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Title:	Methane generation in single and two-stage anaerobic digestion system utilising sago mill effluent in anaerobic sequencing batch reactor
Authors:	Rafiqqah Mohamed Sabri (P80631)
Supervisor:	Jamaliah Md Jahim, Prof. Dr.
Keywords:	Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia Sago industry Effluent Reactor
Issue Date:	28-Jul-2020
Description:	Sago industry is a well-established commodity and has become one of the important agricultural revenue earner for Sarawak. Due to the increasing demand of sago starch export, the sago starch processing mill industry now experienced serious waste disposal problems. Given its high organic content, the waste or sago mill effluent (SME) has a potential to be utilised as a substrate for anaerobic digestion. Anaerobic digestion is a sustainable environmental technology that can be used to recover the energy in organic waste such as SME in the form of biogas. The objectives of this research are to determine the effect of initial pH condition on the production of methane using SME; to evaluate the methane production through single and two-stage anaerobic digestion system using SME in anaerobic sequencing batch reactor (ASBR); to identify the dominant microbial community that presents in two-stage methane producing system. From batch fermentation trials, the results revealed that maximum methane yield of was obtained when the initial pH was 7.5. In single-stage system, SME was fed directly in an ASBR to produce methane. While, acidified effluent, which was the treated SME from the hydrogen fermentation was subsequently used as a substrate in the two-stage anaerobic digestion system. The ASBR was operated over a range of hydraulic retention time (HRT) of 12 to 1.5 days in both single and two-stage anaerobic digestion system, respectively. The corresponding organic loading rate (OLR) were 1.21 to 9.90 kg COD/m3d and 1.41 to 11.17 kg COD/m3d, respectively. The acidified effluent contained COD ranged from 15000 to 16000 mg/L with ending pH ranged from 5.26 to 5.82. Butyric and acetic acids were found to be the major VFAs produced with ethanol as dominant alcohol. The results showed that the highest methane production rate was 1.254 L CH4/L.d, at retention time of 2 days in single-stage system. The highest COD removal achieved in the ASBR was 52.65% at HRT 2 days. Meanwhile, in two-stage anaerobic digestion system, the methane reactor gave an average of 1.711 L CH4/L.d, corresponding to methane yield of 0.2257 L CH4/g CODremoved with maximum COD removal efficiency of 65.04% at retention time of 2 days. Subsequently, the results from different methane stages were analysed from an energy recovery perspective based on the yields achieved and the present findings showed that energy yield (9.04 MJ/kg COD) recovered from two-stage anaerobic digestion system outperformed than that in single-stage (8.88 MJ/kg COD). Methanosarcina sp was identified as dominant methanogen in the two-stage methane reactor. Overall, this study demonstrated the feasibility of producing methane from SME using single and two-stage anaerobic digestion systems. It is also postulated that two-stage anaerobic digestion system is able to provide higher methane productivity as compared to a single-stage system.,Master of Science
Pages:	97
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina

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