Flocculation Efficiency and Particle Distribution of Total Suspended Solids in the Effluent from Semi-recirculating Aquaculture Systems Treated with Polymers

摘要

Interest in effluent treatment is currently increasing and the use of polymetric coagulants is considered as a pretreatment of physical filtration prior to effluent discharge to increase solids recovery. Ajar test evaluated effluent treatment efficiency of polymeric coagulants for semi-recirculating aquaculture systems. The particle coagulation efficiency and distribution were evaluated at different polymer dosages in freshwater and seawater effluents. The polymer was added at 0.005-0.08 mL/g of total suspended solids (TSS) in the effluents. TSS in the supernatant after coagulation decreased with increasing polymer dose in the freshwater, while showing no corresponding changes with dose in the seawater. However, in all treatments for both effluents,the removal efficiency was above 90%, regardless of the dose in the tested range. Both the De Brouckere Mean Diameter (DBMD) and volumetric median diameter (VMD) were all above 100 pm in the freshwater effluent. In the seawater effluent, the particle size appeared to be larger than that in freshwater, ranging from 400-1,000 pm for both DBMD and VMD. Considering that the typical pore size of physical filtration in aquaculture is between 60 and 200 pm, the use of polymers is expected to improve the practicality of physical filtration for efficient treatment.