Biohavens – the only truly bio-mimicking floating wetland – Case Study #13 – nutrient removal

4 November 2015

The BioHaven range of floating wetlands, also known as floating islands, provides a wide range of wetland aesthetic, habitat and treatment options designed from nature.  DH Environmental Consulting (Pty) Ltd (South Africa) has been partnered with Floating Island International, the designers of the BioHaven range, since 2008.  Over the next while our blog will document some Biohaven case studies.

13. Nutrient Removal with Passive Floating Treatment Wetlands

Project Location: Elayn Hunt Correctional Facility, St. Gabriel, Louisiana, USA

This case study demonstrates the ability of patented BioHaven® floating treatment wetland (FTW) technology to clean water by substantially reducing nutrient levels. At a wastewater facility in Louisiana, BioHavens more than doubled removal rates for chemical oxygen demand (COD), ammonia and phosphate.

Overview

Martin Ecosystems of Baton Rouge, Louisiana, an FII licensee, installed BioHaven floating islands into the Elayn Hunt Correctional Facility oxidation pond in March 2011. The primary objective was to determine whether the islands could remove unwanted nutrients that were periodically creating noncompliance with the facility’s discharge permit. The goal is to have the facility continually achieve and maintain compliance.

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The BioHavens installed at Elayn Hunt are passive islands without aeration and were planted with three types of vegetation. Most of the removal efficiency attributed to islands has been found to be due to biofilm attached to both the plant roots and the island matrix itself.

Table 1 shows concentrations of the three parameters of concern before and after BioHaven installation. “Before” data were taken in January and March 2011, while “after” data are the averages of monthly data from April 2011 through September 2012. It is assumed that the higher nutrient concentrations seen post-FTW were also seen periodically before BioHaven installation.

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After BioHaven installation, the average percentage removal has been 73%, 38% and 29% for COD, ammonia and phosphate, respectively. This is substantially better than without the FTWs (52%, 23% and 9%, respectively). Table 2 shows contaminant removal rates before and after BioHaven installation, along with the net removal rates that can be attributed to the islands.

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The BioHaven removal rates are more than double the previous rates for all three parameters and are substantially higher than those measured in other case studies. Based on these rates, FTWs can be sized to remove a given contaminant load (concentration and flow).

Conclusions

BioHavens have a demonstrated capability to remove excess nutrients such as COD, ammonia and phosphate, along with total suspended solids and other parameters (data not shown). The total cost of this project was much less than other treatment alternatives, demonstrating that FTWs can help public facilities and private industry achieve and maintain compliance in a cost-effective manner. BioHaven technology can enhance existing waterways with the concentrated wetland effect, facilitating compliance with increasingly stringent wastewater nutrient, BOD/COD and TSS criteria.

The Louisiana Department of Environmental Quality provided funding for this project, which is owned and operated by the Louisiana Department of Corrections.

Biohavens – the only truly bio-mimicking floating wetland – Case Study #12 – wastewater treatment

3 November 2015

The BioHaven range of floating wetlands, also known as floating islands, provides a wide range of wetland aesthetic, habitat and treatment options designed from nature.  DH Environmental Consulting (Pty) Ltd (South Africa) has been partnered with Floating Island International, the designers of the BioHaven range, since 2008.  Over the next while our blog will document some Biohaven case studies.

 12. BioHaven® Floating Treatment Wetlands Improving Waste Water Treatment!

Project Location: Harrisonburg, Louisiana

Overview

The Village of Harrisonburg has struggled to meet Louisiana discharge permit regulations for several years due to the ineffective design of their waste water oxidation pond. The design of the system limits their ability to treat their waste water by confining treatment to two-thirds of an acre when their pond is actually 5 acres in size. The entire pond is not being used efficiently and effectively. The discharge parameters of concern have been Total Suspended Solids ( TSS), Ammonia, and Carbonaceous Biochemical Oxygen Demand (CBOD). Due to limited budgets, the Village of Harrisonburg has been unable to correct the system problems.

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Project Cost

Martin Ecosystems assisted the Village of Harrisonburg in applying for and securing $50,000 of Strategic Economic Development Program (SEDAP) funding through the Delta Regional Authority for this project.

System Design

Martin Ecosystems strategically installed BioHaven Floating Treatment Wetlands in front of the influent pipe and against the existing curtains in order to have maximum water flow through the BFTWs. This increases retention time and provides maximum treatment.

Challenges

In May, Martin Ecosystems discovered that nutria were climbing onto the Islands and eating the recently planted Vetiver grass. It appears that the damage is minimal as not all BFTWs have been effected.

