Advanced Water Management Centre

AWMC Seminar Program: Sludge lagoons – an overlooked source of GHG emissions

Ms Sarah Aucote (PhD student, AWMC) will give her first year confirmation presentation. 

Abstract: Wastewater treatment forms an essential component of modern society, however is recognised by the Intergovernmental Panel for Climate Change as a significant contributor to anthropogenic methane and nitrous oxide emissions. Emissions are driven by carbon and nitrogen microbial cycling that are promoted in wastewater to remove organic matter and nitrogen. Sludge lagoons are commonly employed to achieve dewatering or drying of biodegraded wastewater sludge in large Australian wastewater treatment plants (WWTPs) due to the arid climate and inexpensive land. Additionally, small WWTPs, a feature of prominent regional Australia, use lagoons for the stabilisation of untreated sludge, which is more biodegradable compared to degraded sludge. While lagoon dewatering is advantageous from an economic and operational perspective, the extended open drying of sludge has recently been shown to contribute significant methane emissions. An indirect mass balance quantification model indicated that sludge lagoon methane emissions could represent one-quarter to two-thirds of the total WWTP carbon footprint. Aside from this study, sludge lagoon methane emissions have previously been overlooked, which warrants further investigation. Additionally, Australian water utilities have a legal requirement to report and subsequently reduce methane emissions, highlighting the need to employ mitigation efforts. This research aims to directly quantify methane as well as nitrous oxide emissions from sludge lagoons, and subsequently investigate mitigation strategies, through the establishment and analysis of laboratory column incubations that mimic these systems. Sludge types affiliated with both large and small WWTPs will be compared for a holistic Australian assessment of emissions. Direct intensive depth profiling of physiochemical and molecular variables over time will reveal the fate of nutrients and the abundance of microorganisms that drive GHG emissions. Minor operational treatments, that can be readily sourced from other parts of the WWTP, will be applied as strategies to attempt to mitigate GHG emissions. One such strategy is the introduction of nitrate with the aim to encourage biological methane oxidation. Toxic nitrite supply will be the other strategy with the aim to inhibit methane production as a biocidal agent. A particular focus will be placed on the elucidation of activity by assessing microbial communities that govern methane metabolism and nitrous oxide production.

AWMC hosts a free seminar every Friday from 9am.

Event Details
Date & Time: 
Friday, 25 October 2019
9am - 10am
Venue: AIBN Building 75, Level 1 Seminar Room
Speaker(s): 
  • Sarah Aucote

Event Contact: awmcseminars@awmc.uq.edu.au