Biological nutrient removal by blue-green algae grown in wastewater and its potential for biodiesel production

• Main Author: Sumang, Soledad De Guzman
• Format: text
• Language: English
• Published: Animo Repository 2011
• Subjects: Biodiesel fuels; Chemical Engineering; Environmental Engineering
• Online Access: https://animorepository.dlsu.edu.ph/etd_masteral/4008; https://animorepository.dlsu.edu.ph/cgi/viewcontent.cgi?article=10846&context=etd_masteral
• Institution: De La Salle University

Biodiesel production from algae has been gaining attention recently because of its environmental benefits as a potential renewable energy source which can be a more sustainable option. This study was conducted to determine the capability of blue-green algae (BGA) for nutrient removal and biodiesel production. The BGA were cultivated in wastewater and was used as the inoculums for the re-circulating aerobic biofilm reactor - photobioreactor system. The system was optimized using Taguchi optimization, L9 34 orthogonal array. The blue-green algae species used were pure culture of Anabaena Variabilis, consortium of Gleocapsa nigrescens, Oscillatoria Foreaui and Oscillatoria Formosa (algal culture 2) and combination of the species (algal culture 3) respectively. Based from the results, the optimum operating conditions for nutrient removal were 16:8 hours (light:dark) cycle, light intensity of 892 lux, recirculation rate of 1150 mL/min and algal culture 2 which produced an optimum NH4 +-N removal of 4.1537 mg/L/day for 7 days. The oil yield were also obtained in the system using oil extraction method and direct transesterification was done in the batch flasks photobioreators set up which utilized adjusted autoclave effluent as a medium to solely attribute the FAME composition to BGA. It was found that algal culture 2 which consists of Gleopcapsa Nigrescens and Oscillatoria Foreaui, Oscillatoria Formosa has the highest oil yield of 2.9054 mg/L/day. This BGA species was the only algal culture used with computed cetane number of 57.34 which met the minimum requirement of cetane number based on the European, American and Philippine biodiesel standards.