Pretreatment technique for decolorization of wastewater at middle plate of paper-making pulping

Abstract

The invention discloses a pretreatment process of wastewater decoloration in a paper-making and pulping process, and the process comprises the following steps of: 1) introducing the wastewater into an anaerobic reactor for anaerobic treatment, transforming part of biochemical organics in the wastewater into methane and carbon dioxide, and reducing lignin substances that have no biochemical ability in the wastewater; 2) introducing the effluent water treated by the step (1) into a coagulation chamber, and adding a composite coagulant in the coagulation chamber to promote the condensation of lignin substances in the wastewater; 3) and introducing the effluent water treated by the step (2) into a sedimentation tank for separating mud and water. The pretreatment process has advantages of simple process, good decoloration effect, low cost, stable reaction process and good treatment effect. Meanwhile, by using the invention, the wastewater can be directly recycled after the pretreatment and advanced treatment.

Description

technical field [0001] The invention relates to a pretreatment process for decolorizing waste water, in particular to a pretreatment process for decolorizing waste water in the middle stage of papermaking and pulping. Background technique [0002] The wastewater in the middle stage of papermaking and pulping belongs to the difficult industrial wastewater with high chroma, high alkalinity, high organic pollutants and low biodegradability. The wastewater contains various organic substances such as hydrocarbons, phenols, acids, benzene, anthracene, quinones and Derivatives, polymers, halogenated substances, especially lignin are difficult to biodegrade. Through the general secondary biochemical treatment, but the chemical oxygen demand (abbreviated as COD) of the effluent is generally above 300mg / L, the dilution factor of the chroma is greater than 128 times, and the 5th biochemical oxygen demand (abbreviated as BOD) 5 ) is usually very low, and the conventional biochemical ad...

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Problems solved by technology

However, there are defects in these conventional processes: the adsorption method needs to add a large amount of adsorbent, which will fail after the adsorption is saturated, the cost is high and a large amount of sludge will be generated; the oxidation method (ozone, hydrogen peroxide, hypochlorous acid, etc.) The decolorization effect is not obvious, and the purpose of decolorization cannot be achieved; the conditions required for high-efficiency decolorization engineering bacteria are harsh, and it is difficult to apply in engineering; the electrolysis method is effective, but the power consumption is high, resulting in unacceptable operating costs; The effect of reducing suspended solids (SS) and desalination is very good, but the removal effect of lignin that causes the color of papermaking wastewater has yet to be verified, and its construction cost and operating cost are very high

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