A Cleaner Tomorrow with Biochar Today

TRANSCRIPT

For the last two years, Seymour Lake has had a blue green algae problem. This makes the water unsafe throughout certain times of the year. I was wondering, "How we can stop this from happening?" I talked to a hydrologist who said that the main cause of our algae blooms is run-off from septic fields and the two main nutrients that cause algae blooms are phosphate and nitrate. I was wondering if I can devise a filter to stop the phosphates and nitrates from even entering the fields so that they can’t run-off into the lake. I heard that biochar was effective at reducing nitrates and phosphates so I thought that I would test homemade biochar, three different sizes of professionally made biochar against sand and gravel, which are two filters you would find naturally in a septic field.

My findings have led me to believe that the most effective septic tank effluent filter would be a combination of sand and fine biochar.

Can biochar be used to create an effective septic system filter? I created this project to find out. The answer is important for the people in my community because I live on Seymour Lake where, for the last two years, the lake has experienced significant cyanotoxin (blue green algae) blooms. When the blooms happen, the water is unsafe to drink and sometimes it is even unsafe to touch. Contact with cyanotoxins can lead to skin and eye irritation, diarrhea, vomiting, headaches, and some potentially fatal conditions such as liver or kidney damage (Health Canada, 2024). According to the Province of British Columbia, the third greatest contributing factor to algae blooms in lakes in Canada is runoff from home septic systems.

Septic effluent is rich in nutrients like nitrogen and phosphorus. In lakes, high levels of phosphorus act like fertilizer, causing rapid growth of algae and weeds. As the algae dies and decomposes, it consumes the oxygen in the water, which increases the likelihood that a fish kill will occur. I created this project because I want to make a filter that people can add to their septic systems so that we can decrease the amount pollutants coming into the lake from this source, thereby lowering the risk or more blue green algae blooms, but this project has the potential to have a global impact because, worldwide, the occurrence of cyanobacteria blooms is increasing due to eutrophication and climate change (Huisman et al., 2018).

My research for this project took me around B.C. because I travelled to meet with people who are working with biochar to tackle different environmental problems. I began by meeting with Patrick Hudson, a local hydrologist to determine that using biochar as a septic filter would have a positive effect on Seymour Lake. Once I had Patrick's confirmation that I was onto a good idea, I looked at a variety of studies on biochar filtration. There were few studies to be found on the use to biochar as a filter for home septic effluent so I searched out BC experts. I met with Phil Marsh, the owner of Big Bear Biochar; Chris Howard from Whanau Forestry; and Natasha Kuperman from Seed the North. Phil, Chris, and Natasha, who are all experts in the field of biochar.

In this experiment, I compared the effect of 6 filter types (Black Bear biochar >6mm, Black Bear biochar 2-6mm, Black Bear biochar<2mm, homemade biochar, sand, and gravel) on raw septic effluent. My filter types were my independent variables. I repeated the experiment 8 times for each filter type.

I measured 9 water quality parameters using test strips, a conductivity tester, a phosphorus test, and a photometer. Specifically, I tested for changes in the levels of phosphates, nitrates, pH, carbonates, conductivity, clarity, calcium, hardness, and alkalinity - these were my dependent variables.

My testing was divided into 2 groups. One was called "Lake Water" because I used the part of my home system that draws water from our well beside the lake. The second group was called "Cistern Water" because I switched over to using our home cistern water system. I used the two different types of water because those are the two ways that people of Seymour Lake get water.

Fine Black Bear biochar (<2mm) and sand were the two types of filters that were most effective at filtering out the two leading causes of algae blooms: phosphate and nitrate. All other filter types showed little to no change in phosphate level in the septic effluent. The phosphate in the sand showed an average decrease of 29ppm in the lake water effluent test batch and an average decrease of 10ppm in the cistern water effluent test group. An Anova data analysis showed P-values of 1.93x10-7 in the lake water effluent test group and a P-Value of 0.016 in the cistern water test group, which indicates that there is a statistically significant difference in both test groups. In the Lake Water test group, Tukey HSD test revealed that the sand and fine Black Bear Biochar <2mm were the two filters that lowered the phosphate level in a statistically significant way. The p-value of the fine Black Bear Biochar <2mm and sand were both 0.001. The Scheffe, Bonferroni, and Holm tests all confirmed these findings. In the Cistern water test group, the Tukey HSD revealed that sand was the only filter that lowered the phosphate in a statistically significant way.

The filters’ ability to reduce nitrates is important because, according to the Petitcodiac Watershed Alliance, phosphates are the primary cause of algae blooms in lakes and nitrates are the second leading nutrient cause. The nitrate level showed a clear statistically significant decrease with fine Black Bear biochar (<2mm) in the cistern group. In the lake water group an Anova analysis revealed that there was a p-value of 0.07, which is close, but does not meet the less than 5% threshold which is needed to determine that a finding is statistically significant. The Bonferroni test confirmed that the finding was insignificant, but the Holm test (which compares only the raw effluent to the fine Black Bear biochar (<2mm) considered the ability of the fine Black Bear biochar (<2mm) to lower the nitrate level in the effluent to be significant. The Bonferroni test is more conservative than the Holm test so this makes sense. In the lake water test group, the decrease caused by the fine Black Bear biochar (<2mm) filter showed a decrease of 85.7% which was far greater than any other filter and in the cistern water test batch it decreased by 96.3%.  No other filter type reduced the nitrate level in a statistically significant way.

The fine Black Bear biochar (<2mm) filter caused the carbonate to rise to 240ppm, making it the only treatment to make a statistically significant change.

