Pulp sludge is green gold
Municipalities and industrial water users can turn their wastewater sludge into fertilizer and biogas using Paradigm Environmental Technologies’ MicroSludge green technology.
It began, as Gordon Skene tells it, with a chance meeting in Leeds, England at a soccer club during a water treatment industry conference a few years ago.
Skene is president and CEO of Vancouver-based Paradigm Environmental Technologies Inc., a private clean tech firm with 14 employees and the patent for MicroSludge. Developed by Paradigm’s chief technology officer Ron Stephenson, MicroSludge is a green technology that converts waste sludge – very efficiently, as it turns out – into biogas and fertilizer. Municipalities use it at wastewater treatment plants.
Paradigm was in England to expand its market and make contacts when he met Allan Elliott. He’s a scientist with FP Innovations, a not-for-profit research and development organization with 600 employees across the country, based in Pointe Claire, Que. FP helps develop and implement innovative and safe solutions to improve the global competitiveness of Canada’s forest products industry. In the pulp and paper sector, FP Innovations identifies new product streams by extracting chemicals and energy from forest biomass, or wood fibres.
Could Paradigm help Canadian pulp and paper mills realize economic and environmental benefits using MicroSludge in their anaerobic digestor systems to treat waste-activated sludge (WAS)? Paradigm was encouraged, among other companies, to submit a proposal to participate in a research project helmed by FP Innovations.
The research project in 2008 was designed to find economically viable ways to effectively manage the sludge that’s created during the anaerobic digestion of the pulp mill’s effluent; recapture and recycle nutrients used in the process; reduce the amount of WAS shipped to landfill or for incineration; and capture CO2 and convert it to biogas, a highly marketable commodity. Paradigm’s MicroSludge technology out-performed all the others in the study, says Brian O’Connor, FP Innovations’ program manager, environment.
Anaerobic digestion is not a new technology, even for the pulp and paper industry. Decaying organics are eaten by WAS microbes. As they consume the decaying organics they grow, and they clean up the effluent, making it safe for environmental discharge, but during this process they grow and become a disposal problem.
Paradigm aims to materially reduce the volume of that waste for disposal and convert it into renewable energy.
O’Connor says it used to take 20 to 25 days to get the organics compressed down to methane. That meant you needed a very large tank. “But with MicroSludge that number drops to five to seven days.” FP also found that at five days, four days or even as low as three days, they got more biogas than they got at 20 days. “That makes it more attractive from a cost point of view,” he says.
“That’s very important because if you can reduce digestion time from 20 days to five days, it means the tank is one-quarter the size. That means it’s far less expensive to construct and far less expensive to run,” says Skene.
The system has another advantage. It creates more nitrogen and phosphorous than an anaerobic digestor could without it. “Pulp mills have to add nitrogen and phosphorous to keep these bugs working,” says O’Connor, adding a medium-sized pulp mill would easily spend $500,000 to $600,000 per year – if not up to $1 million – on these two nutrients.
The noteworthy benefit to pulp mills is the whole process used to treat their sludge actually generates nitrogen and phosphorous. “Here you are generating a waste that you can put back into the process to offset your purchases of nitrogen and phosphorous. MicroSludge technology breaks up the cell wall so the sludge is more of a soupy mixture that’s more easily chewed up by the microbes. So you can generate more methane, too,” O’Connor says.
FP Innovations found the methane content actually improved materially from 65% to close to 75%. This biogas can often be used just to replace natural gas that the plant has purchased. Alternatively, a pulp plant could take the biogas, remove the carbon dioxide and other gases from it and create another product that’s at least 98% or 99% methane. “That becomes pipeline-grade or fuel-grade natural gas.”
There’s a developing market for this biomethane gas in many areas of the world including BC and certainly in Southern California, and it’s typically fetching high price rates from buyers looking for “renewable” energy. In Southern California, with a spot price of natural gas of about $4.25 a gigajoule, biomethane is getting between $11 and $13 per gigajoule.
But that’s all theoretical for now. So far MicroSludge has been proven only in FP Innovations’ lab. Yet the potential benefits have attracted the attention of investors keen to see the rejuvenation of Canada’s forest products sector and the development of a Canadian bioenergy sector.