Martin Ecosystems has plans to install fencing around the perimeter of the islands in order to keep nutria, turtles, and other wildlife off of the islands until the vegetation has had enough time to establish itself.

Results

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Challenges

In May, Martin Ecosystems discovered that nutria were climbing onto the Islands and eating the recently planted Vetiver grass. It appears that the damage is minimal as not all BFTWs have been effected.

Martin Ecosystems has plans to install fencing around the perimeter of the islands in order to keep nutria, turtles, and other wildlife off of the islands until the vegetation has had enough time to establish itself.

April discharge reports have shown reductions of 30%-50% in all three parameters of concern with two achieving compliance. This is only one month, but is very encouraging.

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Biohavens – the only truly bio-mimicking floating wetland – Case Study #11- Bass benefit

2 November 2015

The BioHaven range of floating wetlands, also known as floating islands, provides a wide range of wetland aesthetic, habitat and treatment options designed from nature.  DH Environmental Consulting (Pty) Ltd (South Africa) has been partnered with Floating Island International, the designers of the BioHaven range, since 2008.  Over the next while our blog will document some Biohaven case studies.

 11. Floating Island Provides Bass Spawning Habitat

Project Location: Elephant Butte, New Mexico USA

The New Mexico Bass Fishing Association’s mission is to enhance bass fishing habitat and opportunities within the state. A subgroup of the association, Kids of the Southwest, undertook a project in 2009 to increase the bass population at Elephant Butte, NM. These youth partnered with the New Mexico Game and Fish Department, marina owners and other local interested parties after discovering a Floating Island International licensee, Floating Islands West, which has developed floating botanical gardens to increase fish and other wildlife habitat, along with providing water quality improvements.

Floating Islands West designed a portable spawning bed for fish that includes a cover and protection for the fry. After Kids of the Southwest arranged for the island purchase, they assembled the island, gathered and transplanted the necessary plants, filled the spawning beds with gravel, and used paddle boats to deploy the island.

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Kids of the Southwest is a Junior Bassmaster Club based in Las Cruces, NM, and is affiliated with Cedar Cove Bass Anglers in Elephant Butte, NM. The group strives to develop life skills in young people while educating them to exercise leadership and support for responsible recreational fishing, and stewardship of aquatic resources.

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Biohavens – the only truly bio-mimicking floating wetland – Case Study #10 – Phosphorus to fish

1 November 2015

The BioHaven range of floating wetlands, also known as floating islands, provides a wide range of wetland aesthetic, habitat and treatment options designed from nature.  DH Environmental Consulting (Pty) Ltd (South Africa) has been partnered with Floating Island International, the designers of the BioHaven range, since 2008.  Over the next while our blog will document some Biohaven case studies.

10. From Phosphorus to Fish: Beneficial Use of Excess nutrients

Project Location: Shepherd, Montana

Fishing can be the primary method for transitioning excess nonpoint source nutrients from water, according to recent studies performed by Floating Island International (FII). This case study summarizes results of FII’s patented floating treatment wetland (FTW) technology and associated lake stewardship to remove nutrients from Fish Fry Lake, a 6.5‐acre lake at FII’s research center, along with producing outstanding fishing opportunities. Nearly all of the phosphorus and nitrogen entering the lake from agricultural runoff is now mitigated through a moderately aggressive fish‐harvesting program. The next goal is to address nutrients accumulated at the lake bottom in organic accretion.

The primary factors transforming Fish Fry Lake from a eutrophic pond to a productive fishery have been:

  • Higher dissolved oxygen (DO) concentrations due to aeration and mixing;
  • Lower overall water temperatures and a greatly expanded livable zone for fish due to aeration and mixing;
  • Introduction of substrate to support periphyton, which provides a food source for fish; and
  • Better penetration of sunlight into the water column from reduced turbidity, which enhances growth of diatom‐based periphyton

The last two factors are directly due to introduction of floating islands, while the first two are derived from features installed with the latest embodiment of floating islands.

Background

As recently as July 2008, Fish Fry Lake was a small pond with low DO concentrations, high summer water temperatures, colorful algae blooms and a small population of wild northern yellow perch. Today it supports crappie, a burgeoning population of perch and possibly the easternmost population of Yellowstone cutthroat trout. This dramatic change was made possible by:

  • Deepening the pond to 28 feet and extending its reach to 6.5 acres;
  • Strategically locating several aerators throughout the lake;
  • Adding and growing 5,200 square feet of FTWs; and
  • Introducing crappie and cutthroat.

