Using digestate – the liquid overflow from a digester

Using digestate – the liquid overflow from a digester.

“It has a high nutrient value – the exact makeup of fertlisier will vary depending on the nature of the feedstock. However it has a high nutrient value, generally around

4 to 5 kg / 1000 litres of nitrogen

1-2 kg / 1000 litres of phosphate

1-2 kg / 1000 litres of potash (potassium carbonate)

2 kg / 1000 litres of magnesium” from Cranfield Dr Frederic Couklon and Dr Raffaella Villa. www.cranfield.ac.uk

The liquid overflow from an anaerobic digester is called digestate. It flows out at about the same rate that water is flowed into the digester. Some solids have been removed by settling ( they were too heavy and are now at the bottom of the tank), by being eaten by bacteria and tturned into gas, and by forming a scum layer on top of the liquid. The remaining dissolved solids are still retained in the liquid that flows out of the digester.

An example is shown below: