JPS6031884A - Recovery of contained substance from washing water - Google Patents

Abstract

PURPOSE:To efficiently recover the low concn. substance in washing water, by treating washing water by a medium pressure reverse osmosis membrane apparatus while treating the concentrate therefrom with a high pressure reverse osmosis membrane apparatus and applying electrolytic treatment to the concentrate to recover the contained substance. CONSTITUTION:Washing water A used in photographic treatment passes a pretreating part while the treated water is sent to a medium pressure reverse osmosis membrane apparatus 1 where receives primary separation treatment to be separated into permeated water B and a concentrate A1. The permeated water B is re-utilized as washing water or discharged while the concentrate A1 is supplied to a high pressure reverse osmosis membrane apparatus 2 where subjected to secondary separation treatment to be separated into permeated water B1 and a concentrate A2. The permeated water B1 is re-utilized as washing water or discharged while the concentrate A2 is subsequently treated with an electrolytic apparatus to recover silver. In this case, 10g/l of high purity silver is recovered from the concentrate A2. Waste water B2 from the electrolytic apparatus 3 after silver recovery is discharged after subjected to ozone treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for recovering low-concentration substances contained in washing water, for example, a recovery method suitable for recovering silver contained in photographic processing washing water. It is.

Because silver is used in the photo processing process, the photo processing washing water contains a low concentration of silver, and disposing of this as is would be a waste of resources, raising photo processing costs and causing pollution problems. This will cause

In the case of photographic processing washing water, it has been considered to use ion exchange methods or iron wool replacement methods to recover silver contained in low concentrations, but these methods are expensive and cause secondary pollution. Currently, this method has not been put into practical use, and there are currently several proposals for efficient recovery methods for silver contained in low concentrations.

This invention has been made in view of the above points, and provides a recovery method that can efficiently recover low-concentration substances contained in washing water at low cost and without causing pollution. The purpose is to

The structure of this invention is to sequentially concentrate washing water using medium-pressure type and high-pressure type reverse osmosis membrane devices to increase the concentration of contained substances, and to recover high-concentration substances from this concentrated treated water using an electrolytic device. This is what I did.

Hereinafter, the present invention will be explained based on embodiments shown in the accompanying drawings.

The drawing shows the processing steps of the recovery method according to the present invention, in which photographic processing washing water A passes through a pre-treatment section and is then sent to a medium-pressure type reverse osmosis membrane device 1, where it is separated into permeated water B and concentrated liquid. A
I undergo primary separation processing.

The pretreatment section is composed of, for example, a filter for removing impurities, and is designed not to clog the reverse osmosis membrane device 1 and to not interfere with the separation process at all.

The reverse osmosis membrane device 1 can be of any type, such as one mainly made of cellulose acetate or a polyamide type polymer compound.

Permeated water B is reused as washing water or drained,
The concentrated liquid A+ is supplied to a high-pressure type reverse osmosis membrane device 2,
It is subjected to secondary separation treatment into permeated water B1 and concentrated liquid A2.

This high-pressure type reverse osmosis membrane device 2 has the same structure as the above-mentioned medium-pressure type, but it has a high processing pressure and can perform separation treatment even with highly concentrated permeate water. Water A becomes a concentrated liquid A1 of 59 PPM while passing through a medium pressure type reverse osmosis membrane device 1, and further becomes a 59 PPM concentrated liquid A1 by a high pressure type reverse osmosis membrane device 2.
The concentration of PM is increased in concentrated solution A2.

The permeated water Bl is reused as washing water or drained, and the concentrated liquid A2 is then treated with the electrolyzer 3 to recover silver, so that highly pure silver is produced at a ratio of 10 f/, to the concentrated liquid A2.
can be recovered.

If the waste water B2 from the electrolyzer 3 after silver recovery is subjected to ozone treatment, etc., it can be discharged as it is without causing any pollution.

Although the embodiments have described the treatment of photographic processing washing water, the processing and washing water is not limited to this, and can be widely used for the treatment of wastewater containing metals and the like.

As described above, according to the present invention, the washing water is sequentially treated with the medium-pressure type and high-pressure type reverse osmosis membrane devices, and the concentrated solution is electrolytically treated, so that the washing water is treated with both reverse osmosis membrane devices. It is possible to increase the concentration of contained substances by processing to a high concentration, and it is possible to efficiently recover contained substances such as metals contained in low concentrations in washing water, and the permeated water can be reused as washing water.

Furthermore, by treating the photographic processing water, expensive silver can be recovered in a highly pure state, making it possible to reduce the cost of photographic processing materials.

[Brief explanation of drawings]

The drawings are process diagrams of the treatment method according to the present invention. 1 is a medium pressure type reverse osmosis membrane device, 2 is a high pressure type reverse osmosis membrane device, 3 is an electrolysis device, A is washing water, A+, A2 is concentrated liquid, B, 11 is permeated water. Patent applicant: Fumi Nakafuji Agent: Kama 1) Bun 2

Claims (1)

[Claims] The washing water is first treated with a medium-pressure reverse osmosis membrane device, then the concentrated liquid is treated with a high-pressure reverse osmosis membrane device, and the concentrated liquid is electrolytically treated to recover the contained substances. A method for recovering contained substances from washing water.