The HEI-Group

Page 4.6: Zebra Mussel Disposal Options

The zebra mussel is non-indigenous to North America. Since its introduction in 1989 it has successfully invaded the Great Lakes area and threatens other water bodies.

They have negatively impacted industrial, commercial, and recreational facilities. These facilities have had to pay substantial amounts of money to prevent zebra mussels closing them down.

The zebra mussel has also impacted the ecological system of the water areas they inhabit. Some impacts are positive in that the water contaminant and turbidity levels have improved. Other impacts are negative since the aquatic food chain has changed and the zebra mussel competition with other native species threatens the existence of many native species.

Case studies at a number of facilities regarding the zebra mussel waste handling practices show that the volume of zebra mussel waste can be quite significant. This significant volume translates into costly removal, storage, handling, and disposal costs. At selected sites, chemical analyses of the zebra mussel waste has found the material to be non-hazardous even though they do have the ability to bioaccumulate contaminants.

Zebra mussel disposal options are actively being investigated to solve the growing on-site storage problems at larger facilities. The main emphasis is on diverting the waste away from landfill and utilizing the zebra mussel as a raw material resource (based on chemical composition).

The following is a partial list of waste handling options that can be investigated:

Landfilling;
Composting;
Soil Conditioning Liming Agent, and Mulching;
Animal Feed; and
Biofiltration Applications.

It is suggested that a Cost-Benefit analysis be performed for each option. Furthermore, for large facilities, the construction of an on-site central processing facility could have a quick return on investment since the final product can be sold (subject to regulatory approvals) for a minimum of $24/tonne. Most facilities require a two year return on investment.

Preliminary investigations indicate using zebra mussels for animal feed or as biofilters (for water treatment) would not utilize much of the total zebra mussel waste and therefore should not be considered as a solution. However, zebra mussel biofilter research is very active, particularly in the Netherlands where zebra mussels have been used to assist in the cleanup of polluted bodies of water. In this application, the ability of the zebra mussel to filter out suspended contaminant from the water column and to then excrete the contaminants (in the form of pseudofeces and feces) in a form heavier than water so that they settle (biosedimentation) is being exploited. This filtering ability has numerous potential applications in water treatment but goes beyond the scope of this summary.

Final Words:

Preliminary studies indicate that facilities that handle large volumes of zebra mussel waste should investigate implementing a program to send the waste to a reputable composting site.

Investigation into setting up a central waste processing area for zebra mussel waste to service a number of large water intake facilities should be investigated. The final product from this processing facility can possibly be sold and used as a soil conditioner, liming agent, or mulch.

In general, the majority of the cost for zebra mussel waste handling is in the removal from the water intake areas. Further investigation into more cost effective intake area removal processes can result in substantial annual savings.

If you have any questions please send e-mail to John at: jahibberd@hei-group.com

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Revised on July 23, 2006