Supercritical water oxidation (SCWO) is a promising green technology to completely convert hazardous wastewaters to innocuous products, allowing energy recovery. This process has been extensively applied to many model compounds and real wastewaters at laboratory scale. However SCWO treatments at the pilot plant scale of real wastewaters are much less extensive in literature. Furthermore, the application of this technology to industrial wastewaters has the two main drawbacks of corrosion and salt deposition, and some other problems to be solved related to management of biphasic wastes, presence of suspended solids, high costs, etc., so currently the industrial scale-up and commercialization of the process is still subject to difficulties. This work reviews the main technical solutions studied by numerous authors to avoid the drawbacks mentioned. Besides, since the economic feasibility of the process will depend on the energy recovery of the reactor effluent, this aspect is also presented in this review.

BACKGROUND: Supercritical water oxidation (SCWO) is a promising technology that respects the environment, destroys wastes and allows energy recovery. This process has been applied to many model compounds and real wastewaters at laboratory scale. However, SCWO treatments at pilot plant scale of real wastewaters are scarce. The application of this technology to industrial wastewaters has drawbacks such as corrosion, salt deposition and high cost, so industrial scale-up has been delayed.

The destruction of industrial wastewaters by supercritical water oxidation (SCWO) has been studied intensively in the last two decades due to the powerful and promising advantages of this technology. However, the SCWO process is not yet commercially established due to several drawbacks that limit its application as a general treatment, process costs being one of those limitations. In an effort to enhance the viability of SCWO as a commercial process, a study was performed in a pilot plant (25 kg/h) used to treat industrial oily wastes by SCWO, and a simulation was carried out to evaluate the viability of energy production on an industrial scale. The SCWO pilot plant effluent is good for producing hot water or steam by recovering heat of waste organics. Both alternatives are evaluated for a SCWO industrial plant design with 1000 kg/h, with it being possible to recover a maximum of 118 kW, that is, 71% of the energy content of the wastewater.

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