Aplicació de la metodologia de l’Anàlisi de Cicle de Vida (ACV) a una depuradora de fangs actius (Manlleu)

Abstract

Human activity generates waste water that must be treated before returning to the receiving environment. WWTP are designed and operated to remove contaminants present in the wastewater so that the impact on the receiving environment is permitted; however, WWTPs, like any industrial activity or production process also generate some environmental impacts. There is the need to minimize these impacts both existing plants and possible extensions of plants with new technologies for purification stricter limits. The life cycle analysis is a widely accepted method of evaluation and interpretation of the environmental impacts of a process or product. The aim of this study is to evaluate the potential environmental impacts of the Manlleu WWTP through life cycle analysis (LCA), which is a methodology that takes into account the use of materials, energy and discharges into the environment during the construction stages, transportation, operation and dismantling. The life cycle stages considered in the study were the construction and operation of the WWTP. The environmental impact during the operation phase of a WWTP is due to energy consumption, use of chemicals, emissions to air and water and sludge production. Also taken into account the use of materials for the construction of the plant and has been ruled out include the dismantling process. For the construction phase, we have analyzed the consumption of building materials from the budgets of the civil works and the operation phase inputs (energy, chemicals...) and outputs (water, sludge, emissions... to the atmosphere) system. The functional unit chosen for the study was the volume of treated water for 20 years. Inventory data during the operation phase are taken from different operation controlling documents of the WWTP 2014. Finally, it was considered that the WWTP has a lifespan of 20 years. For evaluation of the inventory life cycle analysis it was used SimaPro® software and the impact categories analyzed were: Climate Change, Ozone Depletion, Eutrophication Freshwater, Marine Eutrophication, Human Toxicity, Metal Depletion and Fossil Depletion. The results obtained from the inventory show that the operational phase of the plant has more impact than the construction phase in almost all categories studied. The separate analysis of each stage of the plant indicates that the secondary treatment and pre-treatment are those with a greater impact due to increased consumption of chemicals and high energy consumption. This study shows that to achieve a lower impact on the water purification process more efficient technologies, opt for chemicals with low environmental impact and reduce the environmental burden of energy consumption in the process need to apply