There has been a trend in recent years for renaming some standard terms in the wastewater industry. Wastewater Treatment Plants (WWTP) are now being increasingly called Wastewater Recovery Plants (WWRP) and wastewater sludge should be referred to as biosolids for example. Some wish to actually change the name of wastewater itself!
So why is this happening?
Well, the most interesting components in typical municipal wastewater (we will keep calling it that for now) are the organics, which we will measure using the term chemical oxygen demand (COD) or how much oxygen is needed to remove them, ammonium and phosphate. We want to prevent these components from getting into our rivers and streams. But if instead of just looking at how to get rid of them, we look at how we might be able to extract and use them, we start to see how the term recovery can be used instead of just treatment.
So why are these components worth recovering?
The COD can straight away be converted into useable energy as biogas and ammonium and phosphate are important for fertilizers.
A term that was exciting a few years ago but seems to have dropped off most peoples radar at the same time they forgot about the whole ‘peak oil’ thing was ‘peak phosphorus’.
Looking at the above graph it is interesting to see that although there is a downward trend in searches for ‘peak phosphorus’, the large peaks in interest were followed by chunks of noone searching in the first few years after 2004 while more recently there seems to be a more sustained albeit lower interest.
I hope that this means there are still people keeping an eye on the ‘disappearing nutrient’. In the wastewater industry there are definitely people looking at all sorts of ways of recovering the phosphorus we are flushing down our toilets. Things like ion exchangers, membranes, electrochemistry and algae are all being investigated as possible methods for recovery.
I personally like the idea of capturing the phosphorus and nitrogen in algae. This algae can then be directly used as a fertilizer on crops. But then we don’t call it fertilizer anymore, we call it Biofertilizer…