A life cycle analysis for the application of decentralised sanitation technologies at Newlands Mashu in the Ethekwini Municipality.

Abstract

Safe sanitation is a privilege and in many developing countries sanitation provision is an ongoing major issue. To meet the growing sanitation demands of developed and developing countries around the world, various sanitation technologies and systems have been proposed. One such technology that is highlighted in this study is the Decentralised Wastewater Treatment System (DEWATS). DEWATS is a wastewater treatment technology that aims to treat and dispose of wastewater near the source that the wastewater is generated and excludes the conventional centralised sewer network that directs wastewater to a regional wastewater treatment plant (WWTP). As with all wastewater treatment technologies, various wastewater treatment phases and processes intrinsically impact the environment. It is important for engineers, planners, designers and stakeholders involved in the treatment of wastewater to be informed of the various environmental consequences as a result of the implementation of DEWATS. The purpose of this study was to undertake an environmental Life Cycle Assessment (LCA) of a DEWATS in a local context. The DEWATS plant considered in this study is located in eThekwini Municipality, KwaZulu-Natal and was designed to treat wastewater volumes of 41.6m³/d. This study was aligned with LCA guidelines produced by the International Organisation for Standardisation. During the Life Cycle Inventory (LCI) phase of this study, data for both the construction and operation phases were collected and subsequently processed using SimaPro LCA analysis software and the CML (Centrum Melieukunde Leiden) midpoint methodology. The key findings of this study revealed that domestic water consumption was the largest contributor to environmental impacts on the impact categories considered. Further to this, it was found that low flush interventions resulted in a large reduction in wastewater and significantly improve the environmental profile of the DEWATS. Based on the results of this study it is recommended that further emphasis on the reduction of greywater generation is required and a reduction on the reliance on municipal domestic water. Although a separate process, the minimisation of the energy requirements of upstream water treatment processes may significantly improve the environmental profile of the DEWATS.