Experimental Validation of a Performance Model of a Biofiltration System

Ulva lactuca is a green alga, commonly named as "sea lettuce", which belongs to the Division Chlorophyta. It has been found to be a potential bio-filter that can assimilate nitrogen and phosphorus in seawater. This study has determined the feasibility of a flow system utilizing U. lactuca which was made possible by establishing a performance model of the system that could meet the ASEAN Marine Quality Criteria (AMQC) in terms of nitrogen and phosphorus effluent concentration. The performance model was validated through a series of laboratory experiments using three treatments. The biofiltration system has shown to have a fair reduction of nitrogen and phosphorus in the seawater with an average removal efficiency of 67% and 68% for nitrogen and phosphorus, respectively. Effluent nitrogen and phosphorus concentrations were observed to have considerable deviations from AMQC. However, biofiltration processes seemed to have decreasing decay ratio as time proceeds which means that AMQC may be sustained when the process time is extended, thereby giving more time for U. lactuca to recover from the stress experienced in its new environment. A three-stage biofiltration system design with increased acclimatization and residence time could improve the performance of the system.