WASTE TREATMENT SYSTEM ALTERNATIVES INTEGRATING PRODUCT DEVELOPMENT
Clifford B. Fedler and Nick C. Parker'

ABSTRACT
Along with the glamour of the Texas High Plains producing nearly 25% of the nations cattle in the concentrated areas comes the spotlight of being the cause of many real and perceived problems, such as contamination of the Ogallala aquifer with nutrients produced by such a large quantity of cattle. Whether surface or ground water contamination problems are viewed as real or perceived by the public, it is in the best interest of producers to address these issues. One method is to develop and adopt new technologies that reduce or eliminates the potential of surface and ground water contamination by integrating waste treatment with development of new products. 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 this integrated wastewater treatment system include algal protein, animal feeds, food fish, and high value extractable compounds such as pigments, pharmaceuticals and reagents.

AGRICULTURAL AND INDUSTRIAL PROBLEMS
A large portion of the earth has an arid or semiarid climate. In the United States, irrigation technology and development of drought-tolerant crops has resulted in agricultural development of arid and semi-arid lands. Irrigation has been a tremendous boon to our agricultural production and economy, but it is not without drawbacks. Water used for irrigation on U.S. farms was only 0.27x109 m3 (71 billion gallons) annually in 1940 but peaked at 0.57x109 m3 (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 m3 (1027 gallons) in 1940 to 7.4 m3 (1953 gallons) in 1989--an increase of 90% in 40 years. Withdrawal of ground water has increased to meet the greater demands; in the High Plains withdrawal from the Ogallala Aquifer has supported population growth and extensive agricultural production. In many areas, withdrawal of water for irrigation has been blamed for alarming declines in the level of water in the vast OgallaJa and, due to concern or the increased cost of pumping water, some farmers have ceased irrigation. Irrigated agriculture is responsible for salinization of soils and water (Camp, 1963). Some areas of the arid southwest that formally produced agricultural crops are now fallow because of the presence of subsurface saline water and an accumulation of salts at the surface. Natural sources of salt water are a liability to traditional agricultural development. Brine springs are found throughout much of the arid western United States. Several retention darns have been built to contain the salt water and protect downstream fresh water supplies needed for agricultural and domestic purposes. Other containment dams have been authorized, but not yet funded by Congress. The oil industry in Texas, valued at $17 billion in 1988, produces considerable quantities of oil-contaminated brine that must be contained to prevent environmental degradation. In addition to water consumptions by crops, large cattle feedlots that also require relatively large amounts of fresh water have been developed in this mosaic of rangelands and row crop agriculture. Cattle are usually maintained in feedlot pens for about 5 months while they gain weight from an initial 200-400 kg (400 800 lb) to about 500 kg (1100 lb) at time of slaughter. In 1989, there were over five million head of cattle shipped from feedlots in the Southern High Plains (Texas Agricultural Statistics Service, 1989). Recent trends have been to develop large feedlots; in 1989, 198 feedlots accounted for 51Sro of the nation's output of fed cattle 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: expects associated with disposal of this waste, such as fines. WORLD FISH SUPPLY The global catch of fish from the oceans increased rapidly from 21 million tonnes (23 million tons) in 1950 to 76 million tonnes (84 minion 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, recommendations are to supplement the conventional crops with high-protein foods, such as those provided from marine life. This protein shortage cannot 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. Fish meal provides the bulk of animal 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, 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 less desirable feeds formulated with higher levels of plant protein. 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
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. Aquaculture is an emerging industry in the United States and has tremendous potential (Joint subcommittee on Aquaculture, 1983a, 1983b). Only 14% of the world supply of fishery products were produced on farms in 1985 (Ratifia 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 over two-fold to 3.6 million tonnes (4 million tons) in 1988 (Ratafia and Purinton, 1989). It has been projected that farrn-raised aquatic animals will require 4.3 million tonnes (4.7 million tons) of feed by 1990 and 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. Dish 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 farms 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 $96 billion in the same year. Clearly, economics alone are not sufficient to increase aquacultural production in the United States 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 are also needed for traditional agricultural crops. Therefore, further development of conventional aquacultural systems will reduce production of crops, such as corn, cotton, and rice. As the world increasingly recognizes the importance of the amount and quality of water, waste discharges from aquaculture facilities must also be considered. In the United States, water discharges are affected by increasingly stringent regulations. These regulations will increase the cost of production and curtail some aquacultural operations. 