The AquaCritox® NC is a hydrothermal oxidation to treat recalcitrant waste streams such as mixed and refinery spent caustics. The process uses purified oxygen (>90%) as the source of oxidant and operates at optimised pressures and temperatures ranging from 100 – 165 bar and 220 – 300°C.
The treated effluent from AquaCritox NC will contain negligible amounts of sulphides. Recalcitrant components commonly found in spent caustic are destroyed, and most of the organic COD will be oxidised. Any residual COD contained within the treated effluent stream is readily biodegradable in downstream wastewater treatment. Due to the complete oxidation of sulphides to sulphates and the absence of thiosulphates, the effluent can be neutralised to neutral pH without any additional treatment steps. The table below indicates the typical effluent quality relating to specific feed conditions.
| Parameter | AquaCritox NC |
| Feed flow rate (Design) | Up to 10 m3/hr per process train |
| Feed COD | Up to 150,000 mg/L or more |
| Effluent sulphide | < 1 ppm (guaranteed) |
| Effluent thiosulphate | < 100 ppm (guaranteed) |
| Organic COD (Phenols, Cresylic Acids, Naphthenic Acids) | 80 – 99+% destruction |
Tailored solutions can be offered for waste streams with flow rates up to 10 m³/h and even higher. The main OPEX consideration for this process is related to the cost of electricity for oxygen generation and electrical heating (specifically for lower-COD waste streams), followed by maintenance relating to high pressure rotating equipment.
AquaCritox NC offers unrivalled performance at a better cost than traditional alternatives such as Wet Air Oxidation (WAO).
