The production of biogas from solid wastes in addition to palm oil mill effluents is necessary due to the shortage of the effluents, operation of biogas plants at low to moderate capacities, and large amount of solid wastes, particularly oil-palm empty fruit bunches (EFB). However, the biogas production from raw EFB gives low yield. This study therefore aims to investigate the effect of EFB pretreatment methods on the improvement of biogas production. The pretreatment of EFB was carried out through chemical (NaOH solutions), physical (size reduction) and biological (activated sludge and bio-scrubber effluent) processes. The experimental data was tested against corrected Gompertz model. The results showed that size reduction and pretreatments of EFB with 7% w/v NaOH, activated sludge and bio-scrubber effluent could improve biogas yield significantly and differently. The highest yield of methane was 429.9 ml/g.VS, obtained from EFB with size reduction. For the pretreatments of EFB with 7% w/v NaOH, bio-scrubber effluent and activated sludge, the methane yields were 345.5, 326.4 and 297.3 ml/g.VS, respectively. Without pretreatment, the methane yield was only 226.0 ml/g.VS. The change in cellulose and lignin compositions of EFB after pretreatment is attributed to the improvement of biogas yield. It is economically interesting that the bio-scrubber effluent from palm oil mills can be recycled to treat EFB. In the modeling study, the corrected Gompertz model could fit all data sets reasonably well.

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The purpose of this research was to synthesize and form fibroin silk air filter (SF filter) coated and non-coated with titanium dioxide. For use in indoor air pollution treatment. The main air pollutant to be treated is PM2.5. However, VOC removal also investigaed in this study. The synthesis involved degumming process using 0.5 wt % Na2CO3 at 90°C for 60 minutes. Titanium dioxide (TiO2) used in the study was a catalyst Tipaque brand (code A-220 (Anatase)). Results from studying on physical property by scanning electron microscope found that silk fibre was an ununiformly arrangement structure. SF filter coated with TiO2 showed that TiO2 distributed uniformly on the filter. The silk fibroin filters were brought to analyze for the energy band gap in order to find the energy value that the catalyst was needed to stimuate reaction in the photocatalytic process. It was found that TiO2 1-7.5 %(w/v) catalyst coated on the silk fibroin filters had the highest value of light absorption at 390 nanometers, which agreed with the value of energy level in the band gap period of 3.18 eV.The results from efficiency studies of SF filters in the treatment of indoor air pollution (generated from incense fume of 0-2 micron in size) indicated that the best treatment efficiency was 99.76%. In which SF filter non-coated with TiO2 was used, and initial PM2.5 concentration was 5 mg/m3, air flow rate was 3.93 m3/min. Treatment period was 8 hours.

This study aims to evaluate how inoculum’s origin affects the methane yield of palm oil mill effluent (POME) by measuring the specific methanogenic activities (SMA) and bio-methane potential (BMP) of POME at different dilutions (100, 80, 60, 40, and 20 % of initial POME) and by using active anaerobic sludge (as inocula) from 3 palm oil mills (S1, S2, S3). The anaerobic digesters were operated in batch mode at a temperature of 40 °C until methane generation ceased. The corresponding SMA were 0.0159, 0.0098 and 0.0333 gCOD /(gVSS d) for S1, S2 and S3, respectively. The results showed that POME without dilution gave the highest cumulative biogas, 4162, 2857 and 2678 mL for S2, S3 and S1, respectively. However, 20 % dilution from original POME gave the highest methane yield (as BMP) 126, 88 and 84 mL CH4/gCOD removed for S2, S3 and S1, respectively. In this study, 2 mathematical models were selected including the corrected Gompertz equation and Gompertz two substrate models. They were applied to characterize the kinetics of the anaerobic digestion processes and to compare the BMP data from the experiments. Both models could represent all BMP data satisfactory although only Gompertz 2 substrate model showed almost perfect fitting and could characterize the influence of slowly degradable portion of POME. Accordingly, the slowly degradable portion of POME was estimated to be 10 % of total COD.