Quality status of fresh waterways in Egypt, especially those that receive agricultural drainage water such as Rosetta Branch (RB), is critical for most of its water uses. However, the country depends on this marginal quality water to fill the gap between demand and supply. Therefore, the need for effective/economic water management tools turn into an obligation. Mathematical models can be considered as effective and practical tools for the quality assessment of water bodies. This paper carries out a statistical comparison between simulated and observed data, error quantification and simulation efficiency in order to assess the functionality of water quality (WQ) models for simulating the WQ of RB. This approach was set up to evaluate the cost-effective RB simulation adequacy using different WQ models and assess the gap between simulation simplicity and results accuracy. The simulation case of RB was compared using advanced MIKE-11 and simple QUAL2K WQ models. Despite the simplicity of the QUAL2K model, it showed a good adequacy compared to MIKE-11. Both mathematical models outputs showed a good agreement against field observations. However, MIKE-11 gives results that are more precise in general and for nutrients specifically.

This work uses computational fluid dynamics (CFD) as a design tool in wastewater treatment modeling practice to assess the specific use of the hydrojets in oxidation ditches. The hydrodynamics and the residence time distribution in an oxidation ditch are simulated using several turbulence models: Reynolds averaged Navier–Stokes simulations (RANS) and unsteady RANS with the standard k ‒ e model; and large eddy simulation with the Smagorinsky subgrid scale model. The influence of the mesh resolution, of the hydrojets placement on the oxidation ditch hydrodynamics and on the energy demand for mixing is assessed. Finally, the effect of the turbulence models on the macromixing data, which can be implemented in the activated sludge model, is also evaluated.

A survey of the process streams at an operating petroleum refinery showed that desalting water from the crude and splitter units had the highest concentrations of pollutants, and accounted for approximately one-third of the BOD and COD of the combined effluent. Combined effluent (234 ± 62 mg BOD/L, 51 0±0m g COD/L, and Microtox EC50 4.9 ± 0.4%) was treated using a laboratory-scale batch biological reactor. Ninety-three percent of BOD and 77% of COD were removed over the first 24 hours of biological treatment. Acute (Microtox) toxicity was reduced in two discrete stages; the first coinciding with BOD and COD removal and the second stage occurring after BOD and COD had been removed. A final EC50 value of 27.8% was achieved in batch tests. The two stages of toxicity removal correspond quantitatively to the toxicity removal observed during secondary and tertiary biological treatment at the petroleum refinery’s full-scale wastewater treatment plant.