1. MOLYBDENUM Nathan Turner

2. Moly B Denum

3. My History Wixom 2002 Wixom 2003 South Huron Valley (SHVUA) 2005 South Huron Valley (SHVUA) 2006

4. 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

5. 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

6. 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

7. 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

8. 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

9. Response to Molybdenum Discovery Denial…Denial…Denial Sampled each storage tank individually Isolated contaminated storage tanks Developed dewatering proposal Locate landfill for dewatered biosolids

10. What’s Next? Evaluate Local Limits Update SIU discharge permits with molybdenum limit Continue monitoring program

11. Molybdenum Sources Wixom WWTP Metal Treatment Processes Cooling Towers & Boilers SHVUA WWTP Metal Treatment Processes Cooling Towers & Boilers Landfills

12. 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)