Challenge

Peru, Indiana, a town of nearly 16,000 on the Wabash River, is known as the circus capital of the world. At one time the winter headquarters of several famous circuses, including Ringling Brothers and Buffalo Bill's Wild West Show, it's host to the International Circus Hall of Fame. It's also one of the few cities in the state with combined sewers.

Peru Utilities needed to upgrade its two wastewater treatment facilities to reduce operations costs and expand capacity to promote economic growth. It also needed to upgrade its old main plant to handle stormwater flows as high as 26 million gallons a day (MGD) and prevent combined sewer overflows the plant had been experiencing.

This plant used a conventional activated sludge process of primary clarification, fine-bubble aeration and anaerobic digestion. The process was limited because dry weather flow was 4 MGD, and wet weather flow was rated at 6 MGD. Sludge remaining after treatment had to be trucked out at considerable expense – averaging 1.8 million gallons of solids a year that had to be hauled away.

Solution

In 2004, Peru upgraded the main wastewater treatment plant (WWTP) from 4 to 8 MGD, using a BioFlowsheet+™ Solution from Siemens Water Technologies. The design required minimal modifications to the existing plant: abandoning the primary clarifiers, converting the aeration tanks to VLR® (vertical loop reactor) systems, and turning the anaerobic digesters into Cannibal® interchange reactors. The utility also added two new VLR tanks, three new Tow-Bro® high-performance final clarifiers, and the Cannibal solids reduction system.

Results

In addition to increasing the Peru WWTP’s dry weather flow to 8 MGD, the upgrade has allowed the facility to handle excessive storm flows up to 26 MGD without violating effluent discharge quality, which is substantially better than pre-upgrade levels.

The upgrade also reduced aeration energy cost by a factor of 3:1. Doing away with anaerobic digestion greatly reduced the utility’s operating costs, saving about $50,000 a year for natural gas. Peru completely eliminated this expense, with installation of the Cannibal solids reduction system.

In addition, the utility reduced waste sludge disposal by a factor of 10:1. Now, it only has to haul sludge away about once a year. Related savings amounted to approximately 30 to 40 percent annually, comparing pre-upgrade expenses to 2009 when about 800,000 gallons of sludge was disposed of at a cost of around $30,000.

The operator-friendly design also allows Peru Utilities to react to any environmental conditions quickly. It has been so happy with the main plant upgrade that it decided to install similar technology (minus the Cannibal system) at the new Grissom WWTP to be commissioned in April 2011.

Watch Our Video to Learn More