Despite the availability of alternatives like dry composting toilets and greywater separation, wastewater continues to be a huge global problem. The amount produced, as well the diversity of contaminants, is on the rise. But wastewater from toilets is comparatively easy to treat using ecological methods.
One method is aerobic composting, in which the solids are retained in a chamber where they are composted in the presence of air.
This can be done using compost worms, which naturally live in manure heaps, to digest the solid waste into a nutrient-rich liquid known as “worm juice”.
This, along with the water, then flows out of the chamber into a soakaway filled with wood chips, where the nutrients are absorbed, broken down and become available to nearby plants.
Another method is anaerobic digestion, in a system called a biodigester. Anaerobic disgestion takes place naturally whenever animal or human waste is mixed with water, and produces methane, a powerful greenhouse gas.
But in a biodigester, this process happens in a controlled way. The methane is captured and can be used for heating, cooking, or to generate electricity, while the remaining “digestate” is used for fertilizer.
Biodigesters can be either commercial or home-made, can deal with waste from the kitchen, garden or farm as well as from toilets, and can be of any size from domestic upwards.
Another approach to blackwater treatment is known as a constructed wetland. Normally this involves separation of solids—which can be treated either aerobically or anaerobically, as already mentioned—followed by a series of containers in which plants and microbes progressively purify the water, as happens in a natural wetland.
A similar system, consisting of tanks with plants and fish often placed in a greenhouse, is known as a Living Machine.
The same processes can be used to clean natural and artificial bodies of water, sometimes using artificial floating islands to host the organisms that do the work of purification.
By applying these different techniques of ecological wastewater treatment, we can heal our relationship with water and enjoy a cleaner, healthier world at very little cost.