We conducted a series of experiments to determine the effect of doses of CaO and Ca(OH)₂ added to a synthetic solution, prepared with the same salt of Cr as that found in Mexican tanneries, to precipitate the chromium and determine the amount of sludge. The stirring was kept at 150 rpm during 10 min of time of contact between reagents, followed by measurements of Cr in the supernatant and determination of the amount of sludge. The study was carried out in a wide range of dose of alkalis, including the stoichiometric value, and also we vary the initial concentration of Cr at fixed alkali doses, and duplicate both the concentration and alkali dose maintaining the stoichiometric ratio. To remove almost 100% of Cr³⁺, a stoichiometric or higher dose of alkali was necessary; nonlinear behavior was found between the excess of alkali and pH. Also, the addition of an excess of Cr in the initial solution was not reflected directly in remaining chromium in the supernatant. Finally, it was found that some excess of alkali contribute to increase the sludge because the impossibility to be dissolved at operation conditions.

我们进行了一系列实验，以确定添加到合成溶液中的CaO和Ca（OH）₂的剂量的影响，该溶液用与墨西哥制革厂中发现的相同的Cr盐制备，以沉淀铬并确定污泥量。在试剂之间接触的10分钟时间内，将搅拌保持在150 rpm，然后测量上清液中的Cr并确定污泥量。该研究是在包括化学计量值在内的各种碱剂量范围内进行的，而且我们以固定的碱剂量改变了Cr的初始浓度，并重复了保持化学计量比的浓度和碱剂量。去除几乎100％的Cr ³⁺，需要化学计量或更高剂量的碱；发现在过量碱和pH之间存在非线性行为。而且，在初始溶液中添加过量的Cr没有直接反映在上清液中剩余的铬中。最后，发现一些过量的碱有助于增加污泥，因为在操作条件下不可能溶解。