JPS6023871B2 - How to remove arsenic in water - Google Patents

Description

[Detailed Description of the Invention] The gist of the present invention is a method for removing arsenic present in water by omitting iron salt injection and coagulation-sedimentation operations and achieving the objective by furnace overtreatment. It is something.

Deep well water, surface water from steel mines, etc. may contain arsenic, but conventionally, to remove it, iron salts with an arsenic content of about 20% are injected together with sulfuric acid. The arsenic was adsorbed onto the iron flocs by coagulation and sedimentation near neutrality, and then removed through a furnace filtration operation.

For this reason, not only is the coagulation-sedimentation operation cumbersome, but also a large amount of settled sludge containing arsenic is produced, which is difficult to dispose of, and it also requires a large installation area for the settling equipment. . This invention heat-treats ferric hydroxide to form an iron catalyst coating on the surface of Romura particles, and filters raw water containing arsenic at a pH value near neutrality through this furnace material. This paper proposes a method of adsorbing and removing arsenic using a catalyst coating and regenerating furnace materials whose removal ability has decreased due to arsenic adsorption.

Next, the present invention will be explained with reference to examples.

First, to create the furnace material, select the core material particles such as furnace sand, immerse them in a Baume 42 degree ferric chloride solution, mix well, and attach the liquid to the particles. After this, soda ash (in powder form) is further sprinkled into this liquid and allowed to float.

At that time, carbon dioxide gas was invented, and the pH was raised to 8 to produce ferric hydroxide, which was then attached to the Romura particles, taken out, and heated at 300 to 400°C for about 1 hour. By carrying out the treatment, a furnace material whose surface of the furnace material particles is coated with an iron catalyst film is produced. This is filled into a furnace tank with an internal capacity of about 125 m2 to a height of 10% to form a furnace bed. Example 1 Water from a well in a volcanic area was pumped 10 times per hour for testing, and the quality of the water was found to be
7.0 Total alkalinity 9 & feed ammonia nitrogen Trace iron 0.3 Blood arsenic 0. It was Hanfu.

In this case, there is a small amount of dissolved iron in the raw water, so in order to remove this as well, a compressor is used to send approximately the same amount of air as the amount of treated water, and after electrical operation,
As a result of furnace filtration at a furnace overspeed of 2 days, treated water with the following water quality was obtained.

Treated water chamber pH value 7.3 iron
There was a trace of 0.0 Atsushi arsenic.

Example 2 The raw water used in Example 1 contained some iron, so the water sample was tested by adding 0.6 liters of arsenic to the tap water, but the arsenic was removed.

Raw water Treated water pH value 7.0
70 Total alkalinity 43.0
43.1 Trace of iron Trace of arsenic
0.6 ppm The furnace material whose arsenic adsorption has reached saturation can be used repeatedly by passing a caustic soda solution of about 1 to 2% to desorb and regenerate the adsorbed arsenic.

Since the present invention can be carried out as described above, it is particularly useful in facilities located in mountainous areas, where a large area of flat land is limited to a small area.

Claims (1)

[Claims] 1. A ferric hydroxide film is formed on the surface of the filter medium particles, and this ferric hydroxide film is heat-treated to obtain a filter medium with an iron catalyst film formed thereon. Arsenic-containing water is filtered in a neutral region, and the arsenic in the water is adsorbed and removed by the iron catalyst coating, and arsenic is removed using an alkaline solution for filter media whose arsenic removal ability has decreased due to the adsorption of arsenic to the iron catalyst coating. A method for removing arsenic in water, which is characterized by desorbing arsenic and regenerating a filter medium.