Turning Biowaste into Compost

The Thames Coromandel District is one of the very few districts in the country mixing biosolids with green waste and turning it into Grade Aa compost with its own Biosolid Composting Facility.

“This is an innovative and sustainable outcome of creating a beneficial product from human waste,” says Thames Coromandel District Council Project Manager Rob Paterson. “This waste would otherwise be disposed of in landfill at an on-going cost to the ratepayer and the environment.”

The retail grade compost will be used on our parks and reserves with the long-term plan that it’s sold to people who can use it to fertilise their gardens, orchards or nurseries.

A rigorous trial was carried out over six months at the Tairua Refuse Transfer Station in which the council followed strict conditions and underwent independent testing and monitoring by the Waikato Regional Council.

Included as part of this process was the establishment of strictly controlled field site trials in which the compost was spread and monitored in the open environment.

The trial proved the compost was safe and of a Grade Aa quality which means it is like any other compost available from retailers. As with the use of all compost products widely available for use by gardeners, caution must always be taken when handling compost.

The composting facility opens up even more opportunities to reuse some of the waste we generate on the Peninsula and reduce the amount disposed of in landfill.

Thames-Coromandel residents produce around 1,673 tonnes a year of biosolids and wastewater treatment plant screenings which are sent to landfill at Tirohia, contributing to the 18,029 tonnes per year of total waste to landfill.

Frequently Asked Questions.

What is Biosolids?

Biosolids is the nutrient-rich organic materials resulting from the treatment of domestic wastewater in a specialized treatment facility

What is Green Waste?

Green Waste is biodegradable waste that can be composed from tree or plant matter. Green waste can also be domestic and commercial food waste. At this stage our Biosolid composter will only be taking garden green waste, not food scraps.

Why is it a good thing to combine the two?

The alternative to creating compost from biosolids at our composting unit would be to transport the material to landfill, where methane gases and C02 is released.

Field Utilities Rep Evan Vaughters explains that the heating process not only retains the carbon inside the compost – making it carbon rich – but has been found to have much wider benefits in combatting global warming.

“Once you put that into the ground, our backyards effectively become carbon sinks, since it has been shown to help extract carbon from the atmosphere.”

2 comments on “Turning Biowaste into Compost

  1. What do you think about turning human waste into compost – I think it is ok for amenity horticulture in the right places but not for food…?

  2. ex hippy on said:

    We used to compost all our faecal and urinary waste. We were miles from nowhere and the compost heap was a long way from our house. it was a distasteful job but the high nitrogen component meant that the compost quality was excellent – fine, black and silkie. it grew vegetables to the size we’ve never been able to replicate since our return to ?civilization. Can’t see how practice this could be applied to most other households though.

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