MOLYBDENUM

Nathan Turner

Moly B Denum

My History

Wixom 2002 Wixom 2003 South Huron Valley (SHVUA) 2005 South Huron Valley (SHVUA) 2006

SHVUA RMP History

1987-1999 Biosolids incinerated & land filled 1998 SHVUA formed and purchased

treatment plant & collection system 1999 Earth Tech awarded O & M contract 1999-2000 Biosolids storage increased from

1.5MG to 4.0MG 2000 Began land application of biosolids

Wixom Molybdenum History

Molybdenum appeared in October 2002 in one of two storage tanks

Began sampling plant influent and each SIU for molybdenum

Molybdenum high in one of two storage tanks

Wixom Molybdenum History

2003 Determined that three of four SIUs contributed various amounts of molybdenum

Determined the MAHL for molybdenum SIUs were able to greatly reduce

molybdenum in discharge by changing process chemicals

SHVUA Molybdenum History

Molybdenum first appeared in November 2005 in one of four biosolids storage tanks @ 95 mg/kg

2006 sampling for molybdenum in plant influent and effluent. Also sampled each SIU and required self monitoring for molybdenum

Molybdenum in two of the four storage tanks in November 2006 @ 83 mg/kg

SHVUA Molybdenum History

2007 Determined that six of the then 12 SIUs contributed various amounts of molybdenum loading

2007 Determined MAHL for molybdenum 2007 Worked with SIUs to reduce or element

molybdenum in discharge to SHVUA WWTP 2008 Molybdenum reduced to 29 mg/kg

Response to Molybdenum Discovery

Denial…Denial…Denial Sampled each storage tank individually Isolated contaminated storage tanks Developed dewatering proposal Locate landfill for dewatered biosolids

What’s Next?

Evaluate Local Limits Update SIU discharge permits with

molybdenum limit Continue monitoring program

Molybdenum Sources

Wixom WWTP

Metal Treatment Processes

Cooling Towers & Boilers

SHVUA WWTP

Metal Treatment Processes

Cooling Towers & Boilers

Landfills

What we Learned

Ferric Chloride addition promotes molybdenum settling in biosolids

Concentration and loading must be considered in determining SIU discharge limits

Include domestic sampling for molybdenum (more on weekend sampling)