An innovative and sustainable water treatment technique using re-purposed organic wastes

Natural organic matter (NOM) is a key component of drinking water sources, significantly influencing water quality. Developing a sustainable and low-cost technology to efficiently remove NOM is a prime concern for delivering cleaner, and safer water. Biological filtration using activated carbon (AC) is an effective, environmentally friendly technology to remove NOM and improve water quality. Activated carbon derived from a renewable source material offers a promising potential for the water treatment sector. In this novel research we have developed an innovative filter media by producing a lab-made activated carbon from garden-organic waste to introduce a more economic and eco-friendly way of treating water. Australia aims to halve the amount of organic waste sent to landfill by 2030, a source that contributes 3% of the nation’s total emissions. Garden organics made up a major portion of Australia’s core organic waste. This approach not only creates a new avenue in water treatment, but also provides a sustainable pathway for managing huge pile of organic waste, which is not only a challenge in Australia but worldwide.

A long-term continuous filtration operation was performed in the School of Engineering, Deakin University and completed in July 2024. A systematic approach was considered for AC production, involving carbonisation and activation within a temperature range of 300 to 800 °C. The production parameters were optimised to improve the physicochemical properties of AC to be applied as an adsorbent. Five different carbon media including garden-waste-derived-AC, commercial AC and biological activated carbon with pre-established biota (BAC) were used to understand their biofilm holding capacity and performance to remove NOM from a drinking water source. During the initial phase of operation, garden-waste-based AC experienced significant fluctuations in the dissolved organic carbon (DOC) removal, however, it ultimately achieved steady DOC removal within the same timeframe as commercial AC. After 8 months of operation, garden-waste-based AC successfully supported biofilm formation evidenced by the effluents’ steady DOC, scanning electron microscope (SEM) and fluorescence imaging. Notably, the DOC removal performance by garden-waste-based AC was comparable to commercial AC, despite having a much smaller surface area. Moreover, garden-waste-based AC showed an outstanding performance in removing UV-absorbing substances including the aromatic NOM content of water, particularly within the molecular weight range of 100-4000 Da. This research offers important insights into the conversion of waste-based AC into biological AC for removing NOM from drinking water sources, exemplifying a clear avenue for increased circularity of resources within the water industry.

The following journal article has been published as an outcome of this research:

Binte Razzak N.R., Milne N, Moon E. Conversion of municipal garden waste to activated carbon: Laboratory production and characterization comparing production parameters, Chemical Engineering Science, Vol 299 (Nov 2024). 
https://doi.org/10.1016/j.ces.2024.120487