Thermophilic biohydrogen production from palm oil mill effluent (POME) using suspended mixed culture

A batch study was conducted to determine the fate of carbohydrate and oil that are present in palm oil mill effluent (POME) during the biohydrogen fermentation process. Sucrose and crude palm oil (CPO) were chosen as substrates and the kinetic profile indicated that mainly sucrose was metabolised by the mixed sludge. The hydrogen yield based on the COD of sucrose added was 146 cm3 g1 which is equivalent to a hydrogen to hexose mole ratio of 2.5. The free fatty acids from hydrolysed CPO were not metabolised further which render insignificant generation of hydrogen and volatile fatty acids from oil-based substrate. The average continuous biohydrogen production rate (HPR) from a unit volume of POME under thermophilic condition at 55 C was 2.64m3m3 d1 at a hydraulic retention time (HRT) of 4 days. Hydrogen constitutes up to 52% of the total biogas and methane was not detected over the 60 day continuous operation. The hydrogen yield (i.e. based on mole ratio of hydrogen to hexose) was 1.72 with an average carbohydrate conversion efficiency of 58%. These limit the potential of recovering more hydrogen energy from POME under current operating conditions

Food waste and food processing waste for biohydrogen production: a review

Food waste and food processing wastes which are abundant in nature and rich in carbon content can be attractive renewable substrates for sustainable biohydrogen production due to wide economic prospects in industries. Many studies utilizing common food wastes such as dining hall or restaurant waste and wastes generated from food processing industries have shown good percentages of hydrogen in gas composition, production yield and rate. The carbon composition in food waste also plays a crucial role in determining high biohydrogen yield. Physicochemical factors such as pre-treatment to seed culture, pH, temperature (mesophilic/thermophilic) and etc. are also important to ensure the dominance of hydrogen-producing bacteria in dark fermentation. This review demonstrates the potential of food waste and food processing waste for biohydrogen production and provides a brief overview of several physicochemical factors that affect biohydrogen production in dark fermentation. The economic viability of biohydrogen production from food waste is also discussed

Production of ligninolytic enzymes by newly isolated bacteria from palm oil plantation soils

Three aerobic lignin-degrading bacterial strains were isolated from palm oil plantation soils. The bacterial isolates were screened using a selective nutrient medium of minimum salt media (MSM), with kraft lignin as lignin substrate and methylene blue as the ligninolytic dye indicator. The newly isolated bacterial strains SHC1, SHC2, and SHC3 were found to have the potential to tolerate high concentrations of kraft lignin and produced all three main ligninolytic enzymes (lignin peroxidase, manganese peroxidase, and laccase); these strains may therefore be useful in the degradation of lignin in oil palm empty fruit bunch biomass. The production of ligninolytic enzymes was carried out by means of submerged fermentation for 7 days using 2 mm of oil palm empty fruit bunch (OPEFB) fiber as a substrate. These bacterial isolates were characterized using biochemical tests from Biolog and identified using 16S rRNA gene sequencing analysis, which identified the strains SHC1, SHC2, and SHC3 as Bacillus sp., Ochrobactrum sp., and Leucobacter sp., respectively with 99% sequence similarity. Bacillus sp. SHC1 produced the highest manganese peroxidase (MnP) of 2313.4 U/L on the third day and the highest lignin peroxidase (LiP) of 209.30 U/L on the fifth day of fermentation. The optimum pH and temperature for the production of ligninolytic enzymes by Bacillus sp. SHC1 were pH 8 and 30°C

Survivability of P. oxalicum T3.3 bioformulation on carrier materials and storage temperature

Good bioformulation play crucial roles in the successfully of commercialize biological control products. The development of bioformulation is necessary to improve product stability, delivery and bioactivity. The aim of this study is to assess the shelf life of P. oxalicum T3.3 conidia in the different ratio(1:1,1:2,2:1) of Biochar:Biocompost (BcBp) and Peat:Vermiculite (PtVm) and temperature (4ºC and room temperature) for 6 months. The results showed that P. oxalicum T3.3 was able to sustain highest viable cell (CFU) at 4ºC storage temperature. BcBp and PtVm have the highest cell viability at ratio 2:1 and 1:1, respectively. Both BcBp and PtVm showed potential carriers for the development of biofungicide for agriculture purposes

Start-up of biohydrogen production from palm oil mill effluent under non-sterile condition in 50 L continuous stirred tank reactor

Feasibility study of biohydrogen production from Palm Oil Mill Effluent (POME) using POME sludge as a mixed culture of natural inoculum was conducted. The experiment was done using a 150 mL serum bottle and 50 L Continuous Stirred Tank Reactor (CSTR) in batch and continuous modes, respectively. The biogas produced from both fermentations was free from methane due to heat treatment of the sludge prior to inoculation. The results obtained showed that the biohydrogen content in 150 mL serum bottle was higher (70%) than that of 50 L CSTR (25%). The biohydrogen rates for serum bottle and 50 L bioreactor were 74 and 33 NmL/h/L, respectively. Butyrate, propionate and acetate were the main soluble metabolites produced during the fermentation and reduced the pH of broth

Optimization of biohydrogen production by Clostridium butyricum EB6 from palm oil mill effluent using response surface methodology

