CNP NUTRIENT

RECOVERY

TECHNOLOGIES

Josh Gable – Regional Sales Manager

MWEA Sustainability Seminar

Discussion Outline

• AirPrex Deep Dive

• How it works

• Review of data

• Review of key benefits

• CNP CalPrex – Basics

• History

• Brushite basics

• Summary

History of CNP and AirPrex

Where AirPrex Plugs In

So Why There?

So Why There?

1. Dewatering is always the problem area for nuisance struvite formation

- Get it to form before dewatering and eliminate the issue

2. We want to mitigate sidestream phosphorus

3. Removing the soluble P upstream of dewatering improves the cake

dryness and reduced the polymer requirement

So Why There?

MAP precipitation area

Mg2+ in solution

PO4-P Concentration (mg/L)

7

7,5

8

8,5

9

10 20 30 40 50 60 70 80 90 100 110 120 130 140

ortho-Phosphat [mg/ l]

pH

Raw Sludge (WAS & PS) Biogas

Digester

Magnesium-Dosage

AirPrex®Reactor

Dewatering

Air stripping

Struvite output

How it Works

1 Aeration to strip out CO2+recirculate sludge

2 Addition of Magnesium Chloride (MgCl2)

3 MAP- Crystallisation and sedimentation

4 MAP- Separation and washing

MgCl2

1

2

34 Struvite

Sequestration - OPTIONAL

How it Works

Notable Pilot Tests

What to Expect as a Result

Struvite sample collected during

Airprex Pilot in Miami-Dade

Improvement Cake Dryness

2 to 5 percentage points

Reduction in Polymer

10 to 40 % reduction

15%

17%

19%

21%

23%

25%

27%

29%

25 35 45 55 65

Ca

ke

TS

(%

TS

)

Active Polymer Dose, lb/dt

15 gpm 90% Target Removal

AirPrex

UntreatedDigestate

Data Collected during Denver Metro Pilot Test, Summer 2016

What to Expect as a Result

Struvite sample collected during

Airprex Pilot in Miami-Dade

90% Reduction of Sidestream OP

0

100

200

300

400

500

600

10/22 10/27 11/1 11/6 11/11 11/16

Co

ncen

tria

tio

n P

O4

-P (

mg

/L)

Date

Inflow

Outflow

AirPrex Cent

Digested Cent

Data Collected during Sun Prairie, WI Pilot Test, Fall 2016

What to Expect as a Result

Struvite sample collected during

Airprex Pilot in Miami-Dade

90% Reduction of Sidestream OP

Subsequent Reduction in Digester TP

0

100

200

300

400

500

600

10/22 10/27 11/1 11/6 11/11 11/16

Co

ncen

tria

tio

n P

O4

-P (

mg

/L)

Date

Inflow

Outflow

AirPrex Cent

Digested Cent

Data Collected during Sun Prairie, WI Pilot Test, Fall 2016

What to Expect as a Result –Reduction in Digester influent Phosphorus as Observed at the SunPrairie, WI

Pilot Test

Pre Pilot Test Average

490 mgP/L

At Conclusion of AirPrex Test

398 mgP/L

19% reduction in 16 days

HRT of digester 25-50 days

200

250

300

350

400

450

500

550

10/22/2016 10/27/2016 11/1/2016 11/6/2016 11/11/2016 11/16/2016

mg

P/L

Digestate P Conc’n

Pilot

Test

Modeling completed by MWH based on Denver Metro Pilot

Suggests 30% Reduction in Digester TP Concentration when System Reaches

Steady State.

Pilot Testing Summary

Example Installation

• Amsterdam, Netherlands – Installed 2014

Amsterdam-West WWTP (170 mgd)Struvite production: 2.5 t/dStart-up: 2014

AirPrex® - Amsterdam WWTP (Netherlands)

Disposal: $ 400,000/yr

Polymer savings: $ 350,000/yr

Maintenance: $ 40,000/yr

Revenue from Struvite pays for MgCl2

ROI 7 Years

AirPrex® - Savings for Amsterdam

AirPrex Installations

As of June 2017 – Denver Metro Announced AirPrex Selected

as Technology of Choice for their Nutrient Recovery Project

CNP CalPrex for Pre-Digestion Recovery

Why Acid Phase Digestion –Soluble Ions During Anaerobic Digestion

Sample from 8 Aug 2007

0

100

200

300

400

500

600

Acid Thermo Meso GBT Filtrate

pp

m

P Ca MgFlow

Phosphorus

precipitated

with calcium

and

magnesium

0%

10%

20%

30%

40%

50%

60%

70%

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Re

co

ve

ry P

ote

ntia

l (%

To

tal P

)

% Total P solubilized

Veolia Struvia™ CNP AirPrex® Ostara Pearl® CNP CalPrex™

Phosphorus Recovery Potential

Post

Digestion

Filtrate

Max

WAS

Max

Acid

Digest

Max

Brushite (dicalcium phosphate or dical) forms in slightly

acidic conditions of pH 4.5 – 6.5 and is a good fertilizer.

Ca2+ + H2PO4- + 2H2O CaHPO4·2H2O + H+

Struvite (magnesium ammonium phosphate) forms in slightly

alkaline conditions of around pH 8 and is a good fertilizer.

NH4+ + Mg2+ + HPO4

2- + 6H2O NH4MgPO4·6H2O + H+

Hydroxylapatite forms under alkaline conditions of pH 9 and is

NOT a good fertilizer.

3Ca2+ +2HPO42- + xH2O Ca3(PO4)·2xH2O + 2H+

What is Brushite?Distinction of Phosphorus Minerals

What is Brushite?Distinction of Phosphorus Minerals

0

2

4

6

8

10

12

14

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0.035

0.040

0 0.01 0.02 0.03 0.04 0.05

pH

Con

ce

ntr

atio

n [m

ol/L

]

Added calcium hydroxide [mol/L]

P Precipitation from Acid Digest

Dissolved-P Brushite Struvite calcite pH

What is Brushite?Distinction of Phosphorus Minerals

Brushite is a higher value product Commercial value = $250 - $300 / ton

versus

$100 / ton for Struvite

Fertilizer Comparison Statistical AnalysisBrushite and struvite were compared to MAP, DAP, and TSP

Various application rates to a P-deficient soil

Corn yield and P in above ground dry matter were measured

CNP CalPrex Pilot

CNP CalPrex Pilot

CNP CalPrex Pilot

Key Benefits of CalPrex

• Lower chemical cost for Ca(OH) 2 versus MgCl2• ~ $0.06 per lb

• Roughly 10-20% the cost of MgCl2 on a per lb. of P-removed basis

• Where acid digester used

• Can remove highest amount of TP of currently available

technologies

• Brushite has higher commercial value than Struvite

Summary

• Implementation of AirPrex

• Reduce sidestream OP by 90%

• Reduce digester influent TP by estimated 30% at steady state

• Improve Cake DS by 3 to 5 percentage point

• Reduce polymer requirement by 10 to 40%

• Implementation of CalPrex

• TP removal rates of over 50% possible as a separate stream

• Key to success is good P-release, best achieved via acid phase

digester

• Produce higher value fertilizer

• Combined Solution

• Maximize TP diversion and fertilizer production while maximizing

solids dewaterability

Questions?