2020 | Australia | Emma Serisier

CRACK for the FUTURE: The use of eggshell waste as a bio-adsorbant of phosphates for water and soil quality

Water issue adressed: Too dirty

Phosphate run-off into natural waterways from agricultural fertilisers and animal manures can cause eutrophication.  Agricultural operations are large consumers of non-renewable fertilisers and large producers of biowaste materials.  These issues come at great economic and environmental cost.

This study’s aim was to offset these issues by identifying eggshell as a potential biowaste adsorbent, examining its effectiveness in decreasing the orthophosphate concentration in aqueous solutions, and its direct application to run-off areas as adsorbents and soil conditioners. Eggshell was selected based on its abundance, availability, cost, renewability and biodegradable properties. Tests conducted in simulated superphosphate run-off rainwater over 24 hours, indicated that eggshell decreased orthophosphate levels by 62% on average.  Testing on eggshell waste, at 6 hourly intervals and in manure/rainwater run-off simulation, showed average orthophosphate reductions of 59% and 55%, indicating effective adsorption. Costs and benefits were investigated comparing the use of eggshell waste for the dual purpose of phosphate adsorption and soil conditioning.  A mathematical model and website (www.po4cleaner.com) was developed to calculate cost savings and application rates of eggshell. History has shown that global change is achieved through action on a local scale. The website provides farmers with a free, accessible tool to help counteract their environmental footprint and create global change. This study concluded that the economic and environmental benefits of agricultural use of biowaste products, such as eggshell, as an adsorbent and soil conditioner, appear to have been undervalued and underutilised.

Project video

This is how I came up with the idea for this project:

Growing up on a property exposed me to the unique balance within ecosystems and the absolute power of nature and its forces. I observed eutrophication and water pollution first-hand which lead me to search for simple solutions to this problem.


Ania Andersch

Programme manager ania.andersch@siwi.org +46 8 121 360 59