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We investigated the feasibility of using Microcystis sp; blue green algae (MB) as a co-substrate to improve the mesophilic anaerobic digestion of cannery seafood wastewater (CSW) supplemented with 1% (v/v) glycerol waste (GW), to maximize bio-methane production. The MB content was set at 5, 10 and 15% (v/v) to find a near optimal methane yield. The maximum 291 mL CH 4 /g VS-added methane yield, corresponding to 4.4 m 3 -CH 4 /m 3 - mixed wastewater, was achieved with a CSW: GW: MB mixture at the volumetric 94:1:5 ratio. The methane yield of CSW digested alone was 278 mL CH 4 /g VS-added (2.2 m 3 CH 4 / m 3 of wastewater). The yields from our other experiments ranged within 81– 150 mLCH 4 /g VS-added. Ratios of MB: CSW exceeding 5% (v/v) gave lower than optimal methane yields. The energy content of methane from 1 m 3 of mixed wastewater, with the near optimal mixture ratio 94:1:5, was 157 MJ or equivalently 44 kWh.

Ethanol production from oil palm frond (OPF) by simultaneous saccharification and Saccharomyces cerevisiae TISTR5048 fermentation was investigated. Solid fraction of OPF (20% TS) was pretreated by 2% H 2 SO 4 , 2% NaOH and 2% NaOH in H 2 O 2 presoaking at room temperature for 24 hours. Pretreated OPF by presoaking in 2% H 2 SO 4 , 2% NaOH and 2% NaOH in H 2 O 2 contained 37%, 42% and 49% of cellulose, respectively. Pretreated OPF was simultaneous saccharification by cellulase enzyme (Cellic CTec2, Novozymes) and sequentially fermentation. Sugar concentration in OPF cellulose hydrolysis of 2% H 2 SO 4 , 2% NaOH and 2% NaOH in H 2 O 2 presoaking was 45.72, 55.73 and 56.94 g/l, respectively. Ethanol concentration of 2% H 2 SO 4 , 2% NaOH and 2% NaOH in H 2 O 2 presoaking was 14.5, 15.0 and 17.2 g/L, respectively. 2% NaOH in H 2 O 2 presoaking was the best pretreatment with 82.11% of total solids recovery and containing 49.9% of cellulose with enzyme digestion ability of 37.6%.

The laboratory-scale UASB reactors were operated at five different hydraulic retention times (HRTs). The various sizes of granules from three different sources: a cassava factory (CS), a seafood factory (SS), and a palm oil mill (PS), having the size range of 1.5-1.7 mm, 0.7-1.0 mm and 0.1-0.2 mm. respectively, were used as inocula for anaerobic digestion of cassava wastewater. For comparison, the first reactor with only granules from its own source (R1, CS) was treated as control. The other two reactors were inoculated with mixed granules from different sources (R2, CS+SS and R3, CS+PS). As HRT decreased from 5 days to 1 day, the organic removal efficiencies decreased from 91.49 to 43.23%, 89.36 to 45.13% and 87.23 to 32.69% for R1, R2 and R3 respectively (or inversely with increasing OLR). In this study selected mathematical models including Monod, Contois, Grau second-order and Modified Stover-Kicannon kinetic models were applied to determine the substrate removal kinetics of UASB reactors. Kinetic parameters were determined through linear regression using experimental data obtained from the steady-state experiments and subsequently used to predict effluent COD. The results showed that Grau second-order and Modified Stover-Kicannon kinetic models were more suitable than the others for predicting the substrate removal for all different sizes of granules. In addition the Upflow Anaerobic Sludge Blanket (UASB) reactor with only granules from a cassava factory gave the best performance.

Effect of organic loading rate (OLR), hydraulic retention time (HRT) and temperature variation on process stability of fermentative hydrogen production from palm oil mill effluent (POME) under thermophilic condition was investigated. High OLR (>70 gCOD/l/d) and low HRT (4 d) has significant affected on hydrogen productivity, process stability and microbial community. Hydrogen production at OLR of 55, 60, 65 and 70 gCOD/l/d was 2.4, 3.4, 4.9 and 3.7 L H 2 /L-POME, respectively. The decreasing in pH and alkalinity and increasing in total VFA could cause the instability of process. The microbial community was changed at OLR >70 gCOD/l/d, HRT 4 d and stop feeding. The dominant microbial community changed from Thermoanaerobacterim sp. to Clostridium sp., Thermoanaerobacterim sp. and Bacillus sp. Hydrogen production at HRT of 2, 4, stop feeding and 2 d was 2.7, 0.8, 0, and 2.6 L H 2 /L-POME, respectively. Hydrogen production, process stability and microbial community was not affected by variation of temperature. Hydrogen production before and after temperature variation was 2.5 and 2.45 L H 2 /L-POME.