The FTWs are a mix of BioHavens® (passive islands) and one LeviathanTM (Figure 1). The Leviathan is a new embodiment of FTW with aeration and forced circulation via an airlift directional diffuser. All islands in Fish Fry Lake, which are constructed of recycled post‐consumer plastic matrix, have been planted with native vegetation.

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Over 4,400 of FII’s floating islands have been launched around the planet over the past decade, with the largest (51,000 square feet) recently installed in New Zealand’s Lake Rotorua. Seven other island projects exceeding 20,000 square feet have been launched in New Zealand, Singapore and the U.S. Over $3 million has been invested in research through FII, the Center for Biofilm Engineering at Montana State University and the National Institute of Water and Atmospheric Research in New Zealand. In combination with these pre‐eminent research centers, FII has compiled a unique database between floating islands and fisheries enhancement.

By biomimicking nature, floating islands provide the “concentrated wetland effect” that transitions nutrients up the food chain. Instead of nutrients short‐circuiting into monocultures of algae, floating islands provide substrate‐‐the enhanced surface area that transitions nutrients from periphyton (the microbial and algae community attached to underwater surfaces) to fish (Figure 2).

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Results

Fish Fry Lake now supports a very productive perch fishery. From June through October 2011, 1,928 perch were harvested from the lake. Experienced fishermen averaged one perch every two minutes, with a typical harvest of 26 lbs/wk. On October 13, 2011, several fishermen caught 166 perch weighing a total of 35 lbs. On March 10, 2012 (shortly after ice‐out), five people caught 161 fish in two hours. Two hundred fish were tagged and introduced to the lake in 2011. Six of these tagged fish were among the 161 fish caught, suggesting that about 5,400 harvestable fish now inhabit the 6.5‐ acre lake. Figure 3 shows a typical perch harvest in 2011.

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In the 2011 study, perch were measured and classified by age, through otolith and scale aging. Perch in Fish Fry Lake were significantly larger than perch in the 95th percentile measured in a study by Jackson and Quist:

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Fish in Fish Fry Lake consume periphyton and organisms generated by nutrients flowing into the lake, from surface water and groundwater, and are not directly fed. In contrast, aquaculture ponds feed fish to maximize productivity. The fish yield measured at Fish Fry Lake was 26 lbs/wk or 4 lbs/acre/wk. Tilapia yield in fertilized freshwater ponds in Indonesia (Hansen et al., 1991) was measured at about 5 kg/ha/day, or 31 lbs/acre/wk. Therefore, fish yield at Fish Fry Lake is 10‐20% of yield in the fertilized ponds. Yield is consistent with the inflow of nutrients, since Fish Fry Lake has about 10% of the nitrogen inflow (0.01 g N/m2/day) as the fertilized ponds in the study.

Phosphorus inflow to Fish Fry Lake is estimated at 0.28 lbs/wk, based on an average concentration of 0.041 mg/L at an estimated flow of 80 gallons per minute. The average phosphorus concentration in perch is 1.0%, based on measurements by FII and other researchers. This means that the average fish harvest of 26 lbs/wk removed 0.26 lbs/wk of phosphorus. Thus, the amount of phosphorus removed via fishing was 0.26/0.28 or 93% over the study period. In a follow‐up study, FII is now tracking whether the total annual phosphorus load can be harvested during 2012.

An experienced fisherman at Fish Fry Lake can catch perch at a rate of one fish every two minutes. For the average fish weighing 0.25 lb, 3.7 hr/wk of fishing time is required to keep up with the incoming phosphorus, and to maintain a healthy waterway (Figure 4). This would require a fish harvest of 110 lbs/mo.

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Water Quality Improvements

During the first 12 months after the lake was filled, water clarity averaged 14 inches via Secchi disk. Introduced substrate, the filter‐like polymer matrix comprising the islands as well as plant roots that grow through the islands and their biofilm‐based periphyton, reduced turbidity significantly. In December 2011, three‐and‐a‐half years after the pond was filled, water clarity exceeded 19 feet. A summary of the water quality improvements is shown in Table 2.

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Similar waterways in the region are typically much more turbid due in part to clay colloids associated with the region’s geomorphology. Another contributing factor to regional waterway turbidity has been phytoplankton blooms associated with nonpoint source nutrient loading of nitrogen and phosphorus.

Biofilm present on the island matrix mechanically removes suspended solids, including colloidals and algae that bond to it. Competition for nutrients provided by biofilm‐ based microbes also reduces the turbidity level associated with algae blooms. Sunlight can then energize additional oxygen and food‐generating diatom‐based periphyton, even at depth.

