8.3 Role of Microbes in Composting

115

rate and compost quality. The waste composition, nutritive supplements, and

environmental setup (ambient or trial) support the type of bacteria and fungi that

emerge during composting [7]. Furthermore, additives in form of microbes will alter

the breakdown process of cellulose, hemicellulose, and lignin during composting.

These microbes release substrate-based hydrolytic enzymes to split up the complex

compounds to produce water-soluble metabolites. In addition, assessment and

monitoring (physiological profiling) of microbial succession within composting can

denote the scale of compost maturity.

Suitable microbial addition during composting of solid waste (organic) is known to

accelerate the degradation process, thus enriching the nutrient composition of the

resulting compost. Microbial additives will speed up the process through nutrient

transformation and production of extra-cellular enzymes (lignocellulases, proteases,

etc.). When added to a compost mixture, effective microbes will influence the tem-

perature, ammonia balance, and production of volatile organic compounds (VOCs)

and nitrogen–sulfur compounds [8, 9]. Hence, microbial inoculation will serve as

a positive stimulation in composting and aims to achieve maximum efficiency. The

same has been illustrated in the Figure 8.1.

Several studies in the past have revealed microbial addition as a positive approach

toward solid waste treatment resulting in enhanced rate of waste degradation

[10, 11]. These microbes can be isolated from various sources such as soil, cow

dung, straw, or waste mixture depending on the requirement [12]. While in some

conditions, a pre-derived mature compost may be applied to waste mixture, in

other conditions either a single bacterial or fungal strain or a viable consortium

of effective microbes (mixed culture) might be substantial enough [10, 13]. Few

examples of potent microbes are Bacillus spp., Cellulomonas, Pseudomonas,

Solid waste

Organic

material

water

microbes

Oxygen

Water

Particle size

Heat

Compost

pile

CO2

Time

Finished

compost

Compost

Microbial

additives

Figure 8.1

Process flow of a SW composting with microbial additives.