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All content in this area was uploaded by Adi Ainurzaman Jamaludin on Oct 12, 2015
Content may be subject to copyright.
International Conference on Environmental Research and Technology (ICERT 2008)
The potential of coffee grounds and kitchen waste in vermicomposting
Adi Ainurzaman Jamaludin
*
and Noor Zalina Mahmood
Institute of Biological Sciences, Faculty of Science, University of Malaya,
50603 Kuala Lumpur, Malaysia
*
Corresponding author. Phone: +603 7967 6753, Fax: +603 7967 6752
Email: conquer_vx@hotmail.com
ABSTRACT
Vermicomposting using Lumbricus rubellus for 49 days was conducted after 21 days of pre-composting. Three
different combination of treatments were prepared with eight replicates for each treatment namely cow dung :
kitchen waste in 30:70 ratio (T
1
), cow dung : coffee grounds in 30:70 ratio (T
2
), and cow dung : kitchen waste :
coffee grounds in 30:35:35 ratio (T
3
). At the end of study, there was a significant difference between numbers of
earthworms among the three different treatments (p < 0.05). In contrast with weights of earthworms there was no
significant difference (p > 0.05) among the three treatments. By comparing the numbers and weights of earthworms
in each treatments (T
1
, T
2
& T
3
) only T
2
indicated the difference was significant (p < 0.05). Therefore it can be
concluded that coffee grounds influenced the development of earthworms’ population. Nutrient elements in the
vermicompost from each treatment were measured and relatively showed high percentage in C, N, P, and K. The
presence of coffee grounds in vermicomposting in resulted significant reduction in C/N ratio and increase in mineral
N. The data reveals that coffee grounds can be decomposed through vermicomposting by using Lumbricus rubellus
into value-added material. With the correct ratio and suitable condition of kitchen waste, coffee grounds can also be
used as stabilizer in vermicomposting.
Keywords: Coffee grounds, kitchen waste, Lumbricus rubellus, nutrient element, vermicomposting.
1. INTRODUCTION
From the statistics reported by the Economic Planning Unit (2006) in Ninth Malaysia Plan 2006-2010, the
amount of solid waste generated in Peninsular Malaysia has increased from 16,200 tonnes per day in 2001 to 19,100
tonnes in 2005 or an average of 0.8 kg per capita per day. Solid waste in Malaysia on average consists of 45 % of
food waste, 24 % plastic, 7 % paper, 6 % iron and 3 % glass and others made of the rest.
From these data, generation of solid waste is expected to reach 30,000 tones per day in 2020. Bolt from the
blue, 58.3% of all the wastes dumped to landfills composed of valuable organic waste (Rahimah, 2007). Organic
wastes become the major waste composition for Kuala Lumpur since 1970’s (Sivapalan et al., 2002),
With the present approach, opening of new landfills and building up high technology incinerator, problems
related to waste cannot be solved easily. Based on the characteristic of the MSW in Malaysia, incinerator is not a
practical treatment to be used because the average moisture content of our waste is about 55% to 60% and with low
calorific value (Sivapalan et al., 2002). With high moisture content, self sustained combustion requires auxiliary fuel
when the energy that need to be used for incineration process also need to be used for drying process. Definitely this
is not economic in maintenance and operation aspect when the price of fuel is increasing rapidly. Therefore Azni
Idris et al. (2004) recommended that solutions should consider practical and economical way to optimize the
utilization of any MSW before finally send for disposal. Under the Ninth Malaysia Plan (Nadzri, 2007), a target was
set to recycle 22 per cent of MSW by 2020.
Vermicomposting has been identified as one of the potential activity in contributing toward the recycling target.
Vermicomposting is cost effective and natural method alternative with shorter duration needed to accomplish; one to
two weeks (Ilyan, 2007). It also can be classified as a simple biotechnology process of composting by using certain
earthworms to enhance the process of waste conversion to produce better end product.
One of the earthworm species that is commonly used in vermicomposting is Lumbricus rubellus.
Unfortunately, L. rubellus is not a local species. It originated from Australia. It is reddish brown or reddish violet,
iridescent dorsally, and pale yellow ventrally. Compared to the local species, L. rubellus is more active in their
eating behaviors and reproduction rate. The sexual maturity period for this species is 4 to 6 weeks under favorable
conditions such as 25°C to 30°C for temperature, 40% to 45% of moisture contents and pH between 5.5 and 8.7.
