Paper No. 954499
AN ASAE Meeting PRESENTATIONWASTE TREATMENT SYSTEM ALTERNATIVES FOR THE 21st CENTURY by
|Clifford B. Fedler
Civil Engineering Department
Texas Tech University
|Nick C. Parker
Texas Coop Fish & Wildlife
Written for presentation at the 1995 International Summer Meeting
THE AMERICAN SOCIETY OF AGRICULTURAL ENGINEERS
June 18-23, 1995SUMMARY Whether water contamination problems are viewed as real or perceived by the public in relation to large animal feeding operations, addressing the issue before regulators is in the best interest of producers. By integrating known technologies, such as an advanced facultative lagoon with aquatic plant production, new revenue sources will be produced to stimulate the economy and meet the food production needs of a growing world population KEYWORDS Aquaculture, Waste, Livestock Feeds, Fish
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1Funding provided by the U.S. Department of Commerce Economic Development Administration Project No. 08 06-02714, the Texas HigherEducation Coordinating Board Advanced Technology Program, Project No. 003644- 064, and the Texas Tech University Water Resources Center. Publication number T-9-710 of the College of Agricuttural Sciences and Matural Resources.
2 The authors are Clifford B. Fedler, Associate Professor a! Civil Engineering, Texas Tech University, Lubbock; and Nick C. Parker, Professor of Range and Wildlife Management and Leader, Texas Coop Fish and Wildlife Research Unit, (Jointly sponsored by Texas Tech University, Texas Parks and Wildlife Department, The National Biological Service, and the Wildlife Management Institute) Texas Tech University, Lubbock.
ABSTRACT Whether surface or ground water contamination problems are viewed as real or perceived by the public in relation to the large livestock and poultry operations, addressing the issue is in the best interest of producers. But if scientists expect new technology available to be adopted by tile producers, a paradigm shift is required. Biomass, in the form of waste, produced at the large production operations must not be viewed as only a liability, but as a feedstock for producing alternative products that are commercially viable in the marketplace or can be used to reduce on-site production costs. By integrating known technologies, new revenue sources can be produced to stimulate the economy and to meet the food production needs of the growing world population. Potential products from an integrated agriculture and aquaculture system for wasterwater treatment and reuse include aquatic plant and fish to be formulated into fish and animal feeds and high value extractable compounds such as carotenoids, pharmaceuticals and reagents.
Engineering improvements in the development of water reuse systems to conserve fresh water and development of aquaculture production systems to use non-potable water would be marketable technology of increasing value worldwide. Many regions of the world already have the resources available to support integrated operations if approaches are taken to use natural resources locally available, to produce products of special interest and high value, and to develop the infrastructure as an integral part of agriculture and other industries. A ponding system that utilizes known technologies in a new way for the treatment of wastewater integrating by-product development is one alternative to providing wasete treatment for the 21st century.PROBLEM IDENTIFICATION Parts of the arid and semi-arid areas in the United States that formally produced agricultural crops are now fallow because of the presence of subsurface saline water and an accumulation of salts in the soil. Natural sources of salt water are a liability to traditional agricultural development, yet brine springs are found throughout much of the western United States. Several retention dams have been built to contain salt water and protect downstream fresh water supplies needed for agricultural and domestic purposes. In addition, the oil industry produces considerable quantities of oil-contaminated brine that must be contained to prevent environmental degradation.
Since a large portion of the earth has an arid or semi-arid climate, irrigation technology and development of drought-tolerant crops has resulted in continued development of these lands. Irrigation has provided a tremendous benefit to our agricultural production and economy, but not without drawbacks. Water used for irrigation on U.S. farms was only 0.27x109 m' (71 billion gallons) annually in 1940 but peaked at 0.57x109 m' (150 billion gallons) in 1980 (U.S. Bureau of Census, 1990). This increase was not due to irrigation growth alone; daily per capita consumption of water increased from 3.9 m' (1027 gallons) in 1940 to 7.4 m' (1953 gallons) in 1989-an increase of 90% in 40 gears. Withdrawal of ground water has increased to meet the greater demands for fresh water to support the population growth and extensive agricultural production. Some farmers have ceased irrigation, not only because of the high cost of pumping but the fact that irrigation is responsible for salinization of soils and water (Camp, 1963).
