Around 36,000 road collectors and 220 mineral oil separators are cleaned and rinsed by Entsorgung + Recycling Zürich (ERZ). Added to this are the residues that the public transport authorities of the city of Zurich (VBZ) collect when cleaning their track systems. The collected residues are divided into two lots. See point 2.4.

The collected residues consist of a mixture of water, liquid and oily sludges, which must be expertly accepted, treated and recycled according to the latest state of the art.

Acceptance, recycling and disposal of 3 500 tonnes of sludge per year from road shafts and track cleaning (VeVa 20 03 06 S) and sludge from phys.-chem. Treatment (VeVa 19 02 06 S).

Acceptance, disposal and recycling of around 2,700 tonnes of oil sludge per year from sand traps, oil and water separators (VeVa 13 05 08 S).