One pair of earthworms can produce 100 cocoons in 6 months (Ismail, 1997).
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International Conference on Environmental Research and Technology (ICERT 2008)
As a final product, vermicompost has higher percentage of nutrient elements than garden compost
(Nagavallemma et al., 2004).
2. MATERIALS AND METHODS
2.1. Indoor Analysis
Plastic bins of size 45cm x 30cm x 30cm with four plots in each box and small holes at the bottom were used as
worm bin. Three different combination of treatments were prepared with eight replicates for each treatment namely
cow dung:kitchen waste in 30:70 ratio (T
1
), cow dung:coffee grounds in 30:70 ratio (T
2
), and cow dung:kitchen
waste:coffee grounds in 30:35:35 ratio (T
3
). The use of cow dung is only for supplement and also used as bedding
material for the earthworms at early stage before they climatize with the treatments given.
In each treatment plot, 60 weighted matured earthworms of approximately the same size were introduced
after 21 days (3 weeks) of pre composting of organic wastes to avoid exposure of worms to high temperature during
initial thermophilic stage. The duration of vermicomposting was 49 days (7 weeks). Moisture content of the
treatment was maintained at about 50-60% by spraying the surface with mineral water.
After 49 days, the total number and biomass of the worms were determined as live weight after hand
sorting and removal of all extraneous material. Two days before the determination, all the treatments were not
watered to make the compost easy for sifting.
2.2. Statistical Analysis
Statistical analysis was carried out using SPSS 11.0.1 (Standard Version) computer software package. One way
analysis of variance (ANOVA) was done to analyze the significant difference between treatments during
vermicomposting at 0.05% level of significance. Paired samples t-test was used to determine any significant
difference between the numbers and weights of earthworms (L. rubellus) in each treatment.
2.3. Laboratory Analysis
The nutrient parameters of vermicompost produced after experiments were analyzed by using standard method.
Organic carbon, C was determined by the partially-oxidation method (Walkley & Black, 1934). Nitrogen, N was
estimated by Kjeldahl digestion. Phosphorus, P was detected by using colorimetric. For K, was measured by ignition
method using atomic absorption spectrophotometry. C/N ratio analyzed through the calculation.
3. RESULTS AND DISCUSSION
3.1. Indoor and Statistical Analysis
-100.00
-50.00
0.00
50.00
100.00
150.00
200.00
Percentage (%)
A1 A2 A3 A4 A5 A6 A7 A8 B1 B2 B3 B4 B5 B6 B7 B8 C1 C2 C3 C4 C5 C6 C7 C8
Plot
Number Weight
Graph 3.1 Multiplication of earthworms using cow dung, kitchen waste and coffee grounds in different ratio.
Waste management (industrial, domestic, natural)
77
International Conference on Environmental Research and Technology (ICERT 2008)
3.1.1. T
1
– Cow dung : Kitchen waste (30 : 70)
The presence of kitchen waste which consists of animal such as fish residues enhance the moisture content that
could result in putrification of waste (Kristiana et al., 2005). Thus, lead to anaerobicity condition which restricted
the air movement through the available pore spaces in the substrates (Singh et al., 2004).
With scarcity of air, it regains more odourous anaerobic bacteria which thrive without air and make the
earthworms became asphyxiate. Therefore, decrease number and weight of the earthworms (A6).
The odour that generated from metabolism of anaerobic microorganisms and anaerobic decomposition invited
the mites and juvenile flies to become pests. Thus, interfere the earthworms’ activities and lead towards the
mortality of earthworms (A3, A5, A6, & A8). The survived earthworms fully utilized the feed materials available
when there have increase in weight although numbers of earthworms were decreased (A2 & A7). For plot A1 and
A4, without any presence of animal based residues while moisture contents were under control, enhanced the
development of earthworms.
The paired samples test for numbers and weights of earthworms in T
1
indicates that the difference is not
significant (p > 0.05, t=0.113, df=7). Thus, the kitchen waste as feed materials did not influence the development of
earthworm population.
3.1.2. T
2
– Cow dung : Coffee grounds (30 : 70)
The fine grind of coffee grounds was recognized to help stabilized the condition in plot B1 to B8 by improving
the texture, moisture retention capabilities which help to aerate the whole plots. Coffee grounds are high in N, P, K,
Ca, Mg and S while pH of used grounds was 6.9 (Starbucks Coffee, 2005); a significant amount of buffer capacity
that can lead towards neutral pH. The aroma of roasted coffee (coffee grounds) contains more than 800 volatile
molecular species (Illy, 2002) is predicted to has the capability to discourage pests which interfering the
earthworms. The presences of fungi during vermicomposting became additional supplement to the earthworms and
contribute to the increase number and weight of the earthworms (Edwards & Fletcher, 1998) as in B1, B3, B4, B7
and B8. The unstable temperature influences by moisture contents, gave impacts to plot B2, B5, and B6.
