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Method for pre-treating alkali PTA wastewater by using combined flocculating agent

A pretreatment and flocculant technology, applied in chemical instruments and methods, water/sewage multi-stage treatment, water/sludge/sewage treatment, etc., can solve problems such as difficult maintenance of equipment, large amount of residual sludge, and high treatment cost , to achieve the effect of increasing compactness, low processing cost, and low dosage

Active Publication Date: 2011-01-12
溧阳常大技术转移中心有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0011] The technical problem to be solved by the present invention is to overcome the above-mentioned problems such as high treatment cost, complicated operation, slow sedimentation velocity, loose sedimentation layer, difficult equipment maintenance and large amount of residual sludge, and at the same time, a method proposed in order to reduce the load of subsequent biochemical treatment A method for pretreating high-concentration alkaline PTA wastewater using a combined flocculation method to fully recover solid PTA and reduce the burden of subsequent biochemical treatment

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] Weigh 400g of alkaline PTA waste water and put it into a beaker, adjust the temperature of the water bath to be heated to about 45 degrees, add coagulant light calcium carbonate, and the addition amount is 0.07% of the waste water quality. After stirring and dissolving, phosphoric acid with a mass concentration of 40% is added to adjust the pH value of the waste water to 3.5. Then add the prepared cationic polyacrylamide solution with a concentration of 0.04%, and the added amount is 0.001‰ of the waste water quality. After 60 minutes of flocculation and sedimentation, the supernatant was taken for measurement. After treatment, the TA removal rate of PTA wastewater can reach 65%, the COD removal rate can reach 50%, the sedimentation velocity is about 1.42 times of the sedimentation velocity without adding chemical agent, and the sedimentation layer height is about 0.59 times of that without chemical agent.

[0027] .

Embodiment 2

[0029] Weigh 400g of alkaline PTA waste water and put it into a beaker, adjust the temperature of the water bath to be heated to about 45 degrees, add coagulant light calcium carbonate, and the addition amount is 0.09% of the waste water quality. After stirring and dissolving, hydrochloric acid with a mass concentration of 50% is added to adjust the pH value of the waste water to 3.5. Then add the prepared amphoteric polyacrylamide solution with a concentration of 0.03%, and the added amount is 0.0017‰ of the waste water quality. After 50 min of flocculation and sedimentation, the supernatant was taken for measurement. After treatment, the TA removal rate of PTA wastewater can reach 70%, the COD removal rate can reach 57%, the sedimentation velocity is about 1.47 times of that without chemical agent, and the sedimentation layer height is about 0.55 times of that without chemical agent.

Embodiment 3

[0031] Weigh 400g of alkaline PTA waste water and put it into a beaker, adjust the temperature of the water bath to be heated to about 45 degrees, add coagulant light calcium carbonate, and the addition amount is 0.10% of the waste water quality. After stirring and dissolving, nitric acid with a mass concentration of 50% is added to adjust the pH value of the waste water to 3.0. Then add the prepared anionic polyacrylamide solution with a concentration of 0.03%, and the added amount is 0.0024‰ of the waste water quality. After 70 minutes of flocculation and sedimentation, the supernatant was taken for measurement. After treatment, the TA removal rate of the PTA wastewater can reach 72%, the COD removal rate can reach 59%, the sedimentation velocity is about 1.48 times of the sedimentation velocity without adding chemicals, and the sedimentation layer height is about 0.52 times of that without adding chemicals.

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Abstract

The invention relates to a method for pre-treating alkali PTA wastewater, in particular to a method for pre-treating high-concentration PTA wastewater by using a combined flocculating agent. The method sequentially comprises the following steps of: adding coagulant aid in an amount which is 0.07 to 0.12 percent of the mass of the treated wastewater into the PTA wastewater at the temperature of about 45 DEG C; adjusting the PTA wastewater by using acid till the pH value is between 3 and 3.5; adding polyacrylamide flocculating agent in an amount which is 0.0001 to 0.0003 percent of the mass of the treated wastewater into the wastewater; and stirring the wastewater, then performing gravity settling, and treating the high-concentration PTA wastewater after the retention time of 0.5 to 1.5 hours. The method has the characteristics of low treatment cost, high settling velocity, compact settling layers, capability of reclaiming a large amount of TA solid, simple operation conditions and the like.

Description

technical field [0001] The invention relates to a method for pretreatment of alkaline PTA wastewater, in particular to a method for pretreating high-concentration PTA wastewater with a combination of flocculants. Background technique [0002] PTA (purified terephthalic acid) is an important chemical production raw material, widely used in synthetic resin, polyester fiber and other light textile fields. The p-xylene oxidation process is adopted in the PTA production facilities at home and abroad, and a large amount of high-concentration organic wastewater is produced during the production process, and the composition of the wastewater is complex. In addition to easily degradable chain compounds, such as acetic acid, benzoic acid, acetate, volatile acids, etc., the wastewater also contains a large amount of refractory benzene ring compounds that contribute greatly to the COD of wastewater. Such as: terephthalic acid (PTA or TA), toluene, p-xylene, phthalic acid, etc., and the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C02F9/04
Inventor 张跃严生虎刘建武沈介发钱杰
Owner 溧阳常大技术转移中心有限公司
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