IJERD – International Journal of Environmental and Rural Development (2014) 5-1

Research article
erdComparison of Inoculated Eri Cocoon and Eco-block for
Pollutant Removal
CARLOS ONAN MENDOZA TOVAR
Graduate School of Agriculture, Tokyo University of Agriculture, Tokyo, Japan
Email: onan14@yahoo.com

KUMIKO KAWABE
Graduate School of Agriculture, Tokyo University of Agriculture, Tokyo, Japan

HIROMU OKAZAWA
Faculty of Regional Environment Science, Tokyo University of Agriculture, Tokyo, Japan

MACHITO MIHARA*
Faculty of Regional Environment Science, Tokyo University of Agriculture, Tokyo, Japan
Email: m-mihara@nodai.ac.jp
Received 7 January 2014

Accepted 1 March 2014(*Corresponding author)

Abstract The most popular medium for microorganism immobilization is eco-block. Theeasiest microorganism to obtain in Japan is Bacillus natto and used for producing food forhuman consumption. While, eri Cocoon has proven to be an efficient immobilization
medium for bacteria. Lactobacillus spp. is a beneficial bacteria easily obtained in every
country in the world. The main objective was to compare the performance of inoculated eri
cocoon and inoculated eco-block for glucose and NO3-N consumption. As a secondary
objective we compared, through the inoculation rates, the capacity of eri cocoon and ecoblock to allocate Lactobacillus and Bacillus natto separately. The methodology of thisstudy was divided into two stages. First, a comparison of eco-block and eri cocoon’s
ability to allocate microorganisms within its structures; and second, the comparison of
consumption between inoculated eri cocoon and inoculated eco-block. The comparison of
the amount of Lactobacillus and Bacillus natto to be allocated by the eco-block and the ericocoon, we found that there are no significant differences between the amounts of bothLactobacillus and Bacillus nattowhich can allocate, however, a higher inoculation rate wasfound in eri cocoon medium. Addition to the consumption of glucose for both
microorganisms showed a significant difference between Lactobacillus and Bacillus
natto.Lactobacillushad a higher consumption rate. When comparing within both different
bacteria, the result foundthat the eri cocoon performed better against eco-block. In
comparison the use of inoculated eri cocoon showed better results in both consumption of
glucose and NO3-N of both Bacillus natto and Lactobacillus. However, when comparing
Bacillus natto and Lactobacillus, the last one showed better consumptions when combinedwith eri cocoon and Bacillus natto showing better results when combined with eco-block.
In conclusion, pending an economical study, eri cocoon inoculated with Lactobacillus spp.
presents the best option as a water pollutant removal tool.
Keywords eco-block, eri cocoon, Lactobacillus spp, Bacillus natto, water pollutant
removal, NO3-N consumption.

INTRODUCTION
The necessity for an effective and economic water pollutant removal tool, recently, has become aninterest in the developing world. Previous studies has given information about the use of effective
microorganisms for this effect (Ongley, 2000; de Vries et. al., 2008; Pebbles, 2003). TheseⒸ ISERD53IJERD – International Journal of Environmental and Rural Development (2014) 5-1

effective microorganisms require an immobilization medium to make them easier to handle andapply.
A known microorganism immobilization medium for water filtering is the eco-block. The ecoblock is any inert material where effective microorganisms can be immobilized and used for water
quality improvement. Park and Tia (2004), conducted an experiment where porous concrete andindustrial by-products was used for water purification. Although it was not inoculated theexperimenter calculated the amount of organisms attached to the block by the consumption ofdissolved oxygen. Matsunaga et.al. (2006), presented data where concrete eco-block inoculatedwith Bacillus natto performed better than regular block for water quality improvement. The use ofimmobilized microorganisms in blocks is usually for bio-filtration systems (Cohen, 2001).
Although, most of the substrates used to immobilize effective microorganisms are nonbiological porous materials. The eri cocoon has the structures to immobilize Lactobacillus spp.
within its fibers (Mendoza Tovar et. al., 2013); it was also determined the best treatment for the ericocoon to be used. A study with Lactobacillus acidophilus has proven capable of removing up to60% of Arsenic (III) from water solution within 3 hours (Singh & Sarma, 2010). In anotherexperiment, Lactobacillus spp. isolated from shrimp farm water samples were capable ofsimultaneous removal of pathogenic bacteria and nitrogen (Ma, et.al., 2009)OBJECTIVE
The main objective of this study was to compare the performance of eri cocoon and eco-block as
porous mediums in glucose and NO3-N consumptions.
As a secondary objective, was to compare eri cocoon and eco-block based on the amount ofbacteria that can be allocated through the inoculation rates from both Lactobacillus and Bacillus
natto.
METHODOLOGY
The methodology of this study was divided into two stages; the first was the comparison between
two mediums, eri cocoon and eco-block, to allocate microorganism, and second was thecomparison of consumption of glucose and NO3-N between inoculated eri cocoonand eco-block(Fig. 1).

eri cocoon

eco-blockFig. 1 Immobilization mediums
Both eco-block and eri cocoon were inoculated with Lactobacillus spp. and Bacillus natto andcultivated for 3 days before making a dilution method to count the colony forming units of eachone. Both microorganisms had the same management for both immobilization mediums.
The inoculation solution was added directly in order to cover half of the sample and allowing
the other half to absorb by capillarity. The inoculated samples were incubated for 72 hours at 37 oCⒸ ISERD

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IJERD – International Journal of Environmental and Rural Development (2014) 5-1(Fig. 2). Five count repetitions were made to get an average colony forming units (cfu) per
milligram of both mediums in order to observe the difference.