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 worldwide protein needs. 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 farm-raised fish are generally high quality, their fatty acid profiles arc 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., l 990). Marine algae, the predominant synthesizers of omega-3 fatty acids, arc 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. INTEGRATED WASTEWATER TREATMENT SYSTEMS The nutrient rich runoff and solid wastes from cattle feedlots 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; Swarninathan, 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 (rnicroalgae, duckweed, 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 & 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 cattle feedlots while producing biomass-based energy and agricultural products. Willis treatment system consisted of a 4-stage system, shown in Figure 1, beginning with an anaerobic pit incorporated into an advanced facultative pond, a high-rate algal production pond (for production of duckweeds and macrophytes) and a final aerobic maturation pond. The final effluent could then be used to raise fish. A second system is being designed to reduce the nutrient discharge from a secondary treated municipal wastewater. This system will consist of constructed wetlands with the option of producing native macrophytes, duckweed, microalgae, ornamental plants or alternately flooded and dried grasslands. Components of these two systems are scheduled for construction at the Texas Tech University cattle feedlot demonstration site near New Deal, Texas. This system provides three options for the third stage of the process - production of algae, duckweeds or macrophyte. (Figure 1).
Figure 1. Schematic of an integrated wastewater treatment system for livestock waste with three options for the third stage of the process (not to scale).
The demonstration treatment system will accept both swine and cattle waste that is screened to separate some of the heavy solid material in the waste. This system is an expansion of technology developed from an existing facility designed to culture marine microalgae using anaerobically digested biomass from cattle feedlots (Fedler and Parker, 1993). The demonstration pilot plant will consist of (1) an advanced facultative lagoon (Figure 2)—a stratified digester with an aerobic surface and anaerobic bottom for digestion of the waste biomass, production of single-cell protein, and generation of methane gas, (2) a pond for the production of microalgae, and (3) a well mixed lagoon for culture of finfish. Water will pass sequentially from unit 1 through unit 3 and be recycled back to the swine and cattle operations for flush water or discharged as water for irrigation of crops. Based on preliminary data, this project will have the potential to not only utilize animal waste and alleviate a major environmental problem, but to create a new industry with the production of single cell protein and protein from aquatic plants (duckweed), 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 radons for fish, livestock, and poultry. Production of single-cell protein and aquatic 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 annually. Typically, microalgae raised on the farm-scale produce between 2.7 and 16 tonnes/ha (3 and 18 tons/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 (2 million tons) of microalgae could be produced from the waste generated by the cattle 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 S240 million. Clearly, more economic value is possible when you consider that several high-valued products (Cohen, 1986) can be extruded 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 weight)/A and could serve as feed for cattle (Culley et al., 1981; Skillicorn a al., 1993). In addition to this potential new industry, ocher existing industries will be impacted through sales of the necessary equipment required to harvest and process the single cell protein (bacteria), microalgae, duckweed, and macrophytes into feeds and feed ingredients. Figure 2. Simplified schematic of the advanced facultativc pond used in the integrated wastewater treatment system (not to scale). Another potential system is the production 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 grown in Texas 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 and poultry. SUMMARY AND CONCLUSIONS Locations in the southwest, for example the Texas Southern High Plains, have the natural resources Squired to develop efficient, commercial-scale systems for culture of algae and fish using the plentiful livestock; waste from feedlots as a nutrient base, saltwater as a culture medium and other associated components of the infrastructure. Because aquaculture is a form of agriculture, it is important to note that many arid and semi-arid areas, such as the Texas Southern High Plains area, has the necessary infrastructure to support aquaculture. Potential products in such a system include algal protein for direct consumption by fish or zooplankton that, in turn, are important food organisms for larval fish 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 produce (fish and caviar) is known but the value and identity of other potential products remain unknown. In arid and semi-arid regions, attaining high production in limited mater volumes means that fish culture must move indoors where temperature can be controlled. Control of temperature allows continuous production, thereby increasing total annual production, and allows the culture of warm water fishes in locations that would otherwise be climatically unsuitable. Environmental control in mater 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 vague to compensate for the additional costs of construction and operation of the facility and (2) the animals reared must tolerate high-density crowding. 