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(The following article originally appeared in Water Conditioning and Purification Magazine, October 2012, and is being reprinted with permission).
Synthetic chemical water contaminants: an often overlooked challenge in international sustainable community development.
Contamination of drinking water sources by harmful synthetic organic compounds (SOCs), such as pesticides, is a major worldwide problem. Pesticide pollution appears twice in the top ten of The World’s Worst Toxic Pollution Problems Report 20111 by the Blacksmith Institute, and has been indicated in every year’s report since initial publication in 2006. Effective, afford-able and scalable green treatment technol-ogies for SOC removal that are accessible to communities in the developing world or in remote areas of developed countries are, however, lacking.
A recent review in Science2 indicates that the 300 million tons of SOCs produced annually, including five million tons of pesticides,
constitute a major impairment to water quality on a global scale. In Thailand, for example, 75 percent of the pesticides used are banned or heavily restricted in the West due to deleterious ecological and human health effects.3 The Science authors state that “small-scale, household-based removal techniques are often the only possible mitigation strategy due to the lack of a centralized infrastructure,” and call for
the development of “reliable, affordable and simple systems that local inhabitants could use with little training.”
Unfortunately, SOCs are not yet ‘on the radar’ of major actors in the water-sani-tation-hygiene (WASH) sector of interna-tional development.The UN Millennium Development Goals, for example, are only concerned with mitigation of biological agents of waterborne disease.4 I recently attended a major international conference on global water and health in developing communities.5 My presentation was the only one that considered SOCs in drinking water and presented a potential treatment technology.6 Microbial pathogens are often the most immediate threat to human health (e.g. diarrhea) and so focus on these disease agents is warranted. However, we cannot discount the threat of bio-accumu-lating chemical toxins, such as pesticides. The immediacy and scale of this problem
Edited by Rick and Ellen Burnette May 2013 | Issue 17
Sustainable Decentralized Water Treatment for Rural Developing Communities
Using Locally Generated Biochar Adsorbentsby Josh Kearns, MS
Asia Notes A Regional Supplement to ECHO Development Notes
Featured in this AN
1 Sustainable Decentralized Water Treatment for Rural and Developing Communities Using Locally Generated Biochar Adsorbents
7 An Introduction to Bokashi Fertilizers and Soil Amendments
11 2013 ECHO Asia Agriculture and Community Development Conference
The ECHO Asia Impact Center operates under ECHO, a non-profit Christian organization that helps you help the poor to produce food in the developing world.
ECHO Asia Impact CenterPO Box 64Chiang Mai 50000 [email protected]
Figure 1. Scanning electron microscope (SEM) images of longan charcoal and commercial acti-vated carbon showing morphological similarities (Charcoal SEM images courtesy of Carl Saquing North Carolina State University.)
Figure 2. Traditional (kiln) charcoal generation systems in Southeast Asia
. . . . . . .2
is highlighted by, for example, a survey of Hmong tribe women living in Mae Sa Mai village, Chiang Mai Province, Thailand, that reported detection of DDT in 100 percent of mothers’ milk samples. A number of other biocides were also frequently detected, and infants’ exposure exceeded by up to 20 times the acceptable daily intakes as recommended by UN-FAO and WHO.7
Charcoal/biochar filtration: an appropriate, low-cost and sustainable option for decentralized water treatment?
Charcoal filtration has been used to treat drinking water for thousands of years,8 and is still widely practiced today, particularly in
rural areas of the major charcoal-producing countries, such as Brazil, India, China, Thailand and throughout SE Asia.9 Locally managed charcoal filtration might represent the most effective barrier to SOC exposure available to households and communities in remote and impoverished regions of the world, as charcoal can exhibit proper-ties similar to activated carbon.10 To date, however, no studies have quantified how effective charcoals are for water treatment.11
Summary and discussion of field and laboratory research outcomes
Regarding recent field studies and labora-tory experiments investigating the potential effectiveness of traditional kiln charcoals
and gasifier chars for water treatment, traditional kiln systems are used to produce charcoals from wood feedstocks typically for use as cooking fuel. Kilning processes are often highly polluting, energy-inefficient and time and labor intensive. Energy-ef-ficient, clean-burning gasifier units that are typically used for cooking and space heating produce a residual char and are easier and more pleasant to operate and make use of a wider range of biomass feed-stocks, including agricultural and forestry wastes and byproducts. More detail on the conceptual background of biomass gasifi-cation for char production is given at www.aqsolutions.org.
Charcoals produced from traditional kiln systems
Preliminary experiments show that some charcoals produced from traditional Asian village kilns (e.g., the 200-liter horizontal drum12 and brick-and-mud beehive models) exhibit appreciable adsorption capacity for herbicides. However, studies indicate wide variability in SOC uptake among charcoals produced by traditional technologies.13 Although these initial results are promising, traditional charcoal manufacturing systems are energy-inefficient and highly polluting,
Figure 3. Herbicide removal by a representative range of simulated traditional kiln charcoals
Figure 5. 200-liter (55 gal.) farm-scale biomass gasifier char production unit
Figure 6 and 7. Gasifier biochar production system made from two 200-liter (55 gal.) drums and scrap metal (photos by Lyse Kong)
Figure 4. Cookstove-scale biomass gasifier char production unit (See Anderson et al. 2007, 27 Anderson 2010 28 and McLaughlin 2010 29 and 2011 30 for theory and detailed construction notes.)(Thermocouple probes are for research purposes and may be omitted.)
