Abstract
The authors are conducting research with the aim of promoting resource recycling of sedimentation solids (fish feces, leftover food, etc.) collected from aquaculture tanks where saltwater fish are raised to agricultural land as fertilizer. As a part of this study, the desalination of sedimentation solids was examined in laboratory experiments, the laboratory experiments showed that (1) the hydraulic conductivity of the sedimentation solids was about 10-5 cm/s, and (2) the EC and Na+ concentration of the sedimentation solids were less than 2.2 mS/cm and 240 mg/L, respectively, when desalinating water (pure water) five times the dry weight of the sedimentation solids was added to permeate the sedimentation solids in consideration of the water content of the sedimentation solids. These EC and Na+ concentrations were lower than EC of 4.8 mS/cm and Na+ concentration of 1,140 mg/L, which were proposed as a rough guideline for the desalination of sedimentation solids in a previous report by the authors. Based on the experimental results of Na+ concentrations, desalination of sedimentation solids was attempted to model using tanks-in-series model. The model calculations for each experimental case were estimated the amount of water required for desalination. The amount was 14.0 mm per unit area and 1.75 L/kg per dry weight of precipitated solids.
