Environmental Assessment of Water Treatment Plants of the Republic of Ecuador and Comparative Analysis of Water Disinfection Technologies using the LCA Method

Abstract

In the study, the environmental sustainability of two small water treatment plants with water intake from surface water sources with a high content of organic substances was evaluated. The life cycle assessment was used as a tool to compare two scenarios developed to solve the problem of disinfection by-products (DBPs) formation in drinking water. Various stages of the obtaining drinking water process were evaluated – from flocculation-coagulation to disinfection. The functional unit was defined as 1 m³ of drinking water produced at a water treatment plant. The proposed scenarios were developed to replace the chlorine disinfection with the UV disinfection of varying intensity (30 mJ/cm² for the first scenario and 186 mJ/cm² for the second scenario), followed by chloroamination. The data were analyzed using the Ecoinvent v.3.01 database, modeled and processed in the OpenLCA software. The results showed that at both water treatment plants, the coagulation-flocculation process has the greatest impact on the environment, which is mainly due to the chemical nature of the coagulant. It was revealed that from the point of view of environmental impact, the UV disinfection with an intensity of 30 mJ/cm² is preferable, since the global warming potential (GWP) was 80% less than in the second scenario, while the acidification potential (AP), eutrophication potential (EP), marine aquatic ecotoxicity potential (MAEP), terrestrial ecotoxicity potential (TETP) and human toxicity potential (HTP) were less by 78%, 71%, 72%, 74% and 79%, respectively.