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.


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).


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.

Algae and Motor Neuron Disease: Diatoms complicate the picture

30 January 2014

Diatoms - a new source of BMAA (Photo: Bill Harding)

Diatoms – a new source of BMAA (Photo: Bill Harding)

Until now we have believed that the production of beta-methyl amino alanine (BMAA), thought to be implicated with neurodegenerative brain disorders (ALS-PDC), was limited to the blue-green algae (Cyanobacteria). Since 2004 we have learnt that all species of cyanobacteria, or almost all, produce this toxic amino acid.  This finding, backed by some early research, suggested that environmental exposure to lakes or reservoirs containing cyanobacteria, or drinking water derived therefrom, may be a cause for this debilitating complex of diseases.

That was until this month (January 2014).

Beta-methyl amino alanine

Beta-methyl amino alanine

A group of researchers have demonstrated that various species of diatoms, the most prolific group of algae on the planet, also produce BMAA.  If the production of BMAA is more widely spread across the diatom genera then this finding significantly alters the level of risk of exposure thereto.  The work also demonstrates that higher organisms, eukaryotes, can produce BMAA.

Jiang and co-authors conclude, inter alia,  that:

Taken together, the data reported here give a clear answer supported by solid evidence that BMAA is not exclusively produced by cyanobacteria. As diatoms are a major bloom- forming phytoplankton in aquatic environments, the impact of this discovery suggests new bioaccumulation routes and that the risk of human exposure may have increased tremendously. 

(search this blog for several other articles on BMAA)

Milking the unwitting: excessive cost of diatom analyses

23 October 2013

Diatoma vulgaris (Photo: Bill Harding)

Diatoma vulgaris (Photo: Bill Harding)

As co-developer of the South African Diatom Protocol, the so-called DAP, it has come to my attention that some service providers are charging exorbitantly high prices for processing a single sample – something that should cost somewhere around R1000.00 per sample ex VAT.  While ‘let the buyer beware’ always prevails, don’t get conned, do your homework.  While there are very few specialists who can perform these analyses, this is no reason to overcharge.

Another issue is the proficiency of the service providers – diatom identification to species is a complex business.  If you are at all unsure, insist that the lab you choose sends a set number of samples (duplicates) to a known and proficient analyst for quality control purposes – or – make duplicates of your samples and send some of them to a second lab yourself.  Finally, insist that duplicates of your processed samples be lodged with the South African National Diatom Collection – currently housed at North West University’s Potchefstroom campus.  By so doing, anyone can check on the accuracy of what was found at any point in the future.

Trust me, I’m an expert …. sage advice for aquatic scientists to heed

7 February 2013

Author of this post, Martyn Kelly (Source: Bowburn Consultancy website)

A few years ago, I was involved in a project financed by the UK water industry.  The project brief was to look at the benefits of phosphorus removal on British rivers. Huge sums of money had been spent on this in recent years but there has been little obvious ecological change as a result.   One of the questions we were asked to address is whether the standards for phosphorus concentrations in UK rivers were appropriate.  However, as the project went on a second agenda came to the fore: how can we (the water industry) “sell” the idea of low phosphorus concentrations to our customers?

Diatoms were at the centre of this mini-storm: they had a strong relationship with the nutrient gradient in UK rivers and were consequently used to establish the values for the standards.  But the water industry had put their finger on a key problem: the word “diatoms” meant nothing to the general public.  They could walk beside a river, look over a bridge, see water plants, even the occasional trout.  The river did not necessarily look polluted and, for the most part, no longer had the faint odour of putrefaction hanging over it as in the past.  You might draw the line at swimming in it but, equally, you could see no particular reason why you were being asked to pay £20 per year more in order that the water company could install more sophisticated wastewater treatment facilities.  Read more »

Cyanobacteria destroying Hawaiian coral reefs, diatoms as predictors of environmental collapse – and other stories

26 November 2012

The impact of blue-green algae (cyanobacteria) on coral reefs north of the Hawaiian island of Kauai has been pronounced as being of ‘epidemic’ proportions.  Possible impacts on other biota associated with the corals have also been noticed.  No indication as yet as to which genus of cyanobacterium is responsible. Read more »

Diatoms used to track climate change response in world’s northernmost lake

13 October 2012

Lake Kaffeklubben Sø (Photo: D. Mazzucchi)

Diatoms provide an extremely powerful means of analysing historical conditions in lakes. The use of this group of algae has recently shown that climate change alone is responsible for marked alterations in the world’s northernmost lake,  Kaffeklubben Sø, in Greenland.  The lake has evidenced a recent reappearance of diatoms, indicating a change from perennial ice conditions under which cyanobacteria are the typical sole dominants.  The lake is now warming up after 2400 years of permanent ice cover. Read more »

Student realizes value of diatoms for water monitoring: wins trip to Sweden

8 October 2012

Sam Cook meets Princess Victoria of Sweden (Source: This is Dorset)

A Dorset school pupil recently won a trip to Sweden – after winning a competition in which he used diatoms for assessing the quality of water (clever kid).  This bodes well for UK education if this level of insight is promoted within school-level curricula.

Sam Cook represented the UK at the international Stockholm Junior Water Prize and was congratulated on his win by Crown Princess Victoria of Sweden. 

Sam’s project investigated populations of diatoms in freshwater habitats and their importance as indicators of water quality.

Diatoms are single-celled organisms invisible to the naked eye but very important because they can photosynthesise like plants and produce useful energy from sunlight in order to survive.

Sam worked with Bournemouth University academics Dr Genoveva Esteban and Dr Andréa Galotti from the School of Applied Sciences to win the Tomorrow’s Water competition organised by the Chartered Institution of Water and Environmental Management (CIWEM).

Béla Cholnoky: A history. Part 3

30 September 2012

This post continues the history of the Father of South African diatomology. This text was originally prepared by Dr Keve T Kiss of the Danube Research Station, Hungarian Academy of Sciences, in 1999, the 100th anniversary of the birth of Béla Cholnoky. This is the third of three parts.
Read more »

Béla Cholnoky: A history. Part 2

30 September 2012

This post continues the history of the Father of South African diatomology. This text was originally prepared by Dr Keve T Kiss of the Danube Research Station, Hungarian Academy of Sciences, in 1999, the 100th anniversary of the birth of Béla Cholnoky. This is the second of three parts.
Read more »

Béla Cholnoky: A history. Part 1

30 September 2012

This post continues the history of the Father of South African diatomology. This text was originally prepared by Dr Keve T Kiss of the Danube Research Station, Hungarian Academy of Sciences, in 1999, the 100th anniversary of the birth of Béla Cholnoky. The text is presented in three parts.
Read more »