Anaerobic Biochemical Reactor (BCR) Treatment of Mining-Influenced - PowerPoint PPT Presentation

Anaerobic Biochemical Reactor (BCR) Treatment of Mining-Influenced Water (MIW): EvaluaAon of ReducAon in ConcentraAons of Metals and AquaAc Toxicity Presented in Webinar Series: FRTR Presents...Heavy Metals-Mining Site Characteriza:on and Treatment Session 2 Dr. Barbara Butler, USEPA July 26, 2016 Office of Research and Development

The views expressed in this presenta0on are those of the author’s and do not necessarily represent the views or policies of the U.S. Environmental Protec0on Agency. 2

PresentaAon Outline • BCR Treatment • Research Ques0ons • Study Sites • Methods • Metals Removal • Aqua0c Toxicity (Acute) • Concluding Remarks 3

BCR Treatment • Passive / semi-passive treatments § May be completely anaerobic, aerobic, or combina0on of both § Natural processes § Minimal or no energy requirement o Solar power has been used • Anaerobic biochemical reactor § Previously (and some0mes s0ll) called sulfate-reducing bioreactor o A primary mechanism is microbial sulfate reduc0on to sulfide that precipitates metal sulfides § Some0mes called anaerobic wetland o But, no vegeta0on 4

BCR Treatment • Chemical, biological, and physical processes § Reduc0on, precipita0on, adsorp0on, reten0on • Hay, straw, wood chips, sawdust, compost, limestone, manure, ethanol, waste milk… • Aerobic polishing § Increase oxygen § Decrease biochemical oxygen demand (BOD) § SeTle solids o Some release of sulfide precipitates, which will oxidize and re- precipitate as metal oxyhydroxides § Degas sulfide and ammonia 5

BCR Treatment • Overall goal of remedia0on is to minimize environmental and human health impacts • Evalua0on of BCR treatment generally through metal removal efficiency § Percentage of dissolved metals removed by the system o 100% * [(influent concentra0on – effluent concentra0on) / influent concentra0on] 6

Research QuesAons Asked • Are the effluents from the different pilot BCRs toxic (i.e., are there adverse effects to either test species that is sta0s0cally different from control water)? • Is the toxicity reduced, rela0ve to the influent? • If effluents are toxic, is a toxicant iden0fiable? 7

Study Sites • LuTrell Repository, Helena, MT • Peerless Jenny King, Helena, MT • Park City Biocell, Park City, UT • Standard Mine, Crested BuTe, CO 8

LuLrell Repository, MT • Upper Ten-Mile Creek Superfund site • 7,644 h AMSL • 2002 • 1.5 gpm treated • Al, As, Cd, Co, Cu, Fe, Mn, Zn 9

Peerless Jenny King, MT • Upper Ten-Mile Creek Superfund site • 7,600 h AMSL • 2003 • 20-25 gpm treated • Cd, Fe, Zn 10

Peerless Jenny King, MT • Upper Ten-Mile Creek Superfund site • 7,600 h AMSL Sampling hose • 2003 • 20-25 gpm treated • Cd, Fe, Zn 11

Park City Biocell, UT • Prospector drain in Silver Creek Watershed • 2002 • 6,900 h AMSL • 29 gpm treated • Cd, Zn 12

Park City Biocell, UT • Prospector drain in Silver Creek Watershed • 2002 • 6,900 h AMSL • 29 gpm treated • Cd, Zn 13

Standard Mine, CO • Crested BuTe • 2007 • 11,000 h AMSL • 1.2 gpm treated • Cd, Cu, Fe, Pb, Mn, Zn 14

Standard Mine, CO • Crested BuTe • Aerobic polishing cells added in 2008 15

Methods 16

Methods • Triplicate influent and effluent samples from LuTrell, PJK, and Park City • Duplicate influent and effluent samples from the Standard Mine BCR and from the APC 17

