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Microalgae is a microscopic plant that has chlorophyll for carrying out photosynthesis. Chlorella sp. is one of the most easily found microalgae in the aquatic. Chlorella sp needs some nutrients such as nitrate and total phosphate for growing. There are many ways to develop microalgae, and an algae reactor is more effective on a large scale. Algae reactor has the same concept with oxidation ditch by using different microorganisms. This study applied an oxidation ditch reactor filled with microalgae Chlorella sp for treating domestic wastewater in terms of nitrate and phosphate concentration. Variation of rotational speed airbrush (45 and 60 rpm) and ratio volume of waste to microalgae (3:1, 4:1, 5:1, 6:1) were performed. The sample was collected for 5 days and measured for nitrate and phosphate concentration. The result shows that the optimum removal of nitrate and total phosphate is about 63.64% and 66.15%, respectively, with an under-speed variation of 60 rpm and a volume ratio of 3: 1. This study concludes that oxidation ditch reactor-filled microalgae Chlorella sp had performed an effective process in removing nitrate and total phosphate under optimum speed rotation and a low ratio of waste microalgae. [ABSTRACT FROM AUTHOR]

Aquatic organic matters refer to chemical compounds that result from natural processes in the environmental including algae metabolic reactions and decomposition of organic matter. The removal of NOM is the most effective effort to minimize the generation of disinfection by-products (DBPs). Aims of this research are to compare various treatments in controlling aquatic organic matters, which caused the formation of the carcinogenic compound. Combination processes of pre-chlorination, coagulation with alum and FeCl3 and adsorption with powdered activated carbon (PAC) was applied under different dosage. TOC and UV254 were measured to quantify organic matters, Fourier Transform Infrared (FTIR) was applied to identify organics properties, and CHCl3 was measured to know carcinogenic concentration. The results showed that pre-chlorination only caused the formation of lower molecular weight, pre-chlorination followed by coagulation combined with adsorption showed a better result than coagulation-adsorption only. FeCl3 coagulant is more effective than alum. Aromatic compounds are a precursor for the formation of CHCl3, since removal UV254 along with CHCl3 concentration. [ABSTRACT FROM AUTHOR]

CO2 emissions resulting from human activities are relatively higher concentrations that disrupt the equilibrium system in the air and ultimately damage the environment and human well-being. One environmentally friendly solution for CO2 gas removal is to use microalgae (Chlorella sp.). Chlorella sp. in photobioreactors has the ability to biofixate CO2 gas. Chlorella sp. was chosen because of the most numerous in freshwater and seawater. The purpose of this study was to determine the kinetic model of the effect of adding substrate concentrations and flow rate variations on the growth and development rates of Chlorella sp. due to exposure to pure CO2 gas emissions. This study uses pure CO2 gas with a flow rate of 0.02 L/min, 0.04 L/min, 0.06 L/min, 0.08 L/min, 0.1 L/min and a substrate of 350 mg/L, 500 mg/L, 650 mg/L, 800 mg/L, 950 mg/L on a laboratory scale. The results showed that the most optimum growth rate occurred at the addition of substrate concentrations of 800 mg/L with a flow rate of 0.08 L/min. [ABSTRACT FROM AUTHOR]