Anaerobic Biochemical Reactor (BCR) Treatment of Mining-Influenced Water (MIW): EvaluaAon of ReducAon in ConcentraAons of Metals and AquaAc Toxicity

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1 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

2 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

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

4 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

5 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 reprecipitate as metal oxyhydroxides Degas sulfide and ammonia BCR Treatment 5

6 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

7 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

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

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

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

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

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

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

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

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

16 16 Methods

17 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

18 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

19 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

20 20 Results - Metals

21 21 Influent Metals ConcentraAons

22 22 Influent & Effluent ph and DO

23 23 Percentage of Metals Removed

24 24 Results - Acute AquaAc Toxicity

25 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% 25 Gray water flea Black fathead minnow

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

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

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

29 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? Acute AquaAc Toxicity 29

30 30 Acute AquaAc Toxicity

31 Effect of Aeration Percent Survival (100% sample) LR-A LR-B ~2% LR-C LR-A aerated ~66% LR-B aerated LR-C aerated SM-A <20% SM-B SM-A aerated SM-B aerated 31 Test species: fathead minnow Sample ID

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

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

34 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

35 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

36 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

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