In addition to water consumptions by crops, large animal feedling operations that also require relatively large amounts of fresh water have been developed in this mosaic of rangelands and row crop agriculture. Cattle, for example, are usually maintained in feedlot pens for about 5 months while they gain weight from an initial 200400 kg (400 800 lb) to about 500 kg (1100 lb) at the time of slaughter. Recent trends have been to develop large feedlots; in 1989, 198 feedlots accounted for 51% of the nation's output of fed cattle (Texas Agricultural Statistics Service, 1989). A typical feedlot will have 50,000 to 100,000 head at one time. Each feedlot steer annually excretes 10 tonnes (9 tons) of waste (88.2% moisture) per 1,000 units of live weight (Midwest Plan Service, 1975). The concentration of waste resulting from these and other intensive agricultural operations, such as swine, poultry, and dairy, creates severe waste management problems. In addition to potential environmental damage, there are economic aspects associated with disposal of this waste, such as fines for non-compliance with current regulations.INTEGRATED WASTEWATER TREATMENT SYSTEMS The nutrient rich wastes from animal production units can be processed through integrated wastewater treatment systems to recover nutrients for conversion into additional farm products (Parker et al., 1992a; Parker et al., 1992b; Swaminathan, 1992; and Fedler and Parker, 1993). Wastewater treatment systems that can be integrated will allow cattle feedlot owners to produce hydroponic and aquaculture products. These new products, or on-site resources, include biogas (methane) for energy, aquatic plants (microalgae, duclcweed, and water lilies), fish (bait, ornamental, and forage) and invertebrate products (crawfish, clams, and worms). Additional benefits of integrated wastewater treatment systems include odor control, aesthetic value, maintenance of habitat for migratory waterfowl and resident wildlife - attributes that may have environmental and public relations values far greater than their commercial value.
Elements of wastewater treatment systems of Oswald (1988) and Hammer (1989) have been incorporated to develop an integrated system to treat effluent from animal production units while producing biomass-based energy and agricultural products. This treatment system consists of a 4-stage system (Figure 1), beginning with the separation of solids from the waste. The second stage is an anaerobic pit incorporated into a facultative lagoon (called an advanced facultative lagoon, AFL) (Figure 2). The third stage consists of an aquatic plant production pond (for production of algae, duckweeds, or macrophytes). The final effluent could then be used to raise fish. This effluent with the algae phormidium boneri, can contain ammonia levels at less than 1 ppm which is necessary for raising most species of fish. Another type of system, currently being designed to reduce the nutrient discharge from secondary treated municipal we will consist of constructed wetlands with the option of producing native macrophytes, duckweed, microalgae, ornamental plants or alternately flooded and dried grasslands using knotgrass, Components of these two systems are under construction at the Texas Tech University animal science demonstration site near New Deal, Texas. This system provides three options for the third stage of the process - production of algae, duckweeds, or macrophytes (Figure 1). ibis demonstration treatment system will accept both swine and cattle waste that is screened to separate some of the heavy solid material in the waste. Water will pass sequentially through the units shown in Figure 1 and be recycled back to the swine and cattle operations for flush water or discharged as water for irrigation of crops.
Figure 1. Schematic of an integrated wastewater treatment system for livestock waste with three options forthe third cage of the process not to scale). Estimated Outputs This waste treatment system will not only utilize animal waste and alleviate a major environmental problem, but create a new industry with the production of single cell protein and protein from aquatic plants, which can be produced and used on location or exported. This protein source can be combined with corn, cottonseed, soybean meal or wheat by-products and processed into rations for fish, livestock, and poultry. Production of single-cell protein and aquatic plant protein could provide new regional and nationwide markets for these commodities. Maximum annual production of marine microalgae is around 66 tonnes/ha (74 tons/A on a dry weight basis. Typically, microalgae raised on the farm scale will produce between 2.7 and 16 tonnes dry wt./ha (3 and 18 tons dry wt./A) (Richmond,1986),indicating the need for improved efficiency in production. Taking an average production rate of 10.7 tonnes/ha (12 tons/A), nearly 1.8 million tonnes a million tons) of dry microalgae could be produced from the waste generated by the carafe produced on the Texas High Plains. If this algae (from 50 to 70% protein) were sold at a price compared to that of soya protein it would generate annual sales of approximately $240 million. Clearly, more economic value is possible when you consider that several high-valued products (Cohen, 1986) can be extracted from the algae without reducing the value of the protein Fedler et al., 1991). Duckweed, containing up to 45% protein, has been produced at about 30 tonnes (34 tons) dry wt./A and could serve as feed for livestock, poultry, and fish (Culley et al., 1981; Skillicorn et al., 1993). In addition to this potential new industry, other existing industries will be impacted through sales of the necessary equipment required to harvest and process the single cdl protein (bacteria), microalgae, duckweed, and macrophytes into feeds and feed ingredients.