Asia Notes Issue 17 . . . . . . . 3
contributing substantial greenhouse gas emissions and often making use of unsus-tainable, and sometimes illegally, harvested feedstocks.14,15,16
When it comes to water treatment, not all traditional charcoals are created equal. We have monitored traditional charcoal production in 200-liter steel-drum/adobe kilns and brick-and-mud beehive kilns in collaboration with farmers and villagers in northern Thailand and the Thai Royal Forestry Department Wood Energy Research Centre in Saraburi Province. These observations provide simulations of the typical range of peak temperature and heating duration characteristic of tradi-tional charcoal production systems using a programmable laboratory pyrolysis unit to generate experimental chars. Figure 3 indi-cates wide variability in herbicide uptake capacity of charcoals produced under a representative range of conditions. Char-coals exhibited essentially no uptake to ~ 80-percent removal under these experi-mental conditions. (Experimental methods and additional data are presented and discussed below.) Thus, the manufacturing conditions and resulting quality of the char product exert a strong influence on its potential effectiveness for water treatment.
Chars produced from biomass gasifiers
Energy efficient, environmentally sustain-able and scalable production of consistent, highly sorptive chars can be accomplished with biomass gasification. Biomass gasifier stoves are rapidly being disseminated for household cooking in developing commu-nities, as they provide energy-efficient combustion with reduced emissions17,18
and produce small batches of char from agricultural and forestry byproduct fuels during normal daily use.19,20 Interme-diate and large-scale gasifier systems are also being deployed around the world for generation of biochar as an agricultural soil amendment to increase crop yields and sequester carbon.21,22,23 Gasifier char production is favorable from environmental and energy standpoints when compared with traditional charcoal manufacturing, since pyrolysis gases are combusted within the unit rather than emitted as pollutants,24,
25 thereby providing the energy that drives pyrolysis and obviating the need for an external heat energy source. Also, biomass gasifiers can be readily coupled with other unit processes for biofuel collection and waste-heat utilization.26
Figure 8. Surface area/pine biochars
Figure 9. Porosity/pine biochars
Figure 10. Plot showing removal of the common herbicide 2,4-D (2,4-dichiorophenoxyacetic acid) from solution by various chars in batch experiments.
. . . . . . .4
Studies to date show that gasifier chars, particularly when operated in high-draft mode (for example, by augmenting airflow when necessary by a fan or blower) consis-tently develop enhanced physico-chemical characteristics, such as high surface area, microporosity and herbicide uptake capacity when compared with traditional kiln char-coals.31,32 Gasifier char may therefore be an optimal choice for sorption of pesticides, industrial and fuel compounds, human and livestock pharmaceuticals and other SOCs of increasing concern to water quality.
Figures 8 and 9 show N2 BET surface area (upper) and porosity (lower) of chars made 1) from split pine logs in a 200-liter, tradi-tional-style steel drum and adobe kiln, 2) from uniform pine wood slats in a program-mable laboratory pyrolyzer used to manu-facture char under controlled temperature and atmospheric conditions, and 3) from a cookstove scale TLUD gasifier using pine pellets. (Surface area and porosimetry courtesy of David Rutherford, USGS.)
2,4-D (see Figure 10) was chosen as a test compound because of its environmental relevance as one of the most widely used herbicides worldwide, and one of the most commonly detected pesticides in environ-mental waters,33 as well as for its human health implications as a potential carcin-ogen and suspected endocrine disruptor.34
Its chemical properties also make it a chal-lenging compound to remove by adsorp-tion. Thus, if 2,4-D is taken up by a char, it is likely that most other pesticides would also be effectively removed.
Batch experiments used 100 mg/L of each char ground by mortar and pestle to pass a 200-mesh US Standard Sieve, and intro-duced to solutions initially containing 100 μg/L 2,4-D (US EPA MCL 70 μg/L; WHO Guideline 30 μg/L) and background organic matter at a total organic carbon concentra-tion of 4 mg/L (to simulate natural waters). Experiment bottles were agitated for two weeks in order to reach equilibrium. The traditional kiln data are an average for three chars made from bamboo, split eucalyptus and pine logs charred in a 200-liter steel drum/adobe kiln. The lab pyrolyzer data displayed are an average of four chars made from bamboo, eucalyptus, longan and pine logs cut into slats of uniform size (15 cm x 10 cm x 1 cm) and pyrolyzed under controlled temperature and atmospheric conditions. The cookstove gasifier data displayed are an average from several batches of pine pellet char made in a one-gallon TLUD unit under natural draft (ND) and forced draft (FD, with an electric fan) conditions. The
cookstove gasifier-FD and 55-gallon gasifi-er-ND chars removed 2,4-D below detection limits (2 μg/L), hence ~100 percent.
Current conclusions from laboratory and field research
In summary, compared with traditional charcoal production, gasifier char produc-tion is more energy efficient and emits far less atmospheric pollution. Furthermore, gasifiers can be operated with agricultural and forestry residues and byproducts and are ideally suited for small-grained, chipped or pelletized biomass fuels. Gasifiers can readily be linked with other processes and applications for capture and use of waste heat. Research has shown both small-scale (cookstove) and intermediate-scale (200-liter/55-gallon drum) pyrolyzers consistently achieve high temperatures (650 to 950°C/1,202 to 1,742°F) required for substantial development of surface area and porosity in the char product, concomitant with improved performance for herbicide uptake in batch experiments. Therefore, gasifier biochars are a promising, appro-priate, low-cost and sustainable technology for affordable decentralized water treatment in rural and developing communities.
Furthermore, the use of biochar for water treatment does not preclude its eventual application as a beneficial agricultural soil amendment and carbon sequestra-tion strategy. In fact, we recommend composting35 and soil application as the preferred mode of processing spent filter char. The best strategy for rural communities and small interest holders to utilize spent filter char is simply to allow ample time and favorable conditions for environmental micro-organisms to biodegrade any sorbed contaminants. Elevated temperatures, such as those achieved during composting of organic wastes (for example in composting toilets), accelerate micro-bial activity and biodegra-dation processes. More-over, based on recent research with carbon adsorbents, we do not expect significant contam-inant release to soils and plants by leaching from spent filter char.36 A
conservative approach to land application of spent filter char can be adopted, using low incorporation rates of ~ 100 kg of char per hectare.
