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Title:	Production of biohydrogen and biomethane from pretreated palm oil mill effluent in two-stage thermophilic anaerobic system
Authors:	Safa Senan Mahmod (P82858)
Supervisor:	Jamaliah Md. Jahim, Prof. Dr.
Keywords:	Hydrolysis Palm oil industry Hydrogen Methane Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia
Issue Date:	14-May-2019
Description:	Palm oil mill effluent (POME), an agro-industrial wastewater with high solids content, was subjected to hydrolysis by 1% (v/v) nitric acid (NA) in order to increase its solubility and the fermentable sugar content from its cellulosic component. Pre-treated POME was then evaluated in an up-flow anaerobic sludge blanket (UASB) bioreactor for the production of biohydrogen (BioH2), subsequently the effluent from the BioH2 reactor was utilised in a continuous stirred tank reactor (CSTR) for the production of biomethane (BioCH4) via mixed culture under thermophilic conditions. The pretreatment conditions such as temperature, hydrolysis time and acid concentration were conducted in 120 mL batch serum bottle experiments and yielded an increase in the monomeric sugars content, that to be utilised for production of BioH2. Maximum BioH2 production was 0.175 (mmol/L/h), which corresponded to the yield of 1.04 molH₂/molglucose achieved at 1% (v/v) NA with initial total reducing sugar concentration of 22.28 g/L. Hence, the results implied that POME pre-treated with 1% (v/v) NA is a potential substrate for efficient biohydrogen yield (HY) that is 65% higher than untreated POME. These conditions were used in a larger scale, whereby 20 L UASB bioreactor was fed with NA pre-treated POME under varied hydraulic retention time (HRT) between 48 to 3 hours at constant cycle length of 24 hours to test the productivity of BioH2 and the stability of UASB; no washout of biomass occurred at any cycle and the system managed to recover its H2 production rate (HPR) after initial fluctuations. In this study, H2-producing granules were formed shortly after the start-up period, and were analysed by FESEM, FTIR, SEM-EDX, and their extracellular polymeric substances content. The maximum HY and HPR achieved were 2.45 molH₂/molsugar and 11.75 LCH₄/LPOME/d, respectively, at 6 hours of HRT. Acetic acid was found to be the major by-product at all HRTs, followed by butyric acid, while polymerase chain reaction- denaturing gradient gel electrophoresis results revealed that Clostridium spp. was the most dominant H2-producing bacteria in the system. A second-stage of anaerobic digester was conducted in a 30 L CSTR, by continuously transferring the effluent from BioH2 reactor. BioCH4 reactor operated at different HRTs; 8, 5, 3 and 2 days. The highest BioCH4 production rate was achieved at HRT of 2 days with 256.77 LCH₄/kgCOD, while maintaining the bioreactor stability and productivity. Methanothermobacter species were found to be the dominant archaea in the BioCH4 system. Applying the two-stage anaerobic process together with the pre-treatment method has dramatically increased the COD removal to reach 92% of the raw POME. An economic evaluation of the BioH2- BioCH4 system was conducted using SuperPro Designer®. A model evaluation was carried out by comparison between the simulation output and the actual data achieved in the experiment. This study has successfully proven the potential conversion of POME into BioH2 and BioCH4 in two-stage thermophilic anaerobic digester system utilising microbial consortia sourced from POME sludge.,Ph.D.
Pages:	192
Call Number:	TP156.H82M334 2019 3 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina

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