Acceptance, operational challenges and conceptual optimization of biodigester system in Embu prison

Abstract

This research was conducted within the Kenyan context in Embu prison on a pioneering and fully operational, since 2011, biodigester system. After three years of operation it was imperative to assess the functionality of the system and also the acceptance level by the users and beneficiaries. This research was significant as it synthesizes the true-life experiences from Biodigester utilizing rare input-human excreta. The study was a cross- sectional descriptive research which sought to examine the operational practices and challenges of the biodigester, alongside with factors influencing the adoption of biogas technology. To achieve this, the study conducted regular field visits to Embu prison, administered interviews and distributed questionnaires (designed in English and in Kiswahili language). The data was organized, edited, coded and analyzed using the Microsoft Excel and Statistical Package for Social Sciences (SPSS). Response rate of detainees was 76%, while for staff it was 43%. To address the issue of gas accumulation at night hours and fully utilize the potentials of human excreta, the study proposed to incorporate microbial fuel cells (for electricity production). Conceptualization and preliminary design of optimized system was conducted according to fundamental engineering design principles. To select the best alternative design a pair-wise comparison known as the drop and re-vote (D&R) method was used in this study. The study confirmed that biodigester in Embu prison is an appropriate solution to produce clean renewable energy. Therefore it is recommended to pursue and replicate this approach in prisons in other areas and in different public institutions of Kenya. The study also identified several directions for further research; the most important one is to conduct detailed structural design of the proposed configuration including economical evaluation of the system. The results and discussions may be also applicable to other countries or regions with similar conditions.