A Scalable Bio-based Solution to Eliminate Cyanotoxins in Drinking Water

One of the greatest global challenges facing human-kind is access to reliable safe drinking water. This is particularly acute in developing countries where human activities significantly impact water quality. While the Earth is known as the blue planet with 71% of the surface covered by water, most of this is seawater and not suitable for human consumption, industrial applications or agriculture, all of which are essential for socioeconomic development. Only a tiny proportion of the Earth's water is freshwater (~3%) but <1% is available for use. This small amount of available water is under strain and a recent UN report predicted that 5 billion people could suffer water shortage by 2050 as a consequence of climate change, increased demand and pollution. One serious threat to water quality and public health is the occurrence of blooms of cyanobacteria (blue-green algae) as a result of nutrient pollution (nitrate and phosphate) from industry, agriculture and domestic waste. Cyanobacteria produce dangerous toxins (cyanotoxins) causing acute and chronic symptoms leading to fatalities, most notably in Caruaru, Brazil with over 71 fatalities and cancer humans, including primary liver cancer documented in China. In addition, there is concern that these toxins may be responsible for rising cases of chronic kidney disease of unknown origin (CKDu) in Asian countries such as Sri Lanka where cyanotoxins can be perennial. These toxins are very stable and not removed by typical drinking water treatment processes or even boiling, therefore an innovative, simple and sustainable solutions are needed for their removal. Professor Pathmalal Manage, (University of Sri Jayewardenepura, Sri Lanka) along with Dr Christine Edwards & Professor Linda Lawton (both of the Aberdeen Industrial Biotechnology Institute, RGU) have demonstrated the effectiveness of microbial populations for safe elimination of these toxins from water. They have found that natural microbial consortia, even with no previous exposure to specific toxins, contain active biodegraders. Degradation is promiscuous meaning that, for example, exposure to peptides will enrich the microbiome with consortia members with the ability to eliminate microcystins (heptapeptide cyanotoxins). Furthermore, there is evidence that some naturally occurring microbes can actively kill toxin-producing species of cyanobacteria. This project aims to harness and stimulate this microbial capability, naturally immobilised on biochar to provide a scalable water treatment system that can be used at all magnitudes from rural wells through to municipal water treatment facilities in Sri Lanka. The biochar will be developed to provide a low cost support for optimized microbiomes and will be produced locally from biogenic waste (e.g. coconut husks/shells, rice straw) exploiting the global expertise of Dr Ondrej Masek, of the UK Biochar Research Centre (UEd). Ensuring that water is rendered free from harmful concentrations of cyanotoxins a simple field kit will be developed using antibodies that react to multiple classes toxins, led by Dr Katrina Campbell (QUB) with world leading expertise on development of innovative diagnostics for a wide range of toxins. On completion of the research, the project will provide low cost, simple, scalable, nature-based water treatment systems for elimination of commonly occurring toxins from cyanobacteria. In addition, local communities will benefit from better use of agricultural waste to produce biochar which can be useful for a wide range of applications such as fertiliser with the added bonus of gas generation as it is produced providing an alternative energy source. This water treatment solution will have wide application in many developing countries and will contribute to achieving UN SG6 while embracing the philosophy of the United Nations World Water Development Report which emphasises the benefits of 'Nature-Based Solutions for Water.'

