Digestate enhancement and treatment technologies have become more important due to the increase in the number and capacity of AD plants and industrial processes. Colloide have a wide range of physical, chemical and biological technologies available for treating digestate, for land application and other novel products. Due to growing environmental and regulatory concerns the volatile organic compounds within the effluent from Anaerobic Digestion processes must be removed or captured for alternative uses.
Colloide’s main methods are vaporisation (flash distillation/evaporation/stripping), reverse osmosis (including pre-filtration), chemical dosing (used in conjunction with other technologies) and a combination of SBR and MBR treatments.
Vaporisation: Flash distillation/evaporation/stripping
These different methods of vaporisation ensure that ammonia is removed (>75%) from whole digestate, allowing the solids to be spread on land at a much higher coverage and approved for exporting off site. Alternatively, the ammonia can be captured as a liquid product for storage as a concentrated fertilizer, which can also be transported off-site for other markets. These systems help reduce the production of greenhouse gases, such as methane and CO2 and target the removal of suspended solids and VOC.
Reverse Osmosis (including pre-filtration)
This treatment recycles the digestate waste water into water (clean water recovery >75%), that can be re‐used for washdown, irrigation, evaporative cooling or disposed directly to a watercourse, thus prolonging the availability of freshwater resources. It can remove microplastics, viruses, bacteria, pharmaceuticals and pesticides from treated water, as well as recovering specific nutrients. A pre‐filter is installed before the reverse osmosis (RO) membrane and extends the life of the more expensive RO membrane, thereby reducing our client’s overall operating cost. The treated effluent can be used as a concentrated liquid fertilizer for exporting from a digestor site.
Chemical dosing (used in conjunction with other technologies)
Colloide design and build customised chemical dosing systems for a wide range of chemicals and applications. These packages are tailored to suit our clients’ requirements while adhering to European Standards, Ciria and HSE guidance. Our chemical dosing systems in conjunction with other technologies aid in the removal of chemicals such as phosphorus and ammonia. This treatment also enhances the separation of solids from liquid digestate and/or removal of suspended and dissolved solids as well as improving overall sterilisation.
SBR & MBR
The Sequential Batch Reactor (‘SBR’) and Membrane Bioreactor (MBR) are extremely compact and flexible solutions to waste water treatment. They offer an extremely high quality of treated effluent and both technologies achieve the removal of ammonia, suspended solids and COD. Our specialist MBR systems can also remove microplastics. The liquid fraction of digestate from these processes can be disposed to sewers, land or pre-treatment for further technologies.