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Modified clay granules were used to promote Azotobacter vinelandii cell adhesion. The A. vinelandii cells in the clay granules were used as a biofertilizer and a plant material. The production process was carried out under variable temperatures. The raw ingredients consisted of clay, sawdust waste, and spent coffee grounds in different ratios. Scanning electron microscopy (SEM) was used to analyze the microstructure. The results of the study showed the addition of sawdust waste and spent coffee grounds had increased the water absorption of the fired clay granules based on their porosity. However, increasing the firing temperature in the range of 900°C - 1100°C decreased the water absorption and porosity and increased the bulk density of the fired clay granules. A. vinelandii was enriched to be used as a cell suspension. The fired clay granules were immersed in a cell suspension to immobilize the A. vinelandii cells for 48 h. The SEM-based investigations indicated that the fired clay granules were suitable for containing A. vinelandii cells. The results demonstrated high viability of bacterial cells fixed in the fired clay granules at 2.7× 107 CFU/g. Furthermore, the test results of bacterial cells in the fired clay granules for marigold planting media revealed that it had effectively encouraged plant growth. The nitrogen-fixing bacterial cells in the clay granules obtained from this research were determined to be appropriate for use as an ecological soil replacement in the future. [ABSTRACT FROM AUTHOR]

H2 production from lactic acid rich medium and H2 production from cassava starch wastewater by isolated bacteria were investigated. The isolation of H2 producing bacteria from heat treated sludge was carried out. The H2 production from lactic acid rich medium which used 1.5 g/L sodium acetate, 1.5 g/L sodium lactate and 1 g/L sucrose as carbon sources. The effects of inoculums size of 10, 20, 30 and 40 % (v/v) and incubation temperature of 35, 45 and 55°C using cassava starch wastewater as the substrate on H2 production by isolation strains were investigated. Results showed 6 isolated strains i.e. isolation code of MK01to MK06 indicated the H2 production capability when cultured in lactic acid rich medium. However, 3 isolated strains i.e. MK01, MK04, and MK06 were preferred to use as seed inoculums for further experiments depend on a high H2 production capacity obtained. Results indicated that the optimal condition of H2 production from cassava starch wastewater was 30% (v/v) inoculum size of MK06 under 35°C of incubation temperature. The maximum H2 production potential, H2 yield and H2 production rate of 4.20 L H2/L medium, 1.47 L H2/g substrate consumed, and 14.00 mL H2/L/h was obtained. Identification and characterization of MK06 were investigated using 16S rRNA gene sequence analysis followed by phylogenetic analysis. The 100% similarity of 16S rDNA compare with closely related species was indicated Klebsiella pneumoniae subsp. pneumoniae DSM 30104(T). [ABSTRACT FROM AUTHOR]

In this paper, the effects of incorporation of sawdust waste on the properties of fired clay bricks were investigated. Clay bricks fabricated with 0%, 2.5%, 5%, 7.5%, and 10% by weight of sawdust waste were tested. The clay brick specimens were firing at 900 °C, 1000 °C, and 1100 °C for study the water absorption, bulk density, apparent porosity, compressive strength, and thermal conductivity of the fired clay bricks. The experimental results found that the using of sawdust waste reduced the bulk density and compressive strength of the specimens. It was observed their apparent porosity ratios up to 30% improved with increasing of sawdust waste up to 10% by weight after firing at 900 °C. The compressive strength of bricks specimen with 2.5% by weight of sawdust waste addition and fired at 1100 °C showed a higher than of value strength as required by ASTM C62-13a. In addition, the thermal conductivity of the porous fired clay bricks specimens with 2.5-10% by weight sawdust waste addition produced at 1000 °C compared to the fired clay brick specimens without additive, decreased from 0.47 to 0.22 W/mK. The results thus showed that sawdust waste was a potential material for use as a pore former additive to raw clay-brick production. [ABSTRACT FROM AUTHOR]