In April of 2000, the City of Wichita initiated the Silver and Mercury Code of Management Practices (CMP). This program is a voluntary program designed to decrease the silver and mercury levels entering the City’s Sewage Treatment Plant. Using Best Management Practices, (BMP) the voluntary program serves the same purpose as permitting, which is reduction of mercury levels at the POTW. Permitting requires extensive monitoring and paperwork, numeric limits, and a costly annual permit fee. The BMPS include:

• All Photo-finishers or medical offices performing diagnostic photo imaging x-rays must install and operate a silver recovery unit so that it removes 90% of the silver from the photo-processor effluent or

• Dispose all fixer waste from the photo processor at an approved off-site disposal facility

• Dental clinics to install Best Available Technology (BAT) for mercury amalgam separator equipment.

• Operate and Maintain the Separator so that it operates at a 90% removal efficiency rate.

• Perform annual wastewater monitoring

• Submit an annual compliance summary report.

As part of this initiative to reduce silver and mercury loadings to the POTW, the Sewage Treatment Plant has purchased a Batch Silver Recovery Unit. Businesses utilizing this program include any business that performs photo imaging for diagnostic purposes and photography development businesses. These include dental and medial offices, chiropractors, veterinarians, and print shops. Due to the high participation rate, it is expected the unit payback was less than two years. This is a turnkey operation, with minimal maintenance, providing a convenient avenue for silver waste disposal for small quantity dischargers, who process silver laden film for either photographic or x-ray diagnostic purposes. It will significantly enhance the compliance rate of the discharger. To date, the City has been reimbursed for approximately 300 pounds of silver which has been recovered from this operation. Previously, this silver would have been discharged to the sanitary sewer and entered the environment and would not have been reused.

Program Summary

Since the inception of the program, several meetings with staff and the Wichita District Dental Society and Kansas Dental Society Officials have taken place. These meetings provided education for both parties and assisted in determining fair program requirements. Through these meetings, and several open workshops for the entire dental community, the staff and the dental community have developed a strong partnership to address this issue.

At this time, 98% of the 200 dental offices in the City have complied with the Mercury CMP Program. Over 80% of all silver dischargers are complying with the silver portion of the CMP program. The cooperation of the dental community with staff has contributed to this enormously successful program, and will set a standard for other cities.

Since implementation of this program the amount of silver and mercury entering the sewage treatment plant has been reduced by 70% and 74%, respectively. This is a significant reduction and illustrates the environmental stewardship these small businesses have exhibited.

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