Application of sequencing batch reactor (SBR) for treatment of refinery wastewater containing nickel

A petroleum refinery is a complex combination of interdependent industrial processes that
generate wastewater effluent containing hydrocarbons, heavy metals and dissolved minerals which
cause harmful effects to human and environment. While physicochemical systems are widely
accepted as effective methods for treatment of industrial wastewater, biological processes are
beginning to play an increasing role in the treatment of metal containing effluents. The objective of
the present study is to investigate the biological treatment of refinery wastewater containing nickel.
The SBR performance was assessed by measuring Chemical Oxygen Demand (COD), Mixed
Liquor Suspended Solid (MLSS), Mixed Liquor Volatile Suspended Solid (MLVSS) as well as nickel concentrations. The SBR was operated on a 12-hour cycle basis which consisted of five distinct modes: fill, react, settle, draw, and idle. The wastewater was brought from an equalization
tank of a refinery plant and was fed to the reactor after characterization. The nickel concentration
ranged from 2.3 to 2.6 mg/L. The experimental results demonstrate COD and nickel removal efficiencies of 70-90% and 77-80%, respectively.