Macon, located about 175 miles northeast of Kansas City, is the county seat of Macon County. In the mid-1800s, westward trekking pioneers and the construction of two railroad lines that intersected in Macon led to the area's rapid growth. Among the newcomers was a Prussian immigrant, Colonel Frederick William Victor Blees. In 1896, Blees inherited the wealth of his father's coal and iron mining interests in Germany and began using his fortune to improve the town. He built Macon's first theater and the First National Bank of Macon. He founded a "horseless carriage" factory and the Blees Military Academy. He also built the city's first sewer system.

Years later, in 1960, Macon Municipal Utilities built a trickling filter wastewater treatment facility. Major additions were made to the plant in 1985 and 1988, including an additional primary settling basin and a 660,000 gallon storm-water overflow basin, doubling the solids processing capacity of the facility. The plant has a design flow of 2.5 mgd, a maximum flow of 5.4 mgd and an actual flow of 1.5 mgd. The plant serves a population of 5,680 residents of the City of Macon.

In 2009, the MDNR established a new regulation requiring the state's wastewater treatment plants be equipped with disinfection systems. When Macon Municipal Utilities began investigating ultraviolet systems, they were impressed with one technology that featured safer operation and promised lower whole-life costs based upon increased bulb life and lower maintenance. In 2011, the utility chose that technology, the MicroDynamics® OCS660 open channel wastewater microwave UV system.

In April 2011, the MDNR awarded Macon Municipal Utilities a $1.3 million low-interest loan for the wastewater plant improvements. The funding was a joint effort between the Clean Water State Revolving Fund and the USEPA. Installation of the system took place in March 2012 with system start-up on April 1, 2012.

"There were a number of system features we liked," said Ronny Smith, plant superintendent. "For example, with traditional UV systems, the bulbs are configured horizontally – so the entire unit has to be taken out of the water when changing bulbs. The MicroDynamics unit's bubs are configured vertically, which makes changing the bulbs easier. And with the three-year bulb warranty, we don't have to change bulbs as frequently and bulb replacement costs are lower."

The revolutionary MicroDynamics® microwave UV technology is available in modular, open channel and closed vessel designs suitable for use in municipal water and wastewater treatment. The systems use microwave energy to energize the bulbs and generate consistent-strength UV disinfection. The electrodeless lamps operate at similar fill pressures as traditional low pressure lamps.

MicroDynamics systems offer extended bulb life and reliability, operating cost savings and simplified and safer maintenance compared to conventional systems. The bulb replacement and maintenance costs of MicroDynamics systems can be as little as half of competing UV technologies, primarily driven by the unique electrodeless lamps. Each system comes with a three-year bulb life warranty. And the MicroPace™ flow pace technology matches UV dose to operating conditions in real time, resulting in additional energy savings. The MicroDynamics system activates and deactivates modules as needed based on an external flow meter signal. The modules offer quick restart, and unlimited start and stop, providing a more finely tuned flow pace than is possible with traditional systems, thereby saving money on electricity costs.

Improved safety is inherent in the MicroDynamics system, as the electrodeless lamps have very low residual radiation of energy and thus an almost instant shut-off capability. Additionally, with electrodeless lamps, there are no electrical connections to fail, corrode or leak, which dramatically increases system efficiency and lamp life when compared to traditional UV lamps. Because the electrodeless lamps have no wires under water, safety concerns inherent with the repair of possibly corroded electrodes or wiring are eliminated.

MicroDynamics systems do not require that the lamps be submerged in the channel. They can operate in air, thus reducing concerns regarding precise water level control. "This is an important feature, especially for systems where the flow rate can vary widely" said Stan Shmia, disinfection product manager for Severn Trent Services. "It's one less thing for the plant operator to worry about."

Lower lamp temperatures also make for lower maintenance costs. Unlike other low-pressure, high-output UV systems whose lamps run more than 200 degrees F (93 degrees C), the MicroDynamics quartz sleeve is kept at 115 degrees F (46 degrees C), making them less susceptible to foulants baking on the sleeves. Chemicals are not needed to clean the sleeves, so the system's chemical-free wiper system is sufficient.

The Macon facility employed the new microwave UV system from April 1 to October 31 – the city's "recreation season" (Long Branch State Park, Atlanta State Wildlife Area and Macon Lake are all nearby). According to Smith, the new UV systems' operation has been "fantastic."

"We liked the idea of going with a newer technology – one that other utilities were using successfully," said Smith. "From a whole-life perspective, the MicroDynamics system offers safer and less frequent maintenance and lower maintenance costs; longer bulb life; and greater operational flexibility. We've been very happy with the microwave UV technology."


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