PROCESS PARAMETER VARIATIONS DURING THE CO-COMPOSTING OF MIXED FILTERCAKE, BAGASSE

AND VEGETABLE WASTES

A. BHAWOO, A. MUDHOO, R. MOHEE

Department of Chemical & Environmental EngineeringFaculty of Engineering, University of Mauritius

1st International Conference on “Waste Management in Developing Countries and Transient Economies”

Mauritius, Africa, 5–7 September 2011

1

IntroductionComposting

Organic component of the solid waste stream is biologically decomposed under controlled aerobic conditions to a state in which it can be easily and safely handled, stored, and applied to the land without adversely affecting the environment.

2

In Mauritius, sugar-processing factories have problems with filter cake management:

Handling Storage Transportation

Introduction

Filter cake produced - 243,430 tonnes. Direct usage of filtercake - phytotoxicity and soil nitrogen immobilization (Khwairakpan and Bhargava, 2009).

Greenhouse gas (GHG) emissions due to direct disposal to land (Ochoa George et al., 2010).

3

Filtercake Composting(Meunchang et al., 2005)

ObjectivesASSESS THE CO-COMPOSTING OF FILTERCAKE

WITH BAGASSE AND VEGETABLE WASTE

Determining the effects on composting parameters in three composting experiments with different masses of filtercake but fixed masses of the other two substrates

Monitor the time-domain variation of Temperature, Free Airspace (FAS) and porosity, Moisture Content, wet bulk density, dry bulk density, Particle density, pH, Volatile Solids, CO2 generation

4

Methodology

Substrates• Mixed green vegetable wastes• Fresh bagasse & Fresh filter cake

5

SubstrateMix 1 Mix 2 Mix 3

Mass (kg) Mass (kg) Mass (kg)Bagasse (1) 16 16 16

Filtercake (2) 44 34 26Vegetable Wastes (3) 7 7 7

Total mass (kg) 67 57 49

Average Matrix

Moisture Content (%)

≈ 65.9 ≈ 65.1 ≈ 64.3

Average matrix C/N

ratio

≈ 24.3 ≈ 26.7 ≈ 29.6

Methodology

6

Methodology

Source: Mudhoo and Mohee (2007)

Methodology

Monitoring Procedures

Bulk Density DeterminationBulk Density Determination

Daily Temperature monitoringDaily Temperature monitoring

Moisture ContentMoisture ContentFree Airspace TestFree Airspace Test

Respiration Rate Tests ,pH

Respiration Rate Tests ,pH

Volatile Solids, Average Specific Gravity

Volatile Solids, Average Specific Gravity

8

Methodology

Average Compost Particle Density of substrates

Liquid Hexane displacement method100mL Liquid hexane +5 to 10g ground dried sampleMettler PM400 balance

Formula

9

Methodology

Free Airspace (FAS) and Porosity measurement

Formulaic method to measure porosity Porosity = (1-(Dry Bulk Density)/(Particle Density)×100%

Free airspace of compost.FAS = Porosity – MC volumetric

MC volumetric = (BDwet × MCwet)/(Density of water)

10

Results and Discussions

Temperature

Mix 1 ‐ 54.5°C – Day 4 Mix 2 ‐ 59.4°C – Day 3Mix 3 ‐ 52.0oC – Day 2 11

Results and Discussions

Wet basis moisture content

Mix 1 ‐ (65.9 ‐51.2)%Mix 2 ‐ (65.1 ‐ 51.7)%Mix 3 ‐ (64.3 ‐52.3)%

12

Results and Discussions

Wet bulk density

Mix 1 ‐ (202.62 – 708.83) kg/m3

Mix 2 ‐ (197.94 – 583.79 ) kg/m3

Mix 3 ‐ (169.14 – 474.26) kg/m3

13

Results and Discussions

Dry bulk density

14

Results and Discussions

Particle density of composting materials

Mix 1 (821 – 1835) (kg/m3)Mix 2 (1055 – 1998) (kg/m3)Mix 3 (416 – 1544) (kg/m3) 15

Results and Discussions

Porosity variation within compost matrix

Net decrease

Mix 1 ‐ 20.30 %Mix 2 ‐ 22.08  %Mix 3 ‐ 25.41  %

16

Results and Discussions

FAS variation within composting matrix

Net decrease

Mix 1 ‐ 43.40 %Mix 2 ‐ 38.69 %Mix 3 ‐ 38.49 %

17

Results and Discussions

pH measurements

Mix 1 ‐ (65.9 ‐51.2)%Mix 2 ‐ (65.1 ‐51.7)%Mix 3 ‐ (64.3 ‐52.3)%

18

Results and Discussions

Volatile solids measurements

Mix 1 ‐ (69.27)%Mix 2 ‐ (57.76)%Mix 3 ‐ (62.48)%

19

Results and Discussions

Carbon dioxide generation

Mix ‐ 1     39.82 mgCO2.C/day.gVSMix ‐ 2     43.86 mgCO2.C/day.gVS Mix ‐ 3     36.98 mgCO2.C/day.gVS 

20

Interim Conclusions

• Qualitative and quantitative data for physical parameters were as per typical parameter behavior and range of values, respectively.

• Potential for production of commercial compost by diverting them to a compost facility.

• A 5-week composting period is normally required

Bhawoo, A.,Mudhoo, A. and Mohee, R., 2011. Process parameter variations during co–composting of filtercake, bagasse and vegetable wastes. Proceedings Mauritius 2011, 1stInternational Conference on Waste Management in Developing Countries and Transient Economies, Mauritius, 5–9 September 2011. (Full Length Research Paper/Oral)

21

Interim Conclusions

• Filter cake can be composted with various proportions of bagasse and vegetable wastes

• Potential use as soil conditioner.

Bhawoo, A.,Mudhoo, A. and Mohee, R., 2011. Process parameter variations during co–composting of filtercake, bagasse and vegetable wastes. Proceedings Mauritius 2011, 1stInternational Conference on Waste Management in Developing Countries and Transient Economies, Mauritius, 5–9 September 2011. (Full Length Research Paper/Oral)

22

NEEDS FOR FURTHER STUDY ‐ Nutrient contents; Phytotoxicity assays; Fate and mobility/bioavailability of Heavy metals; 

Details of impact on soil structure

References• KHWAIRAKPAM, M. AND BHARGAVA, R., 2009. Bioconversion of filter mud using vermicomposting

employing two exotic and one local earthworm species. Bioresource Technology, 100, 5846-5852

• MEUNCHANG, S., PANICHSAKPATANA, S. AND WEAVER, R.W., 2005. Co-composting of filter cake and bagasse; by-products from a sugar mill. Bioresource Technology, 96(4), 437-442

• MUDHOO, A. AND MOHEE, R., 2007. Overall heat transfer coefficients in organic substrates composting. Journal of Environmental Informatics, 9(2), 87–99.

• OCHOA GEORGE, P.A., CABELLO ERAS, J.J., SAGASTUME GUTIERREZ, A., HENS, L. AND VANDECASTEELE, C., 2010. Residue from Sugarcane Juice Filtration (Filter Cake): Energy Use at the Sugar Factory. Waste and Biomass Valorization, 1(4), 407-413

23