In addition to the positive effect of sunlight, laminar aeration has also contributed to higher DO levels at depth. In summary, the combination of sunlight and dissolved oxygen at depth has resulted in the natural transition of excess nutrients into fish via periphyton.

Biohavens – the only truly bio-mimicking floating wetland- Case Study #9 – marine applications

31 October 2015

The BioHaven range of floating wetlands, also known as floating islands, provides a wide range of wetland aesthetic, habitat and treatment options designed from nature.  DH Environmental Consulting (Pty) Ltd (South Africa) has been partnered with Floating Island International, the designers of the BioHaven range, since 2008.  Over the next while our blog will document some Biohaven case studies.

9. Marine Environment Case Study

Project Location: Elfin Cove Area, Southeast Alaska, USA

This case study demonstrates the capabilities of patented BioHaven® technology to function in a harsh marine environment. The purpose of this application, which was the first seawater evaluation of the BioHaven floating treatment wetland (FTW) from Floating Island International (FII), was to study plant survival, biota colonization and island durability under marine conditions.

Two BioHaven islands were launched—a large module at Port Althorp (the “Port Althorp” FTW) and a small module in a private setting near Elfin Cove (the “Hobbit Hole” FTW). The larger island was moored to a piling at one end and chained to a mooring block at the other; the smaller island was tethered to an existing dock with nylon line. The Port Althorp FTW was constructed as a dock, with Trex decking applied to the top surface.

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Results

  •  The BioHaven matrix was not adversely impacted by exposure to seawater and Alaska wintertime temperatures/wave action
  • Numerous marine biota, including mollusks, starfish, worms and filter feeders such as anemone, populated the BioHavens. Several species of kelp also took up residence.
  • Perennial plants survived the winter and reemerged in the spring.
  • Both BioHavens remained buoyant under snow loads up to five feet.
  • The BioHavens remained intact with up to two-foot waves. The Port Althorp BioHaven was towed five miles in the summer of 2009 to the Hobbit Hole location to replace an existing section of dock. It is still in use and performing well.
  • Boats were able to tie and moor to the BioHaven FTW.

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Biohavens – the only truly bio-mimicking floating wetland – Case Study #8 – Floating islands outperform constructed wetlands

30 October 2015

The BioHaven range of floating wetlands, also known as floating islands, provides a wide range of wetland aesthetic, habitat and treatment options designed from nature.  DH Environmental Consulting (Pty) Ltd (South Africa) has been partnered with Floating Island International, the designers of the BioHaven range, since 2008.  Over the next while our blog will document some Biohaven case studies.

8. Floating Islands Outperform Constructed Wetlands

Project Location: Rehberg Ranch Residential Subdivision, Billings, Montana USA and McLean’s Pit Landfill, Greymouth, New Zealand

Promising pilot studies with BioHaven® floating islands or floating treatment wetlands (FTWs) show superior results when compared to constructed wetlands. In comparing municipal wastewater and landfill leachate treated with both systems, BioHavens had higher removal rates and percent removal for ammonia, total nitrogen, biochemical oxygen demand (BOD) and total suspended solids (TSS).

FTW for Municipal Wastewater

Located on the outskirts of Billings, Montana (pop. 120,000), the Rehberg Ranch residential subdivision (pop. 560) was built beyond the reach of the city’s municipal sewer system. Developers constructed an aerated lagoon wastewater treatment system engineered and designed to meet US EPA secondary standards for BOD and TSS.

In November 2009 Floating Island International (FII), with funding from the City of Billings and the Montana Board of Research and Commercialization Technology, installed an experimental FTW design in one of the subdivision’s two aerated lagoons. The City implemented a rigorous monitoring regime to measure efficacy of the FTW system in comparison to the control lagoon with no FTW. Both lagoons received the same wastewater.

FTW for Landfill Leachate

Landfill leachate is a problematic water stream in New Zealand and worldwide. Greymouth is a South Island town of approximately 3,000 people. The town identified a need for improved treatment of its municipal landfill leachate, which is a dilute stream because of the area’s extremely high annual rainfall (3.5 m or 140 inches).

In Stage 1 of the project, FII licensee Waterclean Technologies constructed and installed 288 m2 (3100 ft2) of BioHavens to cover approximately 20% of the lagoon surface in half of the lagoons, in November 2009. The wetland plants being utilized are Carex virgata and Cyperus ustulatus.

