Sustainable Utilization of RO By-

Product Solids

By

Bijoy Krishna Halder, Vivek Tandon, Anthony Tarquin,

Guillermo Delgado

The University of Texas at El Paso

Agenda

Introduction

Challenges

Objective

Material Used

Micro Scale Test

Sample Preparation and Curing Condition

Compressive Strength Test

Conclusion

Introduction

Introduction

• Water is an important resource.

• To produce potable water, various techniques e.g. desalination

is used.

• One desalination process is The Concentrate Enhanced

Recovery Reverse Osmosis (CERRO©)

• However this process yield high concentration CaSO4 as RO

by-product.

Challenges

Challenges

The disposal of this waste CaSO4 by-product in an

environmentally friendly manner is an issue.

Objective

• Evaluate the feasibility of using RO by-product in cement

mortar and AACB (alkali activated complex binders) mortars .

Objective

Material Used

Material Used

• Cement (Type I/II OPC, ASTM C-150)

• Quickrete all purpose sand (ASTM C 33 )

• Water

• NaOH (10M)

• Sodium Silicate (Na2O:SiO2=1:1)

• CaSO4 salt, RBG (passing #16 sieve )

• Class F fly Ash

• Fly ash Property (Collected from Boral Material Technology)

Material Used (Cont.)

Component Results

SiO2 50.69 %

Al2O3 23.68 %

Fe2O3 4.68 %

SiO2+ Al2O3+ Fe2O3 79.05 %

CaO 13.19 %

MgO 1.62 %

SO3 1.78 %

Na2O 0.05 %

K2O 0.90 %

Total Alkalies (as Na2O) 0.64 %

Loss of Ignition, % LOI 1.69 %

Specific gravity 2.29 1

MICRO SCALE TEST

XRD Analysis of RBG

0 5 10 15 20 25 30 35 40 45 50 55 60 65

Br

Br

Br

H BBB B

BB

B

B

B

Inte

nsity

(A

.U)

2-Theta

B

B: Bassanite

Br: Brucite

H: Hallite

• Bruker D8 X-ray diffractometer

• Bassanite, (CaSO4, 0.5 H2O)

SEM Analysis of RBG

(a) (b)

SEM Analysis of RBG (Cont.)

SEM EDX of Rod Shape Particle

-1 0 1 2 3 4 5

0

1000

2000

3000

Mg

K

Na

K

S K

O K

Ca

L Cl K

Ca

K

Ca

K

Cou

nt P

er S

econ

ds

Energy, KeV

Cl K

SEM EDX of Gel layer

Laser Diffraction Particle Sizing of Fly

Ash

Parameter Outcome

D (0.1) 3.92 µm

D(0.5) 34 µm

D(0.9) 139.80 µm

Surface weighted mean D[3,2] 8.855 µm

Volume weighted mean D [4,3] 85.5 µm

Specific surface area 678 m2/kg

Mean particle size 65 µm

Sample Preparation

& Curing Condition

Sample Preparation (Cont.)

ASTM* C-109 (2008)

Cement: Sand: Mixing Liquid= 1:2.75:0.49

AACB mortar (Fly Ash:Sand= 1:2.75, Sodium Silicate: NaOH=0.67,

minimum base water 5% by mass of geopolymer paste )

Samples were prepared in 2 × 2 × 2 in..

*American Society of Testing material

Curing Process

• Tap Water (For standard samples)

• Cement Mortar cured at room temperature, submerging under

water.

• AACB mortars were kept at 75 ̊ C for total 3 days accelerated

curing.

Compressive Strength

Test (ASTM C 109-08)

Compressive Strength Test Result

Compressive Strength Test Result

Compressive Strength Test Result

Conclusion

Conclusion

• The compressive strength test results indicate that there is

feasibility of disposing RO byproduct CaSO4 in geopolymer

based mortars.