A comprehensive treatment method for recovery and recycling of semi-coke wastewater with phenol and ammonia

Abstract

The invention discloses a method for recovery and comprehensive resource treatment of phenol and ammonia in semi-coke waste water. The method comprises the following steps: performing standing on the semi-coke waste water to realize gravity oil removing and separating recovery, filtering an effluent through a coke filter to remove a solid suspension, and introducing the effluent in an extraction pre-oil removal reactor for deeply removing oil residue, coke powder and tar pollutants in the waste water; performing stripping depickling on the waste water after extraction and pre-oil removal, performing ammonia distilling and performing extraction processing to remove and recover the acidic gas, ammonia and phenol in the waste water, and introducing the processed waste water which reaches the standard in a biochemical treatment system; performing extraction processing to obtain a phenol-rich organic phase, and converting phenols in an extract phase to sodium phenolate through alkali washing processing to realize separation of an extractant and the phenols; and introducing a sodium phenolate solution to an acidifying workshop section for acidifying to prepare crude phenol and sodium salt. The method can realize separation and enrichment of phenols, heavy oil, light oil, ammonia and acidic gas in the semi-coke waste water, realizes resource recovery, at the same time, realizes regeneration and cycle utilization of the extractant and alkali lye, and has good application prospect.

Description

technical field [0001] The invention relates to the field of semi-coke wastewater treatment, in particular to a resource-based comprehensive treatment method for recovering phenol and ammonia from semi-coke wastewater. Background technique [0002] Semi-coke wastewater is wastewater produced during coal dry distillation (about 550~650°C), which contains refractory organic pollutants such as phenol, tar, and ammonia. It is difficult to treat and has great environmental hazards. [0003] For semi-coke wastewater, the current conventional treatment methods usually include two stages: phenolic ammonia recovery pretreatment and biochemical treatment, in which the phenolic ammonia recovery pretreatment unit is not only a security system for the subsequent biochemical treatment system, but also directly related to the operation of the biochemical treatment system. It is also related to the recovery of valuable resources in semi-coke wastewater, so it is the key to the success of se...

AI Technical Summary

Problems solved by technology

[0005] Although the traditional phenolic ammonia recovery and treatment technology can effectively treat and recover the phenol and ammonia pollutants in semi-coke wastewater, due to technological limitations, the traditional phenolic ammonia recovery and treatment process has high energy consumption, low purity of recovered phenol resources, and systemic problems. Problems such as poor running stability are manifested in the following points:

[0006] 1. In the traditional phenolic ammonia recovery technology, the waste water often goes directly into the subsequent stripping tower after gravity degreasing or air flotation degreasing. Due to the special water quality structure of the semi-coke waste water, only physical degreasing often cannot solve the coke suspended in the waste water. Powder, coal powder, tar micelles and other solid pollutants with a density close to water will cause these pollutants to enter the subsequent stripping tower, which will easily cause blockage of the stripping tray and affect system stability;

[0007] 2. The ether or ketone single-component extractant used in the traditional phenol ammonia recovery technology usually has high solubility in water, which causes a large loss rate of the extractant during the treatment process, and the extractant enters the treated wastewater, increasing the The COD index in the wastewater is increased, and the processing load of the subsequent biochemical system is increased; therefore, for the wastewater after the extraction treatment of the traditional process, it is often necessary to perform another evaporation to recover the extractant dissolved in water, which greatly increases the operating cost;

[0008] 3. In the traditional phenol ammonia recovery and treatment system, the recovered phenol is obtained by rectifying the extracted phenol-rich organic phase. Since the phenol in the phenol-rich organic phase will form azeotrope with organic substances such as extractant, light oil, and heavy oil, The crude phenol obtained by rectification has low purity and high impurities, which makes it difficult to separate light oil, crude phenol, and heavy oil, and it is impossible to classify and obtain various organic products

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