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, deal protein is valued in comparison to the cost of soya protein. 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 alga protein as a value-added 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 to use saline waters would be marketable technology of increasing value worldwide. Semi-arid and arid regions can support significant aquaculture operations if approaches are taken to use natured 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. ACKNOWLEDGEMENTS Funding provided by the U.S. Department of Commerce Economic Development Administration. Project No 08-06-02714, the Texas Higher Education Coordinating Board Advanced Technology Program, Project No 003644-064, and the Texas Tech University Water Resources Center. Sansby, M. E., H. Schlenk, and E. H. Gruger, Jr. 1990. Fatty acid composition of fish. Pages 6-39 in M.E. Stansby (Ed.), Fish oils in nutrition Van Nostrand Reinhold, New York. Swaminathan, M. S. 1992. Cultivating food for a developing world. Environmental Sci. Technology, 26(6): 1105-1107. Texas Agricultural Statistics Service. 1989. 1989 Texas Agricultural Statistics. Texas Department of Agriculture and U.S. Department of Agriculture. U.S. Bureau of Census. 1990. Statistical Abstract of The United States: 1990 (110th edition), Washington, D.C. REFERENCES 'The authors are Clifford B. Fedler, Associate Professor of 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. Texas Tech University, Lubbock Pages 219-225 in Storm, D.E. and K.G. Casey (editors). 1994. Proceedings Great Plains Animal Waste Conference on Confined Animal Production and Water Quality. Great Plains Agricultural Council Publ. No. 151, National Cattlemen's Assoc., Englewood, Colorado. Camp, T. R 1963. Water and its impurities. Reinhold Publishing Corp., New York. Cohen, Z. 1986. Products from microalgae. Pages 421-454 in Richmond, A. (Ed.) 1986. CRC handbook of microalgal mass culture. CRC Press, Boca Raton, Florida. Culley, D. D. Jr., E. Rejmankova, J. Kuet, and J. B. Frye. 1981. Production, chemical quality and use of Duckweeds (Lemnaceae) in aquaculture, waste management, and animal feeds. J.World Maricul. Soc., 12(2):27-49. Fedler, C. B. and N. C. Parker. 1993. High-Value Product Development Potential From Biomass. Paper No. 936056 presented at the International Summer Meeting of the ASAE/CSAE. Spokane, Washington. Fedler, C. B., N. C. Parker, H. L. Schramm Jr., and J. Borrelli. 1991. Integrated production of dad proton, omeza-3 fatty acids, and fish in West Texas. Anal Report to the U.S. Department of Commerce, Economic Development Administration, Project No. 080~02714. Austin, Texas. Hammer, D. A. (ed.). 1989. Constructed wetlands for wastewater treatment - municipal, industrial and agricultural. Lewis Publishers, Inc. Chelsea, Michigan. Hunter, J. E. 1987. Fish oil and other omega-3 sources. Journal of the American Oil Chemists Society 64(12):1592-1594, 1596. Joint Subcommittee on Aquaculture. 1983a. National aquaculture development plan. Volume I, Washington, D.C. 67 pages. Joint Subcommittee on Aquaculture. 1983b. National aquaculture development plan. Volume II, Washington, D.C. 196 pages. Land, W. E. M. 1986. Fish and human health. Academic Press, Orlando. Lees, R. S. and M. Karel. 1990. Omega-3 fatty acids in health and disease. Marcel Dekker, Inc. New York. Midwest Plan Service. 1975. Livestock waste facilities handbook. Iowa State University. Ames, Iowa. National Marine Fisheries Service. 1988. Aquaculture and captive fisheries: impacts in U.S. seafood markets. U.S. Department of Commerce. National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Washington, D.C. National Marine Fisheries Service. 1990. fisheries of the United States, 1989. Current Fisheries Statistics No. 8900. U.S. Department of Commerce. National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Fisheries Statistics Division, Silver Spring, Maryland. Oswald, W. J. 1988. The role of microalgae in liquid waste treatment and reclamation. Pages 255-281 in Algae and Human Affairs. Cambridge University Press, Oxford. Parker, N. C., C. B. Fedler and M. C. Bates 1992a Aquaculture: bioremediation for agriculture and industry. 1992. Annual Proceedings of the Texas Chapter American Fisheries Society 14:13-21. Parker, N. C., M. C. Bates and C. B. Fedler. 1992b. Integrated aquaculture based on Spirulina, livestock wastes, brine and power plant byproducts. Pages 369372. In: J. Blake, J. Donald, and W. Magette, (eds) National Livestock. Poultry and Aquaculture Waste Management. American Society of Agricultural Engineers Publ. 03-92, St. Joseph, Michigan. Ratafia, M. 1990. Aquaculture growth creates demand for pharmaceuticals. Feedstuffs April 30:16-17, 21. Ratafia M., and T. Purinton. 1989. Emerging aquaculture markets. Aquaculture Magazine l5(4):3244. Richmond, A. (Ed.). 1986. CRC handbook of microalgal mass culture. CRC Press, Boca Raton, Florida Skillicorn, P., W. Spire, and W. Journey. 1993. Duckweed aquaculture: a new aquatic farming system for developing countries. The International Bank for Reconstruction and Development, The World Bank. Washington, D.C. Stansby. M. D. 1990. Nutritional properties of fish oil for human consumption - modern aspects. Pages 289308 in M.E. Stansby (Ed.). Fish oils in nutrition. Van Nostrand Reinhold, New York.

