This project investigated the source of priority pollutants, assessment of the wastewater treatment plant, and priority pollutant removal efficiency for a single Soderberg-type primary aluminum plant. Forty-eight hour composite samples were collected from the following streams: (1) plant intake water; (2) wastewater from the primary air pollution control system (gas stream cooling water and wet EPS's); (3) secondary air pollution control system (room ventilation wet scrubber liquor); (4) paste plant briquette cooling water; and (5) final effluent after the wastewater treatment plant. Wastewater from the primary air pollution control system entered a conventional chemical coagulation (using slacked lime)-clarification plant. Clarified water from the clarifier was combined with the other three wastewater streams and flowed into a settling lagoon with a 20-hr hydraulic retention time. Clarified lagoon water was finally discharged to the river. The principal source of organic compounds in the wastewater was from the primary and secondary air pollution control systems and results from the volatilization of petroleum coke and pitch in the Soderberg anode. Wastewater treatment plant removal efficiencies of greater than 85% were achieved for the majority of the organic priority pollutant species detected.

Contract no. 68-03-2550. Apr. 1979. Includes bibliographical references.