CN111072173A

CN111072173A - Biphenyl thermal extraction sewage treatment process

Info

Publication number: CN111072173A
Application number: CN201911397851.3A
Authority: CN
Inventors: 杨水清; 徐康; 滕海俊; 庄可; 谢韦; 陆文庆
Original assignee: Jiangsu Yingtian Chemical Co ltd
Current assignee: Jiangsu Yingtian Chemical Co ltd
Priority date: 2019-12-30
Filing date: 2019-12-30
Publication date: 2020-04-28

Abstract

The invention belongs to the technical field of sewage treatment, and particularly relates to a biphenyl thermal extraction sewage treatment process. When the biphenyl is used as an extracting agent, the volatility is low, secondary pollution is not easy to bring, the layering effect is good, and meanwhile, the biphenyl has good extracting effect on organic matters with or without benzene rings or benzene ring-like structures.

Description

Biphenyl thermal extraction sewage treatment process

Technical Field

The invention belongs to the technical field of sewage treatment, and particularly relates to a biphenyl thermal extraction sewage treatment process.

Background

Many waste water components are relatively complex, and it is often difficult to achieve ideal purification effect by adopting a single treatment method, for example, when purifying waste water, the requirement for matching is relatively strict in the traditional AAO (anaerobic-anoxic-aerobic) method, so once the polluted components in the water body become complex, new filamentous bacteria are required to be domesticated and cultured to adapt to the new polluted components, and the treatment effect of the original bacteria on the complex sewage becomes very limited, which finally results in many processes, long flow and high cost of waste water treatment.

Disclosure of Invention

The invention provides a biphenyl thermal extraction sewage treatment process, which comprises the steps of adding biphenyl into sewage to be treated, stirring fully under a heating state, standing for layering, separating liquid while hot to obtain a purified water layer and a biphenyl organic layer,

wherein, the mass ratio of the biphenyl to the sewage to be treated is 1: 5 to 8 percent of the total weight of the steel,

the temperature of the stirring system in the heating state is more than 70 ℃,

the pollutants contained in the sewage to be treated comprise water-soluble organic matters without benzene rings in molecular structures,

and standing and layering are carried out in a liquid separation instrument wrapped with a heat insulation layer, so that hot liquid separation after layering is realized.

According to the scheme, the biphenyl is used for carrying out thermal extraction on the sewage, so that the biphenyl is low in volatility and is not easy to cause secondary pollution; the layering effect is good after extraction, an emulsion layer is not generated, the content of organic matter components in sewage after liquid separation is obviously reduced, and the treated organic layer biphenyl can be recovered through simple distillation.

Detailed Description

Example 1

Preparing simulated sewage:

adding 1 part by mass of benzene, toluene, benzoic acid, phenol, pyridine, methanol, ethanol, triethylamine, tetrahydrofuran, ethyl acetate and dichloromethane and 2 parts by mass of sodium chloride into 300 parts by mass of distilled water, fully dispersing by ultrasonic at 35 ℃, and cooling to normal temperature (25 ℃, the same below) to obtain simulated sewage.

Adding 30g of biphenyl into 200g of the simulated wastewater, placing the simulated wastewater in a closed container, mixing the simulated wastewater at the temperature of 76-78 ℃ and the stirring speed of 300 r/min for 3 min, completely liquefying the biphenyl, continuing to stir the simulated wastewater at the temperature for 20 min, immediately transferring the mixed system into a liquid separation instrument wrapped with a heat-insulating layer, standing and layering the mixed system for 30 min (at the moment, the upper biphenyl layer is in a liquid state at the temperature of 73 ℃), separating the liquid to obtain a purified water layer and a liquid biphenyl organic layer,

after the obtained water layer is cooled to normal temperature, the purified water layer obtained in the embodiment is analyzed and detected by GC (Agilent GC-column elite-WAX ETR), and the pollution component pairs of the simulated sewage water body before and after purification are as follows:

the kind of contaminant	Mass concentration before purification	Mass concentration after purification
			Benzene and its derivatives	0.32％	0.025％
Toluene	0.32％	0.020％
			Benzoic acid	0.32％	0.039％
Phenol and its preparation	0.32％	0.031％
			Pyridine compound	0.32％	0.052％
Ethyl acetate	0.32％	0.150％
			Methylene dichloride	0.32％	0.183％
Methanol	0.32％	0.203％
			Ethanol	0.32％	0.205％
Triethylamine	0.32％	0.193％
			Tetrahydrofuran (THF)	0.32％	0.270％
Biphenyl	/	0.095％

And (3) carrying out reduced pressure distillation (10torr) on the biphenyl organic layer, collecting fractions with the boiling point of 127-131 ℃, cooling 28.5g of biphenyl to obtain a light yellow flaky crystal, and measuring the purity (mass content) of the recovered biphenyl to be 98.6% by GC (gas chromatography) columns of Agilent J & W DB-624.

