Ecover cleans using detergents. Your laundry would stay dirty without detergents, which also contain organic components that help them do their job.
A detergent is a molecule consisting of a part that bonds to water and another part that bonds to fat or grease. Water and fat cannot mix together because they have different surface tensions. Detergents form a bridge between water and fat particles that neutralises this difference and allows dirt to be removed.
Ecover explains this using a practical example: If you shake a bit of pepper onto a water surface and then add a drop of detergent, the molecules spread out and the pepper will be distributed over the entire surface. If you carefully place a needle on a water surface so it floats and then add a drop of detergent, the needle will sink to the bottom. The same principle applies to dirty laundry: the dirt is dissolved and dispersed by the detergents.
You will be pleased to hear that Ecover goes further than the law governing biodegradability requires. Ecover uses only raw materials that are also fully degradable in oxygen-poor conditions and ensures that the entire product is fully degradable, with nothing left except minerals. That means all the ingredients are decomposed, not just the detergents, and decomposition occurs under oxygen-rich (aerobic) conditions as well as oxygen-poor (anaerobic) conditions.