Application of advanced oxidation processes for the treatement of cyanide containing effluent

Abstract

Batch experiments were carried out for the removal of cyanide in the effluent of plating industry by the application of advanced oxidation processes. Four systems with different modes of oxidation in combination of ultra violet (UV) light with hydrogen peroxide and /or ozone were investigated. Of all the applied systems, UV‐light with two oxidants, i.e. O₃ (32 me min⁻¹), and H₂O₂ (1.36 g l⁻¹) was found successful in bringing down the amount of cyanide from 157.32 mg l⁻¹ to 1.0 mg l⁻¹ , which is the limit set by the Ministry of Environment of Korea for cyanide‐containing discharges. Other systems, however, could not bring the cyanide abatement to the targeted value even with higher dosage of oxidants and an extended period of reaction time. Regardless of the oxidation modes applied, all the heavy metal ions in the treated effluent were reduced to 90%. Ultra violet light with the combination of two oxidants had the economic preference over the other systems since a relatively lower dosage of UV‐light (2484 W‐S cm⁻²) was found effective at achieving the targeted level of cyanide removal.

Key words:

• UV‐reflecting reactor
• plating wastewater
• hydrogen peroxide
• ozone