Risk analysis of immobilized iron copper nanoparticle for sewage treatment

Abstract Immobilized iron–copper nanoparticles (iFeCu) treated sewage effectively, and the treated effluent complies with Malaysia's effluent discharge standards. The good stability and reusability of iFeCu demonstrate its potential as an alternative to existing sewage treatment methods, which rely on microbial activity. However, no risk assessment has been conducted to evaluate the safety aspects of this method for real‐life applications. The objective of this study is to assess the safety of using iFeCu for sewage treatment in a pilot‐scale study. The risk analysis was carried out through the development and evaluation of hazard identification (HAZID), hazard analysis (HAZAN), and hazard and operability analysis (HAZOP). In a pilot‐scale continuous flow reactor (10 PE, flow rate 210–1200 mL/min, retention time 0.69–3.97 h), iFeCu achieved stable pollutant removal over 10 reuse cycles, with average removal efficiencies of 85%–95% for ammonia, 80%–90% for biochemical oxygen demand (BOD), and 60%–70% for chemical oxygen demand (COD). HAZID and HAZAN identified NaBH 4 as the highest‐risk chemical (severity 5, R = 15), while nanoparticle inhalation and Na 2 CO 3 spillage were medium‐risk hazards ( R = 8), both reduced to low risk after mitigation ( R = 2). Periodic maintenance of equipment and daily sewage quality monitoring minimizes the likelihood of flow, reaction, and level hazards. Emergency measures, such as emergency shutdowns and bypassing damaged components, were proposed to manage potential incidents. In conclusion, the risk assessment of using iFeCu for sewage treatment indicates that it is safe, and the recommended mitigation steps further enhance the practicality of this method for real‐life applications.