A wholelife cost and carbon perspective of alternatives to septic tanks utilising nature-based solutions

Abstract Septic tank systems (STSs) are a widely utilised treatment flowsheet for decentralised wastewater in the UK. With growing consensus that STSs have sizeable detrimental impact on environment, there is need rural flowsheets with improved capabilities. This study examines lifetime cost and carbon emissions of using an enhanced septic nature-based solution (EST-NBS) to improve STS compared package system (submerged aerated filter (SAF)). The wholelife (WLC) Scope 2 cradle-to-grave (LCEs) were assessed. EST-NBS represent lower than SAFs at population equivalents (PEs) from 5 1,000. An averages LCE over 4,000 kg CO2eq PE−1, all other considered having emissions. had SAFs. Even low populations upgrading competitive abatement strategy, costs £260 tCO2eq−1 avoided, 1,000 PE NBS has –£17 tCO2eq−1. shows potential providing both incentive against traditional designs.