Small Town in Maryland Gets Big Energy Savings

Hurlock, Maryland is home to just over 2,000 people and sits near Delaware between the Nanticoke and Choptank rivers. The town provides wastewater treatment services to all of its residents as well as to the nearby poultry processing plant. Despite the high organic content the plant received, the town wanted to keep costs low for ratepayers, and Atlas Copco stepped in to help.

Ten years ago, the town decided to upgrade their wastewater treatment system to provide better quality effluent. They took out the old lagoon system and replaced it with a 1.65 MGD four-stage activated sludge facility. The activated sludge process was developed in the United Kingdom in the early 20^th century and is currently used in medium- to large-scale wastewater treatment plants.

High quality, higher price tag

They immediately saw results, winning the Maryland Rural Water Association Wastewater Treatment Plant of the Year in 2008, followed by an operations and maintenance excellence award from the EPA in 2009. Despite the success, there was a problem: the plant now used nearly seven times as much energy as their previous system, spending an average of $18,000 per month on electricity costs.

In 2015, the plant took a look at their energy usage and determined they could reduce it. In order to address the issue and pass savings on to ratepayers, they first determined the largest energy consumer in the plant: the blower.

Blowers for aeration and mixing account for 40 to 75 percent of total energy consumption in a wastewater treatment plant. In Hurlock, blowers were using nearly $7,000 per month. The original design used positive displacement lobe blowers, but at 10 years old, these machines were highly inefficient.

Finding a better solution

Wastewater plant superintendent Eric Barnhart learned about the advantages a screw blower could provide and quickly elected to replace two of their lobe blowers with 75 HP Atlas Copco ZS rotary screw blowers. Both new ZS blowers were installed at the end of 2015 and have been running ever since.

In only a few months, the facility saw results. While lobe blowers typically operate at 28 Hz and draw approximately 74.3 amps, the Atlas Copco ZS75VSD rotary screw blowers consume only 67.5 amps when operating at the same frequency. The plant’s electrical bill has dropped from an average of $18,000 to $16,800 per month, adding up to an annual savings of over $14,000.

Has your facility seen savings with Atlas Copco? Leave a comment below and tell us your story.