Acidification and Separationof Slurry: Effects on slurry composition and gaseous emissionsduring storage

Innovative strategies to improve the recycling of energy,

nutrients and organic matter from waste materialsMay 26th 2015, Erfut, Germany

Funded by the

European Union

I. Regueiro, F. Gioelli, P. Balsari, E. Dinuccio, J. Coutinho, D. Fangueiro

FIRe, Joint Scientific Workshop

Presentation overview

Introduction

Background & Context

Objectives

Materials & Methods

Results & Discussion

Conclusions

Livestock production is an important source ofenvironmental problems:

Introduction

The release of NH3 andGHGs emissions fromslurry storage

Nutrient surplus in thesurrounding fields of thefarms

An efficient manure management should:

Avoid pollution (Water, air and soil)

Increase manure fertilizer value (reducing N loss andimproving P availability for plants)

Reduce costs (mainly due to storage and transport)

Introduction

Added to the environmental problems:

Fertilizer value of slurry: Decreases through N loss

The slurry storage capacity: Limited and costly

HOW COULD THESE REQUIREMENTS BE ACHIEVED?

Proposed solution:

Manure Acidification + Separation

Introduction

Acidification:

• To efficiently reduce NH3 emissionsKnown

• H2SO4 and HNO3 Studied in the past

• Practiced in Denmark by using H2SO4Today

Background and context

Background and context

Solid-liquid Separation:

• Easier to handle slurry: By reduction ofvolumes to store

Commonpractice in farms

• By Nutrients and Organic Matterconcentration in Solid fraction

Transport costsare reduced

• For on farm use as fertigation technique (butproblem of application: high emissions)

Liquid Fraction

Background and context

Separation: The efficiency is affected by slurry composition

Increases gas emissions

Acidification: Affects chemical and physical slurry composition

Reduces gas emissions

Acidification + Separation: Can increase separation efficiency

Can reduce gas emissions

Objective

To study the effects of acidification + separation oncomposition and gas emissions during storage of pig slurry.

Materials & Methods: Slurry sampling

Pig slurryinitial pH 7.34

Raw pig slurry was collected in 30 L barrels from a farm in Turin, Italy.

Total Solids (TS) = 4.6%Volatile Solids (VS): 0.9 %

Materials & Methods: Acidification

Acidified to pH 5.5 by adding Al2(SO4)3 (aluminum sulfate or alum)

Alum was chosen as analternative to H2SO4 because: It is easy to handle Of its flocculation properties

Materials & Methods: Separation

Separated by using a tomato machine which simulates a Screw Press

pH values of SFs

Total amount of SFs obtained

pH values of LFs

Total amount of LFs obtained

Materials & Methods: Experimental Setup

Samples (4L) stored in 5 L glass jars for gas emissions measurementduring 69 days of undisturbed storage.Samples in 3 replicates.

Sample analysis:pHTotal Solids (TS)Volatile Solids (VS)Total N (TN)Total P (TP)N-NH4

+

Initial conditions:

Slurry volume: 4 LHeadspace: 1 L

Air flow rate: 1 L min⁻¹

Materials & Methods: Gas measurement

Photoacousticanalysermeasureseach sample continuouslyduring 8 minutes.

Samples ventilated onlyduring measurement.

Air flow Rate:Adjusted to an air renewalrate of oneheadspacevolume per minute.

DYNAMIC CHAMBER METHOD

Results & Discussion: Slurry composition

Proportionof slurry

(%)

pH Total Solids(g kg¯¹ slurry)

Total N (g kg¯¹ TS)

N-NH₄⁺ (% TN)

Total P

(g kg¯¹ TS)

Pig Slurry (S) - 7.3 46 52 66 26

Acidified Pig Slurry (AS) - 5.5 60 40 76 20

Solid Fraction (SF) 15 7.6 161 24 39 14

Acidified Solid Fraction (ASF) 21 5.9 136 25 53 13

Liquid Fraction (LF) 85 7.5 16 156 64 43

Acidified Liquid Fraction(ALF) 79 5.7 40 58 81 25

Results & Discussion: NH3 emissions

S: Raw Slurry AS: Acidified SlurryLF: Liquid Fraction ALF: Acidified Liquid FractionSF: Solid Fraction ASF: Acidified Solid Fraction

0

50

100

150

200

1 14 27 40 53 66

NH

3Fl

ux

(mg

h¯¹

m¯²

)

t (days)

S AS

LF ALF

SF ASF

0

20

40

60

80

Ave

rage

NH

3Fl

ux

(mg

h¯¹

m¯²

)

-78%

-92%

-31%

Reduction efficiency

Results & Discussion: CH4 emissions

S: Raw Slurry AS: Acidified SlurryLF: Liquid Fraction ALF: Acidified Liquid FractionSF: Solid Fraction ASF: Acidified Solid Fraction

0

200

400

600

800

1000

1 14 27 40 53 66

CH

4Fl

ux

(mg

h¯¹

m¯²

)

t (Days)

S AS

LF SF

ALF ASF

0

50

100

150

200

250

Ave

rage

CH

4Fl

ux

(mg

h¯¹

m¯²

)

-81%

-92%

-46%

Reduction efficiency

Results & Discussion: CO2 emissions

0

1000

2000

3000

4000

5000

Ave

rage

CO

2Fl

ux

(mg

h¯¹

m¯²

)

-48%-48%

-40%

0

2000

4000

6000

8000

10000

1 14 27 40 53 66

CO

2Fl

ux

(mg

h¯¹

m¯²

)

t (Days)

S AS

LF ALF

SF ASF

S: Raw Slurry AS: Acidified SlurryLF: Liquid Fraction ALF: Acidified Liquid FractionSF: Solid Fraction ASF: Acidified Solid Fraction

Reduction efficiency

Results & Discussion: N2O emissions

SF: Solid Fraction ASF: Acidified Solid Fraction

0

100

200

300

400

1 14 27 40 53 66

N2O

Flu

x (m

g h

¯¹ m

¯²)

t (Days)

SF

ASF

Reduction efficiency

0

20

40

60

Ave

rage

N2O

Flu

x (m

g h

¯¹m

¯²)

-88%

Conclusions

Acidification of slurry with alum has the potential to increase:

Total Solids content of slurry Total N content through N-NH₄⁺ which remains in the

slurry.

Acidification of slurry with alum before separation:

Increases the proportion of Solid Fractions by 6%. Increases separation of N and P to the Solid Fraction. Avoid emissions during separation

Conclusions

Acidification of pig slurry reduces NH3 and GHG emissionsduring storage:

NH3 emissions up to 87%. CO2 emissions up to 62%. CH4 emissions up to 96%. N2O emissions by 96% in solid fraction.

Acidification of pig slurry increases the Total N and OrganicMatter content

Thank you for your attention!

Innovative strategies to improve the recycling of energy,

nutrients and organic matter from waste materialsMay 26th 2015, Erfut, Germany

Funded by the

European Union

I. Regueiro, F. Gioelli, P. Balsari, E. Dinuccio, J. Coutinho, D. Fangueiroiriaregueiro@isa.utl.pt

FIRe, Joint Scientific Workshop