Worms for Waste Management

July 2011

An abbatoir uses worms to manage the process waste stream on site

An abattoir in Ashburton trying to reduce waste disposal costs and become environmentally friendly has developed a worm farm with a profitable byproduct.

Ashburton Meat Processors (AMP ) is one of the few privately owned abattoirs left in NZ.

It is a wholly owned subsidiary of Verkerk ltd.

Seven years ago Ashburton Meat Processors was told it would have to pay to cart offal out of town. Their waste product used to be put into the Ashburton landfills offal pit. But when the landfill closed they were faced with the option of trucking that waste to Christchurch or coming up with another plan.

That got them looking for an alternative solution and in the process created another business.

The company bought hundreds of kgs of worms and moved into the worm farming business.

In March 2004 they took delivery of the offal eating tiger worms from a worm farm in Cromwell.

Initially the worm farm was built in long rows on the ground but its become more sophisticated with worms housed in boxes with mesh floors to allow the vermicast to fall through.

The worms were $45 a kilo which was easily more expensive than any of the cuts of meat the abattoir processes.

All up the company spent around $200k setting up the farm and buying in the worms. But with an annual fee of $75k to use the landfill, it didnt take long to pay off their investment.

Turning offal into compost has to be done reasonably carefully. The worms have to be given the right amount of food. The worms food is topped up every six days or so. Too much food isnt good for them. The worm boxes also have to be kept well watered and at an optimum temperature between 18 and 24 degrees.

The waste is largely paunch and toenail waste along with cardboard and paper waste. Brad says approximately 30 tonne of waste material per week. The waste material is first pulverised by a silage cutter. This is then spread over the farm in a six day rotation.

The tiger worms the farm is using live six to eight years and breed every 21 days.

With that kind of breeding cycle they arent far off selling worms as well as the vermicast the worms produce.

Aside from being kept wet and warm they arent too demanding. If they arent kept warm they simply march off.

Nowadays all the plants waste material is disposed of on site. Brad comments that meat processors have traditionally had a fairly poor environmental reputation but their investment in the wormfarm has dealt with that. The farm has also dealt with the smell issue since the process is essentially odourless.

On-going trial work is happening with raised beds being one area they have looked at.

Each week around 16 tonnes of organic waste material is produced on site. That is then fed to 1000 metres of worm beds. The worms eat their way through that material and the end result is vermicast. The vermicompost isnt sterilised and biologically alive.

The product is screened and bagged for retail sale(marketed as Wormworx).

After about four years the system was pretty well up and running and gardeners, vineyards and even local farmers are using the vermicompost. Brad told me one local dairy farmer says his urea application has plummeted since he started using their product.

Advantages are that it is a natural alternative to chemical or artificial fertilizers. It has a neutral ph and is virtually odourless. The nutrients from vermicast/compost are immediately available to the plants. It contains N, K, magnesium, carbon, iron. Advocates of vermicast/compost also point out that it contains micro organisms, bacteria and enzymes and 50% more humus than what is found in topsoil.

It sells for about $420 a tonne. It is a nutrient rich organic soil conditioner.

The AMP has hung onto some the vermicast it produces and has planted out an area in grapes, fruit trees and ornamentals.

The Verkerks owned plant has been the winner of an award recognising its green approach to business - the Wastebusters Clean Green Business Award.