Lead adsorbent of hydroxyapatite production from self-aggregated calcium-Sualo prawn shell waste and phosphate-rich wastewater of an integrated multi-technology whiteleg shrimp aquaculture system

Abstract

This study presents a new approach to convert aquaculture waste into useful material. Shrimp shell waste (SSW) provides calcium, while aquaculture wastewater provides phosphorus to produce hydroxyapatite (HAp). Unlike conventional methods that use synthetic materials, this approach reuses waste, reducing resource consumption and pollution. The increasing consumption of seafood leads to a significant accumulation of waste from shrimp aquaculture, which is high in calcium and phosphorus. This study aims to investigate the valorization of this continuous and abundant waste into a renewable resource to produce a bioadsorbent, hydroxyapatite, for application in the removal of lead from wastewater. The calcined Sualo shrimp shells, sourced from the shrimp peel market, have great potential as they provide calcium resources and calcium carbonate recovered from waste. With increasing environmental concerns and strict water quality regulations, practical solutions for wastewater treatment, especially phosphorus removal, are in high demand. Using shrimp aquaculture wastewater as a phosphorus source and shrimp shell waste as a calcium precursor, hydroxyapatite was synthesized by a direct wet precipitation process. Optimized experimental conditions at a pH of 10 and a calcium/phosphate ratio of 1.67 during the 72-h synthesis process resulted in promising hydroxyapatite formation from these biogenic wastes. Characterization experiments showed that the hydroxyapatite produced from shrimp aquaculture waste was comparable to commercial samples and had a remarkable lead adsorption capacity of 1247.66 mg/g.