Briquetting of sugarcane bagasse as a proper waste management technology in Vietnam

The present research describes an application of high-pressure briquetting technology to the waste management of sugarcane processing in Vietnam. The amount of generated sugarcane bagasse was monitored during sugarcane processing within the street juice production in Hue city, Vietnam. Generated sugarcane bagasse was subjected to fuel parameters analysis within its suitability for direct combustion. The obtained sugarcane bagasse was converted into bio-briquette fuel by a high-pressure briquetting press and its mechanical quality was determined. Results proved that the proportion of generated sugarcane bagasse from whole sugarcane stem mass was equal to 35.45%. This indicated generation of an abundant amount of sugarcane bagasse worldwide in general. Fuel parameters analysis proved high quality level of low ash content = 0.97% and high calorific values (gross calorific value = 18.35 MJ·kg^-1, net calorific value = 17.06 MJ·kg^-1), which indicated good suitability for direct combustion processes. Indicators of mechanical quality proved the following observations: mechanical durability = 99.29%, compressive strength = 150.82 N∙mm^-1 and bulk density = 1022.44 kg·m^-3, with all these indicators representing positive results. In general, the observed results indicated suitability of sugarcane bagasse valorization within the production of bio-briquette fuel by using high-pressure briquetting technology. Finally, analysis of such waste biomass proved its great potential for energy recovery, thus, the advantage of its valorization within the sustainable technologies.

Growth optimization of Saccharomyces cerevisiae and Rhizopus oligosporus during fermentation to produce tempeh with high β-glucan content

Abstract. Rizal S, Murhadi, Kustyawati ME, Hasanudin U. 2020. Growth optimization of Saccharomyces cerevisiae and Rhizopus oligosporus during fermentation to produce tempeh with high β-glucan content. Biodiversitas 21: 2667-2673. Saccharomyces cerevisiae grows and produces β-glucan during fermentation in tempeh production. The content of β-glucan in tempeh is influenced by the growth of S. cerevisiae throughout fermentation. The purpose of this study was to determine the effects of different types and concentrations of carbon sources on yeast growth, fungi growth, and β-glucan content in tempeh inoculated using Rhizopus oligosporus and S. cerevisiae. This study used a Factorial Randomized Complete Block Design (RCBD) with two factors and three replications. The first factor was the types of carbon sources, tapioca and wheat flour; the second factor was the concentrations of carbon source, 0.0%, 2.5%, 5.0%, 7.5% and 10.0% (w/w). Tempeh produced was investigated for yeast number, fungi number, β-glucan content, and pH value. The obtained data were tested using Tukey's Honestly Significance Difference (HSD) test. The results showed that the addition of various types and concentrations of carbon source significantly influenced the increase in yeast number, fungi number, β-glucan content, and pH in tempeh. The growth of yeast, fungi, and β-glucan content increased along with the increment of carbon source concentration. The amounts of yeast, fungi, and β-glucans in tempeh added with tapioca were higher compared to tempeh with wheat flour. The addition of 10% tapioca produced the highest amount of yeast with 9.505 Log CFU/g and the highest β-glucan content with 0.707% (w/w).

Palm oil mill effluent treatment and utilization to ensure the sustainability of palm oil industries

The purpose of this study was to evaluate the current condition of palm oil mill effluent (POME) treatment and utilization and to propose alternative scenarios to improve the sustainability of palm oil industries. The research was conducted through field survey at some palm oil mills in Indonesia, in which different waste management systems were used. Laboratory experiment was also carried out using a 5 m(3) pilot-scale wet anaerobic digester. Currently, POME is treated through anaerobic digestion without or with methane capture followed by utilization of treated POME as liquid fertilizer or further treatment (aerobic process) to fulfill the wastewater quality standard. A methane capturing system was estimated to successfully produce renewable energy of about 25.4-40.7 kWh/ton of fresh fruit bunches (FFBs) and reduce greenhouse gas (GHG) emissions by about 109.41-175.35 kgCO2e/tonFFB (CO2e: carbon dioxide equivalent). Utilization of treated POME as liquid fertilizer increased FFB production by about 13%. A palm oil mill with 45 ton FFB/hour capacity has potential to generate about 0.95-1.52 MW of electricity. Coupling the POME-based biogas digester and anaerobic co-composting of empty fruit bunches (EFBs) is capable of adding another 0.93 MW. The utilization of POME and EFB not only increases the added value of POME and EFB by producing renewable energy, compost, and liquid fertilizer, but also lowers environmental burden.

Application of modified supercritical carbon dioxide extraction to microbial quinone analysis

Supercritical carbon dioxide (scCO2) was applied to extract microbial quinones from activated sludge. Identification and analysis was then performed using high-performance liquid chromatography (HPLC) equipped with ultraviolet-visible (UV-Vis) detector and photodiode array detector (PDA). Extracted microbial quinones were trapped and separated as menaquinones (MK) and ubiquinones (Q) species using two Sep-Pak Plus Silica cartridges joined in series. Four ubiquinones and 12 menaquinones species were identified in 0.1 g dried activated sludge based on retention time and spectrum analysis. Among the tested various polar solvents, methanol showed to be the best modifier, based on the highest total quinone content extracted and the lowest dissimilarity index. The diversity index of quinone and the number of quinone species using methanol-modified scCO2 were similar to that of the conventional method (organic solvent extraction).

Dynamic changes in environment condition and microbial community structure in trench and flat seabed sediments of Tokyo Bay, Japan

Dynamic changes in the chemical environment in the bottom of overlying water and microbial community structure in trench and flat seabed sediments were evaluated during summer and autumn in Tokyo Bay, Japan, to elucidate the response of microbial community changes as a consequence of dredging activity. Quinone profile analysis was performed to evaluate the changes in microbial community structure in the sediments. Bottom shape and location of each station affected the chemical environment of the overlying water. The trench bottom shape had longer anoxic conditions than the flat bottom shape. Nitrogen and phosphorus concentrations affected the microbial density in the sediment. During anoxic conditions, the ubiquinone/menaquinone ratio (UQ/MK) was less than unity and increased with rising dissolved oxygen (DO) concentrations. The dominant quinone species in the trench and flat seabed sediments were MK with 6 and 7 isoprene units (MK-6 and MK-7) and UQ with 8 and 9 isoprene units (UQ-8 and UQ-9). MK-6 and UQ-8 containing bacteria might have a great influence on the sulfur cycle of the aquatic ecosystem. While, MK-7 and UQ-9 containing bacteria correlated with the deposition of phototropic bacteria cells onto the seabed sediment. The trench bottom shape contained higher concentrations of MK-6, MK-7, UQ-8 and UQ-9, especially during summer.