Microalgal biomass is the most promising and attractive alternative to replace the terrestrial crop utilization for renewable biomass fuel feedstock. The potential for biomass fuel is due to its fast growth rate and high ability for CO 2 fixation as compared to terrestrial vegetation. There are many species in the globe, growing both in marine and freshwater. In this work, the marine microalgae Nannochloropsis oculata (N. oculata) had been investigated in terms of potential abundance and physicochemical properties, which determine its feasibility as biomass fuel feedstock. The chemical composition was evaluated by energy-dispersive X-ray spectrometry, and the proximate analysis was done by performing experiments in the thermal gravimetric analyzer. During 7 days of cultivation, the average rate of increase in algal biomass was about 1.5 9 10 6 cells/ml/day. The proximate analysis of N. oculata indicated that it had compositions of low moisture content and fixed carbon, whereas high volatile matter and ash content, i.e., 3.99, 8.08, 67.45, and 24.47 %, respectively. The energy content, which was calculated through the proximate analysis results, was 16.80 MJ/kg. The algal biomass and its residue after 1,200°C were characterized by Fourier transform infrared spectroscopy to investigate their chemical macromolecular compounds. This present study concludes that N. oculata is feasible as biomass fuel feedstock, either to direct or co-combustion mode by giving special attention to high ash content.

The thermal behavior of Nannochloropsis oculata combustion in air atmosphere were investigated by performing experiments on STA PT1600 Thermal Analyzer at heating rates of 10°C/min, 40°C/min and 70°C/min and range of temperatures from room temperature to 1200°C. The kinetic parameters were evaluated by using Kissinger and Ozawa methods. The result showed that Nannochloropsis oculata combustion occurred in five stages. Started with initial devolatilization, the main thermal decomposition and combustion process, transition stage, the combustion of char and the last stage was the slow burning reaction of residual char. In line with increasing heating rate, the mass loss rate increased as well, but it delayed the thermal decomposition processes toward higher temperatures. The average activation energy at the main thermal decomposition stage and the stage of char combustion were approximately 251 kJ/mol and 178 kJ/mol, respectively.

No abstract

No abstract

Pesticides are recognized as serious pollutants in the aquatic environment with the potential to cause genotoxic on the aquatic organism, especially fish. The micronucleus (MN) assay has been used to evaluate genotoxicity of many compounds in polluted ecosystems such pesticides. im of this study to determine genotoxic effect of methomylbased pesticide on tilapia (Oreochromis niloticus). Fish were exposed to six different concentrations base on range finding test (0 ppm, 3.2 ppm, 4.2 ppm, 6.5 ppm, 8.7 ppm and 10 ppm) of methomyl-based pesticide. The micronucleus were collected from peripheral blood erythrocyte of fish after 96 h exposure. Peripheral blood samples smears were stained with Giemsa, MN frequencies were counted and statistically analyzed using one-way ANOVA. The result of this study showed after 96 hours exposed to methomyl-based pesticide, at concentration 0 ppm causes 0% mortality, at concentration to 3.2 ppm causes 30% mortality, at concentration 4.2 ppm causes 60% mortality, at concentration 6.5 ppm causes 70% mortality, at concentration 8.7 ppm causes 80% mortality, at concentration 10 ppm causes 100% mortality of fish test. Lethal Concentration 50 (LC50 -96 hours) of methomy-base pesticide towards tilapia (O. niloticus) is 4.015 ppm. Through micronuclei assay during 96 hour exposure of methomyl-based pesticide, the result shows that frequencies of micronuclei in erythrocyte of fish test at concentration at 0ppm is 12‰, 18‰ and 16‰; at concentration at 3.2ppm is 33‰, 26‰ and 29‰; at concentration at 4.2ppm is 41‰, 38‰ and 46‰; at concentration at 6.5ppm is 68‰, 81‰ and 82‰; at concentration 8.7ppm is 133‰, 130‰ and 137‰; at concentration 10ppm is 163‰, 166‰ and 156‰. It revealed that methomyl-based pesticide exposure induced after 96 h significantly (P<0.05) increased genotoxic potentials simultaneous with increased concentration.