10% dry weight) increases biomass recovery up to 94% by selecting the most rapidly settling microalgae species without compromising the biomass production and improving the wastewater treatment in terms of TSS removal.Peer ReviewedPostprint (author's final draft

CO2 addition to increase biomass production and control microalgae species in high rate algal ponds treating wastewater

Challenges regarding microalgal cultivation need to be solved in order to enhance microalgae potential as a feedstock for biofuel, bioenergy, and bioproducts. The optimization of the operating strategy in high rate algal ponds treating wastewater still requires research on microalgal ecosystem response to variations in nutrients availability. For this reason, the aim of this study was to determine the effect of CO2 addition on microalgal population diversity and wastewater treatment performance. To this end, batch and continuous experiments were carried out in an experimental plant constituted by four high rate algal ponds (500 L each) treating urban wastewater with and without pH regulation. As expected, CO2 addition induced a significant increase in biomass concentration (between 66 and 100%). Moreover, a positive effect on microalgal biomass concentration was observed, reducing the effect of the variation in influent wastewater characteristics. Concerning the microalgal populations, the variation of inorganic carbon availability induced a shift in the dominant microalgae species. In spite of this, no variations were observed in terms of wastewater treatment efficiency. Taking together, this study highlighted the positive effect of CO2 addition to increase biomass production and control microalgae species in high rate algal ponds treating wastewater.Peer ReviewedPostprint (author's final draft

Influence of liquid-to-biogas ratio and alkalinity on the biogas upgrading performance in a demo scale algal-bacterial photobioreactor

The influence of the liquid-to-biogas ratio (L/G) and alkalinity on methane quality was evaluated in a 11.7 m3 outdoors horizontal semi-closed tubular photobioreactor interconnected to a 45-L absorption column (AC). CO2 concentrations in the upgraded methane ranged from <0.1 to 9.6% at L/G of 2.0 and 0.5, respectively, with maximum CH4 concentrations of 89.7% at a L/G of 1.0. Moreover, an enhanced CO2 removal (mediating a decrease in CO2 concentration from 9.6 to 1.2%) and therefore higher CH4 contents (increasing from 88.0 to 93.2%) were observed when increasing the alkalinity of the AC cultivation broth from 42 ± 1 mg L−1 to 996 ± 42 mg L−1. H2S was completely removed regardless of the L/G or the alkalinity in AC. The continuous operation of the photobioreactor with optimized operating parameters resulted in contents of CO2 (<0.1%–1.4%), H2S (<0.7 mg m−3) and CH4 (94.1%–98.8%) complying with international regulations for methane injection into natural gas grids.Peer ReviewedPostprint (published version

Producción de biogás a partir de residuos organicos en biodigestores de bajo coste

PRODUCCIÓN DE BIOGÁS A PARTIR DE RESIDUOS ORGANICOS EN BIODIGESTORES DE BAJO COSTE Ivet Ferrer*, Enrica Uggetti**, Davide Poggio***, Enric Velo**** Grup de Recerca en Cooperació i Desenvolupament Humà C. Jordi Girona, 31 08034 - Barcelona, Spain Phone: +34 93 401 64 63 Pàgina web: http://www.upc.edu/grecdh [email protected] *, [email protected]**, [email protected]***, [email protected]**** Palabras clave: Digestión anaerobia; Biodigestor; Biogás; Energía; Fertilizante. RESUMEN La digestión anaerobia, o biodigestión, es una tecnología ampliamente difundida a escala familiar en países como China, India o Nepal. En estos sistemas los residuos orgánicos son convertidos en productos aprovechables como el biogás y el biol. En los proyectos piloto que se presentan, ubicados en Perú, hasta la fecha se han implementado alrededor de 20 biodigestores familiares, en comunidades rurales de la zona de Cusco y de Cajamarca. La mayoría se encuentran a 3000-4000 m.s.n.m, y la temperatura dentro del biodigestor oscila entre 10-23 ºC gracias a la implementación de invernaderos que permiten amortiguar las oscilaciones térmicas día-noche. Los biodigestores producen aproximadamente 0.2 m 3 biogas m -3 biodigestor día -1 , dentro del rango psicrofílico, que con biodigestores de 5 m 3 es suficiente para cocinar 3-4 h diarias, sustituyendo los combustibles tradicionales. El coste de construcción de los biodigestores (40 €/ m 3 ) seria asumible, al menos parcialmente, por familias campesinas. A nivel financiero, la instalación es más viable cuando el biogás sustituye un combustible con valor de mercado como el gas propano, resultando en un payback de 2 años y 8 meses; o bien cuando permite elaborar productos con valor añadido (quesos, yogures, mermeladas, etc.). Por otro lado, la eficacia del sistema también podría aumentar mediante la integración del biodigestor en la granja, conectándolo con la letrina y usando el biol como fertilizante para los cultivos. Estas aproximaciones son objeto de trabajos futuros. INTRODUCCIÓN Biodigestores familiares de bajo coste La digestión anaerobia, o biodigestión, es una tecnología que permite mejorar el aprovechamiento energético tradicional de la biomasa, tanto desde el punto de vista medioambiental, como social y económico [1]. Al mismo tiempo, permite una gestiónPostprint (published version

Promoting sustainability in education through the implementation of green walls for greywater treatment

This study describes the methodology followed to design, build and operate a pilot green wall treating greywater from a vocational training center. The study was carried out in the framework of a master thesis in Environmental Engineering carried out in collaboration with the vocational training center where the pilot system was built. The system consisted of several pots arranged in rows planted with different species of macrophytes. Results showed a successful removal efficiency of the main pollutants (total solids and organic matter), while further post-treatment would be needed to reduce turbidity and pathogens in order to fulfill water reuse standards. This work shows how teaching in certain engineering studies can focus on sustainability and perform a practical work involving younger students from a vocational training center