Sewage treatment in Nigeria’s oilfields is failing, increasing the risk of health problems

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People need both clean, safe water and sustainable energy. This means that both resources must be properly managed. But when it comes to the oil and gas industries, there is a problem.

The water that comes out of the ground with oil and gas during oil and gas exploration and production operations is anything but clean.

Oil well structure.

This wastewater, called “produced water”, is often heavily contaminated with salt, oil and grease, as well as potentially hazardous compounds. Some are linked to lung, skin and bladder cancer in men. These compounds can also harm or kill aquatic life.

Thus, producing energy compromises another key element of human and environmental health: water. That won’t change anytime soon. The Produced Water Society, made up of oil and gas professionals focused on water quality, predicts a doubling of the volumes of water produced worldwide over the next ten years.

Adequate wastewater treatment systems are essential to ensure that produced water causes less harm. Proper treatment means the water can be recycled and reused for irrigation, livestock and other industries. That way it won’t be wasted entirely and humans will be much safer.

There are worldwide standards for such systems. But in oil-rich countries in sub-Saharan Africa – like Nigeria – there is little or no adherence to these standards. Studies also show that most treatment systems are tailor-made for the removal of a few families of compounds, in order to achieve the specific treatment objectives of each production site in that region.

In recent research, we studied samples of produced water from an oilfield in Warri, in the Niger Delta region of Nigeria. Samples were examined before and after treatment. Our findings were troubling: hazardous compounds were present at levels far higher than allowed by global standards. The processing process was not robust enough to filter everything.

Damage caused

The Niger Delta region produces about 2 million barrels (320,000 cubic meters) of oil per day and has historically accounted for more than 75% of Nigeria’s export earnings. Together, oil and natural gas extraction accounts for 97% of Nigeria’s foreign exchange earnings, 80% of annual government revenue and 70% of budgetary expenditure.

A map of the Nigerian Niger Delta showing some oil fields and pipelines.

But despite the fact that the oil industry has contributed significantly to the prosperity of the country, the producing regions have suffered serious environmental damage. The people who live there have been subjected to incalculable hardship due to oil pollution, environmental degradation, destruction of aquatic life and other negative activities resulting from the extraction and processing unhealthy oilfield waste.

A number of studies have reported various effects of exposure to heavy metals and organic pollutants from produced water discharges. There have been numerous anecdotal reports of health complications attributed to oil and gas operations in this region.

Most reservoirs in the Niger Delta oilfields are at a mature stage of their productive life. This means they tend to produce less oil and more water. Thus, they could release more toxic contaminants into the environment, causing more ecological damage.

There are no regulatory guidelines to ensure that an increase in produced water does not lead to additional environmental and health risks. There is also very little data available on the quality of existing produced water. Without this type of information, it is impossible to scientifically assess the risks and potentially negative effects of the water produced in the region. This is what motivated our research.

Worrying findings

We sampled raw and treated produced water from an onshore operational production facility located in Warri, Delta State in accordance with environmental guidelines and standards for petroleum industries in Nigeria. Next, we analyzed the levels of heavy metals, organic compounds and aromatic compounds in the water.

Comparison of the concentration with allowable discharge standards showed that the produced water contained several different contaminants with varying concentrations before and after treatment due to inadequate treatment by the treatment plant.

A disturbing finding was that phenol releases were four times the limit set globally. Phenols are aromatic compounds that act as carcinogens in the human body; even at low concentrations, they can damage red blood cells and the liver. They are also potentially deadly to aquatic creatures.

Heavy metals like iron and nickel were also present in quantities well above the allowed global release limits. This poses a serious threat to the aquatic environment and agricultural resources, which in turn affects the livelihoods of people in the Niger Delta region.

Additional findings indicate that the treatment technology focused primarily on a single group of hazardous components and was specific to each production site.

Operational discharges from the oil field remain a public concern as contaminants continue to flow into the sea, creeks and farmland from numerous widely dispersed sources.

The solution in the Niger Delta region could be to apply integrated water treatment processes that treat a variety of pollutants.

Environmental agencies should work together, as they do in the North Sea and the Gulf of Mexico, to ensure that the water produced in Nigeria is properly managed.

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