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

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%

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