Page 94 - Industrial Wastewater Treatment, Recycling and Reuse

Industrial Wastewater Treatment, Recycling, and Reuse: An Overview 69

Figure 1.21 Improved clarifier designed using CFD simulations (Pophali, 2007).

The CFD simulations were used to evolve several new features such as a
low-level gradually enlarged inlet that ensures hydraulic energy dissipation
through plume formation, improved flocculation because of the plume,
uniquely sloped bottom of the clarifier, and specially devised sludge removal.
The design has also resulted in a patent (Pophali et al., 2009).
In recent years, there have been large numbers of publications on using
CFD models for variety of applications. Applications of CFD models for
flocculation in water treatment are reviewed by Bridgeman et al. (2009).
Fayolle et al. (2007) have demonstrated use of CFD models for predicting
oxygen transfer in aeration tanks. Ranade et al. (2006, 2013) have used
CFD models to devise a patented design of vortex diodes for water treatment
and disinfection. Dedicated vertical applications based on CFD simulations
for water treatment are being developed (see for example, www.tridiagonal.
com/products/mixit.html). There is also a dedicated Linkedin group on
applications of CFD for wastewater applications (www.linkedin.com/
groups/CFD-Wastewater-4664268/about).
It is not possible or necessary to summarize all of the publications/
reviews here. Please refer to Ranade (2002) to gain an understanding of
the general philosophy of using CFD models for performance enhancement.
The application of such advanced computational tools with the creative use
of hybrid treatment technologies has the potential to significantly bring
down treatment cost and spatial footprint.

1.8 COST OF WASTEWATER TREATMENT AND POSSIBLE
VALUE ADDITION

The challenge of removal or recovery of materials from dilute streams is
unique in several respects and is expected to become a much larger problem
in the future. Government regulations, as well as the growth of biotechnol-
ogy and the pharmaceutical sector, will be forcing increased attention on this
area. Separation processes generally represent 40–70% of both capital and
operating costs and account for approximately 45% of energy cost in the