Case studies integrating biochar filtration into multibarrier treatment trains for decentralized systems
Figure 11 illustrates a passive-flow, multi-barrier, intermediate-scale (up to 3,000 L/day) water treatment system using a series of gravel, biologically active sand and char filters. The system costs less than $500 (USD, at local labor and materials costs) to construct and provides years of service with periodic maintenance of the bio-sand filter and char refurbishment every two to three years. The system was installed in February 2008 and serves a farm commu-nity in northern Thailand with a seasonally varying population of 10 to 100 people (average 40) and treats all water used on the farm for direct drinking, plus kitchen and restaurant uses (food and beverage prepa-ration, washing dishes).
For households and communities in very remote areas, low-cost, decentralized water treatment for removal of biological and chemical contaminants can be accomplished using filter media generated/acquired locally. Figures 12 and 13 depict a passive-flow portable drinking water treatment plant that provides up to 300 L/day (enough to meet
Figure 11. 3,000 L/DAY multi-barrier ‘off-drid’ water treatment system
Asia Notes Issue 17 . . . . . . . 5
minimum daily drinking water requirements for 100 people) using a series of gravel, biologically active sand and char filters. Containment is provided by four 200-liter, BPA-free, high-density polyethylene (HDPE) drums. Empty drums weigh less than 10 kg (22.04 pounds) and can be carried into remote communities on foot, connected with a small number of PVC fittings and filled with the acquired media. The system costs about $125 to construct, can be assembled with minimal hand tools (e.g. a Leatherman multi-tool) and provides years of service, with periodic maintenance of the bio-sand filter and char refurbishment yearly. The system depicted in Figure 12 serves a boarding school for ethnic Karen migrant/refugee children on the Thai-Burma border.
Open-source instructional handbooks and videos detailing the design, construction and operation of these water treatment systems and low-cost gasifier units for production of enhanced water filter biochar from local
surplus biomass can be accessed from Aqueous Solutions.
References
1. Harris, J. and McCa-rtor, A. The World’s Worst Toxic Pollution Problems Report 2011: The Top Ten of the Toxic Twenty. Blacksmith Institute, 2011. (www.worstpolluted.org/).
2. Schwarzenbach, R.P.; Escher, B.I.; Fenner, K.; Hofstetter, T.B.; Annette Johnson, C.A.; von Gunten, U. and Wehrli, B. 2006. The Chal-lenge of Micropollutants in Aquatic Systems. Science (313) p. 1072.
3. PAN-NA. Pesticide Use in Thailand. Pesticide Action Network North America Updates Service (PANUPS). Pesticides News, March 1997. Accessed online 03/21/07. www.panna.org/panna/.
4. World Health Organization and UNICEF 2010, Progress on Sanitation and Drinking Water, 2010 Update.
5. http://whconference.unc.edu/index.cfm
6. Kearns, J.P.; Nyer, B.; Mansfield, E.; McLaughlin, H.; Rutherford, D.; Knappe, D.R.U. and Summers, R.S. Top-Lit Up-Draft (TLUD) Cookstove Biochar: Appropriate Technology for Sustainable Low-Cost Household Clean Energy, Water Treatment, Agronomic Enhancement, and Distributed CO2 Sequestration. Poster presentation at Global Water and Heath Conference, University of North Carolina, Chapel Hill, NC October 2011.
7. Stuetz, W.; Prapamontol, T.; Erhardt, J.G. and Classen, H.G. Organochlorine pesticide residues in human milk of a Hmong hill tribe living in Northern Thailand. The Science of the Total Environment, 273, 2001. p. 53.
8. “It is good to keep water in copper vessels, to expose it to sunlight, and filter through charcoal.” Translation by FE Place of the Sanskrit Ousruta Sanghita, written c.a. 2000 B.C.
9. United Nations Energy Statistics Data-base, United Nations Statistics Division, http://data.un.org/Browse.aspx?d=EDATA, accessed 11/5/2011.
10. Chen, J.; Zhu, D. and Sun, C. 2007. Effect of heavy metals on the sorption of hydrophobic organic compounds to wood charcoal. Environmental Science & Tech-nology, 41(7), 2536–2541.
11. Thus this is a major objective of our research at Aqueous Solutions (www.aqsolutions.org) and the subject of Josh Kearns’ doctoral dissertation in envi-ronmental engineering/engineering for developing communities at the University of Colorado-Boulder.
12. Burnette, R. Charcoal production in 200-liter horizontal drum kilns. ECHO Asia Notes, No. 7, October 2010.
Hugill, B. Biochar–An organic house for soil microbes. ECHO Asia Notes, No. 9, April 2011.
13. Kearns, J.P.; Wellborn, L.S.; Summers, R.S. and Knappe, D.R.U. Removal of 2,4-D herbicide from water by indigenous charcoal carbons (biochar). Submitted to Journal of Water and Health (in review).
14. Smith, K.R.; Pennise, D.M.; Khum-mongkol, P.; Chaiwong, V.; Ritgeen, K.; Zhang, J.; Panyathanya, W.; Rasmussen, R.A. and Khalil, M.A.K. Greenhouse Gases from Small-Scale Combustion
Figure 12 and 13. Illustrations showing configuration of media in a 300 L/day, multibarrier portable drinking water treatment system. (Diagrams by Nathan Reents)
. . . . . . .6
Devices in Developing Countries: Char-coal-Making Kilns in Thailand; Report EPA-600/R-99-109; 1999. Office of Air and Radiation and Policy and Program Evalua-tion Division, US EPA: Washington, DC.
