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Arrival of the Zebra Mussel In the late 1980's zebra mussels (Dreissena polymorpha) first arrived in North America by traveling in the ballast tanks of freighters where the mussels ultimately were discharged into the Great Lakes. Since that time, zebra mussels have had a significant negative impact on the environment and industries in both the United States and Canada. Native North American wildlife is being destroyed by the zebra mussel, pipelines and inlet structures are being encrusted, heat exchangers are being plugged, and general all around havoc is being created as the zebra mussels migrate south. Present Location The migration has occurred at a very rapid rate (Figure 1) and zebra mussels are now found as far south as New Orleans and have invaded most of the major river systems (Mississippi, Illinois, Ohio, Tennessee, Arkansas and Cumberland) as well as inland lakes and reservoirs. 
Figure 1 Zebra Mussel Range Credit National Biological Service |
Life Cycles Zebra mussels grow from microscopic size to sexual maturity in approximately one year (Figure 2). Populations appear to rise and fall on a ten year cycle. 
Figure 2 Life Cycle Credit: Ontario Ministry of Natural Resources Females are capable of releasing 30,000 to 40,000 microscopic eggs per year. The eggs are soon larvae which swim and move with the current through the post-veliger stage and to the settling stage where attachment to any hard surface is achieved. Attachment is through byssal threads and the zebra mussel can attach and reattach as water conditions change. Life spans are three to five years with mature mussels growing to approximately 35 mm in length. Reproduction begins when water temperatures approach 55º F and spawning peaks as water temperatures reach 70º F. |
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Monitoring Methods Fine mesh planktonic nets (Figure 3) are used to monitor veligers with analysis being performed by microscope. Settling zebra mussel larvae are monitored with plexiglass test plates, adults are monitored with test blocks or plates in the raw water source and with bio boxes inside the plant. 
Figure 3 Planktonic Net Credit: E. Marsden Pro-Active vs. Defensive Treatments Controlling the zebra mussel in the veliger stage eliminates the possibility of fouling the plant water system components. Treatment after adult mussels are present could cause clogging of critical plant system components (Figure 4) and generate the need for flushing and removal of the dead mussels, which could generate tons of debris and may impact the capacity and availability of the plant. |
Infested Traveling Screen Credit: Ontario Ministry of Natural Resources Treatment As A Control Method The selective thermal process focuses on inlet bays and service water systems since these are the main areas for zebra mussel infestation because of decreased water velocities. Trash racks and inlet tunnels are usually better suited for treatment by other processes. It has long been known that temperatures above 110º F are lethal to zebra mussels. This proven process employing steam or hot water injection techniques to assure 100% mortality, offers a simple, reliable, cost effective alternative to zebra mussel control by employing standard off-the-shelf hardware and the use of plant generated steam sources or portable boilers or self-contained, trailer mounted, direct fired water heating equipment. The injection systems come in various configurations (Figure 5) and can be offered as very simple manual processes or sophisticated processes that employ constant temperature controls, computer controls networked to a central office, and with in-line shredding devices that will allow the dead zebra mussels to pass through the service water system or be backflushed away. |
The process offers the following advantages:
Steam Injector |
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The Solution Environmental Technologies Inc. (E.T.I.) is a subsidiary of the T.L. Maddox Companies (Figure 6) and stands ready to assist in solving the zebra mussel problem at your facility. E.T.I. offers a guaranteed solution and will work with you to establish |
a plan, develop a monitoring program, engineer the hardware for your system, and implement the process. Various lease/buy equipment options are available as well as service agreements and on-going zebra mussel control application cycles by E.T.I. |
contracted personnel. Please print and fill out the following form and mail it to the St. Louis office for additional information or assistance, or call the St. Louis office for an immediate response. |
Figure 6
T L Maddox Companies Corporate Headquarters
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Industrial
Plant Layout
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