Where does arsenic in water come from?

Arsenic is a contaminant commonly found in raw water sources across Canada. It occurs naturally in rocks and soil, and released from industrial and agricultural pollution. Once released, arsenic remains in the environment for a long time, and eventually settles to ground and eventually into surface and ground water. High arsenic levels in private wells may come from certain arsenic containing fertilizers used in the past or industrial waste. It may also indicate improper well construction or overuse of chemical fertilizers or herbicides in the past.

What does arsenic do to the body?

Although used in beauty treatments in the past, the science is in – exposure to arsenic has negative effects on our health.

Long-term exposure to low levels of arsenic can lead to diabetes, higher rates of cancer, vascular disease, lung disease, heart disease, and skin lesions. It has also been associated with developmental effects and neurotoxicity. Exposure to very high levels of arsenic can lead to abdominal and muscular pain, diarrhea and vomiting, skin rash, and numbness.

On January 1, 2018, the province of Ontario reduced the limit of arsenic in drinking water from 0.025 mg/L to 0.010 mg/L, which is in line with the Guidelines for Canadian Drinking Water Quality Maximum Allowable Concentration (MAC) of 0.010 mg/L.

In many communities, the amount of arsenic in their well water can be as much as 1,500 times the allowable amount.

How do you remove arsenic from your drinking water?

Typically, when water quality is very poor, communities will be put on a boil-water advisory, meaning they must boil all water prior to consuming it. Unfortunately, boiling your water will not remove arsenic. Because some of the water evaporates during the boiling process, the arsenic concentrations can increase slightly as the water is boiled. At the treatment level, even chlorine disinfection will not remove arsenic.

For millions of years, the environment has been cleaning up after us. Bacteria have been purifying our soil, air, and water by decomposing or recycling contaminants. Today, scientists have discovered a way to harness this natural biological treatment process to remove arsenic from water.

Biological Filtration can remove arsenic from water

Biological Water Filtration is the process by which naturally occurring bacteria are employed in large numbers to purify water through natural metabolic processes. To remove arsenic from raw water, biological filtration is typically combined with membrane filtration in a process known as Integrated Biological Reverse Osmosis Membrane (IBROM) filtration.

In the Sapphire IBROM (SIBROM) process, raw surface water enters the treatment plant and flows directly into a series of biofiltration tanks. These biofiltration tanks contain Filtralite®, a ceramic media that provides a large surface area to house the desired bacteria. The high porosity of Filtralite® offers a larger surface area than other media such as sand, which provides more space for bacteria to attach to. As water flows through the tanks, the bacteria find a suitable home and attach to the pores of the Filtralite®.

Close-up of sand used in some biofiltration tanks.

Close-up of Filtralite used in Sapphire Water’s biofiltration tanks.

As contaminants such as arsenic flow through the tanks, the bacteria remove them. To be biologically removed from the raw water, contaminants must be either nutrients or energy sources for the bacteria employed. Some contaminants are consumed by the bacteria, some remain within the biomass, and others are transformed into compounds that can be easily removed by membrane filtration. Essentially, the contaminants become nutrients or energy sources for the bacteria.

As the bacteria consume the contaminants, they begin to reproduce and form a biofilm. Within the biofiltration tanks, conditions are optimized to improve the health and growth of the desired biofilm populations. The biofilm increases the efficiency of the water purification process, which occurs at a rate 10,000 times faster than in nature!

The bacteria can oxidize contaminants such as iron, manganese, arsenic, ammonium, and hydrogen sulphide. Depending on contaminants present in the water, different bacteria populations can be cultivated to focus on removing certain contaminants.

SIBROM – A PRoven Method

Sapphire Water has installed over 20 IBROM systems across Western Canada. In early 2018, we revisited a few of our older sites to check on how well they are still working. After up to 15 years in operation, the systems are still effectively removing arsenic to well below the Guidelines for Canadian Drinking Water Quality.

LocationArsenic in Raw Water (µg/L)Arsenic after Biofiltration (µg/L)Arsenic after SIBROM (µg/L)
Muskeg Lake12.250.280.00
Saulteaux11.350.350.00
George Gordon50.672.20.00
Kahkewistahaw20.3311.330.00

Is biological filtration the right solution for me?

At Sapphire Water, each water treatment system we design is based on raw water quality data. While the IBROM process is very effective at removing a number of troublesome contaminants, it is not effective on every raw water source. To find out exactly what type of water treatment system can most efficiently remove the contaminants you are dealing with, contact Sapphire Water today. We will review your raw water quality data and recommend a smart solution.

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