LOCOS: Wastewater treatment


The LOCOS technology (LOCOS) was developed for the neutralization of industrial wastewater and formation water from toxic inorganic sulfides (NaHS, Na2S, (NH4)2S, NH4HS) by liquid-phase oxidation in the presence of a heterogeneous phthalocyanine catalyst KSM. LOCOS technology is applicable in solving the following problems:

  • neutralization of alkaline sulphurous effluents from oil refineries and alkaline pyrolysis effluents: LOCOS SA process
  • formation water treatment (treatment): LOCOS PW process
  • purification of aqueous process condensates: LOCOS PC process

When using LOCOS technology to neutralize wastewater, there is no pollution of the atmosphere with emissions of hydrogen sulfide and sulfur dioxide. This method is characterized by low heat consumption and does not require continuous consumption of reagents. It provides a more complete removal of toxic malodorous sulfur compounds from wastewater: sulfides and mercaptides. The alkaline nature of the reaction medium and the relatively low temperature of the process make it possible to use carbon steel apparatus in the circuit.

The LOCOS technology does not require a large consumption of heat and reagents, does not pollute the atmosphere with hydrogen sulfide emissions, the technological scheme uses devices made of carbon steel.

The essence of the technology lies in the oxidation of toxic sulfides with air oxygen into inert, odorless sodium thiosulfate and sodium sulfate according to reactions (1-2). The process of waste disposal takes place in the presence of a KSM catalyst at 60÷70°C and a pressure of 0.5÷1.0 MPa.

9Na2S + 9O2 + 4H2O → 4Na2S2O3 + Na2SO4 + 8 NaOH (1)
9NaSH + 10O2 → 4Na2S2O3 + NaHSO4 + 4H2O (2)

The resulting sodium thiosulfate and sulfate are less toxic than sulfides, which makes it possible to send neutralized effluents to biological treatment facilities (BTP).