Extract phosphorus from dairy waste water

New technology recycles disappearing essential nutrient to ensure that it doesn’t end up where it isn’t needed


Researchers in Israel have developed a way to create phosphorus fertilizer from dairy waste water. If implemented on a large scale, the process could help stretch Earth’s finite supply of phosphorus.

Scientists have warned about a disastrous shortage of phosphorus in 100 to 250 years unless we can find ways to recycle it. Phosphorus is a basic component in all life forms. Without it, nothing grows or survives.

As a side benefit of the process, the researchers take the phosphorus from the dairy waste water and combine it with aluminum that’s left over from making clean drinking water.

“The material left after purification is called aluminum water treatment residue, and it’s normally taken to a landfill to be buried,” said Michael Litaor, lead researcher on the project from Tel Hai College and MIGAL Institute.

We changed this material by mixing it with dairy wastewater rich with phosphorus and organic matter. It can be just as good as common fertilizers.”

In their study, Litaor and his team mixed the aluminum water treatment residue with dairy waste water that comes from washing cow udders before milking and from cooling cows during hot summer days.

It is high in phosphorus because of detergents used while cleaning sheds, as well as runoff from cows urine.

The chemical reaction between the phosphorus, aluminum and organic matter results in fertilizer. Litaor then put the fertilizer on lettuce and found that it did just as well as common commercial fertilizers.

“This experiment clearly showed that we can use aluminum refuse to capture phosphorus from dairy waste water and use it as fertilizer. We showed that the water treatment residue can take phosphorus from the waste water and put it in soil that doesn’t have much phosphorus. This may offset somewhat the mining of this non-renewable resource.”

If this method of making fertilizer became widely practiced, Litaor sees the possibility of building plants next to large dairies. In addition, leftovers from other water treatment systems could be brought to the plant to produce large quantities of commercial fertilizer.

However, scientists must show that no unwanted material such as hormones and antibiotics are in the fertilizer.

The next step in his research is to look at water treatment leftovers that contain iron, because many soils lack this element.

“I want to find an investor who will support us taking this idea to the marketplace. After many years of research on phosphorus in wetlands, streams, and rivers, I decided to look for an efficient means to recycle the element using wastes we were already producing.”

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