Patent ID: 11008240

Abstract:
The instant application is directed towards methods for removing sulfide from a wastewater stream. The pH of the wastewater stream is adjusted to between 7.0 and 8.0. A first oxidizing agent is mixed with the wastewater stream, oxidizing the sulfide to elemental sulfur. The wastewater stream is then softened by mixing lime with the wastewater stream. The addition of lime further raises the pH of the wastewater stream to 10.0 or higher, and converts the elemental sulfur to soluble sulfide (S2-) and/or thio-sulfate. Calcium carbonate is precipitated and sulfide (S2-) and/or thio-sulfate is adsorbed thereon. Thereafter, the wastewater stream is directed to a solids-liquid separation process, which separates the calcium carbonate and adsorbed sulfide (S2-) and/or thio-sulfate from the wastewater stream. The solids-liquid separator produces an effluent that includes residual elemental sulfur. The effluent is then mixed with a second oxidizing agent, which oxidizes the residual elemental sulfur to sulfate, producing a treated effluent.