In-Vessel Composting Down Under or Does Compost Fall Out of Agitated Beds in New Zealand?

Sustainable agriculture and resource recovery are two concepts the county of New Zealand is moving forward with vigorously. Composting such solid and liquid resources discharged by society can move the county toward its goals in both of these areas. This paper presents data on a compost facility that commenced operations in 1999, and is now marketing the product in the North Island of New Zealand.Wastewater from the City of Wellington, New Zealand, had been discharged to Cook Strait for many years until the Moa Point Wastewater Treatment Facility was upgraded in 1999. While the result was a dramatic improvement in effluent discharged to the Strait, the biosolids now presented the challenge. Ultimately, the City selected a team of engineers and composters, led by the Living Earth Company and Waste Management, NZ, to construct an agitated bed compost facility that would compost the dewatered biosolids, but also shredded brush and pallets delivered to the site. The facility composts typically about 20 to 30 dry Mg per day of biosolids dewatered to 25%, along with 125 Mg per day of shredded greenwaste. Living Earth markets the 200 to 300 cu m per day finished compost output in the Wellington area to garden stores, parks, and home gardeners.