Phosphorus adsorption and organic release from dried and thermally treated water treatment sludge

Minh Duc Nguyen; David Donaldson; Sirjana Adhikari; Negin Amini; Deepak Surendhra Mallya; Michael Thomas; Ellen M Moon; Nicholas A Milne

doi:10.1016/j.envres.2023.116524

Phosphorus adsorption and organic release from dried and thermally treated water treatment sludge

Environ Res. 2023 Oct 1:234:116524. doi: 10.1016/j.envres.2023.116524. Epub 2023 Jun 28.

Authors

Minh Duc Nguyen¹, David Donaldson², Sirjana Adhikari¹, Negin Amini³, Deepak Surendhra Mallya¹, Michael Thomas⁴, Ellen M Moon³, Nicholas A Milne⁵

Affiliations

¹ School of Engineering, Deakin University, Waurn Ponds, Victoria, 3216, Australia.
² School of Life and Environmental Sciences, Waurn Ponds, Victoria, 3216, Australia.
³ School of Engineering, Deakin University, Waurn Ponds, Victoria, 3216, Australia; ARC Centre of Excellence for Enabling Eco-Efficient Beneficiation of Minerals, School of Engineering, Deakin University, Australia.
⁴ Barwon Water, Geelong, Victoria, 3220, Australia.
⁵ School of Engineering, Deakin University, Waurn Ponds, Victoria, 3216, Australia. Electronic address: n.milne@deakin.edu.au.

PMID: 37390952
DOI: 10.1016/j.envres.2023.116524

Abstract

The study investigated water treatment sludge (WTS) as a phosphorus (P) adsorbent and examined the release of organic matter during the P adsorption process. Previous studies indicated that WTS is an effective adsorbent for P but also releases organic matter, which may affect the organoleptic properties of treated water, but no study has characterised organic release and conducted an in-depth study on its behaviours. This study characterised the organic release during the P adsorption process from four different WTS samples. This study also offers results from a 60-day column experiment that indicate that WTS columns effectively removed the majority of P from the 2 mg/L feed solution. The total organic carbon (TOC) release was gradually reduced from 24.9 mg/L on day 1 to stable levels of 4.4 mg/L to 4.1 mg/L from day 22 onwards. After 60 days, when the organic matter was nearly exhausted, WTS columns were still effective in P adsorption from the solution. In addition, the thermal treatment of WTS at different temperatures was investigated to reduce TOC release and increase P adsorption. The results showed that thermal treatment not only minimized TOC release but also enhanced the P adsorption capacity of the sludge. In a 24-h batch experiment, WTS treated at 600 °C showed the highest P adsorption (1.7 mg/g) with negligible TOC release when compared to sludge treated at 500 °C WTS (1.2 mg/g), 700 °C WTS (1.5 mg/g) and dried WTS (0.75 mg/g). However, the release of inorganic compounds slightly increased after thermal treatment. Future studies could focus on determining whether the thermal processing of WTS which can enhance the WTS's adsorption to emerging pollutants like per- and poly-fluoroalkyl substances and other contaminants. The findings of this study could influence the management practices of water authorities and contribute to the water sector's sustainability objectives.

Keywords: Organic release; Phosphorus adsorption; Thermal treatment; Water treatment sludge; Zero waste..

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adsorption
Phosphorus
Sewage
Water Pollutants, Chemical* / analysis
Water Purification* / methods

Substances

Sewage
Water Pollutants, Chemical
Phosphorus