Purification of polluted water(As)⑥

Removing arsenic from groundwater without spoiling the water quality unique to the area

Emergence of a problem

A customer who was promoting the effective use of groundwater resources contacted our company. The customer wanted to sell local specialty products using groundwater with water quality unique to the area.

Diagnosis

It is very difficult to remove only arsenic without spoiling the water quality unique to an area.
In addition, the customer had the following requirements:

・The smaller the arsenic treatment equipment, the better, because the production system already occupies the most of the site, including the manufacturing processes such as sterilization and bottling.
・It would be best if systemization and automation is performed by arranging the steps in a continuous process from arsenic removal to bottling.

Validation

First, we conducted validation tests using water from the site.
Before treatment, arsenic concentration was at least 10 times greater than the standard and pH was greater than 9, indicating that the water was not well suited for arsenic adsorption. In such a severe condition, however, CAMZ showed high adsorption performance right from the initial stage of inflow.

Planning

We calculated the per unit cost of treating the contaminated water, which proved to be within the budget of the client.
However, a problem arose in that the pH of the contaminated water decreased slightly during the initial stage, and the original quality of the water was lost. Therefore, we changed the specifications of CAMZ and a pH buffering function was added. A series of experiments was again performed for the new product spec

Solution to the problem

As a result, there was almost no change in pH in the treated water, and we could reduce arsenic below the standard. After the laboratory tests were over, on-site tests started. The extent of the tests was close to that of the actual treatment.
The prior laboratory validation played an adequate role. At the construction site, the client, satisfied with the result, confirmed the adequate performance of the treatment equipment and decided to adopt the system.

Comments from person in charge

While the results were satisfactory for the client, AMEC’s service did not end here.
In this type of uniquely difficult treatment, it is quite possible that some issues may arise in the period from the setup to the stabilized state of the system.
Therefore, we monitored arsenic concentration using our analyzer until treatment became really stable and systematized. We considered the installation to be complete only when we visually confirmed that arsenic concentration was strictly below the standard.
Since then, we continuously take orders for CAMZ for water supplies and the treatment is smoothly performed. Unique and difficult treatment is the area where AMEC can impact the most.