CPV code 90000000 designates Sewage, refuse, cleaning and environmental services in the Common Procurement Vocabulary (CPV 2008), the EU classification used to describe the subject of public contracts.
90000000 is a top-level division — the broadest kind of CPV code. Divisions are usually too general for a contract notice: browse the 5 sub-codes below and pick the most specific code that still covers the whole contract.