A Method for Efficiently Removing Chemical Oxygen Demand in Pulping Wastewater

Abstract

The invention provides a method for efficiently removing chemical oxygen demand of pulping wastewater, comprising the following steps: (1) sequentially adding an acidic inorganic polymer flocculant and an organic polymer flocculant to the wastewater, controlling the pH of a reaction system between 5 to 7 during the adding process, and stirring fully for a short time to complete flocculation; (2) adding Fenton agent to the flocculated wastewater in the same container, controlling the pH of the reaction system between 3 to 5 during the adding process, stirring fully for a short time, mixing themedicinal liquid evenly, and standing for reaction; and (3) adjusting the pH of the reacted wastewater, adding a small amount of high-molecular flocculant for turbidity separation and discharging. According to the invention, a flocculation method and the Fenton oxidation method are used in the same container for improving the complexity of the existing Fenton flocculation auxiliary unit and the Fenton oxidation process combination, saving equipment investment, improving reaction efficiency, and effectively removing organic matter content and chemical oxygen demand in wastewater.

Description

technical field [0001] The invention relates to the technical field of wastewater treatment, in particular to a method for efficiently removing chemical oxygen demand from pulping wastewater. Background technique [0002] Due to the complex composition of pulping wastewater, high pollutant load, and high content of water-soluble lignin that is difficult to decompose by biology, it is one of the main pollution sources of water bodies. At present, the more common wastewater treatment process generally adopts the first-level physical precipitation, the second-level biochemical treatment, and the third-level Fenton advanced oxidation process. [0003] The essence of the Fenton oxidation reaction is a chain reaction in which hydrogen peroxide is decomposed to generate hydroxyl radicals with high oxidative activity through ferrous ions. Wastewater with high COD and difficult biochemical degradation. [0004] In the design of the Fenton reactor for pulping wastewater treatment, a...

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Problems solved by technology

[0004] In the design of Fenton reactor for treating pulping wastewater, fluidized bed system is often used. After vigorous stirring, Fenton agent and wastewater are fully mixed to improve the oxidation efficiency of Fenton reaction, but the power consumption is relatively large.

[0005] In order to improve the oxidation efficiency of Fenton, an auxiliary unit can be added before or after the Fenton fluidized bed. For example, Tian Binghui et al. (patent application number: 201101021014.X) invented "a catalytic oxidation-composite flocculation integrated wastewater treatment process" , add a catalytic oxygen tank before the Fenton oxidation reaction tank to improve the oxidation efficiency of the Fenton reaction, and achieve better results for the treatment of chemical industry wastewater, but it is necessary to add another catalytic oxidation reaction tank; Wu Xiaoyi et al. (patent application No.: 201610789935.1) A method to improve the COD degradation efficiency and biochemical performance of wastewater. The wastewater undergoes steps such as Fenton oxidation, ozone oxidation, and electrocatalytic oxidation to obtain a better COD removal rate for ultra-high concentration wastewater, but the treatment After the wastewater COD is still very high; Wang Xiaojun et al. (patent application number: 200710027102.2) invented the "Fenton and air flotation integrated water treatment method", adding an air flotation device after the Fenton oxidation reaction tank to replace the general flocculation sedimentation tank , can improve the flocculation efficiency after the Fenton reaction, but it is not helpful to improve the Fenton reaction efficiency and reduce the dosage of drugs; Liu Xiyang et al. (patent application number: 201510954688.1) invented "A method for treating dye production wastewater by using magnesium oxide coagulation combined with Fenton oxidation" , Before the Fenton oxidation reaction, flocculate with magnesium oxide at pH 12, and then perform Fenton reaction on the treated wastewater, which has a certain effect on dye production wastewater

[0006] Such methods have a certain effect on wastewater treatment, but they are more or less complex in process and cumbersome in operation, and require multiple sets of independent equipment to operate in series, which consumes a lot of energy and occupies a large space, which is not conducive to the operation control and operation of enterprises. Fenton dosage can not be effectively reduced and other problems