Materials recovery from industrial wastes

In recent years the process of industrial development has led to a staggering increase in the demand for raw materials. The search for increasingly expensive materials offering higher levels of performance has led to ill-judged and indiscriminate exploitation of the world’s stocks and resources, leading in turn to an enormous rise in the costs involved in securing supplies. If we are to limit consumption and solve the ever-increasing difficulties involved in obtaining supplies, it will be essential to reduce waste and recover materials from byproducts of industrial processes, thereby lowering the environmental impact of the processes themselves and lightening the load on the waste treatment cycle. This article illustrates two emblematic cases of recovery indicating two possible ways of recycling residual material: one by recovering it as raw material within the same production cycle; the other by making it suitable for further technological processing after a stage of treatment. As an example of recovery within the same production cycle, we examine the recovery of byproducts in the tanning industry. The wastewater produced during preliminary stages of the tanning process is treated by means of a process combining chemical and biological oxidation in such a way as to recover the chemical substances employed together with a high proportion of the proteins present. In the second case, we examine a process of automobile demolition and scrap recovery and analyse the possibilities for recycling the different materials susceptible of separation.