BIOENERGY ‘94 Presented at the Sixth Natlonal Bioenergy Conference, Reno/Sparks, Nevada, October 2-6, 1994.

BIOENRGY PRODUCTION: INTEGRATING LIVESTOCK TREATMENT WITH BYPRODUCT DEVELOPMENT

Nick C. Parker Texas Cooperative Fish and Wildlife Research Unit Texas Tech University Lubbock, TX 79409-212S

Clifford B. Fedler Department of Civil Engineering Texas Tech University Lubbock, TX 79409-1023

Pages 211-218 in Farrell, J., S. Sargent, D. Swanson, and R. Nelson (editors). 1994. Proceedings of the 6th National Bioenergy Conference, Vol. 1. Western Regional Biomass Energy Program. Department of Energy. Denver, Colorado.
'Sponsored by Texas Tech University, Texas Parks and Wildlife Department, The Wildlife Management Institute, and the National Biological Survey

ABSTRACT
An integrated demonstration lagoon system has been designed to treat waste from a 1000-head cattle confinement facility and an adjacent 180-sow swine facility operated by Texas Tech University. Methane gas, captured from a new design of an anaerobic lagoon, will be used as an energy source to dry grains and operate an electrical generator in the feedmill. Effluent from the first lagoon will be directed to a second pond for the production of microalgae. The final pond will be aerobic and used as a water source for production of bait and other nonfood-type fish. Data on production of gas, algal biomass and fish will be correlated with hydraulic and organic loading rates. This demonstration unit for nutrient extraction and reuse and the allied research is being supported with private, state and federal funds. All data and research will be available for public inspection.

