Treatment method of lignin production waste water

Abstract

The invention relates to a treatment method of lignin production waste water, which comprises the following steps of: treating and recovering lignin residues in lignin waste water through a gas floatation method at first; respectively feeding gas floatation water and condensate water in a multi-effect evaporation stage into an electro-osmosis desalting device to obtain lignin waste water containing no salt basically and highly saline concentrated water; and recovering the lignin waste water containing no salt basically as supplementary water in the lignin production process, feeding the highly saline concentrated water into a multi-effect evaporation device to concentrate and crystallize, recovering the obtained evaporation condensate water in the electro-osmosis desalting device, and directly selling the obtained high-purity solid salt. Due to the process, resource recycling of waste water is realized; closed cycle of water is realized, so that the pollution abatement cost is reduced; organic combination of the electro-osmosis technology, multi-effect evaporation and the crystallization technology is sufficiently embodied; and the treatment method disclosed by the invention is a high-efficiency and economical treatment method.

Description

technical field [0001] The invention relates to a wastewater treatment method, in particular to a lignin production wastewater treatment method. Background technique [0002] Lignin is a complex phenolic polymer formed from four alcohol monomers (p-coumaryl alcohol, coniferyl alcohol, 5-hydroxy coniferyl alcohol, sinapyl alcohol), which is the most abundant in the plant kingdom after cellulose Natural polymers, as a by-product of wood hydrolysis industry and paper industry, have not been fully utilized, and most of them have become environmental pollutants, seriously polluting the environment. With the in-depth study of lignin, people realized the importance of lignin. The molecular structure of lignin contains a variety of active groups, which has broad application prospects in agriculture, forestry, petroleum, metallurgy, fuel, cement and concrete industries, and polymer material industries. [0003] In the process of extracting lignin from lignocellulosic biomass, a lar...

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Problems solved by technology

The main inorganic pollutant of lignin production wastewater is sulfate. In the method described in the prior art, the electroosmosis processor mainly utilizes the principle of electrolysis, and the purpose is to recycle the high-concentration alkali in the papermaking black liquor. After obtaining the liquid alkali At the same time, the negative electrode of the electrolysis chamber will produce hydrogen, therefore, this electroosmotic processor is not suitable for the recovery of sulfate in lignin production wastewater, and aluminum ion precipitant needs to be added in the process of recovering lignin by this method, so that the recycled lignin Aluminum ions are contained in the lignin, which adversely affects the reuse of lignin. In addition, if the above-mentioned prior art adopts sulfuric acid to recover lignin, the filtrate after recovering lignin cannot be reused in the papermaking process due to acidity. Therefore, This method is not suitable for the treatment of lignin production wastewater

[0004] Chinese patent document CN101486524A discloses a comprehensive treatment method for furfural production wastewater. This method uses electrodialysis to concentrate acetic acid, but the efficiency of electrodialysis is low and the energy consumption is large. The dilute-phase furfural wastewater separated by electrodialysis cannot be directly reused or reaches the standard. The discharge needs to be adjusted to pH ~ 7 before entering the biochemical degradation tank. However, in the subsequent biochemical treatment process, the biochemical degradation tank has low adaptability to changes in influent water quality and water volume, and the operating results are easily affected by changes in water quality and water volume. In addition, The main pollutants in furfural wastewater are acetic acid and furfural, while the pollutants in lignin production wastewater are mainly sulfate, acid-soluble lignin and alkaline cellulose. The treatment objects of the two wastewater treatment methods are completely different. And because the lignin and cellulose contained in the lignin production wastewater are biodegradable substances, the biochemical effluent cannot meet the discharge standards, so this method is not applicable to the treatment process of the lignin production wastewater

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