A Cyanobacterial Sidestream Nutrient Removal Process and Its Life Cycle Implications

• Published in: Bioenergy research 2019-03, Vol.12 (1), p.217-228
• Main Authors: Quiroz-Arita, Carlos, Sheehan, John J., Baral, Nawa Raj, Hughes, Alexander, Peers, Graham, Hodgson, Brock, Sharvelle, Sybil, Bradley, Thomas H.
• Format: Article
• Language: English
• Subjects: Activated sludge; Activated sludge process; Air pollution; Air quality management; Anaerobic digestion; Anaerobic processes; Analysis; Biological activity; Biological wastewater treatment; Biomedical and Life Sciences; Chlorophyll; Cyanobacteria; Energy consumption; Environmental performance; Greenhouse effect; Greenhouse gases; Growth models; Growth rate; Life cycle analysis; Life cycle assessment; Life cycle engineering; Life cycles; Life Sciences; Material balance; Municipal wastewater; Nitrogen; Nitrogen removal; Nutrient removal; Photosynthesis; Plant Breeding/Biotechnology; Plant Ecology; Plant Genetics and Genomics; Plant Sciences; Process engineering; Purification; Sewage; Sludge; Sludge digestion; Wastewater; Wastewater treatment; Water treatment; Water treatment plants; Water utilities; Wood Science & Technology
• ISSN: 1939-1234; 1939-1242
• DOI: 10.1007/s12155-019-9963-2

This study proposes a novel integration of a municipal wastewater treatment facility (WWTF) with a cyanobacterial nutrient removal process for sidestream wastewater treatment. A life cycle assessment (LCA) approach was used to determine the effectiveness and environmental performances of the integrated system. The LCA is populated by models of wastewater process engineering, material balance, cyanobacterial growth, and kinetics of anaerobic digestion. The cyanobacteria growth model incorporates chlorophyll synthesis, nitrogen uptake, photosynthesis, centrate inhibition, and competition for nitrogen between cyanobacteria and nitrifiers. Modeling results are validated against experiments with Synechocystis sp. PCC6803 grown in sludge centrate. With a maximum specific growth rate of 1.09 day −1 , the nitrogen removal rate of the proposed WWTF would be increased by 15% when compared to the baseline wastewater treatment facility with a biological nutrient removal process. Incorporating the cyanobacterial nutrient removal process as the sidestream wastewater treatment of a conventional activated sludge process reduces the total nitrogen concentrations discharged from the WWTF from 25.9 to 15.2 mg 1 −1 . Methane yield was found to be increased by 4% of the baseline value when cyanobacterial biomass was co-digested with the activated sludge. Life cycle energy use and greenhouse gas emissions were found to be reduced by 8% and 17%, respectively, relative to a baseline wastewater treatment facility. Overall, a cyanobacteria-based sidestream municipal wastewater treatment process could be an effective and environmentally sustainable biological nutrient removal process in the future addressing the water-energy-food nexus.