Eco Nappies and Vermicomposting    (to go back use your browser's 'back' button ) Updated August 2007

See how some young students won the Intel Environmental Award 
at the 2003 Esat BT Young Scientist and Technology Exhibition at Dublin's RDS.
Click Here for Details: http://www.ecobaby.net/ecobaby_news/news-esat_bt_exhibition01.htm

How can Eco Nappies be Composted?
The most efficient way to compost Eco Nappies is using earthworm composting. You may find this referred to as 'vermicomposting'. With vermicomposting, the worms are very active in their search for suitable food. They rapidly penetrate all parts of the nappy, breaking down the pulp, and excreting the material, making it available for microbes to break down. 

How does earthworm composting work?
Worms feed on organic material, break it down and then excrete it as worm castings or vermicompost. The castings are in the form of tiny pellets which are coated with a gel. This crumb-like structure helps improve soil drainage and aeration. Worms are constantly tunneling which also helps aerate compost and soil and enables water, nutrients and oxygen to filter down. This is also a major factor in the rapid breakdown of the Eco Nappy.

Why is Worm Compost so good for plants?
The organic matter also undergoes chemical changes in the process. This make the nutrients more readily accessible to plant roots but in a form that is slowly released when required by the plants. Vermicomposting has this same effect on toxins, such as heavy metals found in sewage sludge. The process is called 'fixation' and it prevents plants taking up more than they need. Studies also show significant pathogen reduction in organic matter that has been through the vermicomposting process.

The vermicompost acts like a buffer for plants where soil pH levels are too high or low making soil nutrients available again to the plant The castings are much higher in bacteria, organic material and available nitrogen, calcium, magnesium, phosphorus and potassium than soil itself Vermicompost is biologically active and will continue to condition soils for up to 4 years.

Experiments in the US on tomato crops have shown that adding vermicompost will increase production by up to 33%.

Can Earthworm Composting reduce waste volume?
The vermicomposting process also reduces waste volume (up to 60% ) and compacts it giving it higher nutrient intensity and improved water holding capacity. 

Is Vermicomposting popular?
Vermicomposting is set to become increasingly popular in the next century as it yields rich organic fertiliser, recovers energy rich resources, safely disposes of organic waste and helps tackle environmental problems such as landfill and the expense of collecting and transporting this waste. In fact, a number of local authorities in Ireland already promote the use of Vermicomposting.

Is Worm Composting Fast?
Vermicomposting is much faster than regular composting. Compost can be ready in 1 month whereas normally it might take 6 months).

Can you suggest some more advantages to Worm Composting?

For a sustainable environment, outputs from each production cycle should become inputs to other enterprises as in nature. Vermicomposting is an ideal example, as the worm composting process mimics nature.

Can earthworms deal with toxic substances in the composter?
Some relatively toxic substances can be found in the waste we put into composters. As long as the worm composter is working properly, the worms will be able to handle these substances. Heavy metals become soluble and therefore potentially toxic in acidic environments. Worms prefer a relatively alkaline environment. Normally ground garden limestone is sprinkled into the composter. (Only use garden lime, NOT Quicklime, of course!). Worms carry out fine grinding of the lime particles. This neutralises any excess acidity and liberates plant nutrients stored in the rock. Heavy metals are also fixed in the soil and released slowly avoiding toxicity.

Worms develop and maintain a culture of effective aerobic bacteria by culling pathogens, fungi and anaerobic bacteria. They also ensure the organic mass is well aerated.

How does Worm Composting work?
Vermicomposting is much more complex than worms simply eating and excreting organic material. It is a highly complex chain of chemical, biochemical and biological interactions and reactions. The whole process is based on natural systems which have evolved over hundreds of millions of years. Worms play a vital role in creating the optimum conditions for the beneficial organisms to establish and reproduce. These 'good' organisms compete with and dominate the more harmful microbes. The waste is reduced in volume and increased in nutrient value. 

So who's responsible?
It takes more than just the worms to make vermicompost. The worms eat, chew and churn up the waste. The other organisms which accompany them also break it down. A simplified description of the overall mechanism is described below:

 1.    The worms ingest organic matter, fungi, protozoa, algae, nematodes and bacteria. This is passed through the digestive tract. The majority of the bacteria and organic matter pass through undigested (although the organic matter has been ground into smaller particles). This forms the casting along with metabolite wastes such as ammonium, urea and proteins. The worms also secrete mucus, containing polysaccharides, proteins and other nitrogenous compounds. Through the action of eating food and excreting their casts, worms create “burrows” in the material. This in turn increases the available surface area and allows aeration.

