The Erie, Colorado water reclamation facility was one of the first plants in the U.S to incorporate a small footprint, low-pressure, high-output (LP/HO) amalgam UV lamp technology to treat wastewater without new construction. As part of the WRF's enhancement project, the new state-of-the-art disinfection system replaced an existing legacy system to optimize treatment abilities and modernize the facility.

Challenge

Erie's former vertically-oriented UV wastewater disinfection system consisted of standard low-pressure, low-output (LP/LO) lamp technology. In 2003, the activated sludge WRF decided to upgrade the system to handle increasing plant flows. As the plant could not afford extensive new construction, the technology had to be retrofit into the existing channel. A standard size vertical module would not fit in the channel.

"Erie is a rapidly growing community," says Erie's Bob Smith, WRF technician 3 and Class A operator, "and the existing system would not meet current or future needs."

Solution

Siemens Water Technologies customized a stainless steel vertical module to fit into the existing UV channel, which limited the required construction as well as plant downtime. To increase design flow, Siemens integrated the latest LP/HO amalgam lamp technology.

Each of the modules in the Barrier® Sunlight VE Series systems holds 25 320W lamps that are three times more powerful than their predecessors and have a 12,000 hr lamp life.

Results

Compared to the previous LP/LO UV lamp technology, Erie's new amalgam lamp technology has a longer life due to a revolutionary internal coating, which prevents the lamps from solarizing. This coating also allows the lamps to operate better in both cold and warm water. Since the Erie WRF experiences colder wastewater flows, this new system has increased efficiency during the colder months.

Lamp technology affects UV system maintenance - especially lamp replacement  and cleaning. All lamp connections in Siemens' vertical amalgam system are above the effluent, making it easier to replace lamps while they are in the channel. As for cleaning, the vertical amalgam system can remain online during automatic air-driven quick-stroke quartz cleaning.

"This automated cleaning has greatly reduced maintenance time and costs," says Smith.

Formerly, Erie had to remove the old system from the channel and immerse it an acid bath every month. This took approximately half a day and also involved chemical costs. The plant's cleaning now consists of pulling individual banks out of the water and hosing them off every two weeks with a garden hose. Personnel can do this in under an hour.

Erie's vertical amalgam UV system integrates energy-efficient ballasts. The ballasts consume little power, generate modest heat, and are minimally affected by surges, sags, and power interruptions. This was an upgrade from the existing electromagnetic ballast technology.

Programmable logic controllers (PLCs) make the LP/HO amalgam system easy to operate. The PLCs offer energy and lamp savings through either completed module or incremental flow pacing. The controllers are flexible, expandable and modifiable. They also have greater communication capabilities interfacing with other PLCs and SCADA systems as well as a large range of operator interface choices.

Since installing the new UV system four years ago, the Erie WRF has had excellent fecal results. The WRF's in-house laboratory program ensures it treats wastewater to meet federal and state mandated regulations as well as discharge permit limits. Erie's permit is fairly tight with 176/100 M1. The new permit for 2008, which is also for an additional 0.4 MGD of flow, has even stricter limits of 126/100 M1 of E. coli for a monthly average.

"We have no doubt that the Siemens system will allow us to meet our permit limits successfully and consistently," says Smith.