Constructed Wetlands

Constructed wetlands with horizontal sub-surface flow have been used for wastewater treatment for more than 30 years. Most wetlands have been designed to treat municipal or domestic wastewater, but are now also used to treat wastewaters such as landfill leachate, industrial waters and agricultural wastewater. In a 2009 review article in the journal “Ecological Engineering,” data from several hundred constructed wetlands for municipal and domestic wastewaters, and from approximately ten landfill leachate installations, were summarized (Vymazal, J., 2009, The Use of Constructed Wetlands with Horizontal Sub-Surface Flow for Various Types of Wastewater, Ecological Engineering 35, 1-170).

Results

Table 1 shows the performance of the Rehberg Ranch FTW compared to the average performance of several hundred constructed wetlands for municipal/domestic wastewater as consolidated in the Vymazal study. The percent removals of BOD, total nitrogen and ammonia were much higher for the FTW. Due to its smaller size (Table 1), the load removed was much higher in the FTW for these parameters and TSS.

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Table 2 shows performance of the BioHaven at McLean’s Pit compared to the average performance of approximately ten constructed wetlands for landfill leachate. The percent removals of BOD, total nitrogen and TSS were much higher for the FTW, and the load removed was much higher in the FTW for BOD and total nitrogen.

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Screen Shot 2015-10-23 at 11.01.32Compared to the small size required for FTWs (see above), the large area typically required for constructed wetlands is illustrated in the aerial photo below:

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Biohavens – the only truly bio-mimicking floating wetland – Case Study #6 – wildlife habitat

28 October 2015

The BioHaven range of floating wetlands, also known as floating islands, provides a wide range of wetland aesthetic, habitat and treatment options designed from nature.  DH Environmental Consulting (Pty) Ltd (South Africa) has been partnered with Floating Island International, the designers of the BioHaven range, since 2008.  Over the next while our blog will document some Biohaven case studies.

6. BioHaven® FTWs Remove Algae and Create Wildlife Habitat

Project Location: Barrington, Illinois

This case study summarizes results of Floating Island International’s patented BioHaven® floating treatment wetland (FTW) technology to mitigate runoff from urban and rural developments. The Lake County Stormwater Management Commission named this project “Best Management Practice (BMP) Project of the Year”.

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Overview

As part of a negotiated settlement by Citizens for Conservation (CFC) with a subdivision developer, several ponds were constructed to capture stormwater run-off. This water then flows through restored wetlands for discharge into Flint Creek. To address high algae levels, several BioHaven® floating islands were built on-shore and “launched” into the ponds.

Prior to 2006, the two stormwater ponds were completely covered with algae during the growing season. Algae reduction through use of hay bales as a Best Management Practice was unsuccessful. The CFC’s goal was to transform these water bodies, located only 30 miles from downtown Chicago, into vibrant, productive wetlands in an urban setting, hopefully through the use of floating islands.

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Results

The large pond is about 1.5 acres and the small pond is about 0.25 acre. Each pond contains floating islands.

Dissolved oxygen (DO) levels greatly increased after island launching and subsequent plant growth, resulting in much lower algae levels and lower turbidity. CFC members note that most algae have disappeared and discharged water is much cleaner than before island installation. As the first photo demonstrates, plant growth on the islands developed quickly, a visual manifestation of the nutrient and metals removal occurring in and beneath the islands. Turbidity and DO levels were monitored but data transfer has been hampered by volunteer turnover.

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In addition to native wetland plant habitat, the islands also provide a key riparian environment in this quasi-urban setting. Sandhill cranes were noted nesting on the islands in 2007, just over a year after they were launched. The cranes have successfully fledged young in two of the past three years, even though coyotes and other predators are now abundant in the area.

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The executive director of the Lake County Stormwater Management Commission wrote the following testimonial:

On behalf of the Lake County Stormwater Management Commission (LCSMC) board and staff, congratulations on being awarded the “BMP Project of the Year.”

Your efforts to improve the Flint Creek watershed is a history rich in caring for the environment, for those that live in the watershed and for the generations to come… In our eyes, the Floating Islands Project is yet another example of your vision for the watershed that ties in water quality, habitat and technology to create what is believed to be the first use of “BioHaven” technology in Illinois that can be replicated in other parts of Flint Creek and in Lake County watersheds.

Flint Creek stakeholders … are grateful for the work of Citizens for Conservation. Congratulations and thank you for your dedication to water quality improvements, and taking the lead on grassroots efforts that benefit us all.

Michael Warner, Executive Director, LCSMC

Biohavens – the only truly bio-mimicking floating wetland – Case Study #5 – Bisphenol removal

27 October 2015

The BioHaven range of floating wetlands, also known as floating islands, provides a wide range of wetland aesthetic, habitat and treatment options designed from nature.  DH Environmental Consulting (Pty) Ltd (South Africa) has been partnered with Floating Island International, the designers of the BioHaven range, since 2008.  Over the next while our blog will document some Biohaven case studies.

