Increasing concentrations of CO2 in the atmosphere is causing severe environmental destruction to the earth. Bio-sequestration of CO2 is a promising way to completely sequester CO2 by converting it into biomass by way of photosynthesis. The current research focused on biomass productivity and CO2 sequestration efficiency using microalgae. The experiment choose Spirulina sp. RMUTL by cultivating in working volume 8 liters bioreactor with zarrouks medium for 24-hrs with light nature and aeration air. The CO2 (100%) was flushed into the medium with a flow rate were 0.01 0.02 and 0.03 vvm respectively. The period of all experiments were 30 days. The results showed that the maximum specific growth rate OD560 algae biomass productivity efficiency of CO2 reduction CO2 fixation rate and carbon loading rate were 0.35±0.01 d-1 0.85±0.00 600.00±10.00 mg.L-1 96.83±0.76% 1 128.00±18.80 mg.L-1.d-1 and 2 0 . 4 1 ±0 . 2 6 g. d-1 with 0.01 vvm CO2 flow rate. The average CO2 sequestration over 30 days were 3.15.±0.03 3.11.±0.02 and 3.07.±0.07% in 0.01 0.02 and 0.03 vvm CO2 flow rate respectively.

Energy is an important factor in the necessity of human life. Many countries around the world are seeking alternative energy sources. To use as alternative energy. Our alternative sources of energy are ethanol which can be produced from agricultural products. Including plants with cellulose components. The ethanol can be mixed with gasoline. It is a new product called gasohol. This research use of fresh water weed Hydrilla is a raw material in the production of ethanol. Hydrolysis sweetening and fermentation. The microorganisms used in fermentation processes the yeast is found Hydrilla through hydrolysis the acid is H2SO4 at 0.5 % . Measuring the concentration of the alcohol concentration of 4.0 % VOL 9 Brix %. The Hydrilla through hydrolysis at alkaline NaOH is at a concentration of 1 % concentration of alcohol concentration was 3.5% VOL 8 Brix %. Hydrilla and the Hydro Delight with distilled water (H2O) to measure the concentration of the alcohol concentration of 5.5 % VOL 12 Brix %. Thus it can be said that Hydrilla is a material that has the potential to produce ethanol for energy alternatives. And used as a source of renewable energy. Instead of using raw materials from food plants. And other energy crops.

This work presented the production of biogas using anaerobic co-digestion between hydrilla verticillata (HV) from Songkhla Lake Basin and chicken manure (CM). From the study of compositions of both wastes it was found that the COD of CM and HV were 11200 and 14400 mg/l and pH were 6.5 and 5.5 respectively. The biogas production using anaerobic single-digestion of untreated hydrilla verticillata (UHV) gave accumulative methane of 1251 ml-CH4/g-VS and methane production of 78.28 L-CH4/kg-substrate was obtained. For hydrilla treated with 2% w/v NaOH (THV) the accumulative methane was 1786 ml-CH4/g-VS and the obtained methane production was 91.87 L- CH4/kg-substrate which was 17.5 % increase when compared to the UHV. For the biogas production using anaerobic single-digestion of CM it was found that the accumulative methane and methane production were 978 ml-CH4/g-VS and 78.28 L- CH4/kgsubstrate respectively. These were lower than the studies using HV. The study of anaerobic co-digestion of HV and CM at three different ratios; 1:1 2:1 and 3:1 was studied. It was found that the anaerobic co-digestion using THV and CM at ratio 3:1 and 2:1 gave the highest potential for biogas production. The accumulate methane of 3202.20 and 2079.19 ml- CH4/g-VS were obtained respectively. The methane productions were 2.53 and 82.26 L-CH4/ton-substrate for ratio 3:1 and 2:1 respectively which is no significant different at 95 % confidence interval.

The study of Hydrilla (Hydrilla verticillata) effectiveness in water treatment was investigated using completely randomized designs with 4 Hydrilla densities: 0 (control) 30 50 and 70 plants. Each plot was experimented in round cement tanks added with sandy clay on the bottom. Fifty liters of canal water was then filled in. Along 6 weeks of the experiment each tank was aerated with no water exchanged. Results showed that there were no significant differences in values of temperature pH dissolved oxygen conductivity alkalinity hardness nitrite ammonia phosphate and biochemical oxygen demand in every treatment (p > 0.05). However the experimental plot with 50 hydrilla plants showed the best tendency in eradication of phosphate and improvement of biochemical oxygen demand at 86.00 and 45.73 percent respectively. On the other hand the experimental plot with 70 hydrilla plants showed the best tendency in eradication of ammonia and nitrite at 65.00 and 66.66 percent respectively.

The objective of this research was to compare the effectiveness of water hyacinth and cootail for wastewater treatment by taking water sample from Klong Bangkhen-mai near King Mongkut’s University of Technology North Bangkok. The results showed that there was no diifference on water temperature changes in tanks between two plants. pH of water in coontail tanks was between pH 8.69 to pH 8.91 and pH of water in water hyacinth tanks was slightly increasing between pH 7.71 to pH 8.26. The more amount of coontail added the higher DO would be between 9.18 mg/L to 10.02 mg/L. Moreover COD of water was decreasing according to the amount of cootail addition and more effective than that in water hyacinth tank especially in 150 grams coontail tanks but TS in water hyacinth tanks was much more decreasing than that in coontail tanks. TS was between 21.73 mg/L to 25.91 mg/L. COD was between 45.30 mg/L to 48.34 mg/L.