Life Cycle Assessment of Black and Greywater Treatment Solutions for Remote and Sensitive Areas

Sensitive and remote areas have come under pressure from growing populations and tourism, often resulting in improper wastewater management. Efficiency, durability, the use of renewable construction materials, and the minimization of environmental impacts must be conformed to a sustainable paradigm. A life cycle assessment (LCA) was applied to compare three different decentralized wastewater treatment systems built at tourist facilities: a source separation sanitation system with a hybrid constructed wetland (S1), a sequential batch reactor (SBR) with a hybrid constructed wetland (S2), and a solar-powered composting toilet (S3). Benchmarking showed that S1 was preferred over S2. The differences were up to a factor of two, except for eutrophication, which was significantly higher for S2 (10×). S3 had the lowest environmental impact, but S3 treated only the blackwater fraction, i.e., urine, faeces, and toilet paper, and excluded greywater treatment, i.e., handwashing and/or kitchen wastewater. The scenario analysis showed that the environmental performance could be improved by installing solar panels, but this would increase the impact on the abiotic depletion of elements by 83% for S2. The LCA indicated the advantages, disadvantages, flexibility, and potential for design improvements to meet the environmental sustainability and market demands for system diversity.