On-site sewage treatment facilities, unacceptable quality or too small to count? : cost-benefit analysis of on-site sewage treatment facilities and the zeroeutrophication target

Sammanfattning: Private on-site sewage treatment facilities are only a small part of the Baltic Sea eutrophication problem, but it have caught attention due to its high share of deposition of nitrogen and phosphorus in comparison to the more efficient public sewage treatment plants. The treatment of sewage wastewater is regulated by the Swedish Environmental Code. In this thesis a cost-benefit analysis was conducted to estimate if the improvement of on-site treatment sewage treatment facilities from a non-approved standard to an approved standard is an efficient way to achieve the zero-eutrophication target. The results show a negative value with high costs. However, as the identified impacts were limited, another outcome is possible with another objective together with a broader framework than just eutrophication and the pure efficiency target.