JPH0275387A - Apparatus for treating waste water containing surfactant - Google Patents

Abstract

PURPOSE:To prevent the leakage of a liquid from a membrane by eliminating a lowering of the surface tension of a liquid to be treated at a membrane part, in an apparatus for treating waste water containing a surfactant and salts, by independently removing the surfactant in an air bubble separator and subsequently treating the treated liquid in a membrane evaporation/concn. apparatus. CONSTITUTION:A liquid to be treated containing a surfactant enters a foam separator 1 to generate foam by the air bubbles blown in said liquid from the bottom part of the foam separator and the foam is accumulated in the upper part of the separator 1. The surfactant in the liquid to be treated is conc. in the foam to be discharged and removed from a conduit 10. The liquid to be treated from which the surfactant is removed in the foam separator 1 is drawn out of a liquid discharge pipe 7 to be heated to predetermined temp. in a heating tank 12 and supplied to the evaporation chamber of a membrane evaporation/conc. apparatus 2 by a pump 14 to be recirculated. Cooling water is supplied and recirculated to the cooling chamber of the membrane evaporation/concn. apparatus from a cooling water tank 15. The steam generated from the evaporation chamber of the membrane evaporation/concn. apparatus 2 is passed through a hydrophobic porous membrane 23 and condensed on a cooling wall to be capable of being recovered as pure water.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is an evaporative concentration device for evaporating and concentrating an aqueous solution containing a surfactant and salts and obtaining highly pure water, in particular, an evaporative concentration device that uses a membrane on the evaporation surface. The present invention relates to wastewater treatment equipment that incorporates membrane evaporation concentration equipment.

[Conventional technology]

The membrane evaporation concentrator 2, which uses a hydrophobic porous membrane on the evaporation surface that allows vapor to pass through but not liquid, can be used for recovering pure water from salt solutions or concentrating the salt solution itself. has been considered and is already known. As shown in FIG. 3, the membrane evaporation concentration device is, for example,
As disclosed in Publication No. 45461, an evaporation chamber 20,
It consists of a condensation chamber 21 and a cooling chamber 22, and the evaporation chamber 20 is separated by a hydrophobic porous membrane 23, and a cooling wall 24 is provided opposite to the membrane wall with a space between them.

[Problem to be solved by the invention]

By the way, since the membrane evaporation concentration device 2 uses the evaporation surface +'-hydrophobic porous membrane 23, if a surfactant is contained in the liquid to be treated, the surface tension of the liquid to be treated will be lowered, so the liquid will be removed from the membrane. There was a problem that the information was leaked and it did not perform its function.

An object of the present invention is to provide a wastewater treatment device incorporating a membrane evaporation concentration device capable of treating wastewater containing surfactants.

[Means to solve the problem]

The above object is achieved by, in a wastewater treatment apparatus containing surfactants and salts, first removing the surfactant using a bubble separator and then treating the treated liquid using a membrane evaporation concentrator.

[Effect]

The wastewater treatment device containing surfactants and salts of the present invention firstly blows air bubbles into the liquid to be treated introduced into the foam separator 1 to turn the surfactant into foam and move it to the upper part of the wastewater. do. The surfactant can be removed from the wastewater by separating the foam accumulated on the wastewater surface.Next, by treating the liquid to be treated with the membrane evaporation concentrator 2, the salt content is concentrated and pure water is recovered. be able to.

By the way, if an aqueous solution containing a surfactant is treated as it is in a membrane evaporation concentrator, the liquid to be treated will leak from the hydrophobic porous membrane used in the membrane evaporation concentrator, and the device will not perform its function. This is because an aqueous solution containing a surfactant has a lower surface tension, which lowers the water pressure resistance of the membrane. but.

The water pressure resistance of a membrane is not uniquely determined by the value of the surface tension of the aqueous solution. That is, as shown in FIG.