Freshwater is not usually limiting in Sri Lanka, however ~50% of the country depend on single-household dug wells. Despite preconceptions that well water has low risk of contamination, we have recently found the presence of cyanobacteria cells (>1600 cells/ml) and potent cyanotoxins, microcystins (MCs) and cylindrospermopsin (CYN) at levels up to 7 ug/L. This is particularly concerning as these toxins has been detected throughout the year and this may result is serious chronic illness. MCs are a large family of cyclic heptapeptide toxins varying in structure depending on the amino acids present (e.g. MC-LR contains leucine [L] and arginine [R] in the two variable positions), and other minor modifications such as methylation or demethylation. They are potent inhibitors of protein phosphates, enzymes which are essential for cellular regulation, hence they are classed as tumour promotors. CYN on the other hand has only a few analogues but is also of significant concern in chronic illness since it inhibit protein synthesis causing organ damage. In recent years, there has been significant concern in Sri Lanka related to the increased occurrence of chronic kidney disease (CKDu) of unknown cause, and there is mounting evidence that MCs &/or CYN could be implicated. MCs and CYN are stable and persistent contaminants, but we have shown their biodegradation by a wide number of microbes. We will develop a nature-based water treatment solution by enriching degradative and cyanolytic potential in a microbiome localised on biochar prepared from locally sourced biogenic waste. This will allow us to develop a low cost reliable water treatment module that can be lowered into dug wells, degrading dissolved toxin and reducing regrowth by limiting light ingress. To model the microbiome development and stability community analysis will be performed. We will also develop a simple low-cost antibody stick test to provide a yes/no response when water has safely been treated.

Water quality and scarcity, impacted by climate change and anthropogenic activity, represent a huge, global societal challenge. According to a recent UN report, the most prevalent water quality challenge is nutrient loading, which frequently leads to blooms of cyanobacteria which may produce toxins posing a threat to human and animal health along with reduction of ecosystem function. In Sri Lanka, 50% of the population have access to poor quality water typically from dug wells, which has been implicated as the source for causative agent(s) responsible for rapid increases in CKDu, 7th most common cause of death.

In line with UN Sustainable Development Goal 6.1, to ensure clean water for all by 2030, this project, composed of a multidisciplinary team of established scientists, aims to develop a nature-based treatment solution for destruction of cyanobacteria and their toxins. The team will develop an enriched microbial consortium which will be immobilised on biochar produced from local crop residues (e.g. coconut & rice husk) which are typically dumped or burnt. The outcome of this 3 year project will be a versatile, scalable, nature-based water treatment solution with the team working closely with Sri Lankan National Water Supply and Drainage Board (NWSDB) to undertake microbiome trials. The central impact of this research is the provision of safe drinking water with regard to the presence of cyanobacteria and their toxins using a system which can be applied at the single household level. Exploiting biochar from biogenic waste provides a low cost, locally manufactured support for the microbiome and in the processes enhancing the development of biochar applications in Sri Lanka. The biochar research will also explore the benefits of energy generation during biochar production with the potential to introduce biochar use and application at the single household level. The development of the treatment pod, microbiome enrichment and deployment will focus on valorisation of local crop residues and will develop local manufacturing. Whilst the focus of this project is aimed at providing safe drinking water in Sri Lanka in the first instance, the simplicity of the approach will be readily adopted in other developing countries. It could also be exploited universally given that water supplies, even in developed countries also experience challenges in removal of cyanotoxins, along with an international desire from the UN that simple and natural solutions should be more widely explored. In addition to providing a water treatment solution, the team will also develop a duplex test for MCs and CYN along with local manufacturing and training on the use of the test. This simple-point-of-use tests which will indicate if cyanobacterial toxins are present will empower members of the public to be involved in ensuring the safety of their own water. Working with public health organisations, it will be possible to advance the epidemiology related to CKDu as the provision of simple rapid testing will map the occurrence of cyanotoxins both in water and patient urine.

Close collaboration between project team and stakeholders along with dissemination of key milestones will be communicated via multi-media output targeting both professionals and the public for maximum exposure. This is essential to ensure engagement with water management experts along with organisations committed to UN SDG 6.1 such as UN, FAO, WHO, OECD, IWA, World Bank and WaterAid. Immobilised enriched microbiomes will lead the way to simple, sustainable remediation strategies that will make a difference. The multidisciplinary, international nature of the project, led by scientists with a proven track record of delivering solutions as well as high impact publications is an excellent opportunity to underpin development of PDRAs as early career researchers (ECRs). This will be a unique opportunity for ECR from both UK and Sri Lanka develop their research excellence.