Inoculation of eco-block

Inoculation of eri cocoon
Fig. 2 Inoculation method

Simultaneous consumption experiments for both inoculated immobilization mediums by
Lactobacillus and Bacillus natto were carried out in a water recirculation system to simulate water
movement in a reservoir (Fig. 3). Glucose at two level of concentration; low concentration was of
5% glucose solution and high concentration of 15% glucose solution. NO3-N was determined at 10mg/lat 0 hours before data collection. The data was collected at 3, 12, 24 and 48 hours andanalyzed within 24 hours of the sample taking.
TheSPSS Statistics Version 19 was used to analyze the significant differences andcomparisons among different microorganism, mediums, and consumptions.

acba. Medium application reservoir b. Solution application reservoir c. Water pump

Water flow

Fig. 3 Experiment water recirculation system
RESULTS AND DISCUSSION
Within the inoculation rates (cfu/g), there was a significant difference between the eri cocoon andeco-block (Fig. 4) placing the eri cocoon as the best immobilization medium between them.
Nevertheless, the low mass of ericocoon is an advantage over the eco-block when comparing them

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IJERD – International Journal of Environmental and Rural Development (2014) 5-1

by the same unit of mass of inoculated medium. It is also suspected that the clay material of which
the eco-block consists may have had an effect on the immobilization ability or inoculation rate.
Even though there was no significant difference between bacteria allocation within eachmedium, Bacillus natto presents a higher rate in both mediums, hinting that Bacillus natto may be
more effective in the immobilization process.The document by Matsunaga et.al. (2006) presented
no inoculation rate of Bacillus natto in the concrete block used in his experiment; however,observing the dissolved oxygen in the document, it can be inferred that during the experiment they
multiply after application.

1.20x1010
A**

1.00x1010
A**

Cfu/g

8.00x1009
6.00x1009
4.00x1009
2.00x1009
B**B**

0.00x1000

Bacillus natto Lactobacillus spp.

Bacillus natto Lactobacillus spp.

eco-block

eri cocoon

Fig. 4 Comparison of eri cocoon and eco-block by inoculation rate
A**

a**

C**

c** β**

C**

b**

β**

B**

b**

α**

β**

Fig. 5 Consumption comparison of inoculated eri cocoon and eco-Block
Fig. 5 shows the consumptions of both glucose and NO3-N by both inoculated mediums. It isobserved that the consumption of eri cocoon inoculated with Lactobacillus has a significant
difference when compared with the other combinations. The differences in consumptions can be
assigned to the Lacto bacillus consumption due to the lack of significant difference between
inoculation rates within both mediums
The consumption of NO3-N of eco-block in this experiment is better than the results by
Matsunaga et.al. (2006) where after 24 hours of application there was an increase of NO 3-N.
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IJERD – International Journal of Environmental and Rural Development (2014) 5-1

During our experiments the consumption was observed to stabilize after 24 hours in the case ofeco-block with both Bacillus natto and Lactobacillus spp. but there was no release of NO3-Nobserved.
Overall in the consumptions ericocoon behaves better than eco-block having higher
consumptions even if, when inoculated with Bacillus natto, does not present statistical difference. Itis also observed that the consumption of glucose at low concentration presented asignificantdifference between Lactobacillus and Bacillus natto inoculated in eco-block placing
Lactobacillus in a higher consumption.
CONCLUSIONS AND RECOMMENDATIONSAs there was no significant difference between both microorganisms within the immobilization
mediums while, a significant difference between mediums was found, the best immobilization
medium by inoculation rate is eri cocoon. Due to the fact that it can allocate statistically the sameamount of microorganisms in a smaller mass and volume than the eco-block. This sturdiness andlightness of the eri cocoon as an immobilization medium would make it easier to manage and totransport for any field application.
The eri cocoon inoculated with Lactobacillus spp. has the highest consumptions of all of thesolutions. This infers that the best option to remove pollutant or create an economic pollutant
removal tool is the eri cocoon inoculated with Lactobacillus spp.Lactobacillus spp. proved that ismore effective at consuming nutrients from a water flow than Bacillus natto, nevertheless Bacillus
natto may have with a different immobilization medium such as concrete have a better
consumption results.
It is recommended that the tool may be utilized as a bio-string contactor with inoculated erisilk yarn; the combination of untreated eri cocoon and eri silk twisted yarn may give a better result
when used together in water flow. The application could be by a spillway that ensures the contactof the bio-string contactor and the water for enough time for it to consume the pollutants in thewater.
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Cohen, Y., 2001. Biofiltration - The treatment of fluids by microorganisms immobilized into filter bedding
material: a review. Bioresource Technology, 77, 257-274.
De Vries, F.P., Aquay, H., Molden, D., Scherr, S., Valentin, C. and Cofie, O. 2008. Learning from brightspots to enhance food security and to combat degradation of water and land resources. Conserving Land,Protecting Water, International Water Management, Institute in Association with www.cabi.org andCGIAR Challenge Program on Water & Food, Cambridge, USA.
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Singh A.L. and Sarma P.N. 2010. Removal of arsenic(III) from waste water using Lactobacillus acidophilus.
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