INTRODUCTION
The oil embargo of 1974 stimulated interest in alternative fuel sources. The U.S. Congress supported development of alternative energy resource programs of which conversion of biomass to energy was a major component. Demonstration units and tax credits supported these programs and attempted to move the technology to the private sector. Adoption of the technology has been limited to site specific applications usually based on single industries. In addition, the returns of these alternative energy systems have been of limited economic scale because of the unfamiliarity of the technology, the low cost of traditional sources, and the less stringent regulations of the past. Growth of the human population with concurrent increases in animal production and a decrease of natural resources is driving development of more stringent state and federal environmental regulations. The challenge is to produce sufficient food for the world's population (Swaminathan 1992). This will require reuse of finite resources to increase value of all organic products and to recycle unused resources to minimize environmental degradation. The economic returns from alternative energy systems, including bioenergy, can be enhanced by the integration of industries. Waste products of one industry can become valuable resources in subsequent industries (Parker et al. 1992). For example, livestock and poultry waste can be anaerobically digested to produce bioenergy and a nutrient-rich effluent to be used for the production of aquacultural products, especially microalgae (Oswald 1988) and macrophytic plants. Effluents from the plant production systems can be used to produce various species of aquatic invertebrates and fish. Each of these serially related product streams generates economic return to support the overall project and minimize waste discharge. Alternative energy systems have been proven to be effective and feasible, but have not received wide-spread adoption. Adoption of integrated bioenergy technology has been impeded by lack of demonstration units and availability of adequate performance data. Constraints limiting adoption of these systems in the agriculture industry have included the lack of regulatory and financial incentives and the unavailability of demonstration sites showcasing this technology. The increasing focus of state and federal regulators on environmental issues and the growing pressure on environmental resources makes it timely to consider integrated waste management and energy production systems. PROJECT DESCRIPTION The Department of Energy, through the Western Regional Biomass Energy Program has provided funding to establish an alternate energy production system integrated to produce aquaculture products and treat cattle and swine manure. This demonstration unit is located near New Deal, Texas at the Animal Science Burnett Center of Texas Tech University. The Burnett Center has a fully automated feedmill and facilities to handle 1000 head of cattle and a 180-sow farrow-to-finish swine production unit. Currently, the manure from cattle is collected by an automated scraper system located under the slotted floors of the pens. Manure from the swine unit is collected with a flush system, combined with the manure from the cattle and discharged into one of two settling basins. Effluent from the settling basins flows to a playa lake and then is used for on-site irrigation of farm crops, primarily cotton and sorghum. This treatment facility currently meets all requirements of regulatory agencies charged with maintaining environmental quality. Similar application of playa lakes to store and treat runoff from commercial cattle feedlots is a currently acceptable practice within the High Plains. The cattle feedlot industry of the High Plains usually maintains animals for about 5 months while they gain weight from an initial 200-400 kg (400-800 lb) to about 500 kg (1100 lb) at time of slaughter. In 1989, there were over 5 million head, 25% of the nation’s slaughtered cattle, shipped from feedlots in the Southern High Plains (Texas Agricultural Statistics Service 1989). Previous investigations have examined nutrient discharges and ground water infiltration from playa basins receiving runoff from cattle feedlots (Sweeten 1994, McReynolds 1994, and Stewart et al. 1994). Sweeten (1994) has reported that the low hydraulic conductivity in playa basins and effective sealing by solids essentially protects groundwater from nutrient contamination. Concentration of nitrate-nitrogen at depths greater than 6 feet beneath the playas was reported to be less than 3 mg/L. Other investigators have reported nitrate-nitrogen concentrations in the groundwater beneath playas to range from > 1 to 48 mg/L (McReynolds 1994; Fedler and Parker 1994). Although previous studies have reported only an insignificant level of groundwater infiltration beneath playas associated with feedlots, recent investigation of other playas indicate that these basins are significant areas of groundwater recharge (Mullican et al. 1994, Reddell 1994). The 4-stage demonstration treatment system will accept both swine and cattle waste that is screened to separate some of the heavy solid and fibrous materials. This system is an expansion of technology developed from an existing facility designed to culture marine microalgae using anaerobically-digested biomass from cattle feedlots (Fedler and Parker 1993). The demonstration pilot plant will consist of (1) the existing solid and liquid waste collection and fiber screening system, (2) an advanced facultative lagoon - a stratified digester with an aerobic surface and anaerobic bottom for digestion of the waste biomass, production of single-cell protein, and generation of methane gas, (3) ponds for the production of microalgae, duckweeds or macrophytes, and (4) a well-mixed lagoon for culture of finfish and storage of irrigation water (Figure 1). Water will pass sequentially from unit 1 through unit 4 and be recycled back to the swine and cattle operations as flush water or discharged as water for irrigation of crops. The advanced facultative lagoon contains an anaerobic pit with a minimum depth of 5 m (about 15 ft) into which the influent manure stream is discharged (Figure 2). The surrounding facultative pond of 2-3 m (6-10 ft) depth receives the overflow from the anaerobic pit. A barrier designed to restrict lateral flow of water from the pit surrounds the pit forcing water to flow up and over the barrier. The gas collection system sits above the barrier, but below the water surface. The water surface is free of mechanical obstructions and provides protection of the gas collection and piping systems. This subsurface placement of the gas collection system minimizes damage caused by wind, ice and vandalism.

