In most places water that enters a storm drain will go directly to a local body of water, it generally does not get treated at a wastewater plant. 

That means all those toxic pollutants that are swept away in rain and runoff could end up directly in our waterways. A solution that is becoming more and more prominent is green stormwater filtration infrastructure; called Biorentention cells.

There are many different forms of stormwater filtration designs, many use biology such as plants to absorb excess nitrogen and heavy metals. Most use different sand medias as well.  These are important elements of an urban environment because they help reduce the amount of toxic chemicals, road grime, and excess fertilizer that are washed into waterways. 

Researchers at the Department of Crop, Soil and Environmental Sciences at Auburn University in Alabama have studied the effects of adding natural clinoptilolite zeolite to these biorentention cells. 

By replacing a mere 10% of the sand with natural clinoptilolite zeolite the researchers saw a 15% increase in ammonia removal, and increased the saturated hydraulic conductivity by up to 55%. The overall cation exchange capacity, CEC, of the cell, was also improved. 

Bioremention cells containing as little as 10% zeolite were shown to remove 98% of the total zinc, 85% of the total copper, 96% of the total phosphorous, and 85% of the total ammonium.

Read the original paper here: https://acsess.onlinelibrary.wiley.com/doi/epdf/10.1002/ael2.20060

Or download a copy here: https://drive.google.com/file/d/1slX9mTXzQAzRVD1tJCA2t72kqkxKfD9R/view?usp=sharing