Another potential product from this type of integrated waste treatment system is the production of water lilies, Louisiana irises, and other ornamental aquatic plants. This system is the most labor and capital intensive, however, it provides the greatest potential for economic return. Aquatic plants grown in Texas are now being shipped throughout the country and also to foreign markets, including Germany and Japan. Some of these ornamental plants are produced in open outdoor ponds, others in ponds covered with greenhouse structures. Selected individual plants have sold for $69.95 for a 10-15 cm (4-6 inch) pot. Returns for some ornamental plant crops have been as high as $80,000/A in one year. Of course the average return is much lower, but the potential for managing a nutrient reduction system as a business does exist.
Production and sale of fish will generate additional funds. Bait fish commonly sell for $22-33/kg (($10-15/lb)) and other high-value fish include fingerlings of sport fish such as bass and bluegill; fingerlings of foodfish such as red drum and channel catfish to be stocked and reared in other facilities; and ornamental fish such as swordtails and mollies. Lower value fish, such as carp, can be processed as fish meal and incorporated into feeds for swine, poultry and other fish.
The global catch of fish from the oceans increased rapidly from 21 million tonnes (23 million tons) in 1950 to 76 million tonnes (84 million tons) in 1970 but only slowly to 93 million tonnes (102 million tons) in 1986 and a record 98.6 million tonnes (108.5 million tons) in 1988 (National Marine Fisheries Service, 1988, 1990). Experts consider it unlikely that the future sustained harvest of marine fish will exceed 100 million tonnes (110 million tons) (National Marine Fisheries Service, 1988). The United Nations has predicted the world shortfall of land-based protein to be 39 million tonnes (43 million tons) by year 2000 (Richmond, 1986). To offset the shortage of available protein supplied by meat products, recommendations are to supplement the conventional crops with high-protein foods, such as those provided from marine life. This protein shortage can not be provided solely by harvesting the renewable fishery resources of the oceans.
Although 60% by weight of the fish harvested from the oceans is consumed directly by man, fish and fish by-products have other important uses. One such use is production of fish meal, which provides a large part of the protein formulated into feeds for livestock and poultry. The demand for fish meal increased in the Far East, China, the Scandinavian countries, and the United Kingdom in 1988 as a result of expansion of the aquaculture and poultry industries. As demands increased in other parts of the world, not to the cost of fish meal increased. United States' imports of fish meal decreased by 30% between 1987 and 1988 as the cost increased and the value of the U.S. dollar in the world market declined (Ratafia and Purinton, 1989). As a result, animal producers in the United States were forced to feed feeds formulated with higher levels of plant protein.
Figure 2. Simplified schematic of the advanced facultative pond used in the integrated wasterwater treatment system (not to scale).
For current land-based animal production methods and technologies, the net effect of a limited global fish supply is a limited global protein supply. Not only will the oceans' fishery products be insufficient to provide needed protein for human consumption, they will be insufficient to provide the feeds necessary for intensive production of animals in confinement.
Aquaculture is an emerging industry in the United States and teas tremendous potential. Only 14% of the world supply of fishery products were produced on farms in 1985 (Ratafia and Purinton, 1989), but aquacultural production is projected to increase to 25% by the year 2000 (Ratafia. 1990). Present aquacultural production has created an unprecedented demand for fish meal. Since 1980, feed required by aquaculturists rearing aquatic animals (102 types of fish, 32 crustaceans, 44 molluscs and 3 miscellaneous) on farms has increased from 1980 ova two-fold to 3.6 million tonnes (4 million tons) in 1988 (Ratafia and Purinton, 1989). It has been projected that farm-raised aquatic animals will require 14 million tonnes (15.4 million tons) by year 2000 (Ratafia and Purinton, 1989). Many of the fish presently reared in aquaculture facilities typically require about 2 kg of dry feed to gain I kg of weight. Fish feed is normally formulated with 25-50% protein, of which a large portion may be fish meal. The juvenile stages of fish and carnivorous species typically require higher levels of fish meal protein. It should be clear that aquacultural practices will not greatly increase the net availability of fish and fishery products unless an alternate protein source is found to supplement or replace fish meal.
Economic incentives exist for further development of aquaculture. One percent of the United States' fish supply was farm-reared in 1970; by 1987, 7% of the fish consumed in the United States were produced by aquaculture. In 1989, fish reared on American far were valued at about $750 million (National Marine Fisheries Service, 1990). However, imports of fish and fishery products into the United States were valued at $9.6 billion in the same year. Exports of seafood products are about S2 billion less than imports (Smith, 1995). Clearly, economics alone are not sufficient to increase aquacultural production in the United States.
NEED FOR PROTEIN
Aquaculture, the farming of fish and other aquatic plants and animals, is often touted as the solution to the global need for protein. If we assume aquaculture may contribute substantially to the amount of protein needed (we will ignore the often inverse relationships between protein needs and protein production in different geographic areas), the questions " why hasn't it already been accomplished and "when will it make a significant contribution to the needed protein supply. must be asked.
