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

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 Today’s Presentation  Introduction  Materials and Methods  Results and Discussion a) pH b) C/N ratio c) Electrical conductivity  Conclusion www.monash.edu.my Slide 2

Introduction Vermicomposting – Biological decomposition of organic waste to produce vermicompost via interactions between earthworms (epigeic) and microorganisms. www.monash.edu.my Slide 3

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. www.monash.edu.my Slide 4

Materials and Methods 60 days Eudrilus eugeniae Acidic waste: Orange skin pH pH: 4.37 C/N ratio Alkaline waste: Eggshells pH: 10.03 Electrical conductivity Amendment: Soil pH~ 5.50 www.monash.edu.my Slide 5

Materials and Methods Table 1: Description of different treatments used in vermicomposting experiment 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 of soil www.monash.edu.my Slide 6

OS: Orange skin Results and Discussion ES: Eggshells S: Soil 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 of nitrogen by microbes (Lim et al., 2014). Fig. 1 pH in different treatments www.monash.edu.my Slide 7

OS: Orange skin Results and Discussion ES: Eggshells S: Soil Lower final C/N ratio(24.0- 59.3) was due to: 1. Organic compounds was transformed into CO 2 (Lim and Wu, 2016). 2. Production of mucus and nitrogen excrement (Lim et al., 2014). Fig. 2 C/N ratio in different treatments www.monash.edu.my Slide 8

OS: Orange skin Results and Discussion ES: Eggshells S: Soil Changes in electrical conductivity (EC) was due to: 1. Reduction of EC - stabilization of the mixtures (Kaur et al., 2010) and decomposition of organic acids (Shak et al., 2014). 2. Increase of EC – Release of minerals in the form of cations (Lim et al., 2014). Fig. 3 Electrical conductivity in different treatments www.monash.edu.my Slide 9

OS: Orange skin Conclusion ES: Eggshells S: Soil • 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. www.monash.edu.my Slide 10

THANKS www.monash.edu.my Slide 11

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 Note: Eggshell contains CaCO 3 : CaCO 3 (s) + 2H + (aq) → Ca 2+ (aq) + CO 2 (g) + H 2 O (l) www.monash.edu.my Slide 12