LOCOS process was developed for industrial waste water and produced water treatment from toxic inorganic sulfides (NaHS, Na2S, (NH4)2S, NH4HS) by liquid phase oxidation in the presence of heterogeneous phthalocyanine KSM-X catalyst. 

LOCOS technology is used for:LOCOS

There is no air pollution with hydrogen sulfide and sulfur dioxide emissions at wastes treatment by LOCOS technology. This technology is characterized by low heat consumption and does not require continuous reactants feed. It provides more complete removal of toxic malodorous sulfur compounds from wastewater: sulfides and mercaptides. Alkaline nature of the reaction and relatively low process temperature allows using carbon steel equipment.

Technology is based on oxidation of toxic sulfides with air to inert, odorless thiosulfate and sodium sulfate according to reactions (1-2). Wastewater treatment proceeds in the presence of KSM-X catalyst at 60÷70°C and pressure of 0.5 ÷ 1.0 MPa:

9Na2S + 9O2 + 4Н2О → 4Na2S2O3 + Na2SO4 + 8NaOH (1)
9NaSH + 10O2 → 4Na2S2O3 + NaHSO4 + 4
Н2О (2)

Produced thiosulfate and sodium sulfate are less toxic than sulfides, that allows to supply neutralized wastewater to biological treatment plants.