Treatment of fish processing wastewater through microalgae-based technology
Thesis event information
Date and time of the thesis defence
Place of the thesis defence
Online
Topic of the dissertation
Treatment of fish processing wastewater through microalgae-based technology
Doctoral candidate
Master of Science Saba Khalatbari
Faculty and unit
University of Oulu Graduate School, Faculty of Technology, Chemical Process Engineering Research Unit
Subject of study
Process and Environmental Engineering
Opponent
Professor Monica Odlare, Mälardalen University, Sweden
Custos
Professor Tiina Leiviskä, University of Oulu
Treatment of fish processing wastewater through microalgae-based technology
Fish processing wastewater (FPWW) is a nutrient-rich effluent that requires effective treatment prior to discharge to minimise environmental impacts. In response to this challenge, this thesis investigates microalgae-based systems as a sustainable alternative to FPWW treatment, focusing on treatment results, biomass harvesting strategies, and techno-economic feasibility.
Batch, semi-continuous, and continuous cultivation of Chlorella sorokiniana were evaluated using real FPWW, achieving nutrient removal efficiencies above 80% in batch and semi-continuous systems and over 90% under stable continuous photobioreactor operation with stepwise reductions in hydraulic retention time. Biomass recovery, identified as a major bottleneck in the harvesting process, was evaluated using both biological and chemical methods. Fungus–microalgae co-cultivation with Aspergillus oryzae enabled efficient pellet-based harvesting with recovery efficiencies above 90%, while chemical recovery based on biodegradable coagulants achieved recovery efficiencies of up to 94% with low dosages of tannin coagulant (TC; 15 mg/L), causing only a minor impact on the quality of the treated wastewater and producing protein-rich biomass. Techno-economic analysis showed that the TC-based harvesting strategy reduced operating and annualised capital costs by approximately 10% compared with conventional methods and remained more economically viable during process scale-up.
This thesis demonstrates that algae-based systems offer effective, flexible, and economically viable solutions for FPWW treatment, promoting sustainable and circular management of industrial wastewaters.
Batch, semi-continuous, and continuous cultivation of Chlorella sorokiniana were evaluated using real FPWW, achieving nutrient removal efficiencies above 80% in batch and semi-continuous systems and over 90% under stable continuous photobioreactor operation with stepwise reductions in hydraulic retention time. Biomass recovery, identified as a major bottleneck in the harvesting process, was evaluated using both biological and chemical methods. Fungus–microalgae co-cultivation with Aspergillus oryzae enabled efficient pellet-based harvesting with recovery efficiencies above 90%, while chemical recovery based on biodegradable coagulants achieved recovery efficiencies of up to 94% with low dosages of tannin coagulant (TC; 15 mg/L), causing only a minor impact on the quality of the treated wastewater and producing protein-rich biomass. Techno-economic analysis showed that the TC-based harvesting strategy reduced operating and annualised capital costs by approximately 10% compared with conventional methods and remained more economically viable during process scale-up.
This thesis demonstrates that algae-based systems offer effective, flexible, and economically viable solutions for FPWW treatment, promoting sustainable and circular management of industrial wastewaters.
Created 25.9.2026 | Updated 28.9.2026