Anaerobic Composting

Anaerobic Composting / Conserving Valuable Resources

Composting, often described as nature’s way of recycling, is the biological process of breaking up of organic waste such as food waste, manure, leaves, grass trimmings, paper, worms, and coffee grounds, etc., into an extremely useful humus-like substance.

Today, the use of composting to turn organic wastes into a valuable resource is expanding rapidly in many countries, as landfill space becomes scarce and expensive, and as people become more aware of the impact they have on the environment.

Actinomycetes and More...

Composting is nature's process of recycling decomposed organic materials into a rich humus-like soil booster known as compost. The primary microorganisms responsible for composting are bacteria, fungi and actinomycetes.

Actinomycetes are similar to fungus in the way they grow and spread, but its distinguishing elements are that the types of materials they are efficient at decomposing. The active nature in this microscopic bacteria and the sheer number present (about 10 million per 1 gram of soil), make them highly effective at breaking down materials like tree bark, newspaper, and other hard organic material.

Compost is rich in nutrients that are ideal for soil and plants. Basically, composting is of two types namely aerobic composting and anaerobic composting.

Digging Deeper into the Process

The term "anaerobic composting" is used to describe putrefactive breakdown of the organic matter by reduction in the absence of oxygen where end products such as CH4 and H2S are released. It is mostly produced in a closed system, perhaps in a plastic bag or a sealed bin or sometimes even in open exposed piles.

This process also takes place in nature, such as decomposing organic mud at the bottom of marshes and in buried organic materials with no access to oxygen. Microorganisms that thrive in a low-oxygen environment (mostly bacteria) reduce nitrogen-containing or sulphur-containing compounds found in organic matter to yield organic acids and gases (ammonia etc).

Mix it Up

Anaerobic composting works best with nitrogen-rich materials such as non-fatty kitchen waste and soft green clippings. Although it is less labor intensive because it does not require frequent turning of the pile but it is smellier (methane and sulphate gasses being the by-products).

Moreover, the compost maintains both weeds and pathogens, hence is a slower process. However the reduction in the volume of pile by anaerobic organisms is lot less than the aerobic organisms resulting in more humus. Avoid adding carbon-rich materials such as dry leaves, sawdust and woody yard waste as these materials can retard or even halt the anaerobic composting process.

Composting may be accomplished in large, well packed stacks or other composting systems containing 40% to 75% moisture, into which little oxygen can penetrate, or in composting systems containing 80% to 99% moisture so that the organic material is a suspension in the liquid.

When materials are composted anaerobically in this way, not covered with water, the odor nuisance may be quite severe. However, if material is kept submerged, gases dissolve in the water and are usually released slowly into the atmosphere. If the water is replaced from time to time when removing some of the material, no serious nuisance is created.

Bring the Heat

Since there is no significant release of heat to the mass in anaerobic composting, one may assume that it can pose a problem for treatment of contaminated materials. High temperatures are needed to destroy pathogens and parasites. But high temperatures do not play a part in the destruction of pathogenic organisms in anaerobic composting.

The pathogenic organisms gradually die in the organic mass, because of the unfavorable environment and to biological antagonisms. Their disappearance is slow and the material must be held for periods of six months to a year to ensure relatively complete destruction of Ascaris eggs.

4 Quick Tips

Here are few things that you should keep in mind while composting anaerobically:

A moist composting pile with a "slimy" consistency and a slight sulphur odor indicates your bin is working properly.

Do not be panicked by the presence of insect larvae, worms, beetles, and other scavenging organisms. They are all a part of the composting process and also signify a productive bin.

Remember not to open your anaerobic composting bin more than two times per week. A composting bin should be watered at least once a month or before it is dry.