15. Foley, G. Charcoal Making in Devel-oping Countries. 1986. Earthscan: London.
Figures 12 and 13. Illustrations showing configuration of media in a 300-L/day, multibarrier portable drinking water treatment system (Diagrams by Nathan Reents)
Water Conditioning & Purification Oct. 2012
16. UNDP, UNEP. Bio-Carbon Oppor-tunities in Eastern and Southern Africa: Harnessing Carbon Finance to Promote Sustainable Forestry, Agro-Forestry and Bio-Energy. 2009.
17. Grieshop, A.P.; Marshall J.D. and Kandlikar, M. Health and climate benefits of cookstove replacement options. Energy Policy, 2011.
18. Johnson, M.; Lam, N.; Brant, S.; Gray, C. and Pennise, D. 2011. Modeling indoor air pollution from cookstove emissions in developing countries using a Monte Carlo single-box model. Atmospheric Environ-ment, Vol. 45, Issue 19, p. 3237.
19. International Biochar Initiative, 2011. www.biochar-international.org/technology/stoves, accessed 11/5/2011.
20. Inyenyeri Rwandan Social Benefit Company, http://inyenyeri.org/busi-ness-model, accessed 11/5/2011.
21. Lehmann, J.; Gaunt, J. and Rondon, M. 2006. Bio-char sequestration in terres-trial ecosystems–a review. Mitig. Adapt. Strateg. Glob. Change, 11, 395–419.
22. Bracmort, K.S. Biochar: examination of an emerging concept to mitigate climate change. 2009. Congressional Research Service. 7-5700, CRS Report No. R40186. Available at: http://ncseonline.org/NLE/CRs/abstract.cfm?NLEid=2216
23. UNDP, UNEP 2009, op. Cit.
24. UNDP, UNEP 2009, op. Cit.
25. Grieshop et al. 2011, op. Cit.
26. Biochar for Environmental Manage-ment: Science and Technology. 2009. Lehmann, J. and Joseph, S. eds. Earth-scan, UK and USA.
27. Anderson, P.S.; Reed, T.B. and Wever, P.W. Micro-gasification: What it is and why it works. Boiling Point, No. 53, HEDON Energy Network, 2007. (www.hedon.info/docs/BP53-Anderson-14.pdf).
28. Anderson, P. Making biochar in small gasifier cookstoves and heaters. Chapter 11 in The Biochar Revolution: Trans-forming Agriculture & Environment, Taylor, P. ed. 2010.
29. McLaughlin, H. 1G Toucan for Biochar. January 2010. Bioenergy Lists web archive. (http://biochar.bioenergylists.org/content/1g-toucan-tlud-biochar-jan-2010).
30. McLaughlin, H. How to make high and low adsorption biochars for small research studies. Bioenergy Lists web archive. (http://biochar.bioenergylists.org/content/how-make-high-and-low-adsorption-bio-chars).
31. Kearns, J.P.; Shimabuku, K.; Wellborn, L.S.; Knappe, D.R.U. and Summers, R.S. Biochar production for use as low-cost adsorbents: Applications in drinking water treatment serving developing communities. Presentation to 242nd national meeting of the American Chemical Society, Denver, CO, August 2011.
32. Kearns, J.P.; Nyer, B.; Mansfield, E.; McLaughlin, H.; Rutherford, D.; Knappe, D. and Summers, R.S. Top-lit up-draft (TLUD) cookstove biochar: appropriate tech-nology for sustainable low-cost household clean energy, water treatment, agronomic enhancement, and distributed CO2 seques-tration. Poster presentation: Global Water and Health Conference, University of North Carolina, Chapel Hill, NC, October 2011.
33. Gilliom, R.J.; Barbash, J.E.; Craw-ford, C.G.; Hamilton, P.A.; Martin, J.D.; Nakagaki, N.; Nowell, L.H.; Scott, J.C.; Stackelberg, P.E.; Thelin, G.P. and Wolock, D.M. 2006. The quality of our nation’s waters: pesticides in the nation’s streams and ground water, 1992-2001. US Geolog-ical Survey Circular, 1291.
34. PAN Pesticides Database (www.pesti-cideinfo.org). Online database of pesticide information, Pesticide Action Network. Accessed 11/4/10.
35. Joyce, J. Conditioning biochar for application to soils. Chapter 15 in The Biochar Revolution: Transforming Agricul-ture & Environment, Taylor, P. ed. 2010.
36. Corwin, C.J. and Summers, R.S. 2011. Adsorption and desorption of trace organic
contaminants from granular activated carbon adsorbers after intermittent loading and throughout backwash cycles. Water Research, 45, 417-426.
About the author
Josh Kearns is co-Founder and Director of Science at Aqueous Solutions and a PhD candidate in environmental engi-neering for developing communities at the University of Colorado-Boulder. He holds an MS in environmental biogeochemistry from UC-Berkeley, a BS in chemistry from Clemson and has six years of experience working in sustainable rural development in Southeast Asia. Kearns can be reached at (720) 989-3959 or [email protected], [email protected] and on Skype (“joshkearns”).
About the company
Aqueous Solutions (aqsolutions.org) is a volunteer-based, non-profit consortium of research scientists, field engineers and ecological designers working to promote live-lihood security, environmental and economic sustainability, and local self-reliance through ecological design and appropriate tech-nologies in water, sanitation and hygiene (WASH). The company conducts field and laboratory research on decentralized, small-scale water treatment and ecological sani-tation systems. It also provides technical consulting and project management services for sustainable WASH infrastructure devel-opment in collaboration with rural/remote, indigenous and politically and economically marginalized communities in Southest Asia. The research aims to demonstrate the appli-cability of locally generated chars for decen-tralized household and small-community water treatment in developing communities. This work realizes a triple benefit for human health, environmental sustainability and local economies: 1) to offer economical and technologically accessible water treatment where currently none exists; 2) to offset polluting and energy-inefficient charcoal production with green gasifier technology and 3) to support village-level micro-en-terprise in the manufacture of enhanced sorbents. Through partnerships with govern-ments, small businesses and NGOs, Aqeous Solutions disseminates these research outcomes in the deployment of appropriate technologies that benefit human livelihood as well as the environment.
