Bench-scale Arsenic Treatability Study of Municipal Wastewater to Support the New Jersey Department of Environmental

Protection’s Water Quality Standards Variance Development

March 1, 2018－ May 31, 2019

Xiaoguang Meng, Jie GeStevens Institute of Technology

Project Managers: Biswarup Guha, Division of Water Monitoring and Standards; Dr. Lee Lippincott, Division of Science and Research

Project Team: Bruce Friedman, Kimberly Cenno, Jack Pflaumer, Division of Water Monitoring and Standards; Stan Cach and Anthony Pilawski, Division of Water

Quality; Chris Hoffman, Water Resource Management Municipal Finance Element; Marc Ferko, Office of Quality Assurance; Doug Haltmeier, NJ Department of Health

Inorganic Program Manager

Main ObjectiveDetermine the feasibility of using ferric chloride and alum coagulation toreduce arsenic in municipal wastewater to less than 2 µg/L.

TasksPhase 1: Chemical Characterization of Wastewater and SludgePhase 2: Coagulation Treatment of Wastewater - Jar TestsPhase 3. Filtration Removal of As in Plant A Effluent

a) Adsorptive Filtrationb) Direct Co-precipitation Filtration

Project Overview

3

Plant influent Primary clarifier effluent Plant effluent

Wastewater Treatment Plant A

Phase 1: Chemical Characterization of Wastewater

Wastewater Treatment Plant B

Alum addition for P removal

Arsenic Concentration in Plants A and B

Note: 1). analysis was performed by Stevens; detection limit=0.30 µg/L; reporting limit=1.00 µg/L.

2.432.14 2.12

2.76 2.862.282.28

7.196.99

6.51

5.00

5.50

6.00

6.50

7.00

7.50

8.00

8.50

9.00

1.00

10.00

100.00

PI PCE PE

pH

Con

cent

rati

on (μ

g/L

)

Arsenic Concentration in Grab Samples Collected at MCUA on 7/17/2018

Total Recoverable As (μg/L) Dissolved As (μg/L)

Dissolved Arsenite (μg/L) pH

3.13 2.83

1.542.04

2.51

1.25

7.12 7.19

6.77

5.00

5.50

6.00

6.50

7.00

7.50

8.00

8.50

9.00

1.00

10.00

100.00

PI PCE PE

pH

Con

cent

rati

on (μ

g/L

)

Arsenic Concentration in Grab Samples Collected at MCUA on 5/2/2018

Total Recoverable As (μg/L) Dissolved As (μg/L)

Dissolved Arsenite (μg/L) pH

(a)

2.66 2.742.19

2.50 2.271.941.95

6.997.18

6.36

5.00

5.50

6.00

6.50

7.00

7.50

8.00

8.50

9.00

1.00

10.00

100.00

PI PCE PE

pH

Con

cent

rati

on (μ

g/L

)

Arsenic Concentration in Grab Samples Collected at MCUA on 6/19/2018

Total Recoverable As (μg/L) Dissolved As (μg/L)

Dissolved Arsenite (μg/L) pH

(b) (c)

0.49 0.410.58

0.48

7.617.46

7.57 7.51

6.00

6.50

7.00

7.50

8.00

8.50

9.00

0.10

1.00

10.00

100.00

PI PCE ICE PE

pH

Con

cent

rati

on (μ

g/L

)

Arsenic Concentration in Grab Samples Collected at HMUA on 5/15/2018

Total Recoverable As (μg/L) Dissolved As (μg/L)

Dissolved Arsenite (μg/L) pH

(d)

1.62 1.81

1.050.80

0.35 0.38 0.35

7.787.70 7.73 7.66

6.00

6.50

7.00

7.50

8.00

8.50

9.00

0.10

1.00

10.00

100.00

PI PCE ICE PE

pH

Con

cent

rati

on (μ

g/L

)Arsenic Concentration in Grab Samples Collected at HMUA on 6/26/2018

Total Recoverable As (μg/L) Dissolved As (μg/L)

Dissolved Arsenite (μg/L) pH

(e)

0.750.52 0.48 0.44

7.81 7.747.82

7.69

6.00

6.50

7.00

7.50

8.00

8.50

9.00

0.10

1.00

10.00

100.00

PI PCE ICE PE

pH

Con

cent

rati

on (μ

g/L

)

Arsenic Concentration in Grab Samples Collected at HMUA on 7/17/2018

Total Recoverable As (μg/L) Dissolved As (μg/L)

Dissolved Arsenite (μg/L) pH

(f)

0.00

Plant A 6/19/2018Plant A 5/2/2018 Plant A 7/17/2018

Plant B 7/17/2018Plant B 6/19/2018Plant B 5/2/2018

Biological water treatment processes are not effective for As removal.Soluble As was removed on 6/19 possibly by alum at Plant B.

1.210.719

0.711 0.686 0.602

55.2 47.7 47.9 47.3 46.9 53.6

17.8 18.4 17.9 18.3 17.3 17.9

0.001

0.01

0.1

1

10

100

1000

Co

nce

ntr

atio

nTime

Diurnal Changes of Different Parameters at HMUA on 6/26~6/27

Total Recoverable As (μg/L) Dissolved As (μg/L)

Dissolved Ca (mg/L) Dissolved Si (mg/L)

6/26 09:00 6/26 13:00 6/26 17:00 6/26 21:00 6/27 01:00 6/27 05:00

Grab Sample at 9:39 am on 6/26

Total Recoverable As=Non-detect

Dissolved As=Non-detect

There were no obvious diurnal changes in As, Si, and Ca.

Note: Analyses were performed by NJDOH lab.

