Biotreatment of wastewater from hydrocarbon processing units

Abstract

This invention provides a process for the biotreatment of effluent from waste gas scrubbing systems of hydrocarbon processing facilities and for the biotreatment of sulfide- and ammonia-containing wastewater streams from other sources. Sulfides are minimized by bacteria cultures, particularly Thiobacillus. COD, TKN and BOD are concurrently minimized by co-cultures of the bacteria with various heterotrophs. In a version of the process, the co-cultures of the bacteria with various heterotrophs are also capable of performing nitrification, without application of nitrifiers. Acclimation of the heterotrophs to the species to be removed is accomplished by biological acclimation and enrichment reactors which reduce mycell toxicity to the heterotrophs. To control pH of the heterotrophic reaction with sulfides, magnesium oxide (MgO) and caustic are used separately or in combination. With adequate removal of the COD, TKN and BOD, nitrification and removal of ammonia can be accomplished by nitrifying bacteria cultures, particularly nitrosomonas and nitrobacters. Enrichment of the nitrosomonas and nitrobacters is accomplished by using a biological enrichment reactor. To control pH and provide a carbon source for the nitrosomonas and nitrobacters, a combination of magnesium oxide and sodium bicarbonate is utilized.