Supercritical Water Oxidation (SCWO): A process for the treatment of industrial waste effluents

SuperCritical Water Oxidation (SCWO) process is investigated at the Institut of Technical Chemistry, ITC-CPV. The objectives were to determine destruction efficiencies of model compounds and industrial waste effluents and to study the feasability of the SCWO process. Two continuous SCWO bench scale plants are operated: a pipe reactor and a transpiring wall reactor system (design data: T = 630 °C, P = 32 MPa, feed rate waste water = 10 and 50 kg/h, air feed rate = 20 kg/h, transpiring and quench water feed rate = 50 kg/h). Suspensions containing up to 5 %wt solid material can be fed to the reactor using a membrane pump. With the pipe reactor, efficiencies of up to 99.99 % were achieved for the oxidation of model compounds (ethanol, toluene, phenol) as well as real waste effluents (paper, chemical, pharmaceutical industry, sewage works). The use of the pipe reactor is limited to feeds without salt to avoid plugging. Salty feeds are processed using the transpiring wall reactor, which is consisting of a pressure bearing tube outside and a porous tube as reactor inside. Water is steadily running through the porous reactor preventing the formation of deposits on the wall. SCWO has a high potential at least for the destruction of halogented organic compounds using the transpiring wall reactor system and is seen to be competitive to other processes for waste destruction.