Mitigation of environmental impacts in warm-weather wastewater treatment plants using the life cycle assessment tool

• Published in: International journal of environmental science and technology (Tehran) 2022-06, Vol.19 (6), p.4763-4778
• Main Authors: Rebello, T. A., Gonçalves, R. F., Calmon, J. L.
• Format: Article
• Language: English
• Subjects: Aquatic Pollution; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Science and Engineering; Original Paper; Soil Science & Conservation; Waste Water Technology; Water Management; Water Pollution Control
• ISSN: 1735-1472; 1735-2630
• DOI: 10.1007/s13762-021-03430-y

Literature review provides extensive studies focused on the life cycle assessment of wastewater treatment plants. However, few studies have a mitigation perspective, especially concerning water–energy–nutrient nexus or resource recovery systems for warm-weather countries. In this context, this paper aims to evaluate 10 wastewater treatment plants, based on an upflow anaerobic sludge blanket followed by a high rate aerobic pond. The recovery of biosolids, energy, and water, thermal and alkaline hydrolysis, CO 2 recirculation to supplement carbon, and a membrane system for microalgae harvesting are tested. The paper uses the OpenLCA 1.9 software to evaluate the following categories: global warming potential and global temperature change potential (IPCC 2013); cumulative energy demand (Ecoinvent); acidification, human toxicity, marine and freshwater eutrophication, marine, freshwater and terrestrial ecotoxicity (ReCiPe (H) v.1.13 2008). Input data consist of a background (from Ecoinvent 3.5 and literature) and foreground mix. The work asses the following environmental aspects: energy, chemical materials use, transportation, and emissions. The results indicate that the scenario considering CO 2 recirculation combined with thermal hydrolysis, with higher biosolids and energy production, has the lowest environmental impact for all categories. This result was due to materials manufacture and transportation, and comparative inputs added (natural gas energy, water, and fertilizer). Additionally, transportation variation only affects highly the iron chloride supply scenario. Emissions variation impacted directly on both IPCC categories for all scenarios, due to biogas losses accounted on the upflow anaerobic sludge blanket and anaerobic digester, while energy variation did not affect profoundly any of the scenarios. Graphic abstract