5. Floating Treatment Wetlands May Remove BPA

Project Location: Test Tanks, Billings, Montana USA

This case study suggests that BioHaven floating island technology can reduce concentrations of the endocrine disruptor Bisphenol-A (BPA) in water. It appears likely that a microbial biofilm growing on and around the island in this study degraded BPA below the initial concentration of 50 ng/L.

Overview

One of the most common estrogen mimickers is known as Bisphenol-A (BPA), a chemical commonly used in production of plastics and epoxy resins. BPA has been directly linked to gender ambiguity in fish. BPA is one of many man-made chemicals that have been recently detected in the nation’s waterways through use of more sensitive analytical techniques. Along with pharmaceuticals, concentrations of estrogens and their mimickers have been detected well above background levels.

Previous studies showed that BioHaven floating treatment wetlands (FTWs) will remove contaminants such as nitrogen, phosphorus, biochemical oxygen demand (BOD), total suspended solids (TSS) and propylene glycol from water. The focus of this test was to determine whether a BioHaven could reduce levels of BPA, as measured by gill flares exhibited by male betta (beta) fish.

Background

In 2008, two Billings West High School students, along with their academic advisor, began studying the behavioral effects of estrogen sulfate and BPA. Their initial data showed that either chemical reduced aggression levels of male Betta splendens, the Siamese fighting fish commonly known as betta fish. The focus of their last test was to investigate the effects BPA has on the aggression levels of male bettas in the presence of a BioHaven.

Two small BioHavens (approximately 2 feet long x 1 feet wide x 6 inches thick) were planted with potting soil and a wildflower mix. After the FTWs were grown for two weeks, BPA was added to water at a concentration of 50 ng/L. The following test conditions were run:

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Condition 4 was the actual experiment with BPA in the presence of the FTW, with the other three conditions serving as controls. To measure gill flaring, male betta fish (three per condition) were exposed to a mirror for two minutes while gill flares were tallied. It was beyond the scope and budget of the test to directly monitor BPA concentrations.

Results

Condition 1, the first of the three control groups, did not contain BPA or an FTW. This group exhibited an average of 20 gill flares in two minutes, which is consistent with data collected in an earlier study. Therefore, 20 gill flares was the baseline.

Condition 2 contained BPA with no FTW. Results from this test agreed with the previous year’s data, in that gill flares were reduced from 20 to an average of 6. A standard t-test showed that this was a statistically significant difference at a 95% confidence level. In condition 3, with an FTW but no BPA, male bettas exhibited an average of 19 gill flares per two-minute time trial, which is statistically equivalent to the baseline.

The experimental group (condition 4) exhibited significantly fewer gill flares after one day of exposure to BPA, similar to condition 2. After three days, however, the male betta aggression level (as measured by gill flaring) steadily rose until reaching the baseline of approximately 20 flares in two minutes. The experiment was repeated a week later, with very similar results.

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Conclusions

This test confirmed earlier findings that the presence of BPA in water at a concentration of 50 ng/L significantly reduces aggression levels of male betta fish, as measured by the number of gill flares. The test also showed, in two replicates, that aggression levels increased to normal in the presence of a BioHaven floating treatment wetland (FTW). One possible explanation is that roots of the plants growing on the BioHaven absorbed BPA, thereby removing it from the aquatic system. A more likely explanation, based on previous FTW experience, is that the microbial biofilm growing in and around the BioHaven degraded the BPA. This could be confirmed by repeating the experiment and chemically analyzing for BPA.

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Biohavens – the only truly bio-mimicking floating wetland – Case Study #4 – Bird habitat

26 October 2015

The BioHaven range of floating wetlands, also known as floating islands, provides a wide range of wetland aesthetic, habitat and treatment options designed from nature.  DH Environmental Consulting (Pty) Ltd (South Africa) has been partnered with Floating Island International, the designers of the BioHaven range, since 2008.  Over the next while our blog will document some Biohaven case studies.

4. Floating Islands Enhance Salmonid Recovery by Creating Alternative Nesting Habitat for Caspian Terns

Project Location: Dutchy Lake, Oregon and Sheepy Lake, California USA

Bird monitoring results have demonstrated that floating islands can provide secure nesting habitat for Caspian terns and other bird species in areas where no natural nesting habitat exists, and where construction of rock islands is not feasible. Two recent projects have enhanced recovery of salmonids (salmon and steelhead) by encouraging relocation of Caspian terns to areas far from where juvenile salmonids migrate. Floating islands offer a potentially effective habitat alternative to traditional rock islands if the water depth is greater than 18 inches, or if the water body cannot be drained for construction of a traditional island.

