Water Resources Sustainability Project (WRS) - Manuel de fonctionnement de la station de récupération des effluents chromes des tanneries de Dokkarat, Fes

The process begins with the treatment of raw hides, which are first cleaned and then subjected to a process called "épilage-pelainage" in a mixeur. This process involves the use of a solution of sulfure de sodium and hydroxyde de sodium to remove the hair from the hide. The hides are then treated with a solution of sulfate de chrome, which is obtained by reducing dichromate de sodium in acide sulfurique with glucose or dioxyde de soufre. The basicité of the solution of chrome can be adjusted by adding bases such as soude or acide sulfurique. The chrome is applied to the hide in a foulon de tannage, which is a rotating drum that allows the hide to be treated with the chrome solution. The tannage process involves several stages, including the picklage, acidification, and basification of the hide. The picklage involves the treatment of the hide with a solution of acide sulfurique to remove any impurities. The acidification involves the addition of acide sulfurique to the solution of chrome to lower the pH and allow the chrome to penetrate the hide. The basification involves the addition of a base such as bicarbonate de sodium or oxyde de magnésium to raise the pH and fix the chrome in the hide. The finishing of the leather involves several stages, including the retannage, treatment to make the leather more supple and impermeable, and pigmentation or coloration of the leather. The retannage involves the application of a second layer of chrome to the leather, but in a weaker concentration than the first layer. The treatment to make the leather more supple and impermeable involves the use of various chemicals and processes to improve the texture and water resistance of the leather. The chrome tanning process generates several types of waste, including the rejets du travail de rivière and the rejets des foulons de tannage. The rejets du travail de rivière are characterized by high levels of pH, DBO, Total des Solides en Suspension, Total des Solides, and Concentration de sulfures. The rejets des foulons de tannage are characterized by low levels of pH, DBO, Total des Solides en Suspension, and Total des Solides, but high levels of Concentration de sulfures. The chrome tanning process is an important step in the production of leather, but it also generates significant amounts of waste that must be properly treated and disposed of to prevent environmental pollution. The tanneries must implement effective waste treatment and disposal systems to minimize the environmental impact of the chrome tanning process. The chrome tanning process involves several stages, including the treatment of raw hides, the application of chrome, and the finishing of the leather. The process generates several types of waste, including the rejets du travail de rivière and the rejets des foulons de tannage. The tanneries must implement effective waste treatment and disposal systems to minimize the environmental impact of the chrome tanning process. The chrome tanning process is a complex process that involves several stages, including the treatment of raw hides, the application of chrome, and the finishing of the leather. The process generates significant amounts of waste that must be properly treated and disposed of to prevent environmental pollution. The tanneries must implement effective waste treatment and disposal systems to minimize the environmental impact of the chrome tanning process.