There are a number of parameters we need to take into consideration.
- We need to make sure that the process kills all the fungi, algae and bacteria.
- We need to ensure the water does not smell.
- We want to remove the soaps and surfactants to the extent that all foam is removed.
- The treatment costs money in power and perhaps chemicals. So, the question is to what extent do we process. Where is the balance between effectiveness and cost?
- Because we use ozone to oxidize the soaps, all the C, N, Cl atoms will be removed from the water as gas. However, the sodium from soap and from sodium hypochlorite remains in the water. This will build up the salt concentration and the pH of the water. Hydrochloric acid can fix the pH. But eventually some water needs to be discarded to prevent excessive salt accumulation.
- We need to be aware that there is no point recycling, when the cost rises beyond the cost of buying extra fresh water.