Reuse of powdered eggshells in vermicomposting of acidic waste by - - PowerPoint PPT Presentation

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Dec 29, 2023 540 likes •668 views

Reuse of powdered eggshells in vermicomposting of acidic waste by Leong Hwee Lee, Ta Yeong Wu and Ze Xian Low www.monash.edu.my Content of Todays Presentation Introduction Materials and Methods Results and Discussion a) pH b)

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Reuse of powdered eggshells in vermicomposting of acidic waste

by Leong Hwee Lee, Ta Yeong Wu and Ze Xian Low

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Content of Today’s Presentation

Introduction Materials and Methods Results and Discussion

a) pH b) C/N ratio c) Electrical conductivity

Conclusion

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Introduction

Vermicomposting – Biological decomposition of organic waste to produce vermicompost via interactions between earthworms (epigeic) and microorganisms.

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Introduction

Advantages of vermicomposting process (Singh et al., 2011; Lim et al., 2016):

Short Processing time.
High nutrients recovery.
Texture of vermicompost is finer and heavy metals accumulated in

earthworm bodies.

Disadvantage of vermicomposting process (Lim et al., 2016):

Organic waste must NOT be hard, oily, acidic and

alkaline.

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Materials and Methods

Acidic waste: Orange skin pH: 4.37 Alkaline waste: Eggshells pH: 10.03 Amendment: Soil pH~ 5.50 Eudrilus eugeniae 60 days C/N ratio pH Electrical conductivity

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Materials and Methods

Treatment Treatment description S Soil only (as experimental control) 1OS: 1ES: 1S 1 part of orange skin: 1 part of eggshells: 1 part of soil 1.5OS: 1.5ES: 1S 1.5 part of orange skin: 1.5 part of eggshells: 1 part of soil 2OS: 2ES: 1S 2 parts of orange skin: 2 parts of eggshells: 1 part

f soil

Table 1: Description of different treatments used in vermicomposting experiment

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Results and Discussion

OS: Orange skin ES: Eggshells S: Soil

Fig. 1 pH in different treatments

Optimum initial pH range: 5-8 (Lim et al., 2016) Higher pH (8.7-9) was due to:

1. Reduction of organic

acids (Lim and Wu, 2016).

2. Intensive mineralization
f nitrogen by microbes

(Lim et al., 2014).

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Results and Discussion

OS: Orange skin ES: Eggshells S: Soil

Fig. 2 C/N ratio in different treatments

Lower final C/N ratio(24.0- 59.3) was due to:

1. Organic compounds

was transformed into CO2 (Lim and Wu, 2016).

2. Production of mucus

and nitrogen excrement (Lim et al., 2014).

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Results and Discussion

OS: Orange skin ES: Eggshells S: Soil

Fig. 3 Electrical conductivity in different treatments

Changes in electrical conductivity (EC) was due to:

1. Reduction of EC -

stabilization of the mixtures (Kaur et al., 2010) and decomposition

f organic acids (Shak et

al., 2014).

2. Increase of EC – Release
f minerals in the form of

cations (Lim et al., 2014).

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Conclusion

Orange waste (Acidic waste) + eggshells

(Alkaline waste) and soil (Amendment) could be used as waste mixtures (2OS:2ES:1S) in vermicomposting process.

Vermicomposting > 60 days: Better quality of

vermicompost could be obtained.

OS: Orange skin ES: Eggshells S: Soil

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THANKS

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Parameter Orange skin Eggshell Soil pH 4.37 10.03 5.50 Electrical conductivity (µS cm-1) 1779 80.7 218 TC (g kg-1) 295.73 160.11 643.20 TKN (g kg-1) 6.750 3.375 6.000 C/N ratio 43.81 47.44 107.20

CaCO3(s) + 2H+(aq) → Ca2+(aq) + CO2(g) + H2O (l) Note: Eggshell contains CaCO3: