Sambles of biochar are shown in a lab at the Desert Research Institute (DRI) Tuesday, Oct. 19, 2021. The char is used to remove contaminants from water.
Monday, Oct. 25, 2021 | 2 a.m.
Imagine taking plant scraps from your garden, sticking it in a special oven to turn it into charcoal, and then using that charcoal to filter toxins out of water.
And, finally, once the charcoal finishes filtering out toxins, reusing it as fertilizer in that same garden.
The Desert Research Institute’s Environmental Engineering Lab is experimenting to accomplish that very feat.
“The impact of climate change in large quantities is very well known,” said Erick Bandala, assistant research professor and director. “We are expecting to have less rain, less precipitation. … And it’s very easy to see that from the level of (Lake Mead).”
Something that is missing, however, is information about the quality of water that we do have, Bandala said. “Because no matter how much water you have, if the quality is not good enough you cannot drink it.”
The lab is developing new technologies that can be used for removing pollutants found in water, as some contaminants cannot be removed in natural ways like biodegradation and absorption, Bandala said.
An excess of nitrate is found in water, especially in the northern part of the state where nutrients from fields infiltrate the soil and reach the groundwater, Bandala said. Drinking it can make people sick.
The idea is to develop new ways to remove those toxins using simple and cheap materials so that they are easily accessible to people in both rural and urban areas, Bandala said.
One way to do this is through the use of different types of chars, which are made out of different materials like pine chips by Lake Mead or garden waste that are put into a kind of biochar oven that heats the material up at a higher pressure. The chars look like little bits of charcoal or dark sand, and they range in color depending on what they are made of and at what temperature they are heated.
So far the lab has found that their modifiable char is up to three times better than the other methodology of using activated carbon to filter toxins out of water. The team is writing a paper exploring how to use different chars that come from three or four different materials, Bandala said, with each char targeting a different toxin.
“Think of it more like a polishing system at the end of the (water) treatment,” said Adam Clurman, a student research assistant in the lab.
Nadir Nabah, another student at the lab, is experimenting with hydrochar, a type of char material made through hydrothermal carbonization, which is the process that uses heat to turn wet biomass feedstocks to char. The char will be used as a safer alternative to fertilizers, many of which leach harmful chemicals into groundwater and can contribute to overnitrification of water bodies.
To clean water, the char is placed in a long container that the water runs through, said Ahdee Zeidman, laboratory technician.
Biochar and hydrochar are similar, but one requires the material to be dried whereas hydrochar requires the use of water.
Clurman is working on taking plastics and turning them into chars that will also be able to filter water, a project that is in its preliminary stages. While cleaning water, it will also help address the large amounts of plastic pollution in the Earth’s oceans.
“We’re excited with the idea of finding a way to reuse the plastic waste,” Bandala said. The plastic char was tested and was found to remove dyes from water.
The team is hoping to get the grant to continue working on the experiments, which will take at least four years.