Asia Notes Issue 17 . . . . . . . 7
The Concept of Bokashi
Around the world, many agriculturists and gardeners are adopting soil amendments and fertilizers that are called bokashi. Bokashi is a Japanese word that has no good translation into English, according to Yukiko Oyanagi, a staffer with the Asian Rural Institute (ARI) in Japan. However, all types of bokashi are produced through fermentation processes.
There are at least two distinct types of bokashi being promoted and used by agri-culturists, farmers and gardeners. One we shall describe as fermented bokashi fertilizer and the other is kitchen bokashi. Both are described in this article.
Fermented Bokashi Fertilizer
The fermented bokashi fertilizer promoted and used by ARI and others in Asia is comprised largely of dried manure and forest soil. According to Oyanagi, the dried manure provides nutrients and organic matter, while the soil helps to preserve nutrients, absorb bad smells, and provide a comfortable living space for microorgan-isms. If charcoal is added (i.e. charred rice husks or wood charcoal powder) the effects of the soil are greatly enhanced. The following is a list of bokashi ingredients recommended by ARI:
• Dried manure should comprise 50-60 percent of the materials in a batch of bokashi and can include cow, pig, goat, chicken, duck or water buffalo manure as well as bat guano.
• Soil from the forest should constitute 20-30 percent of the materials.
• Rice bran, a carbohydrate source for bene-ficial microorganisms, should make up 10-20 percent of the mixture.
• Rice husk charcoal should comprise 5-10 percent.
• If available, small amounts of benefi-cial indigenous microorganisms (IMO) collected from forests or fields as well as fermented plant juice (FPJ) or Effective Microorganisms (EM), which helps with the fermentation process, should be applied to other bokashi materials via a water solution (see Multiplication and Use of Soil Microor-ganisms, EDN 110, January 2011 by Dawn Berkelaar). Although these supplemental microbe solutions are recommended to help stimulate the fermentation process for bokashi production, lack of access to such supplements should not deter anyone from making fermented bokashi fertilizer as beneficial microorganisms are already likely to be present in the soil and manure.
ARI recommends that the materials be blended by dumping dry ingredients into a pile and using a shovel to mix the ingredients thoroughly. It is also recommended that the mixing process and fermentation take place under the shade of a roof to avoid strong sunlight, rain and wind. While mixing, add water (with or without IMO, EM and/or FPJ) to provide about 50 percent moisture to the mixture. This level of moisture can be monitored by taking handfuls of the moist-ened materials and squeezing. If no liquid can be squeezed out and the material still holds shape after being released, but crum-
bles when tapped, an appropriate amount of moisture has been reached.
The freshly mixed bokashi fertilizer should be covered with rice straw (or similar dried materials that are available on the farm) to retain moisture and heat. The mixture should be turned whenever it becomes hot (around 60ºC/140ºF); usually once a day. Moisture should be checked and adjusted to 50 percent as needed. When the tempera-ture of the bokashi fertilizer stabilizes and becomes the same as the surrounding air, and you can no longer smell the manure, it is ready to use. Fermented bokashi fertilizer can be dried and stored for a period of six months to one year.
Because the nutrients of the finished bokashi product are fairly concentrated, and because inputs such as rice bran might need to be purchased, ARI recommends that bokashi fertilizer be applied somewhat sparingly. Such bokashi should be applied either topically over the root zone of estab-lished plants or mixed into the soil where new plants are being established.
ECHO Asia has found very limited infor-mation regarding the nutrient content of bokashi fertilizers, probably due to the diversity of “homegrown” bokashi fertil-izer mixtures across the region. However, in 2011, a development organization in Myanmar had their fermented bokashi fertil-izer product analyzed at Mae Jo University in Chiang Mai. This particular fermented bokashi fertilizer was comprised of a mix of dried chicken manure (100 kg/220 lb.), forest soil (80 kg/176 lb.), bone meal (45 kg/99 lb.), rice bran (30 kg/66 lb.), groundnut cake (30 kg/66 lb.), fish meal (30 kg/66 lb.), firewood ash (15 kg/33 lb.), charred rice husk (15 kg/33 lb.), raw sugar (1 kg/2.2 lb.), and wood vinegar (4 liters/1.1 U.S. gallon). This somewhat elaborate bokashi formula-tion included ingredients that supplement certain key nutrients, such as bone meal for phosphorus as well as fish meal and groundnut cake for nitrogen.
Two samples from this batch of bokashi yielded the following nutrient analysis (averaged):
pH - 6.82; electrical conductivity (EC) – 10.34 dS / m; total nitrogen (N) - 1.93%; total phosphorus (P) - 2.47%; total potas-sium (K) – 1.31%.
Thailand’s National Bureau of Agricultural Commodity and Food Standards has devel-oped criteria for commercial compost, which is also applied to organic fertilizer. In view of
ARI students making bokashi. Pictured: Fr MacDonald from Malawi (above left), Eleazar from NE India (bottom left), and Gani from Indonesia (bottom right). (Photo courtesy of ARI)
An Introduction to Bokashi Fertilizers and Soil Amendments
by Rick BurnetteDirector, of ECHO Asia Impact Center
. . . . . . .8
such official criteria, the average pH of the Myanmar bokashi samples (6.82) fell within the acceptable 5.5-8.5 range. However, the average electrical conductivity of the batches (10.34 dS / m) was considerably higher than specifications that require the EC of commercial compost to be less than or equal to 3.5 dS / m as well as specifica-tions by Thailand’s Department of Agricul-ture for natural fertilizers to be less than 6 dS / m. The average N-P-K analysis of the Myanmar sample was 1.93-2.47-1.31 which is well above Thai government spec-ifications requiring commercial compost to be greater than or equal to 1.0 % by weight for N, greater than or equal to 0.5 % by weight for P and greater than or equal to 0.5 % by weight for K.
