Contaminant Removal from Wastewater by Microalgal Photobioreactors and Modeling by Artificial Neural Network

Abstract

The potential of microalgal photobioreactors in removing total ammonia nitrogen (TAN), chemical oxygen demand (COD), caffeine (CAF), and N,N-diethyl-m-toluamide (DEET) from synthetic wastewater was studied. Chlorella vulgaris achieved maximum removal of 62.2% TAN, 52.8% COD, 62.7% CAF, and 51.8% DEET. By mixing C. vulgaris with activated sludge, the photobioreactor showed better performance, removing 82.3% TAN, 67.7% COD, 85.7% CAF, and 73.3% DEET. Proteobacteria, Bacteroidetes, and Chloroflexi were identified as the dominant phyla in the activated sludge. The processes were then optimized by the artificial neural network (ANN). High R2 values (>0.99) and low mean squared errors demonstrated that ANN could optimize the reactors’ performance. The toxicity testing showed that high concentrations of contaminants (>10 mg/L) and long contact time (>48 h) reduced the chlorophyll and protein contents in microalgae. Overall, a green technology for wastewater treatment using microalgae and bacteria consortium has demonstrated its high potentials in sustainable management of water resources.

Microalgae-Enabled Wastewater Treatment: A Sustainable Strategy for Bioremediation of Pesticides

“…HRAPs are designed as shallow raceways that can co-culture microalgae and bacteria to allow the degradation of organic matter by heterotrophic bacteria while consuming oxygen produced from microalgal photosynthesis [123]. Currently, huge efforts have been dedicated to the establishment of photobioreactor (PBR), a closed system design for the cultivation of microalgae using solar or artificial light sources to enable photosynthesis of the photoautotrophic organisms [124]. Compared to its membrane bioreactor (MBR) counterpart, PBR does not require electromechanical aeration for the liquor mixing due to the photosynthetic activity of microalgae, hence it is more advantageous in terms of energetic cost involved for the wastewater treatment.…”