Hydrophobic membranes for ammonia recovery from digestates in microbial electrolysis cells: Assessment of different configurations

The combination of hydrophobic membranes and microbial electrolysis cells (MEC) was assessed in two different configurations in order to recover ammonia from anaerobically digested pig slurry. Politetrafluorethilene (PTFE) hydrophobic membranes were inserted both in an H-type three-chamber cell (MEC-H) and a two-chamber sandwich configuration MEC (MEC-S), both fitted with a cationic exchange membrane (CEM) dividing the anode and cathode compartments. The use of electrochemical techniques such as electrochemical impedance spectroscopy was applied to monitor the increase of the biofilm on the anode, related to the decrease of the charge transfer resistence.This research was funded by the Spanish Ministry of Economy and Competitiveness (INIA project RTA2015-00079-C02-01). The support of the CERCA Program and of the Consolidated Research Group TERRA (ref. 2017 SGR 1290), both from the Generalitat de Catalunya, is also acknowledgedPostprint (updated version

Different approaches to assess the environmental performance of a cow manure biogas plant

In intensive livestock production areas, farmers must apply manure management systems to comply with governmental regulations. Biogas plants, as a source of renewable energy, have the potential to reduce environmental impacts comparing with other manure management practices. Nevertheless, manure processing at biogas plants also incurs in non-desired gas emissions that should be considered. At present, available emission calculation methods cover partially emissions produced at a biogas plant, with the subsequent difficulty in the preparation of life cycle inventories. The objective of this study is to characterise gaseous emissions: ammonia (NH3-N), methane (CH4), nitrous oxide (N2Oindirect, and N2Odirect) and hydrogen sulphide (H2S) from the anaerobic co-digestion of cow manure by using different approaches for preparing gaseous emission inventories, and to compare the different methodologies used. The chosen scenario for the study is a biogas plant located next to a dairy farm in the North of Catalonia, Spain. Emissions were calculated by two methods: field measurements and estimation, following international guidelines. International Panel on Climate Change (IPCC) guidelines were adapted to estimate emissions for the specific situation according to Tier 1, Tier 2 and Tier 3 approaches. Total air emissions at the biogas plant were calculated from the emissions produced at the three main manure storage facilities on the plant: influent storage, liquid fraction storage, and the solid fraction storage of the digestate. Results showed that most of the emissions were produced in the liquid fraction storage. Comparing measured emissions with estimated emissions, NH3, CH4, N2Oindirect and H2S total emission results were in the same order of magnitude for both methodologies, while, N2Odirect total measured emissions were one order of magnitude higher than the estimates. A Monte Carlo analysis was carried out to examine the uncertainties of emissions determined from experimental data, providing probability distribution functions. Four emission inventories were developed with the different methodologies used. Estimation methods proved to be a useful tool to determine emissions when field sampling is not possible. Nevertheless, it was not possible to establish which methodology is more reliable. Therefore, more measurements at different biogas plants should be evaluated to validate the methodologies more precisely.Postprint (author's final draft

Evaluation of manure management systems in Europe

The gross value of the agricultural goods in 2014 amounted up to 370 billion Euros. Almost 50% of all agricultural production is provided by livestock farming.Postprint (published version

Circular Agronomics Overview_IRTA_20190227

Poster presentation on Circular Agronomics project at the 3rd European Nutrient Event during ECOMONDO (Rimini, Italy, 8-9 November 2018

Ammonium and phosphate recovery in a three chambered microbial electrolysis cell: towards obtaining struvite from livestock manure

Ammonia and phosphate, which are present in large quantities in waste streams such as livestock manure, are key compounds in fertilization activities. Their recovery will help close natural cycles and take a step forward in the framework of a circular economy. In this work, a lab-scale three-chambered microbial electrolysis cell (MEC) has been operated in continuous mode for the recovery of ammonia and phosphate from digested pig slurry in order to obtain a nutrient concentrated solution as a potential source of fertilizer (struvite). The maximum average removal efficiencies for ammonium and phosphate were 20% ± 4% and 36% ± 10%, respectively. The pH of the recovered solution was below 7, avoiding salt precipitation in the reactor. According to Visual MINTEQ software modelling, an increase of pH value to 8 outside the reactor would be enough to recover most of the potential struvite (0.21 mmol L-1 d-1), while the addition of up to 0.2 mM of magnesium to the nutrient recovered solution would enhance struvite production from 5.6 to 17.7 mM. The application of three-chambered MECs to the recovery of nutrients from high strength wastewater is a promising technology to avoid ammonia production through industrial processes or phosphate mineral extraction and close nutrient natural cyclesPostprint (published version

