Digestate Biochar as a Lagoon Cover and Additive: 2024
This project aims to assess the effectiveness of biochar derived from digestate feedstock, EcoChar (Emission Control Organic-Char) – in reducing harmful gases emitted by a digestate lagoon. This EcoChar project involves characterising digestate and EcoChar, conducting small-scale testing, and analysing the EcoChar for additional benefits such as nutrient uptake. This project will validate the potential for EcoChar to be used as a low-cost, efficient, and eco-friendly alternative to traditional Anaerobic Digestion (AD) lagoon cover materials.
The Clean Air Strategy will mandate emission abatement for open slurry and digestate stores (lagoons), where they are currently not required to be covered. Significant amounts of ammonia are lost to the atmosphere from open stores, tanks and lagoons that are currently open to the elements. It is expected that any newly constructed store will need a fixed/rigid cover. However, existing infrastructure will be able to use a wider range of options, including straws/organic layers or lightweight aggregate materials.
Typical non-rigid lagoon cover has limitations and is impermeable to gases and liquids. A lagoon cover helps contain harmful gases, controls odour and biogas capture. Fixed covers will be cost-prohibitive in many situations, and it is therefore vital that other methods can be used to bring existing stores into compliance. Biochar as a cover can also be utilised as a potential fertiliser and soil conditioner once its role as an emission suppressant concludes. Moreover, biochar is recognised as an effective carbon sequestration method when applied to soil.
AD lagoons use open-air basins/ponds for the storage of digestate after the AD process. AD systems typically involve enclosed reactors to treat various types of organic waste such as agricultural waste, wastewater and food processing residues. It undergoes microbial breakdown anaerobically facilitating the production of biogas, primarily methane, which can be utilised as a renewable energy source. However it also emits harmful gasses such as ammonia, hydrogen sulphide, methane, and carbon dioxide due to the decomposition of organic matter. These gases pose environmental and health risks, contributing to air pollution.
The EcoChar project will also look at AD digestate as a potential feedstock for preparing biochar. Digestate is composed of partially degraded organic matter making it rich in nutrients and a suitable feedstock. Processing digestate into biochar through a thermochemical process, pyrolysis, facilitates better management of the digestate disposal thus reducing waste and will improve the circularity of the overall process.
Validating FilaChar® Use in Wastewater Treatment: 2024
At present, there is no environmentally sound upcycling solution to screening waste. ‘Screening Waste’ is generated from wastewater treatment (WWT) facilities and is removed from the influent during WWT; it is stored in skips and sent to landfill. This source of waste is increasing annually and causes significant challenges to the infrastructure and financial cost of WWT.
Landfills contribute to soil and water pollution, releasing greenhouse gases and posing a threat to ecosystems and human health through the accumulation of hazardous waste. Screening waste ‘fibre’ is not recycled due to quality and hygiene concerns in the paper industry. However, in our preliminary results, we have explored that using it to create a new carbon-based biochar is promising.
Carbogenics is a member of the Scottish Bio-technology cluster and we will upcycle this under-utilised biomass supply which is a win for communities and the WWT industry. FilaChar® is a patent-pending carbon-rich material called biochar made from organic wastes that can act as a carbon sink by sequestering three tonnes of carbon dioxide for every tonne of biochar. It aims to address issues in WWT such as Odour emissions, high energy demand for inefficient aeration of the biological treatment step, fluctuating pollutant removal performance, especially during peak loads and high costs for the disposal of screening waste and these issues increase the WWT operating costs by more than 5%. Our initial research shows that FilaChar® was able to remove pollutants and odours from wastewater, improve sewage sludge settling, and enhance the activated sludge process. FilaChar® production has a net negative carbon impact and can significantly reduce carbon emissions.
This project seeks to build upon this prior industrial biotech research and evaluate FilaChar’s® practical applications and effectiveness in improving WWT processes. We are partnering with Scottish Water to access relevant biomass supply and their Bo’ness testing facility to progress this work.
The project will conduct a comprehensive assessment of how to process the screening waste and transform it into FilaChar® at scale and evaluate its commercial viability. Subsequently, we will conduct a trial which will investigate FilaChar’s® efficiency in removing contaminants, leaching behaviour, and its impact on the wastewater treatment process. Our efforts will focus on working with relevant authorities to address legislative issues and gather data to substantiate our claims. We aim to establish a regulatory pathway for FilaChar®. Furthermore, we will conduct thorough desk-based research to identify potential future markets for FilaChar®.
