Oil palm empty fruit bunch (OPEFB) was pretreated using white-rot fungus Pleurotus floridanus, phosphoric acid or their combination, and the results were evaluated based on the biomass components, and its structural and morphological changes. The carbohydrate losses after fungal, phosphoric acid, and fungal followed by phosphoric acid pretreatments were 7.89%, 35.65%, and 33.77%, respectively. The pretreatments changed the hydrogen bonds of cellulose and linkages between lignin and carbohydrate, which is associated with crystallinity of cellulose of OPEFB. Lateral Order Index (LOI) of OPEFB with no pretreatment, with fungal, phosphoric acid, and fungal followed by phosphoric acid pretreatments were 2.77, 1.42, 0.67, and 0.60, respectively. Phosphoric acid pretreatment showed morphological changes of OPEFB, indicated by the damage of fibre structure into smaller particle size. The fungal-, phosphoric acid-, and fungal followed by phosphoric acid pretreatments have improved the digestibility of OPEFB’s cellulose by 4, 6.3, and 7.4 folds, respectively.
A packed bed reactor was evaluated for hydrogen sulfide (H 2 S) removal by sulfur-oxidizing bacteria attached as a biofilm on salak fruit seeds (SFS). The bacteria were isolated from the sludge of the wastewater of a biogas plant. The promising isolate from the previous work was used in a biofilter, and its capacity to remove H 2 S was evaluated at effects of time of operation, effects of biogas flow rate, effects of axial distance, and packing material. Obtained results showed that isolate attached to SFS in an 80 cm height and 8 cm inside diameter biofilter column could decrease H 2 S in biogas from 142.48 ppm to 4.06 ppm (97.15% removal efficiency) for a biogas flow rate of 8550 g m À3 h À1 corresponding to a residence time of 4 h. Simple kinetic models of sulfide removal and bacterial growth was proposed to describe the operation of the biofilter. The radial H 2 S concentration gradient in the flowing gas is to be neglected so is the H 2 S concentration in the biofilm at certain axial distance. Meanwhile, the rate of H 2 S degradation was approximated by Monod type equation. The obtained simultaneous ordinary differential equations solved by Runge-Kutta method. Comparing the calculated results and the experimental data, it can be concluded that model proposed can sufficiently describe the performance of the H 2 S removal. The suitable values of the parameters are as follows: m max = 0.0000007 (s À1), K S = 0.0000039 (g cm À3), k G = 0.0086 (cm s À1), H S = 0.9 ((g cm À3)/ (g cm À3)), and Y x/s = 10.
Lignocellulosic carbohydrates, i.e. cellulose and hemicellulose, have abundant potential as feedstock for production of biofuels and chemicals. However, these carbohydrates are generally infiltrated by lignin. Breakdown of the lignin barrier will alter lignocelluloses structures and make the carbohydrates accessible for more efficient bioconversion. White-rot fungi produce ligninolytic enzymes (lignin peroxidase, manganese peroxidase, and laccase) and efficiently mineralise lignin into CO2 and H2O. Biological pretreatment of lignocelluloses using white-rot fungi has been used for decades for ruminant feed, enzymatic hydrolysis, and biopulping. Application of white-rot fungi capabilities can offer environmentally friendly processes for utilising lignocelluloses over physical or chemical pretreatment. This paper reviews white-rot fungi, ligninolytic enzymes, the effect of biological pretreatment on biomass characteristics, and factors affecting biological pretreatment. Application of biological pretreatment for enzymatic hydrolysis, biofuels (bioethanol, biogas and pyrolysis), biopulping, biobleaching, animal feed, and enzymes production are also discussed.
Fruit waste is a part of municipal solid waste which is typically disposed of directly to a landfill site. In order to utilize this valuable renewable resource, anaerobic biological processes can be employed to convert fruit waste to biogas. This usable gas is then used to generate electricity. This paper describes a comprehensive study to set up technology for converting fruit waste to electricity via biogas production. First, the fruit waste characteristics (type and composition) were systematically evaluated, and then laboratory experiments for biogas conversion to explore gas production from the waste were carried out. The biogas plant was then designed, based on the information obtained. Finally, a comparison of biogas plant with landfill was performed using life cycle assessment (LCA) to determine environmental impacts, and economic evaluation to assess daily processing costs. The results from waste characterization in one of the biggest fruit markets in Indonesia showed that the three main component fruit types were orange (64%), mango (25%), and apple (5%). Rotten fruit contributes up to 80% of the total waste in the fruit market. Based on the experimental work, the potential gas production in the biogas plant was calculated to be approximately 1075 Nm 3 /day, comprising 54% methane, based on 10 tons per day of fruit waste. The comparison demonstrates that it is a better option to utilize fruit waste in a biogas plant, in terms of LCA and daily operational costs, than to dispose of it in landfill.
This paper presents an experimental investigation on using mixed culture for immobilization and co-immobilization for hydrogen production. The shape and diameter of the beads were investigated. Hydrogen was produced from 10 g.L 1 glucose in anaerobic batch using immobilized mixed culture with extrusion dripping method. The alginate concentrations as immobilization material were 1%, 2%, and 3%. The mixed culture had three different biodigester sources consisting of cow dung, tofu waste, and fruit waste. The pretreatment of each mixed culture was acidification and enrichment. Then the mixed culture were mixed with immobilization material and inserted into a syringe, then dropped into 0.1M CaCl 2 . Activated carbon was added to alginate (coimmobilization) with ratio 1:1. The results showed that bead using 1% and 2% alginate concentrations were a pear-shaped. The highest concentration of hydrogen (mol H 2 /mol glucose) was 0.029 for immobilized beads with 2% alginate concentration and the lowest hydrogen (molH 2 /mol glucose) was 0.009 for immobilized beads with 3% alginate concentration. Acetic acid was the most dominant.
Purification and characterization of biodegradable plastic namely Polyhydroxybutyrate (PHB) in Cupriavidus necator have been carried out. C. necator was grown on a Ramsay medium with fixed substrate conditions and optimized for time. Stepwise purification of PHB was carried out, by using hydrogen peroxide and chloroform. The effect of temperature, time, and hydrogen peroxide concentration on the purification were also evaluated. The extracted PHB was studied with XRD, FTIR and 1H-NMR and 13C-NMR to determine its structure and purity. Yield and crystallinity were also studied with HPLC and XRD, respectively. The results of the research showed that higher concentrations of hydrogen peroxide gave better yields, whereas higher temperatures and longer lysis times led to different results. Higher crystallinity was observed when purification temperatures were elevated, but higher hydrogen peroxide concentration and longer extraction time gave varying crystallinity. The highest yield ca 66.10 % DCW was reached by purification using H2O2 20 %, at 100 oC for 2 h. The results of TGA analysis indicated that the purity of the PHB obtained was about 75 % and by using DSC, it was found that the PHB showed good thermal properties. Keywords: PHB, recovery, hydrogen peroxide, characterization
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