ReBALANCE - Recycling Biomass to Agricultural LANd for Control of Eutrophication Natural Environment Research Council Bangor University ReBALAN:CE Home Page University of Stirling


Catalyst Grant

This project brings together an interdisciplinary team of experts from across academic, policy and stakeholder organisations in order to prioritise and plan a response to the pressing science needs associated with resource recovery from waste. Specifically, the project will explore nutrient recovery from excessive aquatic plant and algal biomass production in nutrient enriched waters (e.g. ponds, constructed farm wetlands, sustainable urban drainage systems and natural waterbodies) and, crucially, will integrate economic, social, environmental and health-related dimensions that cut across traditional academic disciplines. Thus, the overall aim of this project is to facilitate the exchange of knowledge across the disciplinary boundaries of biology, geography, soil and water science, microbiology, human behaviour, risk perception, waste management, economics and catchment management. In turn, we will develop a comprehensive, holistic and targeted programme of research to 'close the loop' on nutrient transfer from land to water. This will be underpinned by understanding and quantifying the risks, opportunities and multiple benefits of recycling excessive aquatic plant and algal biomass back to agricultural land.

The project will therefore contribute to a paradigm shift in current conceptualisation of 'waste' management to redress the current imbalance of focus on economic benefits of recovering resources from waste. In a wider context, effective and sustainable waste management must take account of the often unquantified and uncertain trade-offs for managing wastes across the environment. For example, recovering nutrients from aquatic plant and algal biomass makes economic sense because fertiliser costs are soaring due to shortages in mineral supply; however, this is only one part of a complex socio-economic-ecological system. We need to couple economics with the safeguarding of human health and protection of key ecosystem services, such as the provision of clean and safe recreational and drinking water, and appreciate the social and political barriers that may hinder or promote efficient nutrient recovery from this 'waste' by-product. While we know that anthropogenic inputs of nutrients to aquatic systems can be assimilated in aquatic biomass we have little knowledge on how pathogens and toxins may be recycled through agroecosystems following reapplication of this biomass to land, and poor understanding of nitrogen and phosphorus release rates from non-composted and composted biomass. Furthermore, the potential role for aquatic plant and algal biomass to be made into biochar (charcoal) as a novel approach to re-cycle nutrients and store carbon in soil (to offset emissions of carbon dioxide) is another dimension of resource recovery from waste by-products that might deliver multiple benefits and ecosystem services for wider society. There are a number of additional policy related dimensions to debate including whether there is an issue surrounding the classification of recycled biomass as non-waste in terms of regulation and licensing. Our team is well equipped with the expertise to develop core work-packages needed for a well balanced research agenda in recycling biomass to agricultural land.

The project team are therefore tasked with framing some important emerging questions that will need innovative science and integrated solutions for 2020 and beyond. By pooling the cross-disciplinary expertise assembled in this catalyst grant we will identify where improvements in fundamental understanding are necessary to deliver step changes in 'waste' management for environmental benefits and help refine regulatory policy and practice to support this.


Phase II

Eutrophication, the enrichment of water with nutrients, is a major water pollution issue & can lead to excessive growth of APB. This is a particular problem in agricultural catchments across the world where nutrients are commonly applied to land in order to promote crop & livestock growth to support the increasing demand for food security. Following rainfall, excess nutrients can 'leak' into surrounding watercourses & lead to a proliferation of APB. Consequently, APB harvesting is carried out routinely in rivers, ditches, canals & shallow lakes to remove nuisance APB from nutrient-rich water. This is primarily for reasons of flood conveyance, land drainage, irrigation, navigation & to support recreational activities such as angling & sailing. Importantly, many of those nutrients that drive the excessive growth of APB can become locked within the plant material itself & so harvesting APB can not only help restore water quality, but also provide a gateway for the recovery & re-use of these 'lost' nutrients. Recovering phosphorus is important because paradoxically it is becoming increasingly scarce (increasing the price of fertiliser) yet it continues to be flushed away through catchments following heavy rain & becomes abundant in eutrophic waters. The overall objective of this research is to identify opportunities as well as the associated challenges (& the trade-offs) linked to nutrient recovery from APB in agricultural systems. Our vision is to couple the remediation of degraded aquatic environments with a strategy for efficient & novel resource recovery from the waste that arises from existing harvesting activity. Thus, our research is aimed at 'closing the loop' on nutrient transfer from land to water while quantifying multiple additional impacts (both positive & negative) to the environment & wider society. Our research will answer some important emerging questions. While we know that anthropogenic inputs of nutrients to aquatic systems can be assimilated in APB we have little knowledge of how pathogens & toxins may be recycled through agroecosystems following the application of this biomass to land, & poor understanding of how to optimise nitrogen & phosphorus release rates from non-composted & composted APB for re-use in agriculture. Furthermore, harvesting APB might exacerbate nutrient problems before local improvements are seen or might lead to disturbance of some species (e.g. invertebrates/fish). We also need to understand how farmers & other catchment stakeholders perceive recycled APB with regard to its use as a soil improver or livestock feed, & the monetary value of wider environmental benefits of APB harvesting measured by improvements in recreation, greenhouse gas emissions or biodiversity indicators. Using a combined field & laboratory-based approach this interdisciplinary project will deliver improvements in fundamental understanding necessary to drive a step-change in understanding resource recovery from this 'waste'. It will do this by demonstrating the importance of valuing the net environmental benefits that may accrue in catchments beyond the financial gains of resource recovery alone.The results will be applicable beyond the immediate area of study & are likely to have significant impact for water quality protection & sustainable management of our natural resources.