13 Oct 2000
Sponsors
 Institute
of Advanced
Studies, UN Univ.,Japan AEON Foundation,Japan |
Material Flow Analysis of Integrated Bio-Systems (March-October 2000) |
Organized by:
Integrated
Bio-Systems Network
UNU/IAS
Alumni Association, UN Univ.,Tokyo
with the assistance of : MFA
Conference Planning Group
UNESCO
Microbial Resources Centre, Stockholm |
In: Foo E.L., Della Senta T., Sakamota K. 2000. Material Flow Analysis of Integrated Bio-Systems (March-Oct 2000)
| Abstract
Pozo Verde Natural Reserve is an integrated farm located in the Cauca Valley Province in Southwestern Colombia at 950 metres above sea level. The main production systems found in the farm are described as follow: 1. Pig production: 73 breeding sows and 595 growing and fattening pigs distributed in three separated buildings. 2. Double Purpose Cattle: 166 F1 (Holstein * Zebu) and F2 (H*Z x H*Z) animals divided in four groups. 3. Buffaloes: 52 buffaloes used for milk and beef production and as a source of animal draught. 4. Forage production: Composed of star grass areas (Cynodon nlemfuensis), areas with mixed star grass and pizamo tree (Erythrina fusca), protein banks including E. fusca, Giant taro (Alocasia macrorhiza) and Trichanthera gigantea, and an area with sugar cane, as well as eight ponds for Azolla spp. and Salvinia sp. production. 5. Organic matter recycling: 300 m² of Eisenia foetida for processing cattle and buffalo manure and other solid residues. Two 75 m³ and two 14 m³ plastic bag biodigesters. Pigs are mainly fed with a prepared ration based on corn and soybean meal, but pregnant sows receive also Azolla spp., Salvinia sp. and Giant taro (Alocasia macrorrhiza) as a source of protein that can replace up to 50% of commercial feed. The main source of feed for cattle and buffaloes are the pastures. However they remain confined during part of the day or overnight in order to feed them with a supplementary ration (sugarcane, tree foliage and chicken litter) and to recover the manure. The solid fraction of the manure equivalent to 230 ton/year for cattle and 37 ton/year for buffaloes is used for worm production (Eisenia foetida) and the buildings washed and the wastewater used for biogas production in two 75 m³ plastic bag biodigesters. Pig manure in the raising and fattening section, equivalent to 1883 kg/day is treated also in the biodigesters. The wastewater from this production is 25 m³/day. In the pregnant sows section, the solid fraction of the manure (133 kg/day) is collected before washing the building using 2.5 m³/day of water. Biodigesters provide biogas for heating
the piglets from birth up to 60 days (51 burners * 14 hours/day) and for
replacing part of the fuel in a combustion engine that provides electricity
to the farm. The biodigester slurry is collected in a basin and pumped
to the grasslands and crops in the farm.
Keywords
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During 70s, 80s and beginning of 90s there was a trend towards the specialisation e intensification of agriculture, including livestock production. This trend caused a negative environmental impact due to the destruction of some forested areas and the drainage of many wetlands in order to increase agriculture areas.
"Pozo Verde" farm is located in the southern part of the valley at 950 m.a.s.l. and 24 °C of average temperature. During the first half of the 80s, the farm had a dairy production with pure Holstein cattle as well as pigs and broilers, all managed independently.
After
1985, with the advice of CIPAV, the farm started a process of change with
introduction of double purpose cattle, aquatic plants, fodder trees and
sugarcane for replacing part of the formulated feed used at that moment.
Biodigesters and earth worms were also introduced to process organic matter
and generate revenues and buffaloes as a source of animal draught and milk.
All these new elements allowed a linkage between the original activities
with all the benefits of integration.
In 1996 the farm joined the "Private Natural Reserve National Network" and started the recovery and protection of a wetland within the property.
Nowadays, with the crisis that agriculture and economy are undergoing in Colombia, integrated systems like this have proved to be less vulnerable due to the reduction of costs and less dependency on the market price of traditional inputs. In addition, it is demonstrating that agriculture production can be carried out causing less deterioration of the environment.
Diagram 1. General layout of the farm (grassland not included)
This paper presents a description of the integrated system and an analysis of the material flow with particular emphasis on the organic matter recycling within the farm. Although some economic values are presented, the economic analysis of the system is out of the scope of this paper.
Animals are mainly fed with a ration based on maize and soybean meal prepared in the farm, although pregnant sows receive Azolla spp., Salvinia sp. and bore or giant taro (Alocasia macrorrhiza) that replace up to 50% of the prepared feed.
