Method for treating alkali residue liquid waste and three-sludge of oil refineries

Abstract

The invention relates to a method for treating alkali residue liquid waste and three-sludge of oil refineries. The method comprises the following steps: at first, contacting the alkali residue liquid waste of oil refineries with an oxygen-containing gas at 100-200 DEG C and at a pressure of 0.3-3 MPa to carry out a mild wet oxidation treatment, so as to convert sulfur in sulfides into sulfates and/or thiosulfates, mixing the alkali residue liquid waste experiencing the oxidation treatment with the three-sludge of oil refineries in a mixing and stirring tank, adding a coagulant, a flocculant, magnetic powder and an oxidant into the mixing and stirring tank, reacting for a period of time, and carrying out solid-liquid separation on materials at the outlet of the mixing and stirring tank in a magnetic separator, wherein the separated water can be directly drained or recycled, and the separated solid is further dewatered after the magnetic powder is recycled. According to the method provided by the invention, the COD removal rate is up to 99%, and the water content of the dewatered sludge is smaller than 60%. The method provided by the invention is simple in treatment process, little in equipment, short in dwell time, simple and convenient to operate and high in treatment efficiency.

Description

technical field [0001] The invention relates to a method for treating alkali slag waste liquid and three sludges of an oil refinery, in particular to a method for simultaneously treating the alkali residue waste liquid and three sludges of an oil refinery by adopting a combination process of mild wet oxidation and magnetic separation. Background technique [0002] The three sludges in the refinery mainly include the scum produced by the dosing of the flotation tank, the remaining activated sludge produced by the biochemical system, and the bottom sludge of the oil separation tank, etc., commonly known as the three sludges. The composition of the three muds in the refinery is very complex, with great variability and contains a large amount of harmful substances. Due to its special properties, the dehydration and treatment technologies are difficult and costly. Due to its high content of residual oil, organic matter, and heavy metals, it is a serious pollutant, and with the de...

AI Technical Summary

Problems solved by technology

Although FRIPP's moderate wet oxidation + SBR process can remove sulfides up to 99.9% under mild conditions, the removal rate of COD is only 40% to 60%, which will inevitably increase the follow-up oily sewage system. handling load and the potential for shock

[0005] CN102285729A discloses a method for high-temperature wet oxidation treatment of spent lye, the method has low energy consumption, S 2- The removal rate can reach 100%, and the COD removal rate can reach 75% to 85%. After the treatment, the waste lye can be directly discharged into the sewage treatment system, which effectively relieves the pressure brought by the high-concentration wastewater of the sewage treatment plant. However, the operation of this method The conditions are harsh, the required reaction temperature is high, and the energy consumption of subsequent cooling and heat exchange is high

This method uses a wet oxidation-neutralization-SBR biological treatment process to treat wastewater. This method can remove sulfides up to 100% under mild conditions, but the removal rate of COD is not high, and subsequent SBR is required. process, and the SBR process has certain requirements on the COD of the influent. If the COD is too high, it will impact the treatment system and affect the treatment effect.

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