The main limitation of the bokashi sample from Myanmar was the high EC level. EC measures the amount of soluble salts in the medium. Most fertilizer materials (e.g. nitrates, ammonium, phosphates, potas-sium) contribute to the EC content (Whipker and Cavins). Organic materials, such as urea, also contribute to the EC content after they have been changed from an insoluble to soluble form. High EC levels can result in poor crop performance, often due to “burn” from the high concentration of salts in the medium. Therefore, it is important for producers and users of natural fertilizers, such as bokashi, to be aware of EC levels and to exercise caution in the amounts applied to nourish crops.
Beng Ngoun, who farms a few hectares in Battambang, Cambodia, reported his expe-rience with fermented bokashi fertilizer. He applied 200 kg (441 lb.) per hectare of rice that had been established less than one month. His 600 kg (1,323 lb.) batch of bokashi was comprised of 200 kg of dried manure, 200 kg of forest soil, 100 kg of rice bran, 100 kg of ground wood charcoal and 5 liters (1.3 US gallons) of fermented plant juice solution.
Around one month after applying the bokashi, Beng Ngoun saw no immediate visible effects from the application of the natural fertilizer, and he began to lose hope that he would see any benefits from his investment. He admitted that his neighbors even laughed at him and asked, “Why do you use this organic fertilizer?” In contrast, the neighbors’ rice fields were very green. They had broadcast chemical fertilizer, which he estimates was applied at 200-300 kg per hectare (178-267 lb. per acre).
Somewhat later, about two weeks before his rice crop began to head, Beng Ngoun
also sprayed FPJ solution mixed with molasses onto the rice crop, applying the solution in the evening or around sunrise. [Ed: no other details on the formulation and rate of FPJ application were provided, and any possible correlation regarding the effect of the FPJ on the crop is unknown.] About the same time, he began to see that the color of the rice crop was changing from light green to dark green. “I was so happy and then my neighbors came to look every day. Now they ask me for the organic fertil-izer method,” he reported.
When he harvested his rice, Beng Ngoun found that his yield was greatly increased. He shared, “Before, we produced 1-1.5 (metric) tons of grain per hectare (0.45-0.67 U.S. tons per acre). But this year I got 3-4 (metric) tons (1.35-1.8 U.S. tons per acre). I praise God so much. Next year I will need to put the fertilizer during first plowing.”
Kitchen Bokashi – A Response to the Global Food Waste Problem
The Food and Agriculture Organization (FAO) of the United Nations reports that roughly one third of food produced in the world for human consumption every year — approximately 1.3 billion tons — gets lost or wasted. However, a considerable disparity exists regarding per capita food waste by consumers in Europe and North America (estimated between 95-115 kg/209-253 lb. a year), compared to consumers in sub-Sa-haran Africa and South and Southeast Asia (who throw away only 6-11 kg/1.3-24.3 lb. a year).
Consumers often purchase more food than can be eaten, or fail to plan their food purchases properly. This results in food being thrown away when “best before” dates expire. In response, the FAO recom-mends that rich-country consumers be taught that throwing food away needlessly is unacceptable. The agency also suggests that given the limited availability of natural resources, reducing food losses might be more effective than increasing food produc-tion in order to feed a growing world popu-lation.
In addition to the loss of potential to nourish humankind, and the wasted money for individuals, families and businesses, food waste has a negative impact on the envi-ronment. Food disposed of in the garbage is a source of flies, unpleasant odors and possible disease. And once in the landfill, food waste produces methane, a potent greenhouse gas.
While some degree of food waste is inev-itable in most households and kitchens, there are earth-friendly and even profitable farm and garden uses for leftover food. For example:
• Add appropriate, non-greasy/fatty food left-overs, such as expired fruit and vegetables, to compost so that these nutrient-rich mate-rials can be recycled to produce more fruit and vegetables. However, greasy and meat-type leftovers are not particularly desirable for composting. They may attract flies, rodents and other pests, as well as produce bad odors.
• Vermicompost (use earthworms to break-down wastes); this is another means of producing an excellent soil amendment for farms and gardens, although greasy, meat-type leftovers are generally undesirable.
• Feed appropriate types of leftovers to farm animals such as chickens and pigs.Use leftovers as feedstock for home biogas systems. Appropriate materials, such as fruit and vegetable peelings as well as left-over cooked rice and vegetables, should be ground or blended and mixed with water to create a slurry that can be fed into biogas digesters (Vig, page 23). For more informa-tion about household biogas systems that can accept food waste and other feedstock see the following: • Appropriate Rural Technology Institute
(ARTI) webpage - ARTI Biogas Plant: A Compact Digester for Producing Biogas from Food Waste
• Heifer International Biogas Manual
Asia Notes Issue 17 . . . . . . . 9
• Baron Small-Scale Biogas Digester (from the Border Green Energy Team website)
Another practical means of putting unused food of all types to use is by turning it into kitchen bokashi, the second type of bokashi. Kitchen bokashi is a soil amend-ment produced by fermenting food wastes under anaerobic conditions. The fermen-tation process keeps the materials from rotting and becoming putrid, as would occur under normal aerobic conditions. The production of kitchen bokashi offers house-holds and institutions the following:
• A convenient and manageable means of reducing the volume of household or insti-tutional waste going into landfills, by recy-cling food leftovers (including greasy food, as well as scraps of meat and fat) without objectionable odors and mess.
