Results of a Pilot Fluidized Bed Reactor Selenium...

Copyright 2010 by CH2M HILL, Inc. • Company Confidential

Results of a Pilot Fluidized Bed Reactor Selenium Treatment Demonstration

17th Annual British Columbia/ Canadian Mine Environment Neutral Drainage Program

(MEND) Mining Leaching/Acid Rock Drainage Workshop

December 2, 2010Vancouver, British Columbia

By Tom Sandy/CH2M HILL


Agenda

• Background• Technology Overview• Pilot Test Objectives• Pilot Unit Design Configuration• Key Design Criteria• Water Quality• Results• Conclusions


Background

• Eastern US Appalachian mountain surface coal mine• Compliance at 3 Outfalls of 4.7 µg/L average month 8.2 µg/L

daily max• One of many end of pipe treatment technologies evaluated

– ABMet®

– Zero Valent Iron– Reverse Osmosis– VSEP®

• Considered in conjunction with other in mine management alternatives

• Watershed hydrology and ecotoxicology studies


Fluidized Bed Reactor (FBR) Technology Overview

• Uses sand, activated carbon or other solid media with similar characteristics

• Small footprint• Lower capital cost

• Attached growth biological treatment

• Heterotrophic anaerobic biogrowth

• Configuration provides efficient mass transfer

• Continuous liquid solid separation

• Relatively Simple


One of Many Attached Growth Reactors…But One of the More Efficient

A) Trickling FilterB) Upflow DraftC) Downflow DraftD) Rotating Biological

Contactor

E) Suspended Biofilm F) Fluidized Bed G) Moving Bed H) Membrane Attached

Biofilm


Pilot Testing Overview

• Easily accessible outfall with similar water characteristics

• Proof of concept-16 weeks mid-February 2010 to end of May 2010

• Design testing-24 weeks mid-September 2010 to mid February 2011

• Parallel flow and water quality basis of design development during design testing both on-going.

General Influent Water QualityParameter Unit

Average Std Dev.TSS mg/L 7 5TDS mg/L 2902 311

Total Solids mg/L 2909 315COD mg/L 8.8 5TOC mg/L 2.6 1

Sodium mg/L 14.7 0Chloride mg/L 9.5 0Ammonia mg/L 0.22 0

Sulfate mg/L 1902 47Strontium mg/L 1.41 0

Total Phosphate mg/L 0.96 0Manganese mg/L 0.03 0Alkalinity mg/L 278 8Carbonate mg/L 0 0

Bicarbonate mg/L 290 14Turbidity ntu 11.28 12Nitrate mg/L 9.52 0

Calcium mg/L 302 8Magnesium mg/L 377 10Potassium mg/L 29.9 2

Silica mg/L 1.56 1Hardness mg/L 2169 35Cyanide mg/L 0.014 0

Orthophosphate mg/L <0.01 0CBOD mg/L <1.0 0Barium mg/L <0.10 0Boron mg/L 0.12 0

Fluoride mg/L 0.17 0TKN mg/L <0.10 0



Proof of Concept Pilot Testing Setup & Configuration



Design Pilot Testing Configuration


Envirogen Pilot FBR

Pilot Exterior Pilot Interior


Pilot FBR


Pilot FBR Configuration

• 61 cm (2 ft) diameter by 4.3 m (14 ft) high stainless steel reactor

• 38 lpm (10 gpm) and 151 lpm (40 gpm) maximum recycle flowrate

• Support equipment in 2.4 m (8 ft) by 3 m (10 ft) Conex Box

• 163 Kg (360 lbs) of granular activated carbon (GAC) or 60% of active reactor volume

• Fluidized bed height 2 to 3 m (8 to 9.5 ft)


Pilot FBR Operation-Proof of Concept

• MicroCg carbon substrate feed• Phosphoric acid, ammonium sulfate and

micronutrients added• 30 lpm (8 gpm) forward feed• 132-151 lpm (35-40 gpm) recycle flowrate • >3:1 recycle rate required for proper bed

fluidization• Hydraulic residence time (HRT) at 30 lpm

(8 gpm) is approximately 28 minute in


Pilot FBR Monitoring

• Monitored a variety of parameters in influent and effluent – pH, temperature, ORP, TSS, VSS, TDS,

DO, COD, BOD, nitrate, sulfate, sulfide, phosphate, calcium, magnesium, selenium forms, micro exams,

• Conducted Toxicity Characteristic Leach Procedure (TCLP) testing on solids in proof of concept


Microscopic Examination


Chemical Oxygen Demand (COD)and Total Suspended Solids (TSS)

0

10

20

30

40

50

60

70

80

0

50

100

150

200

250

300

4/4 4/11 4/18 4/25 5/2 5/9

TSS

Con

c. (m

g/L)

CO

D C

onc.

(mg/

L)

Date

Effluent COD (Total)

Effluent COD (Diss.)

Effluent TSS


Temperature

30

35

40

45

50

55

60

65

70

75

80

2/28 3/7 3/14 3/21 3/28 4/4 4/11 4/18 4/25 5/2 5/9

Tem

pera

ture

(°F)

Date

Influent Temperature

Reactor Temperature


Effluent COD and Biochemical Oxygen Demand (BOD5)

0

50

100

150

200

250

300

4/4 4/11 4/18 4/25 5/2 5/9

Con

cent

ratio

n (m

g/L)

Date

Effluent COD (Total)

Effluent COD (Diss.)

Effluent BOD


COD Stoichiometry and Selenium Removal Performance

0

5

10

15

20

25

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

3/9 3/16 3/23 3/30 4/6 4/13 4/20 4/27 5/4 5/11

CO

D C

onsu

med

(lb/

day)

Se R

emov

al (%

)

Date

Total Se

Dissolved Se

COD Consumed


Selenium Removal Performance

0

5

10

15

20

25

30

35

40

45

50

3/9 3/16 3/23 3/30 4/6 4/13 4/20 4/27 5/4 5/11

Se C

once

ntra

tion

(µg/

L)

Date

Influent - Total Influent - Dissolved

Effluent - Total Effluent - Dissolved

4.7 µg/L - Monthly Av. Limit


Observed Yields

0

2

4

6

8

10

12

14

16

18

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

4/4 4/11 4/18 4/25 5/2 5/9

CO

D C

onsu

med

(lb/

day)

Yiel

d OB

S(lb

TSS

/ lb

CO

D C

onsu

med

)

Date

Yield (OBS)

COD Consumed


Proof of Concept Conclusions

• Soluble selenium removal consistently below 4.6 µg/L

• Effluent TSS will require polishing to meet NPDES selenium requirements

• Effluent BOD will require aerobic treatment to meet expected NPDES requirements

• Residuals nonhazardous per EPA RCRA TCLP 1 mg/L Se


Design Testing Focus On-Going

• TSS removal evaluation: filtration and sedimentation

• BOD removal evaluation-aerobic attached growth bioreactor

• Maximum throughput design capacity• Reliability and operability reviews• Flow equalization/diversion requirements


Questions?

Tom Sandy, P.E.Technology DirectorCH2M HILL11301 Carmel Commons Blvd, STE 304Charlotte, NC [email protected]

Results of a Pilot Fluidized Bed Reactor Selenium...

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