The tannery effluents are characterized by high toxic pollutants such as sulfides; used in the tanning of animal’s skin. The mean objective of this work is the evaluation of the pollution degree of various operating units, and the treatment of tannery effluent generated from unhairing-liming unit. According to physicochemical characterization, this effluent was largely basic and very loaded in sulfides, which have harmful effects on human health and the environment as well. Otherwise, the microbiological characterization showed an absence of pathogenic bacteria and a low concentration of mesophilic aerobic flora, because of this effluent toxicity. Thus, the treatment of this effluent is indispensable before its reject into the environment. In fact, chemical precipitation is a promising approach for the treatment of this effluent. In this regard, ferric chloride was used as chemical agent to reduce and removal sulphide ions from this effluent. As result, this treatment gave an excellent abatement rate of sulphide, which reached more than 90% using a pH of 8.5 and a ferric chloride concentration of 1.4 mol/L.
Industries play a major role in the development of countries′ economy. However, they are known as the biggest source of water pollution in the whole world. In fact, several industries use a huge amount of water in their manufacturing operations, and then, they reject a large volume of wastewaters such as tanneries, brassware, olive mills … etc. The sewage of these industries may contain organic/inorganic matters or toxic components that harm human health and the environment. Therefore, the treatment of these effluents is necessary. For that, there are many treatment processes, including biological and physicochemical processes or both. The choice of adequate process is depending on many reasons, especially on the biodegradability degree of each effluent, as well as the presence of recalcitrant pollutants. Nevertheless, biological technologies, particularly bioremediation, are recently an emerging technology for the elimination of recalcitrant pollutants like heavy metals. Furthermore, these biotechnologies are simple, efficient, eco-friendly and inexpensive. Therefore, this environmental biotechnology may be a new approach for the treatment of industrial sewage, so, it can successfully replace physicochemical technologies that are very expensive.
Part of the book: Sewage