Wastewater can’t be used for much of anything. In fact, it’s pretty much not able to be used for anything at all, unless it’s been treated. Forward osmosis may provide a cost effective way to clean water in the future to bring more options for wastewater that isn’t consumable.
Reverse osmosis is already in use today but it is an expensive process. That being said, it does provide clean drinking water to areas around the world that would otherwise not have as much access as water is limited there.
That’s not the case with the process. The way it works pretty much ensures the water will have some contaminants making it unsafe for drinking but it would still be useful for irrigation, cleaning and other non-consumption activities which would leave more fresh water for drinking. This is still being researched but may lead to new paths in the future.