Introduction to treatment of tannery effluents
43
While working out the costs of an ETP at an individual tannery is quite straightforward, different methods are applied to compute the distribution of CETP operation costs among individual tanneries. The key parameters used are typically the following: • water consumption, m3/day; • production capacity, tonnes of wet-salted hides/day; • actual pollution load in terms of COD, suspended solids, sulphides and Cr; • production output, m2/day of wet blue, crust or finished leather. In developing countries, cost calculation methods for CETPs are usually very simple, being based solely on effluent volume and type of tanning, whereas in Italy, for example, these methods are very sophisticated and are based on many factors measured on-/off-line or estimated.
Figure 37. Schematic chart of typical effluent treatment setup for clusters in developing countries
Figure 38. Schematic chart of typical effluent treatment setup in industrialized countries