• Continual access to an excellent soil amendment that improves garden soil structure and fertility, benefiting helpful soil organisms as well.
To produce kitchen bokashi, food scraps are collected in airtight containers and inoc-ulated with a carrier, such as rice or wheat bran, containing fermentation microorgan-isms (e.g. natural lactic acid bacteria, yeast, phototrophic bacteria). One source of such microorganisms is a commercial product called Effective Microorganisms (EM) which is often sold in various formulations. Non-commercial sources of similar microor-ganisms are IMO-1 or -2, described in the Writer’s Supplement to Berkelaar’s article.
Each shallow layer of food scraps is liber-ally sprinkled with inoculated bran carrier, with layers continuing until the container is full. Stored under near anaerobic condi-tions, microbes will expand throughout the kitchen scraps and ferment the materials.
If done correctly, there will be no spoilage or putrid smell. Fermented food wastes can be collected and stored over the long term, even for months, until burial. Finally, weeks after incorporation into the garden, the bokashi will become soil-like, providing both organic matter and plant nutrients to the soil.
At Mae Jo University, lab analysis of a batch of kitchen bokashi showed N-P-K levels that compare favorably to other natural fertilizers and animal manures (Silva and Uchida):
• kitchen bokashi 2.39 – 0.77 – 0.97
• worm castings 0.5 - 0.5 – 0.3
• blood meal 13 – 2 – 0
• chicken manure 4.4 – 2.1 – 2.6
• cow manure 2.4 – 0.7 – 2.1
Making the Inoculated Bran Carrier for Kitchen Bokashi
Inoculated bran carrier, which is typically bran treated with EM, is used to inocu-late food wastes with the fermentation organisms that are essential for producing kitchen bokashi. The following ingredients and method are widely used for inoculating a small batch (5 kg/11 lb.) of bokashi carrier:
• 5 kg (11 lb.) of rice bran
• 20 ml (1.4 tablespoons) EM•1® (the basic, unextended commercial formulation of EM) or IMO-1/IMO-2.
• 20 ml (1.35 tablespoons) molasses
• 1 liter of water (1.05 quarts)
The Procedure for Inoculating the Bran Carrier is as follows:
1. To activate and extend an adequate supply of EM microbes to produce 5 kg of inoculated bran carrier, dissolve 20 ml of molasses into 1 liter of water (non-chlori-nated is usually advised) along with 20 ml of EM•1® or IMO-1/IMO-2. Keep the solu-tion in a sealed plastic bottle for 5-7 days away from direct sunlight. Quickly vent off excess gases once a day (if needed).
2. After several days, mix the expanded solution of EM or IMO-1/IMO-2 thoroughly with 5 kg of bran in a bucket. Avoid adding too much of the liquid, as a 40-50 percent level of moisture in the bran is desired. To monitor the moisture content while adding the expanded EM or IMO-1 solution, occa-sionally squeeze some of the bran into a ball. As with the fermented bokashi fertil-izer, if no liquid can be squeezed out of the bran ball, and the material holds shape after being released but crumbles when tapped, then the bran contains an appro-priate amount of moisture. It may not be necessary to add the entire liter of expanded solution to moisten 5 kg of bran.
3. If using a strong plastic bag in which to ferment the carrier, press the moistened material down to displace any air pockets
and then tie the bag tightly after displacing excess air. Leave the bag of inoculated bran carrier undisturbed for two weeks or longer.
4. After near anaerobic storage for two weeks or more, the carrier will have a fermented, malt-like smell. It may also have some white mold growing on it, which indicates the presence of beneficial fermentation microorganisms. However, the presence of undesirable black or green mold probably means that the carrier was exposed to too much air or contaminants or that the inoculated bran was too moist when it was stored. Do not use the bran carrier if it has black or green mold growing on it.
5. Break the moist, fermented carrier apart with your hands and spread it out on a canvas in a sunny location to dry. Every half hour or so, use a rake to spread and respread the inoculated bran until the mate-rial is completely dry.
6. Use a rolling pin to break apart any dry clods of bran, both large and small.
7. Store the fine, dry inoculated bran in a sealed plastic bag or other airtight container for long-term storage. Under dry, near anaerobic conditions, the inoculated carrier can be stored for a year or more.
For bigger batches of inoculated carrier for institutional/farm use, all of the materials listed above can be mixed in larger propor-tions. Additionally, other variations of the bokashi carrier are produced and used. Keith Mikkelson at Aloha House in Palawan, Philippines uses the following carrier mix:
• 1 sack of copra (dried coconut meat) meal.
• 3 sacks of carbonized rice husks.
• 3 sacks of low-grade rice bran.
• 200 ml (6.8 US oz.) of extended EM (EME) which is an EM solution that has already been activated and extended, making it ready for immediate use.
• 200 ml of molasses
. . . . . . .10
At Aloha House, one sack of copra meal is mixed with three sacks of low-grade rice bran and three sacks of carbonized rice husks [Ed: for more information about carbonizing rice husks, the PhilRice Open Type Carbonizer]. The ingredients are mixed dry with shovels on a cement floor.
After mixing the dry ingredients, the EM solution (made from 200 ml EME and 200 ml molasses mixed in 10 liters/2.6 U.S. gallons of water) is watered in and mixed with the dry ingredients to obtain the desired 40-50 percent moisture content. The inoculated carrier is fermented and stored in airtight containers (e.g. PVC barrels or 20-liter plastic containers) until use.
Fermenting Food Scraps
When the inoculated carrier is ready, the production of kitchen bokashi can begin. Using a plastic bucket with an air-tight lid, apply a layer of newspaper or cardboard to the bottom to help soak up excess liquid (this step is optional). Then sprinkle a handful of inoculated bran over the bottom of the bucket.
