Wetlands Add Value to Small‑Town Water Cleaning

Europe just tightened its rules for cleaning city wastewater. The new directive says any town with at least a thousand people must treat its sewage. Before, many tiny villages were ignored, but they actually dirty about one‑tenth of the region’s rivers and lakes.

Researchers looked at two treatment plants in Valencia, Spain – Carrícola and Los Monasterios. After the normal cleaning step, they sent the water through man‑made wetlands. These wetlands are filled with a special sludge from drinking‑water plants that is rich in aluminium. The setup pulls out extra phosphorus and reuses materials, fitting the idea of a circular economy.

A team of twelve experts from different fields judged what the wetlands give back to nature and people. They turned those benefits into money using a price of €1.09 per cubic metre, which is what Spain charges for drinking water. The biggest single benefit turned out to be having more water available, making up roughly a third of the total value. When grouped, the services split into providing resources (about 42 %), supporting plants and animals (about 26 %), cultural perks (about 23 %), and regulating processes (about 9 %).

Over a quarter‑century, the wetlands are expected to bring in roughly €242 k for Carrícola and €881 k for Los Monasterios. The benefit‑cost ratio stays between 6.6 and 7.5, meaning the returns are many times the investment even if we assume pessimistic conditions. By spelling out gains like richer wildlife and lower climate impact, the method gives clear numbers that help decision‑makers copy the idea for other small towns facing water shortages.