Pilot-Scale Test for a Phosphate Treatment Using Sulfate-Coated Zeolite at a Sewage Disposal Facility

The objective of this research was to evaluate a zeolite ball coated with sulfate (ZBCS) for the removal of phosphate in a batch, lab-scale column, and pilot-scale plant. Phosphate adsorption in the batch studies satisfactorily fitted to the Langmuir isotherm with a maximum adsorption capacity of 15.13 mg/g and the pseudo-first-order model with the amount of phosphate sorbed at equilibrium of 6.98 mg/g. The breakthrough data were satisfactorily described using the empirical model by Thomas. Phosphate adsorbed on the ZBCS was effectively desorbed using 10 % sulfuric acid and the surface-modified mineral was regenerated as an adsorbent for thrice adsorption and desorption cycles by maintaining the adsorption capacity at the value before regeneration. In addition, since the regeneration solution used for recycling of the ZBCS in the pilot plant is enriched with sulfate ion, the enriched solution could be used for resource recovery by various methods, such as mineral-based and chemical-based methods. Our research suggests a complete system for removal and recovery of phosphate from sewage and wastewater using a novel adsorbent based on minerals.