IN-BATH NOX EMISSIONS CONTROL AND SURFACE FINISHING WASTEWATER TREATMENT

Introduction

Wastewater streams and process baths at metal surface finishing operations can be very challenging to effectively treat. USP Technologies (USP) can help metal finishers and processors by characterizing each unique situation and matching it to our technically sound and proven options for NOx emissions control in stainless steel and titanium pickling operations, as well as for treatment of organic compounds, cyanide and a range of wastewater contaminants.

In-Bath NOx Control: Metal surface treatment operations such as bright dipping, phosphatizing, desmutting and pickling often utilize nitrates, nitrites or nitric acids, which evolve vapor phase nitrogen oxides (NOx) and must be controlled. Hydrogen Peroxide (H2O2) is ideally suited to remove NOx in metal pickling baths, as H2O2 rapidly reacts with NO and NO2 in the liquid phase as it is formed, thereby eliminating volatilization into the gas phase. The oxidation product is nitric acid (HNO3), so in this way, the nitric acid pickling reagent is regenerated/recovered in-situ. In addition to cost savings realized from reducing the consumption of nitric acid, this in-bath approach can reduce or eliminate the expense of gas scrubbers.

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