Identification of facultative anaerobic bacteria for low-cost nutrient removal in treating domestic wastewater

Abstract

Facultative Anaerobic Bacteria is the group of bacteria that can grow with or without oxygen whereby they can make Adenosine Triphosphate (ATP) which is the preferred source of useable energy through aerobic respiration if oxygen is available or switch to fermentation if oxygen is not available. Thus, there is an opportunity to explore the bacteria in enhancing nutrient removal and at the same time has potential for energy saving at the Wastewater Treatment Plant (WWTP). This study aimed to screen and isolate the dominant facultative anaerobic bacteria in WWTP where wastewater from four different categories i.e. Extended Aeration (EA), Oxidation Pond (OP), Sequencing Batch Reactor (SBR) and Conventional Activated Sludge (CAS) across the Klang Valley region has been sampled. From the investigation, bacterial strain from the targeted group was successfully isolated i.e Lactobacillus plantarum which found at SBR plant and the suitable low-cost medium for isolated bacterial cultivation was identified. Based on the result, a 5 % of molasses concentration was selected and used for isolated strain performance study. After that, bacterial dosing rate determination was studied using real wastewater with different dosing rates (1 %, 3 % and 5 %). The result indicates at 1 % dosing rate, the percentage of nitrogen removal is higher compared to others whereas Ammoniacal Nitrogen reduced at 97.3 % after 24 h and achieved 98.2 % after 96 h. Meanwhile, Nitrate removal is 63.9 % in 24 hand 39.8 % after 96 h. This finding is useful for the application of L.plantarum as a bioaugmentation product at full scale.