Interaction effect of high feed to inoculum ratio ( F / I ) and temperature on the biomethanation kinetics of water hyac
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Interaction effect of high feed to inoculum ratio (F/I) and temperature on the biomethanation kinetics of water hyacinth Yessica A. Castro1,2 · Foster A. Agblevor1 Received: 12 June 2020 / Accepted: 5 October 2020 © Springer Nature Switzerland AG 2020
Abstract The anaerobic digestion of the invasive water hyacinth (Pontederia crassipes Mart.) from eutrophic water bodies could contribute to the sustainability of communities that have insecure energy sources. The optimization of critical process parameters, e.g., feed to inoculum ratio (F/I), temperature, supplementation, and inoculum acclimatization is important for large-scale applications. In the present work, water hyacinth was anaerobically digested at different F/I (1.0, 5.0, 10.0, and 30.0), mesophilic temperatures (30 and 40 °C), and supplementation settings using non-acclimatized and acclimatized inoculum to determine the process’s optimal conditions through kinetics (modified Gompertz, Chen and Hashimoto, and first-order) and energy analyses. The F/I ratio had a directly proportional effect on the methane yield [N mL·CH4/g·VS], which ranged from 416.8 ± 6.2 (F/I = 1.0) to 263.8 ± 26.9 (F/I = 30.0). The methane production rate [N mL·CH4/g·VS·day] was highest at 40 °C (9.0 ± 0.8) and lowest at F/I = 30 (5.6 ± 2.8). The biomethanation of water hyacinth followed the modified Gompertz and Chen and Hashimoto models when using the non-acclimatized and acclimatized inoculum, respectively. A 30-day pseudo-lag phase was observed at the highest F/I (30) and low temperature (30 °C) but was negligible at higher temperature (40 °C). For a 5.0 m3 biodigester, the highest estimated net energy occurred at F/I = 30 (370.5 ± 22.6 MJ). The doubling times at 40 °C (16.9 ± 0.3 days) were lower than that at 30 °C (49.6 ± 2.5 days). The anaerobic digestion of water hyacinth in batch mode was optimal at higher F/I ratio and high mesophilic temperatures. Keywords Eichhornia crassipes · Substrate to inoculum ratio · Anaerobic digestion · Modified Gompertz model · Chen and Hashimoto
1 Introduction Using the invasive water hyacinth (Pontederia crassipes Mart.) as a feedstock for bioconversion processes like anaerobic digestion can mitigate the costs associated with weed removal from eutrophic water bodies in developing communities. The energy produced during the anaerobic digestion of water hyacinth as a post weed management practice can be more than 10 times
the energy consumed in mechanical harvesting [1]. The use of this weed as bioenergy feedstock would not only meet the energy needs but also mitigate environmental problems [2]. Parametric studies on the kinetics and energy balance could contribute to the scalability of this bioconversion process. Some of the main factors influencing the anaerobic digestion performance at large scale are related to process control (e.g., organic loading, temperature) and microbiology [3, 4]. However,
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s42452-020-03626-w) contains supplementary ma
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