Feed used in the farm per year amounts 384 ton of formulated feed, 109 ton of azolla and salvinia and 5.6 ton of bore foliage.
The pregnant sows' building is cleaned collecting the solid fraction (132 kg/day) before washing it with 2.5 m3/day of water. The solid fraction is used to feed the biodigesters of system 2 and the wastewater is treated in the system 1 (see below).
The farrowing section is washed daily with 2.7 m3 of water and the lactating sows building with 2.5 m3. In total these two sections produce approximately 135 kg of manure.
In the
growing and fattening sections the cleaning system was similar, but during
the last year small basins were built in most of pens. These basins remain
always full of water and are emptied, washed and refilled daily. Pigs only
defecate and urinate in the basins keeping the rest of the pen clean and
reducing the need of water. With this device, water consumption for washing
was reduced from aproximately 34 to 12 litres/pig/day, and labour for washing
from 90 to 45 minutes per day (Photo 1).
Wastewater from lactating, growing and fattening sections is treated
in the biodigesters of system 2 (see below).
Photo 1. Finishing pig pen with basin at the end.
Animals remain most of the day in the pastures conformed mainly by star grass (Cynodon nlenfuensis). Milking cows are confined during part of the day and stay in the pastures overnight, whilst the other groups are confined overnight to offer a supplement and recover the manure.
Confined animals receive several feed supplements that include mainly chicken litter and pizamo foliage (Erythrina fusca). Total amount of ingredients used per year for cattle and buffaloes is presented in Table 1.
Table 1. Ingredients used as supplement for cattle and buffaloes in Pozo Verde Farm.
| Ingredients Produced on farm | Tons/year | Ingredient from the market | Tons/year |
| Chicken litter | 52.6 | Molasses | 23.2 |
| Pizamo foliage | 46 | Vinaza | 15.5 |
| Sugar cane top | 340 | Rice bran | 6.9 |
| Calcium Carbonate | 0.7 |
In the
stable where cows are kept before milking, solid fraction of manure is
collected before washing the building. Wastewater is piped to the biodigesters
of system 2. In other sections the buildings are cleaned collecting only
the solid fraction with a shovel (Photo 2).
An average of 230 tons of cattle dung are recovered yearly for worm
production and 2883 m3 of wastewater from cattle are treated through system
2.
Photo 2. Cattle and buffalo dung transported
to the worm culture
In addition to this, buffaloes have replace partially the use of tractors in the farm. An analysis done by Galindo (1998) showed that the cost per hour or work, transporting one ton of sugarcane was US$ 2.3 for tractors and US$ 1.31 for buffaloes, and these caused less environmental impact.
Table 2. Forage production in "Pozo Verde" Farm, Colombia. (Adapted from Cuellar, 1998).
| Species | Area or number of plants | Yield per year |
| Star grass (Cynodon nlenfuensis) pastures | 38.5 ha | 5600 tons |
| Star grass + pizamo (Erythrina fusca) | 2 ha | 320 tons of grass
90 tons of pizamo |
| Sugar cane | 2 ha | 120 tons |
| Aquatic plants (Azolla spp. Salvinia sp.) | 1 ha of ponds | 182.5 tons |
| Trichanthera gigantea | 300 plants | 1.5 tons |
| Giant taro (Alocasia macrorrhiza). | 1036 plants | 5.6 tons |
Photo 3 shows the mixed star grass and pizamo tree areas in the farm, photo 4 the ponds for azolla production, and photo 5 the Giant taro crop.
Photo 3: mixed star grass and pizamo tree areas in the farm |
Photo 5: Giant taro crop |
Photo 4: the ponds for azolla production |
In total 230 tons of cattle dung and 37 tons of buffalo dung are used per year, to produce 160 tons of worm-compost that is used mainly to fertilise grasslands and crops, although an important fraction is sold to the market.
Wastewater passes through the two biodigesters and them to the aquatic plants. Table 3 shows the efficiency of the system to remove Biochemical Oxygen Demand (BOD) and Total Suspended Solids (TSS) in kg per year.
Table 3. Average BOD and TSS removal in the productive water decontamination system 1 (kg/year).
| Wastewater | Biodigesters outlet | Aquatic plants channel outlet | |
| Biochemical Oxygen Demand (Kg/year) | 1722 | 111 | 27.9 |
| Total Suspended Solids (Kg/year) | 2663 | 426 | 10 |
Aquatic plants and sludge produced in the channel are used as fertiliser for the associated crops and the water is pumped to irrigate adjacent grass lands. A total of 4.6 tons of water hyacinth (Eichhornia crassipes) were harvested per year in this system.
Biogas obtained in this system is stored in a 49 m3 and used for electric power generation in a diesel engine.
