The Challenge:
Site Solutions recently partnered with a leading Anaerobic Digestion (AD) plant operator whose focus is providing a food waste recycling service for local authorities and commercial organisations and generating green electricity for the national grid. Our organic waste management team was involved in a large scale project at one of their sites in Wales.
The project entailed removing large volumes of AD grit (anaerobic digestate grit) that had accumulated in tankers on site. AD grit refers to the heavy, inert materials such as sand, stones, glass, and metal, which are included in the digester along with the feedstock. Due to its properties, it cannot break down during the digestion process.
Why it’s a problem
Over time AD grit settles at the bottom of the digester tank and requires removal every few years to allow structural inspection of the tank. If grit is not removed regularly, it can also cause several issues:
- Reduces digester efficiency – grit settles at the bottom of tanks, reducing capacity and mixing efficiency.
- Causes wear and tear – abrasive particles damage pumps, mixers, and pipework.
The Solution
Once the grit had been extracted from the digester, Site Solutions managed the transport of the material to sites within our network for further treatment. The material is classed as an animal by product (ABP) Category 3, so needs to be managed carefully to prevent contaminated matter entering the wider environment. The grit is screened to remove contaminants and pasteurised to leave a compost like material that can be used to benefit soils.
Where possible, Site Solutions ensure that we practice sustainable methods for all of our waste management solutions. Over the years, we have worked hard on building a trustworthy and reliable network that share these values.
Images taken on site of anaerobic digestate grit.
