COMPARATIVE STUDY OF ENVIRONMENTAL ASSESSMENT OF WASTEWATER AND SLUDGE TREATMENT METHODS: A LIFE CYCLE APPROACH

Abstract

The Life cycle of Wastewater Treatment Plants (WWTPs) can adversely affect the environment in terms of climate change, ozone layer depletion, resource depletion and cause a toxicological effect on human health and the ecosystem. The Life cycle Assessment (LCA) approach is reported to be promising to resolve these issues. LCA is a tool for determining a product or a process's environmental effects and its associated by-products. In this study, LCA evaluates the critical sources of environmental impacts in WWTPs. The aim of study is to conduct comparative life cycle assessment of four wastewater treatment (WWT) methods: Activated Sludge Process, Constructed Wetlands, Sequential Batch Reactor, and Up-flow Anaerobic Sludge Blanket; including the sludge treatment methods: Anaerobic Digestion, Anaerobic Digestion with Pre-treatment, Lime Stabilization, and Lime Stabilization with Energy Recovery. Environmental impacts are analyzed using the IMPACT 2002+ approach and Simapro 9.1.1.1 software using the Ecoinvent v3.6 database. The study result shows that the Sequential Batch Reactor has highest impacts due to its high consumption of energy and global warming potential (GWP). Constructed Wetlands have negative GWP due to carbon sequestration. Anaerobic digestion with pre-treatment has the least impacts as compared to other sludge treatment methods. Electricity used for treatment, atmospheric emissions from the treatment methods are the primary contributors to WWT's environmental impacts. The findings of the study were categorized into three groups: midpoint indicators, endpoint or damage indicators, and single-score perspectives. The project's preliminary details will be discussed in the following chapters. This study shows that LCA is an effective environmental system tool that can enhance decision-making processes and create opportunities for achieving sustainable goals for wastewater and sludge treatment technologies.