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Commercial/Industrial Composting with Worms

Commercial and industrial enterprises, in nearly all cases, produce organic waste; often they are not aware of this. The most obvious is waste from processing organic materials, this could be food, baking, brewing, greengrocery etc through to canteen waste and to the less obvious of paper, cardboard and packaging, all of which are capable of being processed by worms.

Because of the locality of the majority of commercial premises, the processing would need to be in an enclosed vessel, there are several available, dealing with small quantities of waste per day (10’s of kilo’s) to much larger quantities (100’s of kilo’s). For the large industrial use there are vessels capable of processing in tonnes.

These vermicomposting vessels reduce the volume of waste by up to 80%, the material left is the nutrient rich casts that should be utilised but even if they are only returned to landfill they can only benefit the site. Small and medium sized flow through systems are now available in this country, they are particularly suitable for premises that have a relatively small output of organic waste materials such as schools, small hotels, canteens etc.

For the large producers on an industrial scale we still have to look overseas for suitable equipment. These vessels are available by importing from countries such as America, Australia and Canada where they have been developed and used successfully for many years or fabricated in the UK according to the need. In certain circumstances where the commercial premises are situated “out of town” it may be possible to use a bed system; this considerably reduces the cost over enclosed vessels particularly where large amounts of material are being dealt with.

Both agricultural and commercial/industrial systems are individually tailored to the needs and require consultancy.

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Domestic Composting with Worms

Worm composting is normally carried out in some kind of bin be it plastic or wood. There are many different makes and types on the market, some are better than others, some do not work at all. Most of the older designs use an enclosed bin, that is, solid bottom and solid sides, usually with a tap on the bottom to drain off excess liquid.

For a worm composting system to work effectively, the worms must have a good supply of air, from bottom to top, they need surface area not depth. Plastic bins generate a lot more liquid, mostly through condensation, than do wooden ones, this liquid collects in the base and unless it is drained off on a regular basis, it will become “anaerobic” i.e. very smelly and give off gases that are not good for the worm population. This liquid is often promoted as being a beneficial product and should be used as a liquid plant feed, it is true that as the liquid passes through the worm bin it will absorb and carry some of the nutrients with it, equally it may well absorb substances and organisms that have not been “processed” by the worms and these may well be harmful to your plants, for this reason Worms Direct U.K. would not recommend the use of this liquid as a plant feed. Proper and safe feeds can be made from the finished vermicompost, these are known as “compost teas” and will be dealt with later. The biggest drawback is once the bin is full, you have to remove the top layers, hopefully with the worm population, upend the bin to remove the compost and start all over again, a messy job at the very least.

More modern worm bin designs are based on stackable trays or flow through systems. The stackable trays consist of a base support onto this is placed the first tray, each tray has a perforated base, the worms are started off in the first tray and fed as you would in any other system, when the tray is full, an empty tray is placed on top and feeding continues, the worms will migrate from the lower tray into the next where there is fresh feed, this continues until the last tray is used, the one now at the bottom is removed, the finished compost emptied and then becomes the next one to use on the top. In this system it must be remembered that worms will not migrate up through a space so it is essential that the base of the top tray remains in contact with the surface of the food layer in the tray below.

Flow through designs consist of one bin but this has a mesh bottom, usually with some sort of mechanism to agitate the casts from below which fall into a collecting tray. The worms are started off in a bedding material, feeding to the surface continues until the bin is almost full, at this point the mechanism in the base is operated, casts are removed, the whole lot settles down and feeding continues. Usually made of wood, therefore less condensation, being ventilated at the bottom allows air to move upwards through the system, no lifting of heavy trays and handling of worms is kept to a minimum.

We have tried many systems and in our opinion, the flow through is generally the best.

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Benefits of Recyling and Composting

Vermicomposting organic waste is an environmentally friendly and sustainable method of dealing with an organic waste problem, it is equally effective in small or large domestic, agricultural or industrial situations with the benefits of comparatively little capital outlay and low management and maintenance costs.

The basic principles are the same in all situations and that is the waste is added to a bed of material that contain sufficient worms to digest the organic matter.

First a few facts that are worth noting:
– Worms will consume between 50% and 100% of their own weight in food per day.
– They will digest anything that has ever lived.
– They multiply rapidly.
– Worms do not get diseases.

The worms

There are many different species of worm but the worms used in waste recycling are all compost or litter worms, these are worms that live on or just below the soil level, feeding off the decaying organic materials on the soils surface, they do not burrow to any great extent. The ones that are found in most domestic compost heaps are Eisenia foetida also known as Brandlings or Tiger worms, Eisenia andrei and Dendrodrilus rubidus these, combined with the much larger Eisenia hortensis, a native to Europe and Asia, also known Dendrobaena, are an ideal combination, Eisenia hortensis is larger than Eisenia foetida and Eisenia andrei and thrives in a wide range of conditions.

Composting

Has been practised since man needed to return goodness to the soil. Traditionally the tried and tested method of inducing aerobic decomposition of piled organic material has been the widest employed method be it in a heap or in a composting bin. This method has certain drawbacks, rarely does the material compost equally throughout the pile even when turned, it may take a long time due to adverse weather conditions or lack of balanced ingredients, it can attract vermin and flies, it can have an offensive smell and the end result can be difficult and unpleasant to handle with little or no nutrient content.

