Algal-Bacterial Synergy for Lipid Production and Nutrient Removal in Tofu Liquid Waste

Abstract

Energy diversification using microalgae biomass offers a solution to the fossil fuel crisis, which has become a global issue. Chlorella sp. is a microalga that can produce lipids and reduce chemical oxygen demand (COD) in liquid waste. In this research, we used Chlorella sp. to produce lipids and reduce COD in tofu liquid waste. This research aimed to identify the interaction between a complex microorganism, as a decomposer agent, with the addition of the photosynthetic microalgae Chlorella sp. as an oxygen producer to reduce COD in tofu liquid waste. Moreover, we aimed to determine the interaction between Chlorella sp. and a bacterial consortium for microalgae growth and lipid production. This study was conducted in batches with the addition of bacteria at five different concentrations (% v/v): 0 (no addition), up to 0.25, 0.50, 0.75, and 1. Cultivation was conducted for 13 days with solar irradiation in a photobioreactor. As a result, the highest density and the highest growth rate were obtained from the treatment with 1% bacteria, achieving as many as 5.65×106 cell/mL and 0.21/day. The 1% treatment was able to produce lipids and COD removal efficiencies of 20.93% and 96.30% at the best-removing detention times, which both occurred on the 13th day of cultivation.