NEW ZEALAND - Steve Mace is passionate about his work - inspired by the massive environmental contribution worms will make when used in a sewerage system that will serve the two towns of Wyndham and Edendale.
Mr Mace is the managing director of BioFiltro, which is based in Wyndham, and has become somewhat of a pioneer.
His company recently built the first vermiculture sewerage system of its kind in New Zealand.
There are about 75 worldwide.
The system was completed two months ago and all that remains is for the households to be connected.
He joked he would be putting a picnic table and chairs at the site as it would be odour-free and the system would be a wonder to behold.
Mr Mace and former Fonterra Edendale site manager Max Parkin were directors in the company and they also had an investor, he said.
Mr Mace described the system as being "no-frills" with low overheads and no odour.
"We like things clean, to look clean and people won't smell it," Mr Mace said.
The system had been designed to take up to 528,000 litres of sewage a day, he said.
The sewage would be piped into the site and would go through a self-cleaning filter system, which included a standby alternative programmed to kick in if there was a problem, solids would be scraped out and put into a wheelie bin.
The self-cleaning mechanism meant the potential for odour was eliminated, Mr Mace said.
There are two underground tanks each capable of holding 100,000 litres.
This means the system has a 12-hour storage capability.
The wastewater is then sprayed on a packed bed of plastic, screens, sawdust, rocks and bacteria.
Worms within the sawdust bed provide aeration and consume the bacteria to create humus.
One of the features of the system was the standby equipment, which featured at nearly every step of the operation including when the effluent was sprayed on to the bed, he said.
The effluent is sprayed on to the bed for 15 minutes, then there is a 10-minute rest period between bursts.
The system runs 24 hours a day.
The worms are at the top of the food chain - they consume bacteria and create pathways through the sawdust, which provides oxygenation.
The remaining clear liquid was treated by a UV unit before being discharged into the Mataura River, Mr Mace said.
The system is extremely quiet with the noise barely audible.
Stainless-steel piping is used in the new system because it lasts longer.
Because Mr Mace and Mr Parkin are from the dairy industry, which is used to getting projects up and running in a tight timeframe, the project was managed to come in within budget and within the timeframe set out and without varying the original plan.
The whole site was contained in a fraction of the land that would have been needed if a lagoon system had been installed, Mr Mace said.
It had been estimated the total cost of the project would be $1 million less than installing a traditional sewage treatment method.
The plant had its own worm farm and tiger worms were used in the operation, he said.
The worms will become a self-sustaining population.
The worms have been fed milk powder and water, but had cow manure added to their diet recently just to get them used to the change in diet they will encounter when the system is hooked up.
"After a while it [the bed] will be just like a writhing plate of spaghetti," he said.
It took 45 days for a worm to mature and there were 10 to 15 worms in one egg and each worm had a life-span of 12 to 14 months.
There was a potential that each worm could have 300 offspring, he said.
The system is also compatible with other conventional sewerage systems.
It can be set up alongside existing systems to provide efficiencies.
While the humus was rich in nutrients, there were a lot of regulations around the use of such material in New Zealand and as yet it could not be used by consumers, he said.
However, that is not the case in Chile where gardeners could buy humus in 1kg bags.
Mr Mace believed that once the New Zealand Government had established that the product was stable and free of pathogens and viruses, it would be able to be sold commercially.
from The Otago Daily Times
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