Chlorine Safety in Water Treatment: A Study of Causes and Preventive Measures Through Fault Tree and Event Tree Analysis

Abstract

Accidents in process industries, especially involving hazardous substances like chlorine, pose significant risks to humans, the environment, and property. This paper examines chlorine-related incidents in water treatment plants (WTPs), where chlorine gas is used for disinfection. Typically, WTPs store over 20 chlorine drums, each containing around 930 kg, increasing inherent risks due to chlorine’s reactivity and health consequences upon exposure. Incidents such as the Bhopal 2022 case, which hospitalized 15 people, and the Kota Belud 2017 case highlight the importance of safe operation. This study aims to identify the root causes of chlorine-related incidents, assess their impacts, and recommend effective preventive measures to enhance safety. Using Fault Tree Analysis (FTA) to identify root causes and Event Tree Analysis (ETA) to evaluate preventive measures. Major failure causes included equipment damage, corrosion, non-compliance with design specifications, and mishandling. Preventive measures like leak detectors, scrubber systems, and Emergency Shutdown Systems (ESD) significantly reduce risks. If scrubbers fail but ESD works with trained personnel, or if scrubbers work but ESD fails without personnel, the impact remains medium. However, chlorine releases become catastrophic when all measures fail or only leak detectors work without effective mitigation systems.