Understanding the 3 Types of Arsenic Removal Used for Wastewater
With the onset of the Industrial Revolution and the development of internal combustion engines and new manufacturing technologies, fresh water became an essential raw material not only for production, but for cooling purposes in manufacturing processes. However, when fresh water is used in an industrial process, it creates industrial wastewater composed of a variety of chemicals and other raw materials, and as the number of industries grew, so did the amount of pollutants released into environments.
The need for controlling and removing chemicals, metals, and other industrial waste became a priority to prevent further pollution of the environment. In 2001, the U.S. Environmental Protection Agency released its Chemical Contaminant Rules that regulated 65 contaminants in three groups: inorganic, volatile organic, and synthetic organic contaminants. The standard for arsenic levels was lowered from 50 parts per billion to 10 parts per billion for water systems.
Arsenic is a metalloid commonly found in the earth’s crust and in the human body. It is naturally present in aquifers across the U.S. and around the world. Arsenic has no odor and no taste. Within safe limits, it is not generally harmful. But if arsenic levels reach the maximum contaminant level, or MCL, in drinking water, it can cause circulatory damage, heart disease, seizures, cancer, and an array of other maladies.
There are a variety of arsenic removal methods available on the market using chemical, physical, and biological processes, with some using a combination of those processes. Choosing the best arsenic removal system is based upon flow rates, the concentration levels of arsenic, other co-contaminants present, and site conditions and limitations. Here are three top-rated options.
Adsorption is a surface-based process where gases, liquids or solutes accumulate. In this process, water flow is directed through pressure vessels, where contaminants break their bond with water molecules, and then chemically attach themselves to a filter media. The granular ferric oxide media is able to reduce up to 99 percent of arsenic present.
This process has numerous benefits, including:
- Requires no harmful chemicals be added to treatment water
- Removes other heavy metals, including antimony and lead
- Used adsorption media can be discarded as non-hazardous waste.
In this arsenic removal system, an iron salt such as ferric chloride acts as a coagulant and is used to pretreat water that has arsenic contamination. It is a widely regarded and cost-effective method of arsenic removal due to its limited footprint and the fact that it generates no hazardous waste.
Additional benefits include:
- Coagulation/Filtration systems have a longer service life, approximately 10 years
- Handles a wide variety of incoming water quality
- Recyclable backwash water
This type of arsenic filtration system is a standalone system used to improve overall water quality and was specifically designed to treat wellheads. In addition to effectively removing arsenic, this system will also remove iron and manganese, which are commonly found in drinking and household water supplies. It can also be used in secondary containment systems.
Other benefits are:
- Coagulants and permanganate additives are not required.
- Long service life of around 10 years
- High performance for a variety of incoming water qualities
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