Develop a pilot digester prototype for biogas generation through co-digestion of organic agro-waste materiale.

The Costa Rican agricultural industry has tended to pose a threat to the environment due to the the dumping coupled with deficient management of the organic agro-waste materials generated from multiple agro-activities. These solid agro-wastes largely include banana and pineapple materials. These substrates have been either burnt or dumped openly in the aquatic bodies, triggering severe environmental and health pollution problems. To address challenges like this one, a pilot digester prototype was designed and constructed to test the three-selected common organic agro-waste materials. The experimental test aimed at using the batch and the constructed conventional pilot digester to evaluate the biogas production potential of the materials. The batch experiment focused upon evaluating each test substrate separately based on their respective BMP, whilst the pilot conventional reactor relied on combining the three substrates into a single feedstock for co-digestion, and hence biogas production. The substrates were obtained from the University banana farm and the banana packing unit, while pineapple peels were obtained from the cafeteria of the institution. The TS and VS values for the three substrates were; Ra: 8.5 % TS, 82 % VS; Ps: 8.6 % TS, 83.5 % VS; and Pp: 13.9 % TS, 91.8 % VS; respectively. The pilot reactor operated under environmental conditions, while the batch work under mesophilic temperature and automated agitation. The pilot reactor was first allowed to undergo a pre-stabilization time of seven days, to allow the biogas-forming microorganisms acclimatise to the new anaerobic environment, after which loading the system with test substrate begun. The pilot digester operated for 80 days of actual experiment, and had a HRT of 93 days, while the batch worked for 29 days. The pilot reactor was operated under the co-digestion technique at a constant feeding load of 0.180 kg/day of VS. A total biogas volume of 7756 L was collected, and a biogas yield of 0.113 m3/kg of VS with an average CH4 content of 32.3 % were obtained. The reactor’s maximum CH4 concentration was 76.4 %. The average biomethane volume for pineapple peels and banana rachis ranged between 427 mLN and 539 mLN of CH4 per day within the first 29 days of the experiment. In first 24 days, banana pseudostem produced an average biomethane volume of 703 mLN per day. The pilot reactor’s OLR used was 0.180 kg/m3 of VS per day, with a fermentation volume of 0.360 m3. The experiment indicated that, the pilot reactor generated nearly 0.097 m3/day of dry biogas, and that 1 kg of VS produced 113 L of dry biogas. Results confirmed that the three residues could be suitable for biogas production, but, their fibrous morphology makes it difficult.

Bibliographic Details

Main Author:	Luwondera, Fred
Other Authors:	Linkimer, Mildred
Format:	info:eu-repo/semantics/bachelorThesis biblioteca
Language:	eng
Published:	Universidad EARTH 2017-12
Subjects:	BIOGAS, DIGESTORES, DESECHOS ORGANICOS, RESIDUOS DE COSECHAS, https://purl.org/pe-repo/ocde/ford#4.01.01,
Online Access:	https://repositorio.earth.ac.cr/handle/UEARTH/483
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