ABSTRACT

WITH WATER BEING AN ESSENTIAL FOR LIFE ON EARTH, IT IS VITAL TO PRESERVE IT AND REGENERATE IT, IN ORDER TO BE AVAILABLE FOR A MYRIAD OF USES. THOUGH MANY TYPES OF WASTEWATER MANAGEMENT AND TREATMENT ARE AVAILABLE, MOST RELY ON HIGH ENERGY INPUT AND ARE THEREFORE NOT IDEAL FOR MANY CIRCUMSTANCES. CONSTRUCTED WETLANDS (CW) ARE AN ALTERNATIVE NATURE-BASED SOLUTION TO BE APPLIED TO WASTEWATER TREATMENT. THIS STUDY UNDERTAKES A LIFE-CYCLE ASSESSMENT (LCA) OF A CW AS A MEANS OF WASTEWATER TREATMENT AND AIMS TO UNDERSTAND HOW THESE SYSTEMS CAN BE AN ENVIRONMENTALLY CONSCIOUS ALTERNATIVE. THE CW UNDER STUDY IS LOCATED IN A RURAL MOUNTAIN AREA IN THE NORTH OF PORTUGAL. RECEIVES WASTEWATER FROM A TOURISM UNIT AND OPERATES WITH HORIZONTAL SUBSURFACE. THE LCA ANALYSES THE CW THROUGH THE CONSTRUCTION, OPERATION (TREATMENT), AND COMPOSTING PHASES. THIS APPROACH ALLOWS THE ENTIRE SCOPE OF THE LIFE CYCLE TO BE INCLUDED, OF WHICH, THE COMPOSTING PHASE HAS BEEN ABSENT IN SIMILAR LCA PREVIOUSLY UNDERTAKEN. ANALYSIS FOCUSES ON THE IMPACT CATEGORIES: OZONE LAYER DEPLETION POTENTIAL, GLOBAL WARMING POTENTIAL, ACIDIFICATION POTENTIAL, EUTROPHICATION POTENTIAL AND HUMAN TOXICITY POTENTIAL. OF THE FIVE CATEGORIES, NONE INCREASE DURING THE TREATMENT PHASE, AND INDEED, ACIDIFICATION POTENTIAL, EUTROPHICATION POTENTIAL, AND HUMAN TOXICITY POTENTIAL ALL DECREASE. OZONE LAYER DEPLETION POTENTIAL AND GLOBAL WARMING POTENTIAL INCREASE SIGNIFICANTLY DURING THE CONSTRUCTION AND COMPOSTING PHASES RESPECTIVELY. BOTH CAN BE RATIONALIZED, WITH THE FORMER BEING A RESULT OF HEAVY DIESEL MACHINERY USE IN CONSTRUCTION AND THE LATTER A NATURAL BYPRODUCT OF COMPOSTING. THE RESULTS ARE NET POSITIVE AND DISPLAY THE ABILITY FOR CW AS A LOW ENERGY WASTEWATER TREATMENT WHICH CAN LIMIT ENVIRONMENTAL IMPACT BY CHOICE OF CONSTRUCTION AND COMPOSTING METHODOLOGY