The textile and footwear industries have long been regarded as one of the most ecologically harmful industries in the world. This is due to a large number of chemicals and the large quantity of water used to process textiles and leather as well as the complex processes and supply chain involved. The resultant potentially toxic discharges may often result in detrimental effects to the environment and human well-being. Industrial waste water treatment plants produce solids that are also referred to as sludge. This can be generated from biological or physical-chemical processes.