Hydrodynamics Overhaul Delivers Improved SAF Efficiency

• Major energy and cost savings on packaged wastewater treatment process
• Rate of removal of organic contaminants significantly improved
• WPL technical director Andrew Baird to share research at conference

Refining the hydrodynamics of a submerged aerated filter (SAF) packaged wastewater treatment systems can deliver major reductions in cost and carbon footprint, according to research carried out by Andrew Baird, technical director of wastewater treatment specialist WPL.

Baird will share his findings in a presentation at the European Waste Water Management (EWWM) Conference, which takes place in Leeds on 3-4 October 2017.

The research was carried out in-house on a test-rig, in WPL’s laboratories and through field trials with UK utilities. The findings build on earlier research sponsored by WPL which looked at optimum fill rates for bioreactors as part of an MSc project at Cranfield University. The latest pilot engineering design project successfully identified how the flow through a SAF can be accurately observed and measured with varying media fill rates.

The results have provided WPL with optimum fill rates for the bioreactor, enabling the optimisation in terms of site footprint and energy reduction. It was found that the WPL SAF media moved slowly whilst the internal hydrodynamics created a significant flow over the media, encouraging higher contact times.

Andrew Baird said, “The configuration of the treatment process and hydraulics in packaged wastewater treatment plants has been underexplored and, as our research shows, it was ripe for optimisation. When whole-life equipment costs are considered, there are a number of ways packaged wastewater treatment systems can be made more efficient.

“Most importantly, they require electricity, so improved efficiency throughout the process train can reduce energy footprint and cost. With this in mind, we have sought a new media with a lower specific gravity and by reconfiguring the baffles to fully-segment the biozone, we have successfully eliminated the risk of process shortcuts and dead zones.”

Research and development into SAF technology undertaken by WPL has culminated in the WPL SmartCell, which is a compact module with counter-current hydraulics to ensure constant flow over the optimised media. With a 90% fill rate, the SmartCell has sufficient open-voidage to avoid fouling or becoming sludge-bound when applied in secondary treatment.

Efficient installation
The SmartCell is at the heart of the WPL Hybrid-SAF, which incorporates off-site build and modularisation to aid the efficiency of installation and commissioning as well as enhanced process and energy efficiency. The hybrid process model, which has a patent pending, has been applied in nearly 10 UK water utility and large commercial projects for carbonaceous and tertiary nitrification.

“The industry is learning quickly that process efficiency, offsite construction, faster installation and easier maintenance of packaged treatment all provide significant scope for enhanced competitiveness,” Baird said. ”I look forward to sharing our learnings with delegates at EWWM.”

The EWWM Conference takes place on 3-4 October 2017 in Leeds. Andrew Baird presents his paper Practical application of modular off-site build: a commissioning perspective on 3 October.

For more information, visit http://ewwmconference.com and www.wplinternational.com.