Comparative example 1

When the simulated sewage in the example 1 is purified, the biphenyl is replaced by the toluene with equal mass, and the rest of the operation is the same as that in the example 1:

adding 30g of toluene into 200g of the same simulated wastewater, placing the simulated wastewater in a closed container, mixing the wastewater at the temperature of 76-78 ℃ and the stirring speed of 300 r/min for 23 min, immediately transferring the mixed system into a liquid separation instrument wrapped with a heat-insulating layer as in example 1, standing and layering the mixed system for 30 min, separating the liquid to obtain a purified water layer and a toluene organic layer,

after the obtained water layer is cooled to normal temperature, the purified water layer obtained in the comparative example is analyzed and detected by GC (Agilent GC-column elite-WAX ETR), and the pollution component pairs of the simulated sewage water body before and after purification are as follows:

the kind of contaminant	Mass concentration before purification	Mass concentration after purification
			Benzene and its derivatives	0.32％	0.075％
Toluene	0.32％	0.543％
			Benzoic acid	0.32％	0.052％
Phenol and its preparation	0.32％	0.041％
			Pyridine compound	0.32％	0.057％
Ethyl acetate	0.32％	0.170％
			Methylene dichloride	0.32％	0.180％
Methanol	0.32％	0.223％
			Ethanol	0.32％	0.253％
Triethylamine	0.32％	0.212％
			Tetrahydrofuran (THF)	0.32％	0.230％
Biphenyl	/	NA

Comparative example 2

When the simulated sewage in the embodiment 1 is purified, the standing layering and the liquid separation are completed at normal temperature, and the rest operations are the same as those in the embodiment 1:

adding 30g of biphenyl into 200g of the same simulated wastewater, placing the wastewater in a closed container, mixing the wastewater at the temperature of 76-78 ℃ and the stirring speed of 300 rpm for 3 minutes, completely liquefying the biphenyl, keeping the temperature and stirring the wastewater for 20 minutes, immediately transferring the mixed system to a liquid separation instrument (without any heat preservation measure) in the same example 1, standing the mixture at normal temperature for layering for 30 minutes, completely solidifying the upper biphenyl layer, discharging the lower water layer, twisting the upper solid biphenyl layer into small pieces, and taking out the small pieces.

the toluene of comparative example 1 is a polar solvent and has benzene rings, and a large amount of organic substances having benzene ring structures or benzene-like ring structures enter the toluene layer after extraction, and other organic substances not having benzene ring structures or benzene-like ring structures can enter the toluene layer, but the ratio is reduced,

the biphenyl in example 1 has benzene ring but is a non-polar organic solvent, but the applicant found that the biphenyl is not comparable to toluene in the effect of absorbing and dissolving polar organic substances (such as benzoic acid, phenol, methanol, ethanol, triethylamine, ethyl acetate, etc.) with benzene ring or benzene ring-like structure or not, even has advantages, which are not easily foreseen by the skilled person,

the melting point of biphenyl is lower, is about 70 ℃ probably, and this scheme divides the liquid system to divide the liquid under the heat preservation condition, and the biphenyl layer floats in the water top with the form of liquid this moment, and biphenyl is better to organic matter thermal extraction effect. Compared with toluene thermal extraction, the biphenyl has higher boiling point, is less prone to volatilization, has small smell, has less influence on the surrounding environment during operation,

during the recovery of biphenyl, because the difference between the boiling point (the boiling point is 255 ℃ at normal pressure) of biphenyl and a conventional organic solvent is large (such as 110 ℃ at normal pressure) and high-quality biphenyl is easy to recover during distillation recovery, the recovery rate is high, the recovery and the reuse of a biphenyl solvent are facilitated, and the cost of biphenyl is low, so that the comprehensive cost is further reduced. Although the energy consumption of biphenyl cold extraction is low, biphenyl can be crystallized when being cooled, and the formed crystals are easy to be agglomerated into large blocks, so that the operation in a large reaction kettle is not facilitated; meanwhile, biphenyl forms crystal lattices when being cooled, the biphenyl crystal lattices have poor wrapping performance to other organic matters, dissolved organic matters are released into water again in the process of forming the crystals by the biphenyl, the impurity removal effect of extraction is lost,

the sewage is subjected to thermal extraction through the biphenyl, so that organic matters in the sewage can be effectively reduced, and subsequent treatment pressure and cost are reduced.

Claims

1. A biphenyl thermal extraction sewage treatment process is characterized in that: the treatment process comprises the steps of adding biphenyl into sewage to be treated, stirring fully in a heating state, standing for layering, separating liquid while hot, and obtaining a purified water layer and a biphenyl organic layer.

2. The biphenyl thermal extraction wastewater treatment process according to claim 1, wherein: the mass ratio of the biphenyl to the sewage to be treated is 1: 5 to 8.

3. The biphenyl thermal extraction wastewater treatment process according to claim 1, wherein: the pollutants contained in the sewage to be treated comprise organic matters which do not have benzene rings in molecular structures and are soluble in water.

4. The biphenyl thermal extraction wastewater treatment process according to claim 1, wherein: the temperature of the stirring system in the heated state is 70 ℃ or higher.

5. The biphenyl thermal extraction wastewater treatment process according to claim 1, wherein: standing and layering are carried out in a liquid separation instrument wrapped with a heat insulation layer.