Greenhouse gas inventory of a state water and wastewater utility in Northeast Brazil

Abstract

The growing concern about climate change and related greenhouse gas emissions (GHG) has been shared by many companies who are now involved in emission reduction efforts. In order to do this, it is necessary to first develop GHG emission inventories. The construction of inventories is not common practice in developing countries and among Brazilian water and wastewater companies, only four companies, among the top 25, have developed their GHG inventories, and none in the Northeast of the country. This paper aims to identify and estimate GHG emissions from the activities of a water utility, Empresa Baiana de Aguas e Saneamento S.A (Embasa) in the State of Bahia during 2012. The method used for the inventory was the GHG Protocol proposed by World Business Council for Sustainable Development (WBCSD) and World Resources Institute (WRI), the most widely adopted method worldwide. In addition, the guidelines of IPPC (Intergovernmental Panel on Climate Change) were used to calculate emissions from wastewater treatment plants. It was found that the emissions resulting from sewage treatment (mostly carried out by anaerobic processes) constitute the largest source of GHG at the sanitation company studied, when considering the activities defined in this work. The assessment of GHG sources and emissions identified in this research can support proposals for reduction targets and benchmarking. The results form the basis for the incorporation of GHG reduction measures in the company's strategic planning as well as for integrating its sustainability report. The findings of this work can also help other companies to undertake GHG reduction measures.