Domestic Wastewater Treatment with Microalgae Chlorococcum Humicola in an Airlift Photobioreactor

Abstract

The objective of the study on secondary treated domestic wastewater quality improvement by using microalgae Chlorococcum humicola. The microalgae was cultivated under batch condition for 14 days with pH between 6.0 – 9.0 at 28 – 32 ^oc. The first factor studied, the initial density of cell (OD), varied from 0.1 to 0.3 which the microalgae cultivation was performed in a conical flask with the synthetic wastewater of 500 ml. The second factor studied was the flowrate of air fed to an Airlift photobioreactor (ALPBR) with a superficial velocity varied from 0.1 to 0.3 cm s^-1 which was conducted in the ALPBR having the synthetic wastewater of 10 l. The results revealed that the initial cell OD of 0.3 was the most suitable cell density for reducing the amount of total nitrogen and phosphorus compounds and COD to meet the standard requirement of releasing wastewater for the culture period of 6 – 8 days. Meanwhile, the most suitable conditions for microalgae cultivation in the ALPBR were the initial cell OD of 0.3 and the flowrate of air fed with the superficial velocity of 0.3 cm s^-1. These conditions provided a shorter period of 5 – 7 days to meet the standard requirement of releasing wastewater. The results also indicated that the ALPBR is more efficient in wastewater treatment than that of the flask due to higher efficiency of mixing resulting in high mass transfer between phase of liquid and gases.