A combined process coupling aerobic biochemical treatment, ozone catalytic oxidation and biological denitrogenation for acrylonitrile wastewater

Abstract

A combined process coupling aerobic biochemical treatment, ozone catalytic oxidation and biological denitrogenation for acrylonitrile wastewater is disclosed. The combined process comprises an aerobic biochemical process, an ozone catalytic oxidation process and a biological denitrogenation process. Discharged water subjected to aerobic biochemical process treatment in an aerobic biochemical unit is led into an ozone catalytic oxidation unit. Ozone catalytic oxidation process treatment is performed in the ozone catalytic oxidation unit, and discharged water after the ozone catalytic oxidation process treatment is led into a biological denitrogenation system and subjected to biological denitrogenation process treatment.

Description

Technical field [0001] The invention relates to a combined treatment process of high-concentration sewage containing acrylonitrile and its by-products (hereinafter referred to as acrylonitrile sewage) discharged during the production of acrylonitrile. Background technique [0002] Acrylonitrile is the main raw material in the production of chemical products such as acrylamide and acrylic fiber. Acrylonitrile wastewater has high pollutant concentration and complex water quality components, which are the main sources of water pollutants in chemical companies. At present, domestic acrylonitrile plants are generally equipped with acrylonitrile, acrylamide and other equipment, and the supporting sewage treatment plant treats the mixed water of acrylonitrile and its downstream sewage. With the continuous improvement of water-saving and emission-reduction requirements in recent years, downstream devices such as acrylic fiber and acrylamide have successively adopted recovery measures su...

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Problems solved by technology

[0019] 1. The CODcr of acrylonitrile sewage is relatively high. As the service life of the acrylonitrile catalyst increases, the CODcr value of the discharged sewage will increase year by year. After three years of catalyst replacement, the average COD is above 2000mg / L. It is very difficult to pass the general treatment process. It is difficult to meet the first-level emission standard

[0020] 2. Poor biodegradability, generally B / C<0.3, and because the influent COD is too high, the water contains some refractory organic matter and cyanide (cyanide ≤ 3mg / L), biochemical treatment alone cannot treat refractory organic matter is degraded

[0021] 3. The total nitrogen content is high, and the carbon-nitrogen ratio is seriously unbalanced

[0023] To sum up the above four points, the treatment of acrylonitrile sewage is carried out through biochemical treatment alone, advanced oxidation or a combination of the two processes, which can achieve partial treatment effects on CODcr and ammonia nitrogen. In engineering practice, only 9 companies in the country have acrylonitrile equipment Among the chemical enterprises in the world, none of the treated effluent can reach the first-level standard of CODcr≤60mg / L and ammonia nitrogen≤15mg / L "Integrated Wastewater Discharge Standard" (GB8978-1996)

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