2.    There is an abundance of oxygen and nitrogenous compounds (urea, proteins and NH3) in the excreta (vermicast) and mucus secreted from the external tissues of the worms. Some bacteria require oxygen (aerobic bacteria) whereas some object to oxygen and prefer its absence (anaerobic bacteria). Anaerobic bacteria are responsible for the stench from stagnant drains, refuse sacks and landfill sites. With the aerobic conditions in vermicompost, aerobic microbiological growth increases. It is believed that the initial burst of microbiological activity mainly consists of nitrogen fixing bacteria, nitrification bacteria, and to a lesser extent, aerobic bacteria. This is based upon previously established information that burrow walls have a high proportion of the total nitrogen fixing bacteria and that casts have higher concentrations of soluble salts and greater nitrifying power. Accompanying this microbiological growth is the breakdown of organic nitrogen compounds to ammonia and ammonium.

The good news is that the sweet smelling aerobic process overcomes the ugly smell of anaerobes. That is why worm compost piles (properly fed and maintained) smell so nice!

3.    The whole process consumes organic matter and creates a ruffled surface in the burrow walls. The large surface area and improved aeration results in favourable conditions for obligate aerobes (such as Pseudomonas spp., Zoogloea spp., Micrococcus spp. and Achromobacter spp.). The continued growth of the microbiological population continues to increase the rate of decomposition of the material.

Air flows through the material more readily, minimizing the likelihood of anaerobic biochemical reactions occurring. This minimizes the formation of sulfide and ammonia gasses, odors that are typically present if anaerobic conditions are established. Objectionable odors disappear quickly, due to microorganisms associated with the vermicast

What about dangerous pathogens, enteric viruses and parasites?
Naturally, it is important that where potentially harmful organisms are in materials being composted, they should not be present in harmful numbers when the process is finished. With earthworm composting, this is indeed the case.  

The vermicomposting process has a profound effect on the levels of pathogens namely E.coli, Faecal Coliforms and Salmonella spp. with reductions of >99.9% possible. Material that is Vermicomposted exhibits greater pathogen reduction than that achieved with conventional composting. As all three of these pathogens are not obligate aerobes (that is requiring oxygen to survive, grow and multiply), it is likely that these organisms are subject to exploitative competition. The obligate aerobes namely Pseudomonas spp., Zoogloea spp., Micrococcus spp. and Aebromobacter spp. have evolved to process nutrients and reproduce at the highest efficiency in aerobic conditions and so the pathogens are excluded from nutrients and space as the obligate aerobes continue to increase under ideal conditions. 

A similar reduction in numbers exists for enteric viruses due to the lack of host species, exposure to a microbiologically active environment and the secretion of virucidal enzymes by the earthworms during the digestion process. An identical pattern is observed during the vermicomposting process when examining parasite Helminth ova) numbers, primarily due to the lack of host organisms and possibly direct digestion by the earthworms. 

Benefits of Vermicompost
The typical levels of the nutrients (N, P, K) in vermicomposted green waste are of the order of 1-2
%. It would appear that the vermicompost does not compare favourably with commercial chemical fertilisers however two important factors are overlooked when comparing the two, the microbial content and the organic matter content.

Chemical fertilisers are either sterile or have negligible microbiological activity. The chemical fertilisers are composed primarily of water-soluble chemical salts and as such organic material rarely forms part of chemical fertilisers. Once the salts have been depleted from a chemical fertiliser, then re-application is required to maintain the nutrient levels. The presence of nitrifying and nitrogen fixing bacteria in vermicompost means that nitrogen can be fixed from the atmosphere and converted to plant soluble nitrates.

The process continues as long as there is sufficient organic matter (which is present in vermicompost) and so re-application is not required at the same rate as chemical fertilisers. The ability of the microbiologically active vermicompost to regenerate the nutrients from the atmosphere, organic matter and water replaces those lost from chemical fertilisers by leaching, plant uptake and chemical reactions. In relation to moisture holding capacity and improvement of soil structure, chemical fertilisers have negligible effect, as they primarily consist of water-soluble salts. Vermicompost, on the other hand, due to the aggregate nature of the worm castings has appreciable water holding capacity and its use leads to improved soil structure. 

Vermicompost requires no curing (as traditional composted materials do) as it is already populated with beneficial microorganisms The overall time required (and hence the cost) for processing is therefore greatly reduced, and the process produces no toxic by-products or waste. The vermicompost itself is highly valued by gardeners all over the world and has a significant market value.

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