Impact of Natural Microorganisms on the Removal of COD and the Cells Activity of the Chlorella sp. in Wastewater

Abstract

In the treatment of wastewater containing only chemical oxygen demand (COD) by Chlorella sp., the cell activity and proliferation ability of Chlorella sp. decreased with the culture time, which affected the removal of COD in wastewater. To solve these problems, the Chlorella sp.–natural microorganism symbiosis system was prepared. The system was used to explore how natural microorganisms affect the cell activity and the proliferation ability of Chlorella sp. in wastewater. In the treatment of COD by Chlorella sp., the removal rate of COD decreased from 45.47% to 28.88%, with a decrease in the cell activity and proliferation ability of Chlorella sp. In the Chlorella sp.–natural microorganism symbiotic system, the removal rate of COD reached 45.75%. With the introduction of natural microorganisms, the circulation of CO2 and O2 between Chlorella sp. and natural microorganisms promoted photosynthesis and respiration, which enhanced the cell activity of Chlorella sp. Under the condition that the dosage of natural microorganisms was between 1% and 6%, the concentration of Chlorella sp. was close to the logarithmic growth phase, which maintained the proliferation ability of Chlorella sp. At the same time, the natural microorganisms grew and proliferated in wastewater containing only COD through preying on Chlorella sp.