A new effluent treatment facility proposed to handle wastewater from a Northern Pulp paper mill in Abercrombie Point, Pictou County, Nova Scotia, is under fire from environmentalists for its plan to have an open system for managing effluent from its bleached kraft pulp mill, meaning that its effluent stream cannot be recycled in the process.
Local fishermen concerned about fish and ecosystem health over effluent entering the Northumberland Strait, have been calling for the province to only approve a treatment facility with a closed-loop system contained completely on land, something Northern Pulp has deemed impossible based on its current bleaching process. According to its website, Northern Pulp uses a five-step bleaching process “where chlorine dioxide, caustic, hydrogen peroxide and oxygen are used to produce a white product,” known as an elemental chlorine free, or ECF, process.
The mill’s new plan is to build a treatment facility to handle some 75,000 m3 of wastewater daily, using an activated sludge treatment system that would aerate and settle the effluent into a large tank on the mill’s property. A pipe running along the floor of Pictou Harbour to the outflow area would use a defuser system to release the effluent in smaller intervals, the company says. Montreal-based consulting firm KSH Solutions Inc. undertook a study to investigate the best location to release the treated effluent.
Parties concerned over the new treatment plant’s potential environmental impact, however, point to a 2007 study into the Northumberland Strait ecosystem by consulting firm AMEC Earth & Environmental, which found that pulp and paper wastewater has a high organic load even when it does receive treatment.
Northern Pulp’s mill at Abercrombie Point in Pictou County is a northern bleached softwood kraft mill that produces some 280,000 tonnes annually of pulp, primarily for export, in the form of tissue, towel and toilet paper, along with writing and photocopy paper.
In the 2017 book, Biological Wastewater Treatment and Resource Recovery, co-author María Noel Cabrera explores what makes kraft pulping the primary choice for so many producers: (1) all wooden materials including low-quality wood can be used as raw material; (2) superior fibre strength of pulp compared to other chemical pulping methods; (3) simpler chemical and energy recovery process; (4) scale of economy for kraft methods prevents competition, and (5) low environmental risks in modern mills.
Cabrera adds that, printing, writing and tissue papers require the pulp to be bleached because it removes the excess lignin and chromophores to produce a “white” pulp.
According to a 2016 Alliance for Environmental Technology report, Trends in World Bleached Chemical Pulp Production: 1990-2005, about 95% of all bleached kraft pulp is made using chlorine dioxide in ECF bleaching sequences.
The proposed effluent treatment facility would replace Pictou County’s controversial Boat Harbour treatment facility owned by the Nova Scotia government and leased to Northern Pulp. The facility has processed Northern Pulp’s effluent for some 50 years, but after a pipeline break, was essentially ordered by the province in 2015 to shut its doors by 2020.
At the bottom of the 140-hectare wastewater lagoon for Boat Harbour are contaminants such as zinc, cadmium, mercury and small amounts of organic pollutants like dioxins and furans. The area will be drained and dredged in a pilot project over the next year, as part of a cleanup estimated to cost some $133 million. In May 2017, the province awarded a $6.7 million cleanup contract to consulting firm GHD.
An environmental application for the new effluent treatment plant isn’t expected until spring 2018. The province has decided the new effluent treatment facility will be subject to a Class 1 environmental assessment, which gives the public 30 days to comment once the project is formally registered.