From that point, food scraps (not rotten) can be layered inside the bucket with a thin layer of inoculated bran sprinkled on top of the layered material. The inoculated bran does not need to be added thickly. At minimum, the bran should be sprinkled atop every 1-2 inches of layered food scraps. To increase anaerobic conditions, press down on the food scraps inside the bucket to eliminate air spaces. Continue layering in such fashion until the bucket is full.
If the container is not completely airtight, plastic bags may be used as a supple-mental seal between the bucket and lid. To further lessen contact with air, you might
place another layer of plastic bags on top of the compacted materials and weigh them down with a heavy item, such as a wooden chopping block.
To keep mess to a minimum, you can try to exclude liquid from the bucket. However, some commercial kitchen bokashi buckets come equipped with spigots that allow liquid “bokashi tea” to be easily removed, diluted with water and used to nourish plants.
Once the bucket is full, it should remain sealed with the lid tightly closed. Allow the contents to ferment for at least two weeks in a cool, shaded location. With lactic acid fermentation, little if any pressure will build up as the production of gases will be minimal. However, white mold is likely to appear on top of the product, indicating the presence of beneficial bacteria. As noted above, should there be mostly gray, black or green mold and a putrid odor, the fermentation process was probably unsuccessful and the materials should be disposed of. Under appropriate conditions, kitchen bokashi can be stored for months.
Despite efforts to seal bokashi fermentation containers, somehow, adult black soldier flies (Hermetia illucens) often manage to enter containers of bokashi and lay eggs. Masses of the oval, yellow or cream colored, 1 mm long eggs may be found deposited within the sheets of plastic covering the bokashi. Several days after the eggs are laid, a mass of larvae will emerge. Fortunately, neither the black soldier fly adults or larvae are pests; the larvae are actually a good source of protein for chickens or fish. The larvae may be fed to chickens and/or fish or relocated to compost/vermicompost produc-tion areas with abundant food suit-able for their development. There, they can continue to be harvested as long as they last.
Applying the Fermented Kitchen Bokashi as a Soil Amendment
After it has fermented sufficiently, the finished bokashi should be buried in holes or trenches in the garden under at least 15-20 cm (6-8 in.) of soil to keep it from being disturbed by rats or other animals. Mixing soil with the bokashi will help speed the final decomposition process.
Black soldier flies may burrow down through the soil to any shallow bokashi and lay eggs, with larvae visible several days
later. Again, this should not be a concern. However, if the buried bokashi be disturbed before it has finished composting in the soil, there may be an unpleasant smell.
After several weeks (depending on condi-tions), the fermented kitchen bokashi will have changed into a composted, soil-like material. When the composting process is complete, the former food waste should not have any bad odor.
Once incorporated into the soil, the finished kitchen bokashi will add nutrients and beneficial microbes, and will contribute to improved soil structure. Worms, arthro-pods and other small creatures—indicators of soil health—will thrive in the composted bokashi. Crops will benefit, too.
Conclusion
Both fermented bokashi fertilizer and kitchen bokashi are relatively easy to produce and offer multiple benefits. Use of both types of bokashi has spread well beyond Japan and around the world. Though different in composition and application, both the fermented bokashi fertilizer and kitchen bokashi can be readily produced for use on small farms and in household gardens.
Asia Notes Issue 17 . . . . . . . 11
References
Beng Ngoun. E-mail communication. January 4, 2013.
Department of Agriculture (Thailand). 2005. Organic Fertilizer: Production, Use, Stan-dards and Quality (translated from ปุ๋ยอินทรีย์ การ
ผลิต การใช้ มาตรฐานและคุณภาพ). Document 17/2548, ISBN 974-436-479-3. Ministry of Agriculture and Cooperatives.
FAO. 2011. Cutting food waste to feed the world. The FAO Media Center. http://www.fao.org/news/story/en/item/74192/icode/; accessed May 1, 2013.
Gazette Vol.122 Section 114D, 8 December B.E. 2548 (2005). Ministry of Agriculture and Cooperatives, Bangkok.
Mikkelson, K.O. 2011. A Natural Farming System for Sustainable Agriculture in the Tropics. Aloha House, Inc. Palawan, Phil-ippines.
National Bureau of Agricultural Commodity and Food Standards. 2005. Compost. Unofficial Translation, ICS Thai Agricultural Standard, TAS 9503 – 2005, ICS 65.080 ISBN 947-403-339. Published in the Royal
Oyanagi, Y. 2010. How to Make Bokashi, a Fermented Fertilizer. Take My Hand: The Newsletter of the Asian Rural Institute, December 2010, Nasushiobara-shi, Tochi-gi-ken, Japan.
Silva, J.A. and R. Uchida, ed. 2000. Plant Nutrient Management in Hawaii’s Soils, Approaches for Tropical and Subtropical Agriculture. College of Tropical Agriculture
and Human Resources, University of Hawaii at Manoa, http://www.ctahr.hawaii.edu/oc/freepubs/pdf/pnm15.pdf. Accessed May 1, 2013.
Vig, Suyog. 2011. Biogas Production from Kitchen Waste and to Test the Quality and Quantity of Biogas Produced from Kitchen Waste Under Suitable Conditions. Seminar report in partial fulfillment of the require-ments for Bachelor of Technology. National Institute of Tech Rourkela, Orissa, India.
Whipker, B.E. and T.J. Cavins. 2000. Elec-trical Conductivity (EC): Units and Conver-sions. NCSU Floriculture Research Report. FLOREX.002, December 2000North Caro-lina State University. http://www.ces.ncsu.edu/depts/hort/floriculture/Florex/EC%20Conversion.pdf, accessed May 20, 2012.
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