An investigation into the impacts of water demand management and decentralized water recycling on excess sewer sediment deposition

Madhu K Murali; Matthew R Hipsey; Anas Ghadouani; Zhiguo Yuan

doi:10.1016/j.jenvman.2020.111788

An investigation into the impacts of water demand management and decentralized water recycling on excess sewer sediment deposition

J Environ Manage. 2021 Feb 1:279:111788. doi: 10.1016/j.jenvman.2020.111788. Epub 2020 Dec 10.

Authors

Madhu K Murali¹, Matthew R Hipsey², Anas Ghadouani³, Zhiguo Yuan⁴

Affiliations

¹ Department of Civil, Environmental and Mining Engineering, The University of Western Australia, 35 Stirling Hwy, M051, Crawley, WA, 6009, Australia; Cooperative Research Centre for Water Sensitive Cities, Level 1, 8 Scenic Boulevard (Building 74), Monash University, Clayton, VIC, 3800, Australia. Electronic address: madhu.murali@research.uwa.edu.au.
² Cooperative Research Centre for Water Sensitive Cities, Level 1, 8 Scenic Boulevard (Building 74), Monash University, Clayton, VIC, 3800, Australia; UWA School of Agriculture and Environment, The University of Western Australia, 35 Stirling Hwy, M004, Crawley, WA, 6009, Australia. Electronic address: matt.hipsey@uwa.edu.au.
³ Department of Civil, Environmental and Mining Engineering, The University of Western Australia, 35 Stirling Hwy, M051, Crawley, WA, 6009, Australia; Cooperative Research Centre for Water Sensitive Cities, Level 1, 8 Scenic Boulevard (Building 74), Monash University, Clayton, VIC, 3800, Australia. Electronic address: anas.ghadouani@uwa.edu.au.
⁴ Cooperative Research Centre for Water Sensitive Cities, Level 1, 8 Scenic Boulevard (Building 74), Monash University, Clayton, VIC, 3800, Australia; Advanced Water Management Centre, Level 4, Gehrmann Laboratories Building (60), The University of Queensland, St Lucia, QLD, 4072, Australia. Electronic address: z.yuan@awmc.uq.edu.au.

PMID: 33310241
DOI: 10.1016/j.jenvman.2020.111788

Abstract

Sewers are a critical part of the urban water system and represent a considerable investment due to the presence of extensive networks in many cities. Consequently, excess sewer sediment deposition, from changed inflow conditions or lack of appropriate sewer infrastructure, can lead to significantly increased maintenance and operational costs. The main aim of this manuscript is to quantify the potential impacts of reduced inflow and increased sediment concentrations from the implementation of sustainable water practices, such as Decentralized Water Recycling and Water Demand Management, on excess sediment deposition in gravity sewers. Experiments in a sewer pilot plant, with municipal wastewater, and modelling using a comprehensive local-scale sewer sediment model were used in conjunction to address this aim. Results from both these methods indicated that a reduction in inflows from the moderate implementation of sustainable water practices had a large impact on the quantity of sediment deposited in gravity sewers. However, further modelling showed that the reduction in bed erosion during peak flows for the same implementations of sustainable water practices occurred more gradually. Overall, our findings showed that in existing gravity sewer mains with reasonable slope and flow velocities, a moderate decrease in peak flow velocity of around 15% due to the implementation of Decentralized Water Recycling and Water Demand Management was unlikely to result in a net increase of sediment deposition. Future work in this area could focus on confirming these findings through case studies in the field or on long-term pilot studies with detailed bed height and density measurements.

Keywords: Decentralized water recycling; Sediment transport; Sewer sediments; Sewer solids; Urban drainage modelling.

MeSH terms

Cities
Recycling
Sewage*
Wastewater
Water*

Substances

Sewage
Waste Water
Water