Biogas production from N-rich wastes: SAOB-HM enriched digester versus hydrophobic membrane assisted digester

Hydrophobic membranes (HMM) are common in water purification processes to separate volatile compounds. When such membranes are combined with anaerobic digesters (AD), inhibitory phenomena affecting methanogenesis due to ammonium nitrogen, would be overcome. In this work, four continuous AD were operated under high N level and similar conditions (feed composition and loading, temperature and inoculum). Two AD were coupled to HMM with different membrane surface area to digester volume ratio (Am/V), while the third AD had not membrane (control AD). A fourth reactor was operated at high retention time to prompt the syntrophic acetate oxidation (SAO) route. Despite the similar total N inlet content (3.5-4.3 gN L-1), reactor performances were completely different, depending on the Am/V ratio for low retention time values. Conversely, upon operation at a high retention time, the enrichment of acetate syntrophic oxidizing bacteria and hydrogenotrophic methanogens (SAOB-HM) prevented ammonia inhibition. A modified ADM1 model, which included ammonia extraction by HMM and the SAOB population, fitted to the experimental data and helped to understand the observed patterns.Peer ReviewedPostprint (published version

Biogas production from N-rich wastes: SAOB-HM enriched digester versus hydrophobic membrane assisted digester

Hydrophobic membranes (HMM) are common in water purification processes to separate volatile compounds. When such membranes are combined with anaerobic digesters (AD), inhibitory phenomena affecting methanogenesis due to ammonium nitrogen, would be overcome. In this work, four continuous AD were operated under high N level and similar conditions (feed composition and loading, temperature and inoculum). Two AD were coupled to HMM with different membrane surface area to digester volume ratio (Am/V), while the third AD had not membrane (control AD). A fourth reactor was operated at high retention time to prompt the syntrophic acetate oxidation (SAO) route. Despite the similar total N inlet content (3.5-4.3 gN L-1), reactor performances were completely different, depending on the Am/V ratio for low retention time values. Conversely, upon operation at a high retention time, the enrichment of acetate syntrophic oxidizing bacteria and hydrogenotrophic methanogens (SAOB-HM) prevented ammonia inhibition. A modified ADM1 model, which included ammonia extraction by HMM and the SAOB population, fitted to the experimental data and helped to understand the observed patterns.Peer Reviewe

Biogas production from N-rich wastes: SAOB-HM enriched digester versus hydrophobic membrane assisted digester

Hydrophobic membranes (HMM) are common in water purification processes to separate volatile compounds. When such membranes are combined with anaerobic digesters (AD), inhibitory phenomena affecting methanogenesis due to ammonium nitrogen, would be overcome. In this work, four continuous AD were operated under high N level and similar conditions (feed composition and loading, temperature and inoculum). Two AD were coupled to HMM with different membrane surface area to digester volume ratio (Am/V), while the third AD had not membrane (control AD). A fourth reactor was operated at high retention time to prompt the syntrophic acetate oxidation (SAO) route. Despite the similar total N inlet content (3.5-4.3 gN L-1), reactor performances were completely different, depending on the Am/V ratio for low retention time values. Conversely, upon operation at a high retention time, the enrichment of acetate syntrophic oxidizing bacteria and hydrogenotrophic methanogens (SAOB-HM) prevented ammonia inhibition. A modified ADM1 model, which included ammonia extraction by HMM and the SAOB population, fitted to the experimental data and helped to understand the observed patterns.Peer Reviewe

Gainsborough in Bath 1758-1774

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN037635 / BLDSC - British Library Document Supply CentreGBUnited Kingdo