Diurnal Changes of Arsenic, Calcium and Silicate

2.73

1.792.58 2.22 2.52

1.96

1.20 1.86 1.55 1.56 1.44 1.71

50 49.5 49.2 49.2 50.0 50.0

11.9 12.3 12.1 11.8 11.9 12.1

1

10

100

1000

Co

nce

ntr

atio

n

Time

Diurnal Changes of Different Parameters at MCUA on 6/19~6/20

Total Recoverable As (μg/L) Dissolved As (μg/L)

Dissolved Ca (mg/L) Dissolved Si (mg/L)

6/19 8:10 6/19 12:10 6/19 16:10 6/19 20:10 6/20 00:10 6/20 04:10

Grab Sample at 9:06 am on 6/19

Total Recoverable As=2.77 μg/L

Dissolved As=1.81 μg/L

Plant A, 6/19 – 6/20 Plant B, 6/26 – 6/27

3.804.00

2.50

0.10 0.21 0.160.00

1.00

2.00

3.00

4.00

5.00

6.00

5/15/2018 6/26/2018 7/24/2018

Co

nce

ntr

atio

n (

mg/

L)

PO43- -P Concentration in Wastewater Samples Collected at HMUA

Primary Clarifier Effluent Plant Effluent

1.00

1.40

1.98

0.32

1.06

1.66

0.00

1.00

2.00

3.00

4.00

5.00

6.00

5/2/2018 6/19/2018 7/17/2018

Co

nce

ntr

atio

n (

mg/

L)

PO43- -P Concentration in Wastewater Samples Collected at MCUA

Primary Clarifier Effluent Plant Effluent

(a) (b)

Removed 97% Removed

95%

Removed 94%

Removed 16%

Removed 24%

Removed 68%

Note: Analysis was performed by Stevens; detection limit=0.02 mg-P/L; reporting limit=0.10 mg-P/L

Removal of Dissolved Orthophosphate at Plants A and B

PO34- - P concentrations at Plant A PO3

4- - P concentrations at Plant B

Alum was added to wastewater before the final clarifiers to remove P at Plant B.P treatment was not required at Plant A.

Phase 2: Coagulation Treatment of Wastewater - Jar Tests

Mixing Settling

Addition of FeCl3 or alum during mixing

1 min of stirring at speed of 120 rpm

4 min of stirring at speed of 40 rpm

1 hr. of settling

Supernatant: total recoverable arsenic

Filtered Supernatant (0.45 μm): dissolved arsenic

Treated Samples on site:

1. Primary clarifier effluent

2. Mixed liquor

3. Mixed liquor supernatant

4. Plant effluent

As Removal from Primary Clarifier Effluent of Plant A

As Removal from As-spiked Effluents of Plants A and B

Arsenic Removal from Mixed Liquor and Supernatant of Plant A

8 mg/L of coagulants, initial As concentration = 7.26 µg/L.

Effect of pH on As Removal from As-spiked Effluent of Plant A

Competing Adsorption As and PO43- for Fe and Al

in As(V)- and PO43-- spiked Plant A Effluent

Initial dissolved PO43-= 0.08 mg-P/L, initial DOC=6.38 mg-C/L.

Phase 3. Filtration Removal of As in Plant A Effluenta) Adsorptive Filtration

Adsorbent media: iron oxide. a) raw effluent (PE) as column influent, EBCT=3 min, flowrate=10 ml/min; b) PE spiked with 5.0 µg/L As(V) as column influent, EBCT=3 min, flowrate=10 ml/min; c) PE as column influent, EBCT=10 min, flowrate=3 ml/min; d) PE spiked with 5.0 µg/L As(V) as column influent, EBCT=10 min, flowrate=3 ml/min.

Iron Oxide Adsorptive Filtration

Original effluent 5 ppb As spiked effluent, EBCT 3 min

Original effluent, EBCT 10 min As spiked, EBCT 10 min

Adsorbent media: adsorbent media=TiO2; plant effluent (PE) spiked with 5.0 µg/L As(V) as column influent, EBCT=10 min, flow rate=3 ml/min.

TiO2 Adsorptive Filtration Results

b) Direct Co-precipitation Filtration

Rapid sand filtration 1.6 m3/m2/h. Sand colum: ID = 5.56 cm, H = 152 cm, sand 61 cm of filter sand (mass=2.0 kg).

Plant effluent (PE) spiked with 5.0 µg/L As(V) as column influent, wastewater flow rate=65 ml/min, coagulant flowrate=1 ml/min, alum dosage= 8 mg-Al/L

Direct Co-precipitation Filtration Results

Summary

a) The total recoverable As (TAs) concentration in the influent and effluent of Plant A was in the range of 2.00-3.00 μg/L and 1.50-2.30 μg/L, respectively. The TAs in the influent and effluent of Plant B was about 0.95 and 0.57 μg/L, respectively.

b) The Biological wastewater treatment processes were not effective for As removal.

c) Ferric and alum coagulation treatment could not effectively remove As from the municipal wastewater. Very high doses of the coagulants (8 and 40 mg/L of Fe(III) or Al(III)) were required to reduce the TAs from 2.84 and 8.61 µg/L in the primary clarifier effluent and arsenate-spiked effluent samples to less than 2.00 µg/L.

d) Adsorptive filtration with iron oxide and TiO2 could only filter less than 8000 bed volumes of Plant A effluent spiked with 5 μg/L As.

e) Direct co-precipitation and rapid sand filtration with 8 ppm Al could effectively remove As from Plant A effluent spiked with 5 μg/L As.

Acknowledgment

NJDEP managers: Bruce Friedman, Kimberly Cenno, Nicholas Procopio, and Gary Brower.

HMUA: Kathleen Corcoran and her staff

Stevens Institute of Technology: Dr. Amalia Terracciano, Dr. Jinshan Wei