Effluent Treatment Plant (ETP) In the Effluent Treatment Plant, all the liquid streams of the Zeology tanning process are treated to be reused or ready for disposal. The tanning effluents typically have a whitish color before treatment and can be processed into clear waters after the ETP. As Zeology does not contain heavy metals, these do not end up in the effluent streams. Based on the use of organic acids in the pickle, the aqueous effluent streams will have a higher than typical COD load. The standard working procedures can be applied to the effluent streams coming from Zeology tanning. For example, the outflow concentrations of elements such as the aluminum content are controlled by adjusting the pH. Zeology tanning is compatible with modern effluent treatment plants, does not contain heavy metals, and is readily handled by standard operations. Share this: