Nitrification rate in the bioremediation of organic wastewater using Chlorella sp. and nitrifying-denitrifying bacteria

Abstract

Global nitrogen pollution in the aquatic environment has been increased mostly due to the disposal of organic wastewater from human activities. Chronic disposal of nitrogen compounds into the waters caused eutrophication and death of aquatic organisms. The process of reducing nitrogen in wastewater can be carried out economically and efficiently using nitrifying-denitrifying bacteria. Besides that, another environmentally friendly technology that can also be used is bioremediation using microalgae such as Chlorella sp. The synergistic relationship between bacteria and microalgae has a better performance in reducing nitrogen compounds in organic wastewater. This study aims to determine the rate of nitrification, changes in nitrate concentrations, and the effect of differences in treatments and time on changes in nitrate levels in organic wastewater. This study was conducted from July to August 2020 was an experimental laboratory using a randomized block design. Organic wastewater samples were taken from Lake Rawa Pening Central Java. The results showed the highest nitrification rate was performed by treatment C (a combination of probiotics and Chlorella sp.) of 0.2 mg NH4-N l-1.hour-1, followed by treatment B (Chlorella sp.), D (control), and A (probiotics) of 0.169, 0.009 and 0.008 mg NH4-N l-1.hour-1, respectively. The highest percentage change in nitrate levels during the study was treatment C (1 874%), B (1 664%), D (200%), and A (175%), respectively. The analysis of variance and the DMRT test showed that there were differences between treatments and times of changes in nitrate levels (p-value <0.05), with the highest average change in nitrate levels found in treatment C.