Temporal Trends Of Greywater And Tertiary-Treated Effluent Quality: Implications For Urban Reuse

Salam Akinkunmi Alli; Snigdhendubala Pradhan; Jayaprakash Saththasivam; Gordon McKay

doi:10.29284/xsxq8192

Authors

Salam Akinkunmi Alli Division of Sustainable Development, College of Science and Engineering, Hamad Bin Khalifa University
Snigdhendubala Pradhan Qatar Environment and Energy Research Institute (QEERI), Hamad Bin Khalifa University
Jayaprakash Saththasivam Qatar Environment and Energy Research Institute (QEERI), Hamad Bin Khalifa University
Gordon McKay Division of Sustainable Development, College of Science and Engineering, Hamad Bin Khalifa University

DOI:

https://doi.org/10.29284/xsxq8192

Keywords:

longitudinal water quality, greywater treatment, treated sewage effluent, salinity control, wastewater reuse.

Abstract

The effective reuse of wastewater is essential in water-stressed urban regions. A longitudinal study was conducted over 8 weeks to evaluate the short-term variability and storage-related changes in raw greywater (GW), tertiary-treated sewage effluent (TSE), and tap water (TW) as the control. Weekly samples were collected from the inlet (INL) and storage tank (STK) for GW and TSE, while TW was collected only from the laboratory tap.

GW was found to be highly biodegradable, with turbidity averaging 67.68 ± 53.63 NTU, and organic fractions: COD, BOD₅, and TOC values of 122.54 ± 93.1 ppm, 53.33 ± 25.25 ppm, and 21.12 ± 7.76 ppm, respectively. The BOD₅/COD ratio (0.23 - 0.79) confirmed the presence of biodegradable organic and ammonium-N (2.18 ± 0.81 ppm). Conversely, TSE presented low organic levels (COD < 40 mg/L, BOD₅ < 8 ppm) but higher ionic loads, with EC of 1685.60 ± 116.54 µS/cm, sodium of 125.07 ± 17.24 ppm, chloride of 274.32 ± 30.01 ppm, and sulfate of 268.40 ± 22.72 ppm. The residual chlorine content was in the following order: GW>TW>TSE. More importantly, variations in INL and STK demonstrated that storage conditions influenced water quality, with greater differences in GW solids/organics and slight ionic accumulation in the TSE. These findings underscore the importance of source-specific treatments, including removing solid and organic matter for GW and controlling salinity and nutrients for TSE. Implementing these targeted strategies can improve the sustainability of urban wastewater reuse, particularly in arid regions (e.g., Qatar), and support circular water management efforts in advanced reuse systems (i.e., the Netherlands).

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