Methods • Filtered metals (0.45 µm) – induc0vely coupled plasma – op0cal emission spectroscopy (ICP-OES) • Sulfate – ion chromatography • Total sulfide – ion selec0ve electrode • Total ammonia – gas sensing electrode 18

Methods • Whole effluent toxicity tests [WET] § Series of dilu0ons of the influent and effluent water samples • Acute 48-hr LC50 § Percentage of water mixed with moderately hard dilu0on water • Ceriodaphnia dubia [water flea] • Pimephales promelas [fathead minnow] § Control survival > 90% 19

Results - Metals 20

Influent Metals ConcentraAons 21

Influent & Effluent pH and DO 22

Percentage of Metals Removed 23

Results - Acute AquaAc Toxicity 24

Highest dilu0on volume tested (25%) had 35% mortality Influent samples more toxic to water flea Effluent samples more toxic to fathead minnow LC50 below lowest volume tested < 0.1% Gray – water flea 25 Black – fathead minnow

Not different from control Influent samples more toxic to water flea Gray – water flea 26 Black – fathead minnow

Not different from control Influent samples more toxic to water flea Highest dilu0on volume tested (20%) 35-45% mortality Gray – water flea 27 Black – fathead minnow

Not different from control 35% mortality BCR effluent samples more toxic to fathead minnow than to Influent samples more the water flea toxic to water flea 1% 2% Gray – water flea 28 Black – fathead minnow

Acute AquaAc Toxicity • What caused acute toxicity in LuTrell and Standard Mine BCR effluent samples? • Low dissolved oxygen? § SM-BCR field average 0.6 mg/l DO; LuTrell field average 0.3 mg/l DO § Test units must have > 4 mg/l o Generally > 6 mg/l • Metals, sulfide, ammonia? 29

Acute AquaAc Toxicity 30

Effect of Aeration Percent Survival (100% 100 80 ~66% sample) 60 40 <20% 20 ~2% 0 C A B d d d d A B d e e e e e - - - - - M M R R R t t t t t a a a a a L L L S S r r r r r e e e e e a a a a a C A B B A - - - - - M M R R R L L L S S Sample ID 31 Test species: fathead minnow

Reference Toxicity Levels 2 ug/l H 2 S .2 to 5 mg/l NH 3 32

Reference Toxicity Levels 2 ug/l H 2 S .2 to 5 mg/l NH 3 33

Concluding Remarks • Results suggest toxicity from dissolved hydrogen sulfide gas § Effluents more toxic to fathead minnow than to the C. dubia § Fathead minnow known to be more sensi0ve to dissolved gases than C. dubia § Dissolved H 2 S concentra0ons above species mean acute values § Toxicity from 100% sample removed with aera0on at Standard Mine and reduced at LuTrell • Other BCRs may have different toxicants, depending on: § Contaminants present and efficiency of removal § Concentra0ons of dissolved gases and pH of the effluent 34

Concluding Remarks • BCR treatment is effec0ve at removing significant propor0ons of metals from MIW, but aqua0c toxicity may s0ll be present • Sufficient in-field aera0on following BCR treatment is an important step to remove poten0al toxicants resul0ng from the processes occurring within the BCR cells • Combining chemical and biological monitoring can lead to beTer treatment system designs § To meet the goal of minimizing environmental and human health impacts 35

Acknowledgements • Co-authors: § David Reisman – U.S. EPA ORD (re0red) § Jim Lazorchak – U.S. EPA ORD, NERL § Mark Smith – McConnell Group [deceased, prior contractor to U.S. EPA ORD] • Others: § Pegasus and McConnell Group – contractors to EPA § Regional RPM’s § City of Park City, UT 36

Thank you! Butler, BA, Smith, ME, Reisman, DJ, Lazorchak, JM. 2011. Metal removal efficiency and ecotoxicological assessment of field-scale passive treatment biochemical 37 reactors. Environmental Toxicology & Chemistry. 30(2):385-392.