What is Compost?

Formation of Micellium during
Dry Leaf Compositing Process

Household composting and biopolymers in food waste

Athul Seshadri Ramanujam 

Composting is a biological process in which microorganisms degrade organic matter in biodegradable waste resulting in the emission of CO 2 , H 2 O (g), NH 3 (g) along with the production of a nutrient-rich solid substance known as compost. Composting is often described as a two-stage process – mineralization followed by humification. The process of mineralization refers to the degradation of decomposable organic matter. The type of organic biomass to be decomposed determines the type of microbes to be used for its degradation. Mesophilic microbes decompose easily oxidizable organic matter to form simple substances such as CO 2 and H 2 O (l) and other simple organics and inorganics. The process temperature during mesophilic decomposition can rise until 45 o C. Food wastes generated either from industries or at home consists of biopolymers – lignin, cellulose, hemicellulose, proteins and lipids, are decomposed using thermophilic microbes which operate at a temperature of 55 – 65 o C and at times even higher. As a result, monomers specific to the biopolymers in the biomass are produced. Also, since the thermophilic microbes operate at a higher temperature, simultaneous sanitization of biomass takes place. This prevents the process inhibition by pathogens. After a certain point in time, the process temperature starts to reduce as the activity of microbes starts to slow down due to the lack of biomass. During and after cooling, stable organic matter (mostly humic substances) are formed. This is known as compost.

Athul Seshadri Ramanujam 
Graduate Student, MSc. in Process Engineering (MPE)
Faculty of Mechanical and Process Engineering
Hochschule Offenburg

Badstraße 24, 77652 Offenburg
Email: rathulseshadri@gmail.com, aramanuj@stud.hs-offenburg.de