The Wastewater Treatment Plant is designed to remove heavy metals and other toxic components from the waste water. The water produced by the plant will normally be discharged into the sea, fresh water waterway, or a POWT (publicly operated water treatment).  The quality of this water will meet strict environmental standards.

The Wastewater Treatment Plant will produce two products from the wastewater:

(1)     a gypsum cake suitable for use in wall board manufacturing and/or as a retarder for cement manufacturing, and

(2)   a heavy metals cake suitable for recharging into the smelter.  However, this should be verified with suitable material and energy balances.

The above objectives can be accomplished by a variety of unit operations put together in many different flowsheets. However, there will be several common elements to all of these flowsheets.

The water from a smelter will not normally require treatment to meet BOD (biological oxygen demand) or COD (chemical oxygen demand).  Wastewater from smelters tends to be oxidizing from the presence of sulfites and sulfates; in addition, they do not usually contain large amounts of organics, which would give rise to a large BOD. If sulfides are used in the wastewater treatment, any excess must be scavenged to avoid problems with COD.