The potential to restore eutrophic freshwater systems in the UK with economic benefits

Lead Research Organisation: University of Sheffield
Department Name: Chemical & Biological Engineering


The biggest threat to global freshwater systems is pollution, and considering the World's population is expected to top 9 billion in less than 30 years (1), the problems are likely to worsen. Initially, the major losers appear to be wildlife, tourists and industry. However, the problem will extend much further as the demand for clean drinking water increases with population size. Global spatial time-series analyses have already linked wars to freshwater availability (1). The main cause is hugely increased nutrient levels over the last 50 years, thanks to discharges of domestic waste and pollution from agricultural practices and urban development. Algal blooms occur due to increased nutrients (nitrogen, N and phosphorus, P), which subsequently lead to increases in oxygen demanding bacteria that resulting in further detrimental effects to the ecosystem, including fish kills (termed eutrophication). Often perceived as a problem for developing countries, it is now known that over 75% of England's surface freshwater is classified as eutrophic (2) and the costs for managment extend from £75-114m per year (3).
Efforts to control eutrophication include biomanipulation, e.g. adding predatory fish to alter food web structure and increase presence of 'algae-eaters'. There have also been efforts to limit nutrient input. Both methods have had limited success. Removing the algae by harvesting would potentially produce a more immediate impact and could be used as a stand-alone remediation tool or combined with the aforementioned methods. However, harvesting was an energy intensive process, until now.

An award-winning device invented at the University of Sheffield has been shown to be over 99% efficient at harvesting algae and requires very little energy input compared to competitive technologies (4,5). Termed microflotation, it relies on the creation of tiny, non-coalescing, uniform microbubbles. This method of removing the polluting algae would be applied to accelerate remediation of freshwater systems where algal blooms have formed. The recovered algae biomass can then be used as a resource for a variety of applications and this presents the 'hidden' economic benefits with this remediation method.
Algae are highly diverse, single- or multi-cellular organisms comprised of mostly lipids, protein, and carbohydrates. Lipid content can each up to 80% and these can be readily converted into bio-diesel, a fuel type that can easily integrate into our current energy-use infrastructure. Although cyanobacteria (blue-green algae) have lower lipid levels (15-20%), these too can be converted to biodiesel. The production of fuel here can be used to offset the costs of harvesting and remediation. Algae are also a rich source of protein which can be used for animal or fish feed. The nutrient content (P and N) means recovered algae can also be used a fertiliser and at the same time, condition agricultural soil which has deteriorated due to generations of cultivation use.

In summary, there are arrays of exciting uses for recovered algae from polluting environments. And although tremendous amounts of data on algae in our water systems exist, the numbers have not been collated and translated to quantify the concepts described. This catalyst grant aims to analyse this data. It also aims to assemble a multi-skilled team to look at the impact on the natural environment, landowners, farmers, the public, lake protection groups and tourists. It also aims to draw in expertise from biofuel process engineers. The notion of recovering resources from waste represents an ecological engineering approach to system design, and these concepts will be used to engage students in a local school, widening impact of the research and inspiring next generation engineers and scientists.

1.Levy, M., et al., June 21-23, 2005.
2.JNCC Report, 2001.
3.Pretty, J. N., et al., 2003, 37, 201-208.
4.Hanotu, J., et al., 2011.
5.Zimmerman, W. B., et al., 2011, 16, 350-356.

Planned Impact

The catalyst grant will be used to collate existing data on eutrophic freshwater systems in the UK to select sites for pilot-scale algal harvesting. It will also have the major objective of expanding the current team of partners by adding specific cross-disciplinary expertise. This team will construct a proposal for the next stage of funding and the research carried out here is intended to have significant impact for the present and future and is described below.

Over 75% of surface water in the UK is now classified as eutrophic (1) and management costs are estimated to be £75-114 million per year (2). The major impact of this study is to provide a cheaper, faster and more effective remediation tool through microflotation technology (3). Larger lakes suffering from eutrophication include Lake Windermere and Loch Leven, both used for fishing and popular with tourists. The restoration efficiency in terms of lake remediation will be evaluated in the main grant stage.

