Friday, January 21, 2011

What Is Digestate in Anaerobic Digestion During Sludge Treatment?

What is Digestate?

Digestate is the solid leftover of the original matter which is not biodegraded by the anaerobic microorganism. the process of anaerobic digestion forms two products viz biogas and digestate. The quality of digestate is graded against chemical, physical and biological aspects.


Appearance and odour come under physical quality and in chemical aspects heavy metal and some inorganic contaminants are checked.

Hydrolysis begins the digestion process in which the input biodegradable material is broken down to form insoluble organic polymers which are then used by bacterias. Then these are converted to ammonia, hydrogen and carbon dioxide by acidogenic bacteria. On this the Acetogenic bacteria acts that is followed by the process of methanogenesis.

Types of Digestate

Digestate is formed both during the acidogenesis and methanogenesis process. But each by product has different characteristics.

Acidogenic digestate

It is fibrous and consists of lignin and cellulose. This digestate sometimes also contain remains of bacteria and minerals. Also if checked then there is high moisture retention properties in the acidogenic digestate.

Methanogenic digestate

It has very high nutrient content including nitrates and phosphates and it is also called liquor in sludge treatment.

Uses of Digestate

It acts as solid conditioner as it provides soil the organic content. It provides nutrients that are required for the growth of the plant. Acidogenic digestate give rise to composite plastics. Also with digestate plants with resistance towards few diseases have been developed. It stimulates the biological activity of the soil.

Spreading of digestate in ground as such is prohibited but it can be done with sludge spreader. Also for this waste management license is mandatory.

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