In the United States and throughout the world, most farm-raised foodfishes are cultured in ponds or raceways in warm climates with long growing seasons that are conducive to high annual production. Although these methods are economical and productive, they require large amounts of land and large volumes of high quality water. For pond production, the land should be fertile, have clay available and be in an area with a supply of high quality water. Production in raceways is limited by the amount of high quality water available to continuously pass through fish rearing units. Much of the area, at least in the United States, that has desirable conditions for pond or raceway aquaculture already has been developed. It is important to note that the land and water requirements for present aquacultural production arc also needed for traditional agricultural crops. Therefore, further development of conventional aquacultural systems will reduce production of traditional crops, such as corn, cotton, and rice.
Commonly, fish reared on fish farms, particularly in the United States, are those that are economically desirable for fish farmers. Rearing fish for stocking recreational fisheries (sportfish) or for aquarists (hobby fish) can be lucrative; however, rearing sportfish and hobby fish does little to satisfy the need for protein. For the many farmers producing food fish that are "economically desirable. means rearing high-value fish that typically require large quantities of expensive protein in their diets. Recycling plant and animal protein into high-value fish does little to reduce world-wide protein needs.
Potential Health Benefits
Food quality is an important consideration for aquacultural production. Aquaculturists have often enjoyed receiving a higher price for farm-raised fish than wild-caught fish because of the consistent high quality of farm raised fish-free from environmental contaminants with good flavor and texture. Although farmed-raised fish are generally high quality, their fatty acid profiles are similar to that of soya protein, one of the main ingredients of fish feeds as currently formulated, and does not contain omega-3 fatty acids at levels found in wild-caught marine fish (Stansby et al., 1990).
Marine algae, the predominant synthesizers of omega-3 fatty acids, are at the base of the marine food chain through which these nutritionally important lipids enter fish and, ultimately, the human diet. Recent studies have suggested various benefits of omega-3 fatty acids to human health (Stansby, 1990; Land, 1986). The National Institute of Health and other health organizations have shown that omega-3 fatty acids are essential in the human health (Hunter, 1987, 1988; Lees and Karel, 1990). The effects of dietary omega-3 fatty acids on farm raised fish is now being investigated at several locations including Texas A&M University, Mississippi State University and on fish farms in Japan.
Many locations in the U.S. and throughout the world have the natural resources required to develop efficient, commercial-scale systems for culture of algae and fish using the plentiful supplies of waste produced in concentrated animal production units as a nutrient base and associated components of the available infrastructure. Because aquaculture is a form of agriculture, it is important to note that many areas have the necessary infrastructure to support the integrated wastewater treatment systems. Potential products in such systems include algal protein for direct consumption by fish or zooplankton that, in turn, are important food organisms for larval and several adult fish. Other products include food fish (tilapia and redfish), caviar from paddlefish, and harvested algae. The harvested algae provides products such as animal feeds, health food, and a variety of high value extractable compounds.
The increased demand and declining supply of seafood products world wide identify aquaculture as a growing industry. The commercial value of some products (fish and caviar) are known but the value and identity of other potential products remains unknown. In many arid and semi-arid regions in particular, attaining a high level of production in limited water volumes means that fish culture must move indoors where temperature and water loss can be controlled. Control of temperature allows continuous production, thereby increasing total annual production, and allows the culture of warmwater fishes in locations that would otherwise be climatically unsuitable.
Environmental control in water reuse systems allows great flexibility in the types of fish that can be produced However, there are two constraints: (1) the products must be sufficiently high in value to compensate for the additional costs of construction and operation of the facility and (2) the animals reared must tolerate high-density crowding. For example, in arid regions of the world it may be prudent to rear and sell fry and fingerlings to be stocked and grown by other fish farmers with more abundant water supplies. Other species could be produced to meet specialty markets and could include hobby fish, mollusc, shrimp, and bait fish.
As a food source for livestock and poultry, algal protein is valued in comparison to the cost of soya protein when produced in integrated ponding systems. The cost of algal protein would be lowered by the scale of the production system and the high value of products extracted from the algae (e.g., pigments, pharmaceuticals, reagents, etc.). Processing of the algae to obtain the high-value products leaves algal protein as a value-added protein by-product.
Algal lipids containing omega-3 fatty acids will be valued in comparison to fish oils; however, algal-derived fatty acids could command a higher price if consumer concern about contaminants in marine fish increases. Engineering improvements in the development of water reuse systems to conserve fresh water and development of aquaculture production systems that use waste nutrient resources would be marketable technology of increasing value worldwide. Many regions can support significant aquaculture operations if approaches are taken to use natural resources locally available, to produce products of special interest and high value, and to develop the infrastructure as an integral part of agriculture and other industries.
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