Category - Agriculture
A sophisticated waste-management system recovers all the waste from pigs and treats it so that these by-products can be used on the farm or sold at a profit
Location:
Windermere, Victoria, Australia
Summary:
A piggery waste management system recovers 275,000 liters of daily sewage effluent and transforms it into various by-products that can be used on the farm, such as flush water for farming, gas for electricity, and fertilizer.
Problem Overview:Production of waste, usage of harmful pesticides and fertilizers, and overexploitation of fresh water supplies in agricultural production and animal farms.
Agricultural production and animal farms often produce significant amounts of waste, which, when it's not effectively managed, can contribute to air and water pollution. Many communities, especially those in developing countries, dump sewage waste into the water system or directly on the streets. Without efficient sanitation systems, this can pose direct health risks in a contaminated water supply and ingested air particles.
In addition, farming communities may also utilize harmful pesticides and fertilizers to promote greater agricultural productivity. Even in developed countries, pesticides and fertilizers are used to increase agricultural output.
Furthermore, farming communities may over-exploit fresh water supplies, exacerbating desertification and depleting water sources. As seen through the Berrybank Farm initiative, waste management systems can not only be used to increase farm production through biomass fertilizers, but also can drastically reduce waste levels and excessive use of water supply.
Charles I.F.E. Pty Ltd operates a piggery at Berrybank Farm at Windermere in Victoria, home to 15,000 pigs with an estimated live weight of 800 tons. The Berrybank Farm piggery produces a daily average of 275,000 liters of sewage effluent with an organic solids content of approximately 2%. This compares to the sewage output of a town with a population of about 50,000 people. Pigs are able to utilize only 50% of the feed they consume, the rest of which is returned as waste. Berrybank Farm management considered this a poor return on investment as well as poor use of resources. Consequently, it sought ways to improve efficiency of the operation, abate pollution problems associated with odorous waste, and reduce its dependence on 400,000 liters of water per day. The waste management system recovers all the waste and transforms it into various by-products that can be used on the farm, such as flush water for farming, gas for electricity, and fertilizer.
The system is a seven stage process comprised of 1) automatic continuous collection; 2) grit removal; 3) slurry thickening; 4) primary digestion; 5) secondary digestion; 6) biogas purification; and 7) a co-generation thermic plant.
The existing drainage around and under the piggery was modified to recover the waste products, and automatic flushing valves were installed and linked to the main pumping station. The valves are solenoid activated and enable remote controlled flushing at various times of the day, working in a similar way to an automatic watering system in a domestic garden. Grit removal is crucial in removing granules of bone that reside in the slurry and can potentially damage internal mechanisms of the pump. The slurry thickening occurs when the finer suspended solids are separated from the water, and the clarified water is recycled as flush water and applied directly to the land. The thickening plant separation process is a combination of an existing screen and a newly developed flotation system. Flotation allows the separation of water from the smaller suspended particles. Primary and secondary digestion are the anaerobic processes crucial to biogas production. The digesters provide the ideal conditions for the process to proceed at a faster, more controlled rate, by excluding air, thoroughly mixing the contents and maintaining optimum temperatures. Biogas purification occurs when it is purged of potentially damaging sulfur by scrubbers, traps and a dehumidifier, before being pumped to the co-generation thermic plant where it is converted into thermic heat and electricity.
The plant produces 180 kW/hr of electricity for 16 hours per day (enough to power over 400 households), with potential to considerably boost this output. 60% of the electricity generated during the day is used for the farm's needs, while the remainder is sold to the State Electricity Commission of Victoria.
The solid and colloidal parts of the digested slurry are separated from the water by centrifuge. This reduces the bulk of the slurry by up to 90%. The end result is composted humus - a valuable fertilizer, currently under development trials for the domestic potting mix market. The separated water also has enough residual nutrients so as to be useful for hydroponics, aquaculture or possible phosphate production to fertilize the land.
Status:
Initiated in 1989, the waste management process of Berrybank Farm started producing electricity in 1991. Each day the farm recovers: approximately 7 tons of waste solids at 35% dry matter, to be used as fertilizer; 100,000 liters of recyclable water; 100,000 liters of mineralized water, used as fertilizer; and, 1,700 cubic meters of biogas, able to run a co-generation electricity program with a daily output of 2,900 kW of electricity.
As a result of cleaner production, Berrybank Farm has also achieved 70% reduction in water usage; improved stock and working conditions; and elimination of odor.
The capital cost of Berrybank Farm project was approximately $2 million, over a two year period, which has taken about 6 years to payback. The total annual savings resulting from proper waste management; the production of natural fertilizer, and recycling of water is $425,000. The breakdown in savings of electricity costs, water costs, and fertilizer costs are $125,000, $50,000, and $250,000 respectively.
While Berrybank Farm's waste management system has been largely successful and profitable, there are several constraints in replicating the project. First, in countries with insufficient credit systems, capital investments and transfer of specialized technology are less feasible. And second, the investor (i.e, farm) must be in a position to handle short term costs and debts in the initial implementation.
Submitted by:
Clare Parker
cparker@rona.unep.org
United Nations Environment Programme
2 UN Plaza
Rm. DC2-803
New York, NY, 10017
United States of America
Contacts:
Charles I.F.E. Pty. Ltd
Berrybank Farm
Windermere Ballarat
VIC 3352 Australia
Telephone 035-343-2344
Fax 035-343-2443
Information Date: 1995-07-02
Information Source: EnviroNET Australia: Cleaner Production Case
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