Mercury and Wastewater Treatment
Scott Kyser| Professional Engineer MPCA
wq-iw4-02h6 Hello! My name is Scott James Kyser
I am a MPCA engineer working in wastewater permitting Mercury Water Quality Standards
KS( Wastewater dischargers in NE face lower discharge requirements Municipal Mercury limits in MN Meeting these limits always requires Municipal WWTP WWTPs are upgrades generally compliant with the statewide TMDL and discharge low levels of Hg Digression on Wastewater Infrastructure Funding
“I don’t use the word crisis lightly, but I do think we’re at that point” Marty Seifert, CGMC lobbyist & former MN house majority leader $5 Billion in Wastewater Funding Needs MN Has Aging Wastewater Infrastructure
58% of MN WWTP are over 20 years old! Wastewater Funding Sources Over Time
Construction and Grants Era (1987) Current Era (2019)
10%
33%
90% 67%
State & Federal Ratepayer State & Federal Ratepayer Backdrop of Mercury Treatment in MN
MN cities have substantial wastewater funding obligations and are increasingly less able to affordably fund those obligations Reducing Mercury Water Pollution Is Important
100% of mercury during drought
15% of mercury during drought Next Steps
1. How do municipal WWTPs work? 2. Mercury treatment theory
3. Technologies capable of meeting low level mercury limits 4. Costs of mercury treatment technologies 5. Mercury treatment study 6. Border battle bonus bout How does wastewater treatment work?
Wastewater treatments plants collect and treat wastewater Degrees of Municipal Wastewater Treatment
Chunky stuff Pee & Poop & Particles Solid (DOM, N, P, TSS) particles Pathogens Meeting Low Level Mercury Limits
Treating to < 6.9 ng/L Treating to < 1.3 ng/L
• Possible with ‘conventional’ 1970’s • Not possible with ‘conventional’ solid control technologies 1970’s solid control technologies
• Does not require advanced filtration • Requires advanced filtration • Rarely requires new capital • Always requires new capital investments investments (i.e. $$$) • Often WWTPs can’t meet limits • Every facility in NE MNwill receive when WWTP is past its prime limits Treating mercury by treating solids
Total Hg Treatment Dissolved Hg
Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Solid Particle Solid Particle Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Takeaway: Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Reducing solids Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Solid Particle Hg Solid Particle Hg reduces mercury Hg Solid Particle Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg Hg
Hg Hg Hg Hg
Hg Hg How much mercury do WWTPs remove?
CIRSSD 900 800 Pretty typical 700 concentrations 600 50‐100 ng/L Mercury 500 Occasional outliers (ng/L) 400 300 200 100 0 1/1/2016 7/19/2016 2/4/2017 8/23/2017 3/11/2018 9/27/2018 4/15/2019 11/1/2019 Influent Waste Stream Effluent Waste Stream Where does the mercury come from?
1. Significant industrial users 2. Regular human waste disposal
WLSSD is not typical (Sappi Paper) All Municipal Effluent Total Hg versus Grab TSS (n=514) 100 Suspended solids at < 2 mg/L correlates with 10 very low Hg
Total Hg (ng/L)
1 Unique Effluent Data Point
7052 Mo. Avg. Limit
0.1 0.1 1 10 100 1000 Total Suspended Solids (mg/L) WLSSD Effluent Mercury 5
4.5 Dissolved WLSSD has high Particulate 4 dissolved Hg 3.5 occasionally above
3 limits Hg 2.5 (ng/L) 2
1.5
1
0.5
0 J‐16 A‐16 S‐16 O‐16 N‐16 D‐16 J‐17 F‐17 M‐17 A‐17 M‐17 J‐17 J‐17 40 WLSSD Dual Media Filters Golden Plump MBR 35 WLSSD has detectable 30solids in their effluent
25
TSS 20 (mg/L) 15
10
5
0 J‐15 A‐15 J‐15 O‐15 F‐16 M‐16 A‐16 D‐16 M‐17 J‐17 What current treatment system treat mercury to low levels?
Cloth Disk Filter Dual Media Filter No published treatment Membrane Reactor Contact Clarifier references CIRSSD built a new WWTP that meets low level Hg limits
Cloth Disk Tertiary Filters
Secondary Treatment Tertiary Treatment
Water Quality After Filtration How much does mercury treatment cost?
Cost Estimates of Installing Cloth Disk Filters In the WWTP world 12 these costs are ‘low’ but can still be 10 unaffordable for 8 many cities Capital Costs 6 High ($Mil) Low 4
2
0 0 2000 4000 6000 8000 10000 12000 14000 City Population What does affordable wastewater mean?
Expensive Affordable
Wastewater Financing tools requires make rates massive affordable! amounts of capital! Wastewater Treatment Economic Variance Summary
Unaffordable Economic Treatment Variance Hardship Cost EPA Municipal Wastewater Affordability Index
Primary Affordability Measure