Decontamination
System 2Biodigesters effluent is stored in the tank and them pumped to fertilise
30.8 ha of pastures and crops in the farm. In total it is estimated that
15,000 m3 are pumped every year.
Biogas produced in this system is estimated in 19,200 m3 per year used
in 51 burners for heating piglets from birth up to 60 days. Burners used
for this purpose are shown in Photo 7. The remaining biogas is piped to
the same storage bag of system 1 to be used for electric power generation.
Table 4. Material flow per year in Pozo Verde Farm, Colombia
| SUBSYSTEM | INPUTS | PRODUCTS
(To the market) |
BYPRODUCTS
(To other subsystems) |
| Pigs | Formulated feed: 384 ton
Aquatic plants: 109 ton Giant taro: 5.6 ton |
Pork meat: 107.4 ton | Wastewater: 10,477m3
Pig manure: 48.1 ton |
| Dual Purpose Cattle | Chicken litter: 52.6 ton
Pizamo foliage: 46 ton Star grass: 5920 ton Sugarcane tops: 340 ton Other foodstuff : 46.3 ton (see table 1) |
Milk: 159,200 lts.
Weaned calves: 6.25 ton |
Manure: 230 ton
Wastewater: 2883 m3 |
| Buffaloes | Milk: 13,600
Cheese: 2.2 ton "Kumis": 4160 lts Six trained draught buffaloes |
Manure: 37 ton
Animal draught: 657 Kwh |
|
| Poultry | Formulated feed: 579 ton | Broilers: 303 ton | Chicken litter: 600 ton |
| Forage production | Biodigester effluent: 15,000 m3
Chicken litter: 450 ton Earth worm compost: 80 ton |
Foliage biomass: 6323 ton | |
| Earth worms | Cattle dung: 230 ton
Buffalo dung: 37 ton |
Worm compost: 80 ton | Worm compost: 80 ton |
| Wastewater Decontamination systems | Wastewater: 13,360 m3
Pig manure: 48.1 ton |
Biodigester effluent: 15,000 m3
Biogás: 19,200 m3 |
Diagram 2. Material flow in "Pozo Verde" farm, Colombia
For
generating electricity, biogas is replacing diesel in two engines that
are conected to the biogas storage bag (Photo 8). Percentage of replacement
and time used per year are presented in Table 5.
Photo 8. Biogas reservoir bag for electric power generation
Table 5. Replacement of diesel by biogas in two engines in Pozo Verde Farm, Colombia.
| Engine | % of replacement of diesel | Hours /year | KWh produced per year | Cost of electricity in the market |
| Perkins 100HP - 74KW | 67% | 152 | 14228 | US$ 505 |
| Blackstone 135 HP- 92KW | 47% | 145 | 6231 | US$ 663 |
An analysis carried out by Zapata (1998) demonstrated that 1 Kwh produced with the Perkins engine is 40% cheaper that the Kwh provided by the local electric power company. However, as shown in table 4, the amount of hours of power generation with biogas is still low, due to the priority to the use of the biogas for heating.
The integration allowed the farm to eliminate the need of chemical fertilisers and other external inputs such as foodstuff, fossil fuels and electricity.
Negative environmental impact is reduced due to the recycling of organic "wastes" in the farm, which avoids water, soil and air pollution. The use of organic fertilisers also benefits biota in the soil and improves its physical properties.
Mixed crops with trees, grass and other fodder plants, as well as the wetland in the farm are providing nest and food for wildlife, particularly for birds.
From the social point of view, integrated systems provide more employment
than intensive ones, which is very important for developing countries.
Cuellar P. 1998. Granja "Pozo Verde" como sistema de producción pecuaria integrado. Pozo Verde Natural Reserve. Report. 8 pp.
Galindo W. 1998. Tractor o Búfala: Eficiencia económica y ambiental para labores de tracción. Conference Proceedings. III World Congress on Animal Draught. La Habana, Cuba, Mayo 12 -16, 1998.
Pedraza G. 1998. Valoración económico-ambiental de una propuesta alternativa de descontaminación de aguas de lavado de cerdos. Research Report. ECOFONDO, CIPAV Foundation, Cali.
Polprasert C. 1989. Organic Waste Recycling. Asian Institute of Technology, Bangkok. John Wiley & Sons. London. 357 p.
Pulido E. 1998. Evaluación del flujo de materia orgánica en la Reserva Pozo Verde. Research Report. ECOFONDO - CIPAV Foundation. Cali.
Zapata A. 1998. Utilización del biogás para generación de electricidad. Research Report. CIPAV Foundation: http://www.cipav.org.co/energy.