Chinese academic and industrial groups have shown significant interest in the technology for remediating algal bloom affected lakes (see Support Letter from project partner, Professor Hsu) and are planning to set up a demonstration plant to remediate Lake Dianchi of algae/cyanobacteria. The main motivation is to restore the lake water to overcome the huge water shortage which is threatening the country's economic growth. Although more of a transient issue in the UK, initial interest from UK water companies (United Utilities PLC, Anglian Water, Yorkshire Water) has been shown (personal communication) and particularly where incidences of algal blooms is increasing as well as customer complaints about water odour and taste quality.

Costs are a major factor in remediation strategies and the relatively low energy requirement of microflotation provides a distinct advantage, but perhaps more so, the recovered biomass (resource) has the potential to offset expenses. Algal biomass can be a source of protein for fish/animal feed, a soil conditioner for 'repairing' overused agricultural soils, fertiliser (phosphorus and nitrogen) as well as lipids for biodiesel conversion. Therefore impacts on agriculture, fisheries, livestock farmers and the fuel industry are predicted. The production of high value products e.g. nutraceuticals, phyocyanin pigments, will also impact the biotechnology industry.

Although the focus of the research is environmental, the interdisciplinary subject areas involved means national and international research in ecology, biofuels, engineering, environmental and social sciences will benefit from the research objectives and methodology.

Society would benefit from the increased availability of drinking water (China) and an alternative to fertile-soil sourced terrestrial biofuels will also benefit many countries where food supply has been impacted (Malaysia). The technology and environmental modelling will also impact countries where algal blooms are causing health problems e.g. toxic blooms in Lake Eerie, USA, or problems for the fishing industry.

From a UK perspective, this study demonstrates UK commitment for developing engineering technology that can be applied to fix 'broken' ecosystems. Developing the technology with associated environmental response information in the UK also means intellectual property of the process can be exported to other countries where restoration or algal harvesting for biofuel generation is the goal.

Personal to the applicant, the research will impact career development by presenting the opportunity to develop the field of ecological engineering, a research area that will have major impact on environmental sustainability for future generations.

1. JNCC Report, Peterborough, 2001.
2. Pretty, J. N., et al., Env Sci Tech 2003, 37, 201-208.
3. Hanotu, J., et al., Biotech Bioeng 2011.


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Description This was a travel grant looking to build a network of expertise around lake remediating of use of polluting biomass as a resource. We discovered that polluting environmental algae are a potential feedstock for the bio-based economy. I visited polluted sites in China with the equivalent of their environment agency. Also attended conferences in San Diego and Toronto and met with Ontario Ministry of the Environment. We also worked with a local inner city farm in sheffield producing material for school children o understand that waste causes pollution but there are potential resources in this waste. Brought together a very highly qualified advisory board team for the grant:
Helen Proffitt (C&RT) Site monitoring
Malcolm Bailey (L2E) phosphorus recovery, access to industry contacts for application of resource
David Blythe (Sundrop fuels) Application of resource for biofuels, downstream processing of algae for fuels
Charles Harper (Vision-Five) Human nutrition contact, Africa contact, mega-project for long term
Shane Pugh (ProJen) Anaerobic digestion application
Sian Davies (EA) - Policy, site sampling (responsive and reactive)
Mark Jones (Severn Trent) Polluted water reservoirs
Helen Pickett (Severn Trent) Polluted water reservoirs
Michael Chipps (Thames Water) Polluted water reservoirs
Linda Lawton (RGU) HABs, toxins, high value products also
Gang Pan Flocculation, scaling-up, ecological impacts, Lake Taihu and China contacts,
John Day Strain selections and cultivation
Kenneth Hsu China contacts, lake Dianchi
KTN ESKTN Lis Broom knowledge exchange, impact delivery.

We have since proven the technology at 50 L scale

The work was published in Biology journal in a special issue.

We will demonstrate this technology for a new grant funded by DASA (Minister of Defence) as part of their initiative to decarbonise defence (£300K for 12 months).

I am also lead editor for a special issue of Water journal : "Algae Management and Resource Recovery in Eutrophic Water Systems" (April 2020).
Exploitation Route The network and knowledge that has been built will be used to apply for further funding (Horizon 2020 and EPSRC).
Sectors Agriculture, Food and Drink,Energy,Environment,Manufacturing, including Industrial Biotechology

Description 1. Teaching material for school children (Heeley City farm, Sheffield) 2. BBC Energy Day (Manchester)- engagement with public
First Year Of Impact 2015
Sector Education,Energy,Environment
Impact Types Societal

Description NERC Innovation Award
Amount £125,000 (GBP)
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 04/2017 
End 04/2018