Waste Disposal

Waste Disposal and the Wastestream Hierarchy

The general waste hierarchy shown opposite indicates high level preferences in how solvent waste should be managed. If solvent use cannot be reduced, direct reuse without purification can be investigated. With complex waste streams, purification is first required.  Instead of buying solvents outright, a company may “lease” them from a supplier, returning the used solvent to the supplier who cleans and re-purifies it for reuse.  This allows the company to access a continuous supply of solvent without needing to dispose of large quantities of waste.  If the desired purity cannot be achieved by subjecting used solvent to a recovery process, the used solvent may be sold on for other industrial applications (‘downcycling’). 

The general waste hierarchy shown is misleading, without consideration of the amount of primary energy required across the solvent’s lifecycle, including its production, disposal or recycling.  For solvents whose production has a low environmental impact, incineration with energy recovery (a form of ‘disposal’),  uses less energy than recovering it by distillation [1].