Background:

In 2008, the U.S. Army Corps of Engineers (USACE) began implementing the actions outlined in the January 2005 Final Environmental Impact Statement for “Caspian Tern Management to Reduce Predation of Juvenile Salmonids in the Columbia River Estuary.” This management plan, which was developed jointly by the USACE, U.S. Fish and Wildlife Service, and NOAA Fisheries, seeks to redistribute Caspian terns from the Columbia River estuary to alternative colony sites in interior Oregon, interior California and the San Francisco Bay area by 2015.

The goal of the plan is to reduce Caspian tern predation on migrating juvenile salmonids in the Columbia River estuary, and thereby enhance recovery of salmonid stocks from throughout the Columbia River basin. Thirteen of 20 evolutionarily significant units of Columbia River salmonids are currently listed as either threatened or endangered under the U.S. Endangered Species Act.

Caspian terns require unvegetated, sandy habitat that is proximate to water and isolated from predators, i.e., they require islands upon which to nest. Normal USACE practice for habitat enhancement is to construct a nesting island by simply piling rock, gravel and sand into an existing body of water that has been drained or drawn down until it is higher than the water surface when the water body is at full pool. This labor‐intensive process requires huge trucks and heavy equipment, disturbs the water body, benthic zone and shoreline, and does not guarantee that the new island will remain isolated from land (if the water level drops) or above water (if the water level rises). Floating Habitat Islands suffer none of these limitations since they float on the surface of the water, but they are typically more expensive.

The USACE teamed with the U.S. Geological Survey, Oregon State University (OSU), Oregon Department of Fish and Wildlife, Real Time Research, U.S. Fish and Wildlife Service, Floating Island International (FII), and Floating Islands West (FIW) in an innovative program to create “floating tern islands.” Two large floating islands have been installed, one in Interior Oregon and the other in the Upper Klamath Basin, by a contractor, Just Buckets Inc., in conjunction with FII and FIW.

Dutchy Lake – Oregon:

In February 2009, FII and Just Buckets built and launched a 22,000‐sq. ft. floating island at Dutchy Lake, which is in the Summer Lake Wildlife Area in Oregon. The island is 19 inches thick and has a flat stone perimeter. The interior of the island contains six inches of crushed stone, pumice and rhyolite mix. This island also has a floating observation blind attached to one corner of the island, as well as audio playback systems (broadcasting Caspian tern calls) and tern decoys.

Bird Research Northwest’s monitoring team characterized the 2009 nesting season on the Dutchy Lake floating islands as a great success, with eight nesting pairs having hatched 13 young terns, of which eight succeeded in fledging. In 2010, no Caspian terns initiated nests on the Dutchy Lake floating island, although they and other water birds frequently used it as a roost site. Instead, Caspian terns in 2010 nested on the rock core island in the East Link Impoundment at Summer Lake Wildlife Area, which is approximately five miles away.

Sheepy Lake – California:

In February 2010, FIW and Just Buckets built and launched a 40,000‐sq. ft. floating island at Sheepy Lake in Lower Klamath National Wildlife Refuge. The island thickness was 22 inches, with sloped ends of paving stone to enable access to the water by pre‐fledged young terns. One long side and half of one end included a planting area designed as a wind break. Bullrush, red‐twigged dogwood and sand willows were planted in the seven‐foot‐wide perimeter areas.

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Figure 1 shows the number of Caspian terns colonizing the new floating island during the 2010 nesting season. This innovative island has been a tremendous success, as the Sheepy Lake tern colony appears to have had the highest nesting success of any Caspian tern colony in the region during 2010.

The island interior contains seven inches of the same crushed stone, pumice, and rhyolite mix used at Dutchy Lake. An extensive anchoring system was connected to all four corners. A floating observation blind was attached to one corner of the island, with two audio playback systems, and 250 Caspian tern decoys were placed on the island.

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2010 was a very poor nesting season for Caspian terns in interior Oregon and northeastern California. Small numbers of breeding terns and low nesting success was widespread, but the Sheepy Lake floating island colony was a notable exception.

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Biohavens – the only truly bio-mimicking floating wetland – Case Study #3 – Bioswales

25 October 2015

The BioHaven range of floating wetlands, also known as floating islands, provides a wide range of wetland aesthetic, habitat and treatment options designed from nature.  DH Environmental Consulting (Pty) Ltd (South Africa) has been partnered with Floating Island International, the designers of the BioHaven range, since 2008.  Over the next while our blog will document some Biohaven case studies.