The fine Black Bear biochar (<2mm) and homemade biochar were the only two filter types that raised the pH and conductivity in a statistically significant way.

None of the filter types changed the conductivity, calcium, hardness, or alkalinity in a statistically significant way.

This experiment proves that a home septic tank effluent filter that uses both sand and fine Black Bear biochar (<2mm) has the potential to effectively filter out phosphates and nitrates, thereby lowering the risk of harmful algae blooms on Seymour Lake.

Fine Black Bear biochar and sand were effective at reducing phosphate levels; all other filters showed little to no change. Sand lowered the phosphate level in a statistically significant way in both test groups. The fine Black Bear Biochar <2mm lowered the phosphate level in both test groups, but only did so in a statistically significant way in the lake water test group. The filters’ ability to reduce phosphates and nitrates is important because, according to the Petitcodiac Watershed Alliance, phosphates are the primary cause of algae blooms in lakes and nitrates are the second leading nutrient cause.

The fine Black Bear biochar (<2mm) was the only filter that lowered the nitrate level in a statistically significant way and it did so in both test groups. Thus, the fine Black Bear biochar (<2mm) is a vital part of an effective home septic tank filter system.

The fine Black Bear biochar (<2mm) raised the carbonate level, which makes sense since it biochar is carbon. It also raised the pH level. This was likely because the fine biochar was small enough to slip through the mesh covering the bottle. The filter bag that I make will need to be made of very fine mesh to mitigate this problem.

My next step is to continue work on my prototype for a Black Bear fine biochar/sand septic tank filter for my home. I am also going to working on creating filters to put into the drainage pipes cross the road and drain into Seymour Lake and a farmer who owns a dairy farm beside another local lake is interested in having me make one for his drainage ditch as well. I will also be getting to work on obtaining the permissions that I need before I can put the filters in any of those places.

Thanks to Natasha Kuperman, from Seed the North for the tour of her incredible biochar seed coating operation and lab in the Kispiox Valley. Thanks to Phil Marsh from Big Bear Biochar for spending the morning with me at his biochar resource and development facility in McBride, sharing his passion for creating new technologies that use biochar to tackle environment problems. Thanks to Phil for donating the Black Bear biochar that I used for this project. Thanks to Chris Howard for talking to me about how he used biochar in his tree planting company and for donating the Homemade biochar that I used in this project. Thanks to hydrologist Patrick Hudson for sharing his thoughts on Seymour Lake. Thanks to Karen Price for teaching me how to use statistics to analyze data in a way that makes me see that statistics are an expression of truth and beauty.

Works Cited

Audet, Sebastian. “Phone Interview with Chris Howard, lead on Forest Waste Biochar Initiative in Smithers, BC.” 14 July 2025.

Audet, Sebastian. “In-person Interview with Natasha Kuperman, Owner of Seed the North, in Kispiox,BC.” 29 June 2025.

Audet, Sebastian. "In-person Interview with Patrick Hudson, hydrologist and property owner on Seymour Lake." May 3, 2025.

Audet, Sebastian. “In-person Interview with Phil Marsh, Owner of Big Bear Biochar in McBride, BC.” 14 July 2025.

Chiasson, A. (2024, May 6). Feeling blue about green – phosphate, nitrate, and cyanobacteria (blue-green algae) blooms. Petitcodiac Watershed Alliance. https://www.petitcodiacwatershed.org/2024/05/06/feeling-blue-about-green-phosphate-nitrate-and-cyanobacteria-blue-green-algae-blooms/

Environmental Protection Agency. (2026, January 22). pH. EPA. https://www.epa.gov/caddis/ph

Environmental Protection Agency. (2026, January 15). The Effect: Dead Zones and Harmful Algae Blooms. EPA. https://www.epa.gov/nutrientpollution/effects-dead-zones-and-harmful-algal-blooms

Muoghalu, Chimdi, et al. “Adsorptive Removal of Organics and Nutrients from Septic Tank Effluent Using Oak Wood Chip Biochar: Kinetic Analysis and Numerical Modeling.” Cleaner Water, Elsevier, 27 Feb. 2025, www.sciencedirect.com/science/article/pii/S2950263225000110#sec0105.

Norris, Brent. “Biochar in the Garden: Pacific Biochar.” Pacific Biochar Benefit Corporation, Pacific Biochar Benefit Corporation, 24 Jan. 2022, pacificbiochar.com/how-to-work-with-biochar/in-the-garden/.

Taylor, Russell. “The Dark Side of Biochar - Modern AG Media.” Modern Ag Media - Publications for Modern Agricultural Industries - From Regen to Agtech, Happiness Digital, 13 Mar. 2025, modern-ag.net/the-dark-side-of-biochar/#:~:text=One%20of%20the%20main%20issues,in%20the%20environments%20mentioned%20above.

Water Rangers. (n.d.). Freshwater Testkit field notepad. Retrieved from https://waterrangers.com/product/testkit-field-notebook/

Images

(2025) [Picture of home septic drain field diagram] [drawing] All Wiring Sketch. https://allwiringsketch.com/septic-drain-field-diagram

Paterson, A. (2026). [Picture of radio image to show the relationship between phosphorus and algae]. Phosphorus, Toxic Algae Blooms, and Septics. BeShore Haliburton. https://www.beshore.ca/science_of_p/

(2026). [Picture of Northern Health Logo].Northern Health Stories.Northern Health. https://stories.northernhealth.ca/media-resources/nh-logo-png-0