Clostridium butyricum EB6 successfully produced hydrogen gas from palm oil mill effluent (POME). In this study, central composite design and response surface methodology were applied to determine the optimum conditions for hydrogen production (Pc) and maximum hydrogen production rate (Rmax) from POME. Experimental results showed that the pH, temperature and chemical oxygen demand (COD) of POME affected both the hydrogen production and production rate, both individually and interactively. The optimum conditions for hydrogen production (Pc) were pH 5.69, 36degreeC, and 92g COD/l; with an estimated Pc value of 306ml H2/g carbohydrate. The optimum conditions for maximum hydrogen production rate (Rmax) were pH 6.52, 41degreeC and 60g COD/l; with an estimated Rmax value of 914ml H2/h. An overlay study was performed to obtain an overall model optimization. The optimized conditions for the overall model were pH 6.05, 36degreeC and 94g COD/l. The hydrogen content in the biogas produced ranged from 60% to 75%

Enzymatic hydrolysis of palm oil mill effluent solid using mixed cellulases from locally isolated fungi

In order to optimize the enzymatic hydrolysis of POME solid, the effects of substrate pretreatment using varying concentrations of sodium hydroxide and sulfuric acid, crude enzyme from both strains in different ratio and pH reaction were studied. The best experimental conditions found to degrade POME solids were 12 h incubation time, 0.5% (v/v) sulfuric acid pretreatment, crude enzymes mixture from Aspergillus niger EB5 and Trichoderma sp. EB6 (1.75 mL Asp+0.25 mL Tri with the total cellulase activity equal to 14.76 IU) and incubation pH at 5.0. Under these conditions, the reducing sugar concentration reached 23 g L-1 with the hydrolysis yield and productivity at 32% and 1.90 g L-1 h-1, respectively. The bioconversion of POME solid to reducing sugar by the mixture of crude enzyme from the strains was relatively higher by almost 2 folds as compared to commercial cellulase. The results suggested that the crude cellulases mixture from locally isolated fungi has potential for hydrolyzing the abundant agriculture residues from the palm oil industry

Effect of different chemical treatments on the settleability of palm oil mill effluent

The effect of alum and ferric chloride on the settleability of suspended solids in raw palm oil mill effluent (POME) was compared with that of natural zeolite and calcium carbonate. This work forms part of our overall research on minimal discharge technology in the overall management of POME. The results showed that all the flocculants could effectively reduce more than 80% of the suspended solids but only 40-50% of the COD. The settled volume after 3-7 hours was generally within 35-50% of the original mixture. The best settleability in increasing order were at 3 giL ferric chloride, 11 giL alum, 10 giL zeolite and 20 giL calcium carbonate. The fastest settling rate was obtained with 20 giL calcium carbonate, where settling was almost completed within 2 hours as compared to more than 20 hours for raw POME. The dosage of zeolite was comparable to the traditional coagulants. As for calcium carbonate, although the dosage was higher, subsequent disposal or utilisation of the metalfree sludge solids fits well with our minimal discharge system for POME

Evaluation of methane oxidizer bacteria in the rice soil in Malaysia

Methane is known as a powerful greenhouse gas due to its global warming potential (GWP = 21). Rice fields are methane producers because of the flooding irrigation system. Two microbial communities are involved in methane cycle in the soil including methanogens and methanotrophic bacteria which are responsible for methane production and methane oxidation respectively. Methanotrophic bacteria as aerobic unicellular microorganisms dominantly exist in soil oxic area (e.g. surface of the soil and the rhizosphere). These microorganisms can regulate the methane emission from rice soil. This experiment applied PCR-DGGE to detect methane oxidizer bacteria (MOBs) within the rice soil from two depths 0-5 cm and 5-10 cm in different rice growth stages and cultivation systems. Consequently, several MOBs from type I and type II could be identified. However, type I was detected in depth of 0-5 cm and drained condition rather than 5-10 cm and flooding condition

Biocoversion of oil palm empty fruit bunch by Aspergillus niger EB4 under solid-state fermentation

Oil palm empty fruit bunch (OPEFB) is an abundant lignocellulosic waste material generated from the palm oil industry. In this study, a locally isolated strain Aspergillus niger EB4 was cultivated on a pre-treated OPEFB as substrate to produce cellulase in the solid-state fermentation (SSF) process. The cellulase recovered was then subjected to a saccharification process. The strain was grown on the pre-treated OPEFB in a 250 ml Erlenmeyer flask and a 192 L tray cabinet bioreactor, at 80% moisture content and incubated for nine days under a static condition. The activities of the crude cellulase extract in the tray bioreactor were 19.02 ± 0.85, 6.36 ± 0.38 and 4.56 ± 0.26 U/g for β-glucosidase, CMCase and FPase, respectively on day 6 of fermentation. These results were similar to the results obtained from the flask experiment. The results demonstrated the feasibility of solid substrate fermentation of the OPEFB in both flask and tray cabinet bioreactor for the cellulase production. The enzymatic hydrolysis of OPEFB at 5% (w/v) was performed by utilizing the partially purified and crude cellulase incubated at 40°C for seven days. The partially purified cellullases hydrolyzed the pre-treated OPEFB and released 7.7 g/l of reducing sugar which corresponded to a 15% conversion