3. Elevated BioSwales for Water Quality and Habitat Enhancement

Project Location: Shepherd, Montana

Contaminated surface runoff from stormwater events is a major potential cause of water pollution in urban, residential and agricultural settings around the world. Elevated treatment swales (Elevated BioSwalesTM) containing vegetation are one promising method for treating stormwater and agricultural runoff.

In August 2008, three Elevated BioSwales were installed in irrigation ditches at the Shepherd Research Center located northeast of Shepherd, Montana. The Center is the international headquarters of Floating Island International, Inc., a research and development business focused on developing technologies for water quality improvement and habitat enhancement. The bioswales were durable, successfully grew and maintained vegetation, reduced turbidity and performed well during high-water events. A typical bioswale is depicted in Figure 1.

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These Elevated BioSwales contain a recycled polymer-based nonwoven filter matrix that provides about 250 square feet of surface area per cubic foot of matrix. Numerous independent studies have confirmed that this matrix represents an effective substrate for biofilm development, and that in combination with circulation, it can be highly effective at transitioning agricultural-based nutrients and urban contaminants out of water and into local food webs. A Shepherd bioswale before and after installation is shown in Figures 2 and 3.

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Elevated BioSwales at Shepherd were designed to form-fit into irrigation ditches of irregular dimensions. They were monitored for several criteria:

  •   Plant success
  •   Durability and weathering
  •   Performance in flood or high-water events
  •   Turbidity and nutrient reduction
  •   Laboratory determination of hydraulic conductivity.

Plant Success

The Elevated BioSwales were overlaid with Kentucky bluegrass sod to provide immediate protection of the plastic matrix from potentially-degrading ultraviolet light, and were then sprinkled with a mix of native grass seed. Native plants (both from seeds and neighboring “volunteer” plants) quickly took over the bioswales. The bedding material in each bioswale’s planting pockets included hydrophilic foam to hold and wick up water to the sod. Two elevated bioswales were installed in a shallow ditch (18” deep) with only periodic water flow, while the third bioswale was located in a deeper ditch (40” deep). Even the shallow ditch, with periodic flow and precipitation, provided enough water for native plants to survive and thrive in Montana’s dry climate over two years. While hydrophilic-based bedding soil can lift water up to 16 inches, consistent water flow may be required in deeper ditches until plant roots are established.

Durability and Weathering

The bioswales were inspected weekly and required no maintenance. Although some matrix was exposed on the upstream side, it did not degrade significantly during the three-year study. The bioswales continue to be used as bridges by people and wildlife.

Performance in High-Water Events

Elevated BioSwales essentially serve as a “leaky dam” by reducing water velocity and mediating storm events. During high water flow, up to a six-inch difference in water level was noted between the upstream and downstream sides. Water was high enough at times to create soggy conditions at the top of the swale, with no detrimental effects. The system’s ability to reduce water flow rate suggests that it can function as an erosion mediation tool.

Turbidity

Turbidity in the ditches preceding the Elevated BioSwales is variable. When turbidity is high, the bioswales substantially reduce it visually, although the effect has not yet been quantified. It is also anticipated that the efficacy for water quality improvement will be proportional to bioswale length, although data have not yet been collected to demonstrate this. The stormwater treatment process is illustrated in Figure 4.

Parameters such as nitrogen and phosphorus were not monitored but it is expected that they will be reduced in similar proportions. Nutrients are present primarily as dissolved constituents, so elevated bioswales will mitigate them in the same manner as floating islands—conversion into bacterial and plant biomass, along with biotransformation of ammonia and nitrate to nitrogen gas (Figure 4).

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Hydraulic Conductivity

Controlled bench-scale tests were conducted in the Shepherd Research Laboratory using constant-head permeameters in order to determine hydraulic conductivity values for the Elevated BioSwale matrix. In a first series of tests, new matrix (without biofilm growth) was tested with clean water under constant flowrate conditions. In a second series of tests, matrix was subjected to a constant recirculation flow for a two-week period using water high in dissolved nutrients and native bacteria, which resulted in a rich growth of biofilm on the matrix fibers. Results of these tests indicated an average hydraulic conductivity of the new matrix of 0.042 ft/sec and an average conductivity of the biofilm-coated matrix of 0.007 ft/sec. These values can be used to estimate water backup and required channel cross-sectional area for different flow scenarios using Elevated BioSwales.