Microalgae harvesting from wastewater by pH modulation and flotation: Assessing and optimizing operational parameters

Autor(es)

Leite, Luan de Souza ^[1] ; dos Santos, Priscila Ribeiro ^[1] ; Daniel, Luiz Antonio ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Dept Hydraul & Sanitat, Sao Carlos Sch Engn, Av Trabalhador Sao Carlense 400, BR-1356659 Sao Carlos, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Journal of Environmental Management; v. 254, JAN 15 2020.
• Citações Web of Science: 11

Resumo

Microalgae harvesting is one of the major bottlenecks for the production of high-value microalgal products on a large scale, which encourages investigations of harvesting methods with better cost-benefits. Among these harvesting techniques, flotation stands out as a promising method, however it is still minimally explored when compared to the sedimentation method. In this study, the pH modulation followed by dissolved air flotation (DAF) was tested as a harvesting method for Chlorella sorokiniana cultivated in wastewater. The main aims of this study were to optimize the operational parameters of coagulation (pH, velocity gradient, and mixing time) and flotation (recirculation rate), check their reproducibility and resilience with the variability of wastewater characteristics, and evaluate the final wastewater quality after treatment using an optimized harvesting method. Parameter optimization was carried out using the one-factor-at-a-time method. The optimal parameters were a velocity gradient of 500 s(-1), mixing time of 30 s, pH 12, and 20% of recirculation rate. High efficiencies were obtained for C. sorokiniana removal (96.5-97.9%), making it a successful process. Moreover, the photobioreactor effluent quality was also improved significantly after microalgae harvesting, with high nutrient removal (88.6-95.1% of total Kjeldahl nitrogen and 91.8-98.3% of total phosphorus) and organic matter removal (80.5-86.8% of chemical oxygen demand). The results showed the pH modulation and DAF as an effective process for wastewater treatment and biomass harvesting. This study also indicated the importance of operational optimization, not studied until now, in which the achieved results could be potentially applied as practical guidelines for microalgae harvesting on a large scale. (AU)

• Processo FAPESP: 13/50351-4 - Recovering nutrients and carbon from concentrated black water: a sustainable decentralized approach for wastewater treatment
• Beneficiário: Luiz Antonio Daniel
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 17/14620-1 - Otimização do cultivo de Chlorella sorokiniana em fotobiorreator flat panel e colheita para sua utilização como fertilizante
• Beneficiário: Luan de Souza Leite
• Modalidade de apoio: Bolsas no Brasil - Mestrado