The ocean, the ground, rocks and trees act as carbon drains but are far from places where greenhouses gases are concentrated, especially CO2. A Spanish researcher has proposed human, agricultural and livestock waste, such as urine, as a way to absorb this gas.
Absorbing the large quantities of carbon dioxide and other greenhouse gases present in cities would require millions of tonnes of some naturally occurring substance. A study published in the Journal of Hazardous Materials suggests urine as a reactive. As a resource available across all human societies, it is produced in large quantities and is close to the pollution hubs of large cities.
"For every molecule of urea in urine, one mole (a chemical unit used to measure the quantity of a substance) of ammonium bicarbonate is produced along with one mole of ammonia, which could be used to absorb one mole of atmospheric CO2," as explained to SINC by the author of the study, Manuel Jimnez Aguilar of the Institute of Agricultural and Fisheries Research and Training of the Regional Government of Andalusia.
After absorbing the CO2 another unit of ammonium bicarbonate is produced, which is used in China as a nitrogen fertilizer for 30 years. Jimnez Aguilar points out that "if applied to basic-calcium rich soils this would produce calcium carbonate thus encouraging gas-fixation in the ground.
To avoid the urine from decomposing, the researcher suggests the possibility of including a small proportion of olive waste water (a black, foul-smelling liquid obtained from spinning the ground olive paste). This acts as a preservative. The researcher confirms that "the urine-CO2-olive waste water could be considered an NPK fertilizer (ammonia-nitrate-phosphorous-potassium)."
The result is that the urine mixed with a small percentage of olive waste water can absorb various grams of CO2 per litre in a stable manner and
FECYT - Spanish Foundation for Science and Technology