6. Before deciding on the Sludge Minimisation Facility 16 other options were considered. After a process of cost-to-benefit analysis, and assessment for community and business needs, and mana whenua values, this was selected as the best fit for Wellington.
7. The new facility will reduce the volume of treated sludge produced by up to 80 percent, or the equivalent of 11 full Olympic-sized swimming pools, per year.
8. It will reduce carbon emissions created by the treatment and processing process by up to 60 percent.
9. Sludge will be treated first by thermal hydrolysis – which acts like a pressure cooker on the sludge, breaking down its molecules so it’s easier to digest in the anaerobic digester.
10. What’s an anaerobic digester? It’s a sludge treatment process which mimics the natural decomposition process of waste, breaking down biodegradable matter in the sludge.
11. The sludge will help power all this treatment – as it breaks down it will produce a biogas that is captured and used to create heat and electricity to help run the process.
12. This process creates what’s known as a Grade A biosolids product, which is pasteurised (so safe from a germ and disease perspective) and odourless.
13. That new product will have the potential to be used productively, including as a soil conditioner, fertiliser, and fuel for industrial heat.
14. If we don’t provide a sludge treatment solution for Wellington, we’ll have to truck raw sludge out of the city when the current Southern Landfill consent expires in 2026.
Site works to make it possible to build our new facility at Moa Point are due to start soon, keep an eye on our channels – we’ll make sure you’re updated.