Shenjia Hydraulics

Release Date:

2021-03-11

First, a sewage pump is used to pressurize the wastewater into the preheater for preliminary heating. There, it is directly mixed with the conventional circulating reactants and further heated to raise its temperature before entering the reactor. Subsequently, a compressor pressurizes air or oxygen and injects it into the reactor.

　　Supercritical water oxidation is an emerging technology for the treatment of organic waste and wastewater.

　　1. A simple process flow for supercritical water oxidation

　　First, a wastewater pump pressurizes the effluent and feeds it into a preheater, where it is directly mixed with the circulating reactants and further heated to raise its temperature before entering the reactor. A compressor then pressurizes air or oxygen and injects it into the reactor. In supercritical water, hazardous organic compounds rapidly react with oxygen, leading to their complete oxidation. When the organic‑matter concentration is sufficiently high, the heat released by oxidation is enough to bring all the reactor contents to supercritical conditions, enabling the reaction to proceed under homogeneous conditions. After exiting the reactor, the effluent is cooled and sent to a separator, where solid inorganic salts and other precipitates formed during the reaction are separated from the liquid phase.

　　2. Applications of Supercritical Water Oxidation in Environmental Protection

　　In theory, the SCWO process is applicable to the treatment of any waste containing organic pollutants: high-concentration organic liquid wastes, organic vapors, organic solids, organic wastewater, sludge, suspended organic solutions, or inorganic materials adsorbed with organic compounds. Within a very short time, SCWO completely converts recalcitrant and hazardous organic substances into CO2 and H2O, transforms nitrogen into harmless species such as N2 or N2O, and oxidizes elements like phosphorus, chlorine, and sulfur present in aqueous streams, precipitating them as inorganic salts from the supercritical water, thereby achieving the detoxification of organic toxic contaminants.

　　3. Advantages of Supercritical Water Oxidation

　　Compared with conventional technologies for treating municipal and industrial waste, it offers the following distinct advantages:

　　(1) Under appropriate temperature and pressure conditions, organic components can be completely mineralized into inorganic species such as CO2, H2O, N2, and SO4²⁻, with a conversion rate exceeding 99%; no intermediate products are formed, and no secondary pollution occurs.

　　(2) It has a broad scope of applicability and can be used to treat various toxic, recalcitrant organic compounds.

　　(3) The oxidation reaction is a homogeneous reaction, with a fast reaction rate and a short residence time (<1 min);

　　(4) The reaction is exothermic; at an organic matter content of 2%, the heat released by the oxidation itself can sustain the reaction.

　　(5) Inorganic components and salts exhibit extremely low solubility in supercritical water, thereby simplifying separation during the reaction process.