Anybody who has had a compost heap that has been invaded by worms will recognise the immediate benefits. History shows that our predecessors have used worms to assist in the composting of organic matter but had little understanding of why they were so effective. More recently, studies into this fact have been carried out in many countries across the globe, the results of these studies show that there are far more benefits to using worms in the process of recycling organic matter, not only at the domestic level but also in large scale agricultural and industrial situations, than at first appreciated.

The benefits

First and foremost worms are an environmentally friendly and sustainable method of dealing with organic material. In working they do not use or need additional fuels whether man made or fossil, if properly managed they do not wear out and need replacing, they work 24 hours a day with very little input by man, they work in a wide range of conditions and automatically adjust themselves to these conditions.

When organic material is placed on the surface of a bed of worms it is already beginning to decay, it is being invaded by myriad bacteria, fungi, micro life and larger creatures, some of which along with the decaying matter are food to the worms, after digesting, it is excreted as “casts” earthworms often leave these as little curly mounds of soil on the surface, particularly in grassy areas. These casts are rich in nutrients and microbial life, when produced in a worm composting system they are harvested along with any compost left and the whole lot is a living world of goodness to any plants that receive it either as compost dug in or as a mulch on the surface, naturally growing plants and trees benefit from this all the time, unless man has interfered, rarely do you see naturalised plants suffering from nutrient deficiency.

As long as there is damp organic matter present, worms will continue to feed, breed and grow, they will multiply to the amount of food available and the original volume of organic material added to the bed can be reduced by as much as 90%.

What can be composted?

Worms feed on the micro organisms that are responsible for the decay in organic matter, any organic matter will grow these organisms, some materials are better than others, some are so slow they are best avoided all together, as the saying goes “if it has ever lived, worms will compost it” to be more accurate it should be “if it has ever lived, it will rot and worms will find a meal!” In the domestic situation we are looking at kitchen waste, garden waste and often overlooked, paper and cardboard. Kitchen waste should really be limited to vegetables, raw or cooked the exception being any vegetable that is a member of the onion family, including leeks, these must be thoroughly cooked first and mixed with other materials. All fruit can be fed to worms but again all citrus fruit will need thoroughly cooking, particularly the peel, when citrus fruit is fed raw it is often assumed that it is the acidity of the fruit that causes the problem to the worms, this is not necessarily the case, all peel has a substance called “d-limonene” (the vapour that sprays out when you are peeling it) it is harmful to worms but is driven off when thoroughly cooked. Cooking and “mashing” all fruit and vegetables is to be recommended, it will decompose faster, provide a bigger surface area on which the micro organisms can grow and is therefore processed quicker by the worms.

Used tea bags, coffee grounds, small quantities of bread can all be fed. Avoid dairy products, fat, grease and oil, meat and fish and bones, not because the worms will not compost these items, they will, but they will attract unwanted pests, flies etc.

Any decaying organic matter that is really smelly (not a problem to the worms!) once the worms start to process it, the smell quickly disappears, if a worm system is working effectively there is no smell.

Garden waste such as leaves, dead plants, grass clippings etc can be put into a worm bin but this usually slows the whole system down, particularly when woody material is involved, large quantities, certainly with grass clippings can cause real problems, even with small gardens the amount of waste after an afternoons gardening will overload the average domestic worm composting system, by far the best method is to pre-compost these materials in a traditional compost heap or bin and then feed the partially composted material to the worms, this way the micro life is already well established and the worms can deal with it much quicker, the same applies to the rabbit or guinea pig hutch cleanings.

Newspaper, office paper, paper bags etc (avoid glossy magazines) cardboard can all be shredded and added to the system, in fact this material plays an important part in providing the worms with a balanced micro life diet! Paper and cardboard are also helpful when the bin has become too wet by mixing in shredded paper or cardboard it will absorb some of the moisture and aerate the bin.

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Reaping the Benefits of Composting

The fundamental knowledge of our predecessors about composting, seems to have been somewhat forgotten in recent times with the increase in popularity of composting and composting with worms. This has resulted in both traditional composters and wormeries for sale that too often yield poor results.
Hence, many people give up disappointed, believing that composting in general is a waste of time. This is not so, and we believe that the problems are due to a lack of correct information and the many unsuitable products available today.

Aerobic Composting

The traditional method of composting is known as aerobic composting. Aerobic composting is where the waste to be composted is piled into a heap or a wooden container. As this is done, both moisture and air are mixed in enabling naturally occurring flora and fauna to get to work breaking down the waste. During this decomposition process heat is produced, and in order to keep this action going, more air and moisture has to be added and this achieved by moving or turning over the heap. This requires effort.
The problem we often have today with plastic based composting bins, is that they do not encourage the waste to be turned over, too frequently resulting in the composting process grinding to a halt.

Worm Composting

In the last decade or so we have seen a growth in worm composting, or vermicomposting, as it is properly known. The waste to be composted is slowly added to a colony of specialist worms that eat their way through the waste producing worm compost or casts. This product is considered to be the best of all composts.
Although, this process requires less physical effort than aerobic composting (the heap does not need to be moved), it is limited in that only relatively small amounts of waste can added and processed, which takes more time.