Characterization and Evaluation of Sludge from Seafood Processing Wastewater Treatment: Potential for Composting and Sustainable Reuse

Abstract

This study characterizes the physicochemical and microbiological properties of sludge from the wastewater treatment system of a seafood processing plant (COIMEX) and evaluates its potential for composting. Post-dewatering sludge samples were analyzed for 26 parameters, including organic matter, nutrients, heavy metals, hazardous compounds, and microbial indicators. Results showed high organic content (TOC: 41.3% dw, VS: 82.1% dw), nitrogen (4.26% dw), and phosphorus (2.72% dw), confirming the sludge’s nutrient-rich nature. Heavy metals and toxic organic compounds were mostly below detection limits, while Ba and Zn concentrations remained far below regulatory thresholds. Microbial contamination was moderate (E. coli: 608 MPN/100 mL, coliforms: 7900 MPN/100 mL), with Salmonella absent. However, the fat, oil, and grease (FOG) concentration (8005 mg/kg dw) exceeded the Vietnamese hazardous waste limit, requiring pre-treatment or co-composting strategies. Overall, COIMEX sludge presents strong potential for sustainable reuse as a feedstock for composting, supporting circular economy strategies in Vietnam.