Mystery of the high chlorine consumption in disinfecting a chemically enhanced primary saline sewage

A new approach based on the multigene genetic-programming (MGGP) technique is proposed to predict initial dilution of vertical buoyant jets subjected to lateral confinement. The models are trained and tested using experimental data, and the good matches demonstrate the generalization and predictive capabilities of the evolved MGGP-based models. The best Pareto-optimal MGGP-based model is also compared with the model evolved using a single-gene genetic-programming (SGGP) algorithm and an existing regression-based empirical equation. The comparisons reveal the superiority of the MGGP-based model. This study confirms that the MGGP technique is promising in evolving an explicit, accurate, and compact model, and the developed models can be employed to estimate effectively and efficiently the dilution properties of a laterally confined vertical buoyant jet.

Multigene Genetic-Programming-Based Models for Initial Dilution of Laterally Confined Vertical Buoyant Jets

When the flow rate from a port discharging buoyant fluid into a denser environment is less than a critical value, a counter flow of dense fluid will become established through the port. Experiments were conducted at near prototype scales which confirmed that the critical rate of discharge could be expressed in terms of a densimetric Froude number based on the port diameter and the buoyancy of the discharge. The value of the critical Froude number was found to depend primarily on the port orientation and shape.

Closure of "Avoidance of Seawater Intrusion into Ports of Ocean Outfalls"

On the three-dimensional flow of a stable tangential vortex intake

The target of this paper is to measure the modifications that regular waves induce on the geometrical features and dilution of inclined negatively buoyant jets. In order to achieve this aim, we have carried out a set of experiments in a wavemaker-equipped flume, by measuring the concentration fields via light-induced fluorescence, a non-intrusive and full-field image analysis technique. The wave and jet parameters were selected in order to simulate the case of a typical discharge of brine, from a desalination plant, into the Mediterranean Sea, and compare it to a reference case, i.e., the same jet discharging into a stagnant water body. The mean concentration fields were obtained, as well as the geometrical features and dilution of the jets. The three main effects of waves on inclined negatively buoyant jets are the bifurcation (i.e., the separation in two branches), the rotation of the point of maximum height and the oscillation of the impact point around a fixed position different from the stationary one, and the reduction in size of the sea region interested by the discharge; this last effect increases with the wave period. As a consequence, under waves with high period and amplitude, the dilution of inclined negatively buoyant jets tends to decrease.

On the Effect of Regular Waves on Inclined Negatively Buoyant Jets

A concentrated 10% chlorine solution (in sodium hypochlorite) with a specific gravity of 1.2 is used for the disinfection of treated primary effluent in the Stonecutters Island Sewage Treat...

Modeling of Mixing and Rapid Chlorine Demand in Sewage Disinfection with Dense Chlorine Jets

Multiport diffusers are used in many environmental applications to distribute a discharge flow uniformly through a number of jet nozzles into the same or another fluid. For example, a sewag...

Internal Hydraulics of a Chlorine Jet Diffuser

In the Hong Kong Harbour Area Treatment Scheme (HATS), a concentrated 10% chlorine solution (in sodium hypochlorite with a specific gravity of 1.2) is used directly to disinfect sewage that...

Field Experiments of Chlorine Demand in Disinfection of Treated Primary Effluent

Conference theme: The Wise Find Pleasure in Water: Meandering through Water Science and Engineering

Qingsong Qiao

Papers

On the three-dimensional flow of a stable tangential vortex intake

Modeling of Mixing and Rapid Chlorine Demand in Sewage Disinfection with Dense Chlorine Jets

Internal Hydraulics of a Chlorine Jet Diffuser

Field Experiments of Chlorine Demand in Disinfection of Treated Primary Effluent

Steady Vortex Flow in Tangential Intake