Reducing the Time of Coir Retting by Changing the Conditions of Microbial Environment
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Date
2013
Journal Title
Journal ISSN
Volume Title
Publisher
Uva Wellassa University of Sri Lanka
Abstract
The coir industry in Sri Lanka had a great history as a main coconut based industry which
contributing to the economy of Sri Lanka. There are two types of coir are produced in Sri Lanka
as Brown fiber and White fiber. Sri Lanka is the largest supplier of brown fiber to the world. Sri
Lanka produces about 36% of the world brown fiber production and exports of coir and coir
products amounted to rupees 11.6 billion in 2008 (CDA, Coconut Statistics - 2008). But today
Sri Lanka has faced to difficulties because of the low productivity compared with other
competitor countries. Due to longer retting period and augmenting the microbial activities is one
way of shortening retting time. According to Fernando et al., (2010) Bacillus firmus, Bacillus
macerans and Bacillus badius bacteria can use to obtain good quality bristle fiber within 21
days. The coconut husk which is a fibrous material that covers the fruit of Cocos nucifera is the
raw material for extracting coir fiber. The retting process is responsible for the separation of
bristle fiber from the husk and it undergoes two distinguished physical and biological changes.
The biological process can be accelerated by enriching the retting media with microbial
nutrients. Therefore, this study was done to reduce the retting time of coir by changing the
microbial environment of retting tank and to increase the productivity of Sri Lankan bristle
fiber.
Methodology
Retting of coir and the microbial studies were done at the microbiology laboratory of Uva
Wellassa University in Sri Lanka. Coir extraction and quality analysis were done at Coir
Research and Development Institute in Nattandiya.
Coconut husks with same maturity and same length were used and then crushed and cut in to
pieces with similar width. The retting was done in three stages; the preparation of nutrient
media, changing the pH of retting environment and aeration the retting tank. To enrich retting
media there were two nutrient mixtures as 50% of Coconut water + 6 g Sago + Fresh water and
75% of Coconut water + 6 g Sago + Fresh water mixture. The total volume of the retting tank
was 14 L. There were two nutrient levels as 50% of nutrient media from total volume of retting
tank and 75% of nutrient media from total volume of the retting tank.
There were six treatment combinations and the control. Treatments were arranged according to
3x2 factorial design. Six increasing retting days were used as 7, 14, 21, 28, 35 and 42 days. At
each week microbial studies and coir quality analyses were done. Total plate count of
microorganisms was taken at weekly intervals to determine the change of microbial population
density during retting.
The pH value of the retting media was adjusted by adding 1N Sodium hydroxide (NaOH) to the
media at first day of retting. The aeration was done by using air pump in 3 L/min output and
0.012 Mpa pressure (Model U-8800, BOYU International village, North city, Raoping,
Guangdong, China). The aeration level was same for each and every retting tank.
After completing above three main stages the prepared 20 husk pieces of coconut husks were
added into each treatment and also to the control. Three husk pieces were taken out from each
treatment in weekly intervals and defiberd using defibering machine.
Description
Keywords
Agriculture, Export Agriculture, Coconut Production, Plantations, Industrial