If the water pressure resistance is measured repeatedly using the same membrane, the value will decrease. For example, an aqueous solution containing 35 ppm of the surfactant sodium dodecylbenzenesulfonate has a surface tension of 47 dyne/ai, but the water pressure resistance after the first application is 0.94 kg/d, whereas the same membrane When the water pressure is repeatedly measured using
, decreases to about 1 kg/aJ. In contrast, pure water has a surface tension of 3 dyne/cn.

The water pressure resistance at the first time was 1.2 kg/ffl, and when the water pressure resistance was repeatedly measured using the same membrane, it was 0.85 kg/-, which is a small degree of decrease. This is because in an aqueous solution containing a surfactant, the surfactant adheres to the membrane, resulting in a decrease in water pressure resistance when repeatedly measured. Therefore, in order to treat an aqueous solution containing a surfactant in a membrane evaporation concentrator, it is necessary to remove the surfactant.

Therefore, when an aqueous solution containing a surfactant was treated with a foam separator and the residual liquid was repeatedly measured for water pressure resistance, the value was the same as that of pure water, and the surfactant was removed by the foam separator. It was confirmed that the treated residual liquid had a water pressure resistance comparable to that of pure water.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a wastewater treatment apparatus in which the surfactant of the present invention contains salts. This device consists of a foam separator [1] that removes surfactants from a liquid to be treated, a membrane evaporation concentration device 2, a system 3 that heats and circulates the liquid to be treated, a system 4 that circulates cooling water, and a membrane evaporation concentration device 2. It consists of a storage tank 5 that collects purified water from the water. The foam separator 1 includes a supply 6 for a liquid to be treated, a discharge pipe 7, a near compressor 8 for generating foam, a disperser 9, a conduit 1o for recovering the generated foam, and a foam storage tank 11. The heating circulation system 3 for the liquid to be treated is provided with a heating tank 12 for the liquid to be treated, a heater 13 for heating the liquid, and a pump 14 for circulating the liquid. The cooling water circulation system 4 is provided with a cooling water tank 15, a cooler 16, and a cooling water circulation pump 17.

Next, the operation of the wastewater treatment apparatus of the present invention will be explained.

The liquid to be treated containing a surfactant is first transferred to a foam separator 1.
will be introduced in The liquid to be treated generates foam due to air bubbles blown into the bottom of the device 1, and the foam accumulates at the top of the device 11. Since the surfactant in the liquid to be treated is concentrated into foam, this is discharged from the upper conduit 10, collected in the foam storage tank 11, and removed. On the other hand, the liquid to be treated from which the surfactant has been removed in the foam separator 1 is extracted from a liquid discharge pipe 7 provided at the bottom and transferred to a liquid heating tank 12. The liquid heated to a predetermined temperature in the heating tank 12 is supplied to the evaporation chamber of the membrane evaporation concentrator 2 by a pump 14 and circulated. Further, cooling water is supplied and circulated to the cooling chamber of the membrane evaporation concentrator 2 from a cooling water tank 15 . Therefore, in membrane evaporation concentrators, the steam generated from the evaporation chamber is
It passes through the hydrophobic porous membrane 23, condenses on the cooling wall, and can be recovered as pure water.

〔Effect of the invention〕

According to the present invention, even for an aqueous solution containing a surfactant,
Stable processing is possible without deteriorating its functionality.

[Brief explanation of the drawing]

Figure 1 is a system diagram of a wastewater treatment equipment according to an embodiment of the present invention, Figure 2 is a diagram showing the results of repeated water pressure resistance measurements of a hydrophobic porous membrane, and Figure 3 is a membrane evaporation using a hydrophobic porous membrane. FIG. 3 is a longitudinal cross-sectional view of the concentrator. 1... Foam separator, 2... Membrane evaporation concentrator, 23.
・・Sparse 1st figure 2nd figure λri hunger 0 leather dohiki 2

Claims (1)

[Claims] 1. An apparatus for treating wastewater containing surfactants and salts, comprising: a bubble separator for removing the surfactant; and concentrating the salt content of the liquid to be treated and recovering pure water. A device for treating wastewater containing a surfactant, comprising a membrane evaporation concentration device using a hydrophobic porous membrane on the evaporation surface.