The solid residues in livestock slurries and wastewater sludges are being researched for potential as a great biomass source
Animal waste can be used for energy recovery and nutrient recycling
SLURRES is a low cost technology and business model to mobilise livestock slurries for community based Anaerobic Digestion. The study was a collaboration between University of Limerick (UL) and TCBB Resource, and was funded by the SEAI Research, Development & Demonstration Funding Programme
TCBB RESOURCE is an R&D company that works with Irish State agencies, universities and companies to commercialise renewable energy technologies.
One of Ireland’s biggest biomass sources are the solid residues in livestock slurries, wastewater sludges and similar materials. These materials have historically been treated as wastes and were processed for disposal. These valuable resources however can be used for energy recovery and nutrient recycling.
This project was undertaken to develop the technology that will facilitate use of these materials as renewable energy resources as opposed to waste.
On a farm, sawdust is blended into animal slurries with the mixture filtered through a very high-pressure filtration process to remove the solids. The filtered solids are a compost-like material that can be cost-effectively collected and transported to a renewable energy site to convert into gas or electricity. This process is a very low-cost process that minimises the cost of renewable energy for the surrounding community.
At the farm, the residual slurry liquor is clarified to facilitate precipitation of the residual ammonia, which is removed in a crystaline form that can be used as a fertiliser. The treated water is quite pure, and can then be discharged with no environmental impact.
Support from the SEAI Research, Development & Demonstration Funding Programme provided the resources to answer key questions related to development of a separation technology that could efficiently remove solids to a standard that allowed ammonia removal from the residual liquors.
The project identified the business model and methods required to introduce this technology into the agricultural and wastewater management sectors
The SEAI research funding provided the resources to answer key questions related to development of a separation technology that could efficiently remove solids to a standard that allowed ammonia removal from the residual liquors. There are many types of filtration or separation technologies but they are generally unable to meet the separation efficiencies required to clarify the liquors without the addition of costly and environmentally damaging chemicals. The funding facilitated identification of methods that could do this without the need for the chemical additives.
An inside view of the learning outcomes for SLURRES
With Bart Bonsall, Managing Director of TCBB RESOURCE
How would you describe the journey of the project
There were two principal processes that had to be developed and tested. These included the development of an efficient, non-chemical aided filtration process, which included iterative testing and process optimisation, that resulted in a process that clarified liquors to a standard that could be processed for ammonia removal. The second step was to test and develop the ammonia removal process that resulted in a useful fertiliser, and water effluents purified to a standard that could be discharges to the environment. Each of these steps had to be outlined and tested at small laboratory scale, and then the filtration process had to be tested at a somewhat larger scale to ensure it worked.The next steps, which are the subject of a follow on project, are to engineer these processes into units that can be run on a continuous basis at scale.
Are you happy with its success, if so why?
Yes – the project identified the process that work and provided an outline as to how these can be engineered into commercial scale units.
What was the biggest learning outcome throughout the project for the team?
It provided the fundamental scientific data required to undertake the process engineering with a high chance of success.
What was the most challenging element?
The biggest challenge is the design and integration of an automated control system that will maintain the pressure, throughput and filter bed depth in the filtration unit to allow continuous operation while generating consistent efficient filtration results. This step has only been progressed to theory stage, and has to be developed and tested in a follow on scale up project.