In contrast to the paired samples test for T
2
, the difference in numbers and weights is significant (p < 0.05,
t=3.749, df=7). Therefore, the coffee ground influenced the development of earthworm population.
3.1.3. T
3
– Cow dung : Kitchen waste : Coffee grounds (30 : 35 : 35)
The ability of coffee grounds to generate heat (Starbucks Coffee, 2005) and preserve the moisture content of the
feed materials help to reduce the moisture content in the kitchen waste. Simultaneously, amend it to be suitable
places for the earthworms’ reproduction by stabilize the pH, increase the aeration circulation and turn down the
temperature to the suitable range for reproduction process (25°C to 30°C). Thus enhance the earthworms’
reproduction in plot C2, C3, C5, C6, and C8.
The high moisture content caused by the presence of animal based residues decreases number and weight of
earthworms (C1 & C7). Consequently, invite the mites and juvenile flies to become pests. The ability of survived
earthworms in C4 to fully utilized available feed materials, increase the weight of earthworms.
With the used of kitchen waste in T
3
though the ratio is smaller than T
1
, there is no significant difference in the
numbers and weights of earthworms (p > 0.05, t=0.994, df=7). It clearly indicated that the mixture of kitchen waste
and coffee grounds at the same ratio did not influence the development of earthworms.
3.2. Laboratory Analysis
Table 3.1
Nutrient elements in vermicompost from three different treatments.
Vermicompost
Nutrient elements
T
1
T
2
T
3
Organic carbon
15.1 % 14.9 % 15.2 %
Nitrogen ( as N)
1.07 % 2.01 % 2.13 %
Phosphorus (as P)
0.32 % 0.29 % 0.24 %
Potassium (as K)
0.41 % 0.99 % 0.79 %
C/N ratio
14.1 % 7.4 % 7.1 %
The increase in the earthworms’ population lead to rapid decrease in C as CO
2
as well as water loss by
evaporation during mineralization due to enhanced oxidation of the organic matter (Pramanik et al., 2007). The N
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78
International Conference on Environmental Research and Technology (ICERT 2008)
content in vermicompost also relics on to the extent of N fixed by free living nitrogen-fixing bacteria (Kale et al.,
1982).
Referring to Kaviraj and Satyawati (2003), acid production during organic matter decomposition by the
microorganisms is the major mechanism for solubilisation on insoluble P and K. Therefore, the presence of large
number of microflora in the gut of earthworm might play an important role in increasing P and K content in the
process of vermicomposting. The increase of P is direct action of earthworm gut enzymes and indirectly by
stimulation of the microflora (Satchell & Martein, 1984).
The C/N ratio used as a parameter to determine the degree of maturity of compost. Thus represent its agronomic
quality. C/N ratio below 20 is indicative of acceptable maturity, while a ratio of 15 or lower being preferable
(Morais & Queda, 2003). Vermicompost from all treatments are considered preferable (Table 3.1). The difference
for C is not very significant among three treatments rather than N. The percentage of N for T
2
and T
3
are doubled
than T
1
which definitely influence the C/N ratio.
4. CONCLUSION
The coffee grounds can be decomposed through vermicomposting by using Lumbricus rubellus into value-
added material. With the correct ratio and suitable condition of kitchen waste, coffee grounds can also be used as
stabilizer in vermicomposting that indirectly provide a better environment for the earthworms (L. rubellus) to
develop their population (grow) and produce a high quality of vermicompost. Consequently, vermicompost can play
a role as a conditioner that act as organic soil stabilizer which is more environmental friendly to the soil in
agriculture.
5. ACKNOWLEDGEMENT
Authors are thankful to MIF Sdn. Bhd. for consultation of vermicomposting, coffeehouse around Petaling Jaya
and cafeteria within University of Malaya (UM) campus for fully support of coffee grounds and kitchen waste
collections.
This work done in fulfilment the requirements for degree of M.Tech and financially supported by the IPPP, UM
under PJP Vot (FS257 2007C) managed by UPDiT.
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