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Pabon-Pereira, C., Slingerland, M., Hogervorst, S., van Lier, J., & Rabbinge, R. (2019). A Sustainability Assessment of Bioethanol (EtOH) Production: The Case of Cassava in Colombia. Sustainability, 11(14), 23 pp.
Abstract: This paper shows how system design determines sustainability outcomes of cassava bioethanol production in Colombia. The recovery of the energy contained in by-products is recommended as compared to single product production. In particular, this study assesses the energy, greenhouse gases, water, and land use performance of alternative cassava cascades working at different scales, highlighting the implications of including anaerobic digestion technology in the chain. The centralized systems showed a poorer energy and greenhouse gases performance as compared to decentralized ones in part due to the artificial drying of cassava chips in the centralized facility. Under solar drying of cassava chips, systems with anaerobic digestion produced three to five times more energy than demanded and produced greenhouse gas savings of 0.3 kgCO(2eq) L EtOH-1. The water balance output depends upon the water reuse within the ethanol industry, which demands 21-23 L EtOH-1. In the anaerobic digestion scenarios, assuming liquid flows are treated separately, complete water recovery is feasible. Land use for cassava cultivation was calculated to be 0.27-0.35 ha tEtOH(-1). The energy and water content of the material to digest, the options for digestate reuse, and the recovery of the methane produced are major considerations substantially influencing the role of anaerobic digestion within cassava cascade configurations.
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Pabon-Pereira, C. P., Castanares, G., & van Lier, J. B. (2012). An OxiTop (R) protocol for screening plant material for its biochemical methane potential (BMP). Water Sci. Technol., 66(7), 1416–1423.
Abstract: A protocol was developed for determining the biochemical methane potential (BMP) of plant material using the OxiTop (R) system. NaOH pellets for CO2 absorption and different pretreatment methods were tested for their influence in the BMP test. The use of NaOH pellets in the headspace of the bottle negatively affected the stability of the test increasing the pH and inhibiting methanization. Sample comminution increased the biodegradability of plant samples. Our results clearly indicate the importance of test conditions during the assessment of anaerobic biodegradability of plant material, considering BMP differences as high as 44% were found. Guidelines and recommendations are given for screening plant material suitable for anaerobic digestion using the OxiTop (R) system.
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Pabon-Pereira, C. P., de Vries, J. W., Slingerland, M. A., Zeeman, G., & van Lier, J. B. (2014). Impact of crop-manure ratios on energy production and fertilizing characteristics of liquid and solid digestate during codigestion. Environ. Technol., 35(19), 2427–2434.
Abstract: The influence of maize silage-manure ratios on energy output and digestate characteristics was studied using batch experiments. The methane production, nutrients availability (N and P) and heavy metals' content were followed in multiflask experiments at digestion times 7, 14, 20, 30 and 60 days. In addition, the available nutrient content in the liquid and solid parts of the digestate was evaluated. Aanaerobic digestion favoured the availability of nutrients to plants, after 61 days 20-26% increase in NH4+ and 0-36% increase in PO43- were found in relation to initial concentrations. Digestion time and maize addition increased the availability of PO43-. Inorganic nutrients were found to be mainly available in the liquid part of the digestate, i.e. 80-92% NH4+ and 65-74% PO43-. Manure had a positive effect on the methane production rate, whereas maize silage increased the total methane production per unit volatile solids in all treatments.
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