If fish die, the test fails
Experts offer insight on proposed design of plan for effluent into Northumberland Strait
There’s a test that’s common when it comes to examining the acute toxicity of effluent.
You stick trout in 100 per cent effluent and see if they survive in it for 96 hours. If the fish live and show no sign of dramatic health change, it meets the standard. If they die, it fails.
But when it comes to the complexities of how much damage pulp effluent does on a longterm basis, the answers may be less black and white, say experts The News spoke with.
In an effort to address the concerns expressed by fishermen and others about the impact that effluent released into the Northumberland Strait could have regarding a proposed new treatment system for Northern Pulp, The News reached out to two scientists who are experts in the field of environmental monitoring as well as the engineer hired to design the replacement treatment facility.
Dr. Michael van den Heuvel is a professor at UPEI and Canada Research chair in watershed ecological integrity. As part of his work, he studies the effects of agriculture and chemical use on freshwater and coastal environments and for the past 30 year he has studied the impact of pulp mill effluent.
Dr. Michelle Gray is an assistant professor at the University of New Brunswick where she teaches environment and ecosystem management. Among her areas of interest is environmental monitoring.
Both said there are two common side effects that scientists have seen when it comes to bleached kraft pulp effluent. The first is that it causes a degree of nutrient enrichment that can cause fish and marine life to grow larger.
Gray explained that the nutrients going into the water cause more food for the bugs, making them grow bigger, meaning more for the fish to eat so that means the fish grow larger.
But nutrient enrichment can lead to more environmental problems such as depleted oxygen levels near the ocean floor because it causes more algae growth, says van den Heuvel.
He said that since lobster on the sea floor this is where they could be impacted.
Stantec is the company hired to do a receiving waters study that looked at nitrogen and phosphorus, the two common nutrients found in pulp effluent. According to its research, these nutrients will be at essentially the same level that is currently in the water within two metres of the proposed diffusing pipe.
Other areas that affect oxygen levels are chemical oxygen demand and biochemical oxygen demand. Both of these can cause low levels of oxygen in the water. Those would also be essentially the same as existing levels within 100 metres of the diffuser.
Van den Heuvel predicts the amount of nutrients released from the effluent would be small in comparison to other causes of nutrient enrichment. For example, he said the Northumberland Strait is already affected by nutrients leaked into the water from Prince Edward Island where farmers often use nitrogen-based fertilizers.
While the effect of the mill shouldn’t be discounted because it could cause an additional strain on an already overloaded system, van den Heuvel said it wouldn’t be a major contributor.
The other side effect is an impact on reproduction with fish near waters impacted by pulp effluent often having smaller gonads, said Gray. Studies also indicate that fish exposed to pulp effluent mature later.
To what degree those effects are seen varies widely depending on the quality and quantity of the effluent. In the past, effluent was untreated and people mistakenly believed nature would take care of it.
Van den Heuvel said that standards in Canada require effluent to be a certain quality before it is released and those standards have gotten more stringent since 1992 when the federal government introduced the Pulp and Paper Effluent Regulations to protect fish, fish habitat, and human health. Mills are now required to conduct environmental effects monitoring (EEM) every three years to identify the impact on fish and fish habitat.
Salinity, amount of salt in the water, was also tested in the receiving water study. Projections show it would meet with the existing levels of salinity within 100 metres.
Van den Heuvel believes Northern Pulp’s proposed system would meet modern industry standards and would be an improvement over the current system that releases treated effluent into Boat Harbour where it flows into the Northumberland Strait.
But having a proper effluent treatment system isn’t enough.
“Treatment alone is not everything. It’s how it’s operated,” van den Heuvel said.
A system that isn’t properly run could cause more contaminated effluent to be released, which is why constant testing is needed.
Overall, van den Heuvel said that the proposed treatment system and the release of the nutrients isn’t cause for huge concern, but is something that will need to be scrutinized and will require the monitoring for environmental effects that is already required by law.
Gray agreed it would be an improvement over what’s currently in place.
“If they’re improving the treatment, it’s probably in the long term a plus,” she said.
Guy Martin, lead project engineer with KSH Solutions, is the man responsible for the design of the new effluent treatment plant and says it is designed according to industry best practice.
A key element that is going to be added to the Northern Pulp plant around the same time that the effluent treatment facility is replaced is a $70 million oxygen delignification system.
The system, which consists of oxygen reactors and wash presses, will be used in the process before the existing bleaching stages. The benefit is that it will result in the use of less bleaching chemicals to whiten the pulp in the existing bleach plant. It will reduce chlorine dioxide bleaching chemicals by 30-40 per cent as well as the amount of organic material by an equivalent amount. It is also expected to reduce the effluent colour and reduce wood losses.
Another benefit is the fact that the pipe is located farther out into the Northumberland Strait.
While the location of the proposed effluent discharge has been the primary concern from fishermen, it was chosen based on projections that show it is the best place within a reasonable distance for the effluent to quickly mix with water instead of hanging around the coast in higher concentrations.
A common misconception that people have, says Northern Pulp’s technical manager Terri Fraser, is that the treated effluent will be something new flowing into the Northumberland Strait.
In reality it’s already been flowing there after leaving Boat Harbour and this new process will be an improvement that meets and exceeds the environmental standards.