The acetylene manufacturing process uses water and calcium carbide as the primary materials, generating acetylene in the form of gas and a liquid solution of calcium hydroxide. Afterwards, this solution can be pressed in order to obtain a solid compost. Because of its composition, liquid or solid, it can be managed as a by-product in different production processes as a substitute for raw materials.
The liquid calcium hydroxide can be utilised for the neutralization of acidic waters, by coagulating for the generation of metallic oxides and for the stabilization of sludge in sewage treatment plants. In both cases it represents a substitute for basic reagent. In the solid state, calcium hydroxide is used as a substitute for lime in the cement manufacturing process.
These are all examples of by-products approved by the Waste Agency of Catalonia under the Catalan regulatory framework.