A scaleable pilot project is now underway to test MicroSludge at the Catalyst Paper mill in Crofton, BC. Investors include Natural Resources Canada at $2.5 million; the BC Ministry of Forests, Mines and Resources at $1 million; and a $1.5-million contribution from the BC Bioenergy Network to Elemental Energy Inc., the industrial lead on the project. In-kind contributions of $1.12 million from Elemental, Paradigm, Catalyst and the University of British Columbia bring the total investment to $6.2 million.
The fully automated, transportable demonstration plant at Crofton includes a MicroSludge unit, sludge thickening equipment, anaerobic digesters, and a laboratory. A 15-month demonstration aims to replicate mill operations to measure the operating savings at full scale. Then the unit will be moved to other pulp mills for further trials.
Crofton was selected as host because it’s a large plant, with three operations: paper making, thermal mechanical pulp and a kraft mill that make 1,000 tonnes of market kraft pulp and about 800 tonnes of paper used for telephone directories and newsprint.
“There are not a lot of plants out there that have both pulp and paper,” says Bob Ericksen, Catalyst’s utilities manager at Crofton.
Another important consideration was the Crofton site’s size. Skene says it could be a secondary treatment plant for a community of half-a-million people. The demonstration project is testing just one per cent of the plant’s flow. “This little plant is processing what would be the effluent for about 5,000 people. So, it’s a pretty decent size.”
Catalyst has some environmental cred in its own right. With a 100% recycled fibre mill in Snowflake, Ariz., it’s one of the premier recycled paper operations in North America. It specializes in lighter basis weight papers, an environmentally sound choice because they require fewer resources to make. Catalyst maintains a low carbon footprint by using 86% renewable energy at its BC operations, and it has reduced greenhouse gas emissions by 85% from a 1990 baseline, allowing the company to offer manufactured carbon-neutral specialty papers.
“All of the other technologies we looked at in the past have really been focused on reducing the cost of disposal,” says Ericksen. “This is the first one to hold the promise of being a net energy benefit to the plant. And then reducing our chemical impact is certainly a plus.”
In the past, the need for a very large vessel prevented many plants from installing anaerobic digesters. But Paradigm’s technology uses a vessel that’s one-quarter the size of others, which greatly improves the economics.
Michael Weedon, executive director of the BC Biotechnology Network, a not-for-profit group that invests in bio-energy projects, says what drew his organization’s support for the project was the technology being transportable to at least 13 similar facilities in BC alone. “Across Canada the numbers are even larger. It has fairly broad applications for the pulp and paper industry; not every mill, but the vast majority of them.”
But the technology could be used in other industries as well, says Skene. Meat-packing plants, breweries and distilleries, petrochemical plants, and pharmaceutical plants – all have large wastewater treatment processes.
“This is the first such project in the hard-pressed pulp industry, which has been under pressure the past few years. We hope to introduce something to help them be more competitive, sustain jobs and do it with less of a carbon footprint,” says Weedon. “In the face of higher fuel costs I think you’re going to see a lot more of this type of activity and this sort of thinking. We just need to be better at how we use our resources.”
Almost felled by the mountain pine beetle, the great economic recession, and the drawn-out trade dispute with the US over softwood lumber, the Canadian forest products industry is now optimistic about its role as a “pivotal force in Canada’s efforts to become a clean energy super-power,” according to Avrim Lazar, president and CEO of the Forest Products Association of Canada. The association recently undertook a study, The Future Bio-Pathways Project, which examines renewal options for the industry. It places traditional products, especially lumber and pulp, at the heart of a new green business model.
“If we follow this new model we will be able to produce power on the scale of nine nuclear reactors, enough to meet the energy needs of 2.5 million homes, or one out of every five homes across Canada,” says Lazar.
MicroSludge is one of many projects to come that will contribute to a greener forestry industry as this new era unfolds.
Kim Laudrum is a writer and editor based in Toronto who specializes in sustainability issues. E-mail firstname.lastname@example.org.