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Keywords

Diclofenac, Wastewater treatment plant, Fate and transport model, Tigris river, Diyala river

Document Type

Article

Abstract

Diclofenac is a widely used non-steroidal anti-inflammatory drug that is incompletely removed by conventional wastewater treatment. This study evaluates its fate and transport from consumption and excretion, through the three Al-Rustamiyah wastewater treatment plant (WWTP) units in Baghdad, to the Diyala River, the Tigris River, and the Al-Tuwaitha drinking-water intake. Discrete ``grab'' samples were collected during 12–14 November 2020 from WWTP influent and effluent streams and from river and intake sites. Diyala River concentrations ranged from 0.094 to 2.184 μg/L. At the Tigris confluence, diclofenac was 0.052 μg/L; the two immediate downstream measurements were below 0.01 μg/L for inferential purposes, while the more distant Al-Tuwaitha intake contained 0.087 μg/L. The calibrated WWTP response corresponded to 83.0–84.6% removal and is reported through a single dimensionless composite removal parameter because its constituent kinetic, solids, and residence-time factors are structurally non-identifiable from the available steady-state data. A segmented river-model sensitivity scenario in the archived model output improved predicted-versus-observed agreement from R2 = 0.567 to 0.957 when WWTP flows were increased. The river elapsed-time regression was excluded from inferential results after a hydraulic consistency check showed that the archived elapsed-time values do not represent physical travel times over the short Tigris reaches. The results provide a November 2020 baseline for the Diyala–Tigris corridor and identify hydraulic loading and multi-outfall mixing as model-sensitive controls that require seasonal field verification before operational use.

DOI

10.30684/2412-0758.2421

First Page

192

Last Page

210

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