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.'

The overarching aim of this research is to develop a scalable bio-based strategy to eliminate cyanotoxins (blue-green algal toxins) in drinking water which are known to frequently occur in dug wells in Sri Lanka and are thought to be linked to an increasing occurrence of Chronic Kidney Disease (CKDu) and other adverse health effects. The aim will be achieved through the following specific objectives: 1. To develop an in situ naturally immobilised aquatic microbiome enriched for biodegraders of microcystins (MCs) and cylindrospermopsin (CYN) (two of the most prominent and hazardous cyanotoxins) and cyanolytic bacteria. We have demonstrated that microbes capable of degrading cyanotoxins are present in most water bodies although enrichment greatly enhances speed of degradation. 2. To develop a biochar-based simple low cost support for the aquatic microbiome using widely available biogenic waste. We will explore potential waste streams (e.g. coconut husks/shell, rice straw/husks), then optimise and characterise biochars. 3. To evaluate microbiome formation on a range of selected biochars to determine compatibility (biofilm formation, absence of microbial inhibitor), optimum surface area, particle size and residual elements. 4. To use our expertise to select the most suitable microbiome activators which will ensure the rapid degradation of MCs and CYN. These will be selected from biogenic wastes which share chemical similarity to cyanotoxin groups, e.g. peptone-rich waste such as spent yeast would be predicted to be selective for MCs (heptapeptides) degraders and the high nucleotide content should enrich for CYN degraders. 5. To perform microbiome community structure analysis to determine if key characteristic profiles indicate the suitability of consortia for cyanotoxin removal (MCs, CYN or both) and cyanolysis (bacteria that actively attack cyanobacteria). Microbiome stability over time will also be determined. 6. To develop the first simple rapid low cost duplex stick test to detect microcystins and cylindrospermopsin at levels above safe exposure concentrations (c. 1 ug/L). The design of the test will be suitable for general use and will facilitate a 'citizen science' opportunity to map cyanotoxin occurrence and highlight the need for water treatment and success of treatment. Easy of testing will support on-going epidemiology to determine the link between chronic kidney disease and cyanotoxin exposure. 7. To develop local capability in the production and quality control of a duplex cyanotoxin stick test, providing low cost production and distribution. 8. To design and fabricate a scalable enriched microbiome treatment module for deployment in single-household dug wells. This will include selecting the optimum depth for deployment, the best geometry for the module such that it allows maximum contact with well-water, material for module construction (this will exploit natural fibres) and appropriate dosage. 9. To perform a full evaluation of the performance of the enriched microbiome in multiple locations, screening with rapid duplex stick tests, performing detailed quantitative analysis by LC-MS and water quality parameters. 10. To evaluate the suitability of the enriched biochar microbiome for application in larger scale treatment systems including full scale drinking water treatment plants.