Turbo Charged

CLT Water owns and operates five major water resource recovery facilities ranging in permitted capacity from 45.4 million to 242 million L/d (12 to 64 mgd). The Sugar Creek Wastewater Treatment Plant is one of Charlotte Water’s oldest facilities, originally constructed in the late 1920s, with major improvements in the late 1950s, late 1980s, and early 1990s. This facility serves residential,...

Before the upgrade project, Sugar Creek used single-stage blowers and fine bubble diffusers to treat wastewater in a standard activated sludge biological process. On the solid treatment side, Sugar Creek is unique, compared to other CLT Water facilities, in that it does not process primary or secondary solids. These solids are pumped, by force main, to CLT Water’s McAlpine Creek Wastewater...

In pursuit of that goal, the existing aeration basins at Sugar Creek were modified and upgraded to provide much more efficient biological treatment. HST blowers were planned to replace the old, original blowers. Better instrumentation also was included in the scope along with controls to operate the HSTs at their most efficient settings. Lastly, swing zones with Invent Helical mixers and internal...

A big part of the upgrade process involved implementation of extensive measurement capability in the biological process. This included optical probes to measure total suspended solids and dissolved oxygen (DO), ion-selective electrode probes for nitrate, ammonia, and wet chemistry analyzers for alkalinity, ortho-phosphate, and ammonia. With the added process equipment and monitoring capabilities,...

The upgrades and retrofits, in conjunction with the process optimization, has resulted in stark improvements. Currently, Sugar Creek is seeing a greater than 30% decrease in power requirements, in large part because of the new blowers, their turndown capabilities, and reduced air demand resulting from ABAC. The aforementioned magnesium hydroxide use reduction has also been significant, with some...

The optimization process has not been without a hiccup. The facility has seen some issues with sludge settleability, which has been noted in other systems operating at low DO concentrations that occur with ABAC control. The CLT Water team has continued internal efforts to monitor and optimize the process to minimize negative effects. Additionally, the team plans to participate in a Water Research...