Composting toilets are designed to convert materials into humus - a rotted but not matured material, which is free of harmful pathogens and safe to handle. Before compost is buried, however, it is recommended that it matures - becoming soil-like in its smell and appearance.
If you've got a continuous or batching split-system, there is no need for a Secondary Treatment System - both of these mature compost in the chamber. If you have a self-contained system that requires frequent emptying, however, it is WCTNZ® recommended practice to set up a secondary treatment system in which the compost can mature prior to burial. This gives compost ample time to break down, readying it for removal into your designated land application area. This process is especially important in NZ, where we have limited seasonal warmth.
Setting up a Secondary Treatment System is easy!
All you need to set up your Secondary Treatment System is 2* x 220L, open-base compost bins that are sealed around the sides (do not use flat packs as they can leach through the sides).
Here is how to use your Secondary Treatment System:
- Place the bins in a sunny location on your property, and allocate a 1 year retention period to each.
- Empty the contents of your composting toilet's chamber into one bin for one year.
- Leave the bin that you have been using to collect compost to sit and mature the compost for a further year.
- Empty the contents of your composting toilet's chamber into the second bin for one year, while the first bin matures its contents.
- Once the first bin has matured the compost within, empty and bury its contents into your designated land application area.
- Put the first bin back into use to collect compost from your composting toilet for a year, while you mature the contents of the second bin.
- Use the bins on the rotational basis described above.
IMPORTANT: use the Secondary Treatment System to collect compost from your composting toilet only. Do NOT add foreign materials such as food scraps. You can add green and brown garden matter, but make sure honour ratio proportions of 2 parts brown: 1 part green. (Green is fresh garden material, brown is decayed).
*More composting bins may be required, depending on number of users and climate.
Choosing the Best Location for your Secondary Treatment System:
- Place the composting bins 2m away from boundary lines, 3m away from the main property, and up to 10m away from a downwards slope that leads to a boundary line.
- Place the bins in a dry location with maximum sun exposure. Note that in summer, some re-hydration of the compost may be required. In hot climates (24+ degrees), a shaded area may be preferred.
If setting bins up on a slope, you will need to remove a layer of grass, level the soil, and chip in a channel on the high ground behind the bins to avoid surface water run-off washing out the base of the compost pile.
Need help choosing a system? Call WCTNZ® on 0800 022 027 for free advice on system specification and setup. Advanced design consultancy services are also available.
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