POTENTIAL BENEFITS
The design of this advanced facultative pond provides simple and economical collection of biogas to be used on site. In phase I of this project, we will quantify gas production. In phase II, we plan to install heating and electrical generation systems to utilize the gas on site. The major use of the biogas will be to heat grains in the flaking process of the on-site feedmill. This is the preferred and most efficient method of biogas utilization requiring minimal capital expenditures for equipment and no separation of water vapor and other noncombustibles in the gas stream. In areas where on-site utilization of biogas as a heat source is not seasonally attractive, conversion to electrical energy through use in internal combustion engines coupled to an electrical generator is the second best option.
FIGURE 1. Schematic of an integrated wastewater treatment system for livestock waste with three options for the third stage of the process (not to scale). Based on preliminary data, this project will have the potential to not only utilize animal waste to produce biogas and alleviate a major environmental problem, but to create a new industry with the production of single cell protein (microalgae and bacteria) and protein from aquatic plants (duckweed and macrophytes), 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, FIGURE 2. Simplified schematic of the advanced facultative pond used in the integrated wastewater treatment system (not to scale) 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 metric tons/ha (74 tons/A) on a dry weight basis annually. Typically, microalgae raised on the farm-scale produce between 2.7 and 16 metric tons/ha (3 and 18 tons/A) (Richmond 1986), indicating the need for improved efficiency in production. Taking an average production rate of 10.7 metric tons/ha (12 tons/A), nearly 1.8 million metric metric tons (2 million tons) of microalgae could be produced from the waste generated by the cattle 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 metric tons (34 tons) (dry weight)/A and could serve as feed for cattle (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 cell protein (bacteria), microalgae, duckweed, and macrophytes into feeds and feed ingredients. Another potential revenue stream is from 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 the United States 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 grown in Texas 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 fingerings 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 and poultry.

SUMMARY AND CONCLUSIONS

In today's world, recycle and reuse are not only the politically correct words, they reflect the future. The rapidly growing global population is increasing both the demand and value of all natural resources. Although reuse of waste products is environmentally correct today, it will likely become mandatory in the near future. Producers within the agricultural industry who become knowledgeable of reuse options today position themselves for economic gain as discharge regulations become more stringent and reuse becomes mandatory. Those who voluntarily adopt reuse technology today will have an advantage over those who will be forced by regulators to adopt similar technology in the future. The development of technology to produce and use biogas for energy was intensively investigated in the United States following the oil embargo of 1974. The economics and regulatory pressure supporting implementation of this technology was not sufficient to maintain its adoption. The changing economic and regulatory environment of the 1990's will almost ensure adoption of reuse technology by the year 2000. As the number of farmers in the United States continues to decline and as large industry moves into agriculture production, the integration of industrial and farm operations is expected to increase. To remain competitive, independent farmers must adopt similar cost saving techniques. The demonstration project designed for the Texas Tech University animal science center at New Deal, Texas will provide the technology transfer necessary for producers to adopt integrated reuse processes, including energy from biomass. REFERENCES
Cohen, Z. 1986. Products from microalgae. Pages 421-454 in Richmond, A. (Ed.) 1986. CRC handbook of microalgal mass culture. CRC Press, Boca Raton, Florida. Culley, D. D. Jr., E. Reimankova, J. Kuet, and J. B. Frye. 1981. Production, chemical quality and use of Duckweeds (Lemnaceae) in aquaculture, waste management, and animal feeds. J.World Maricul. Soc., 12(2):27-49. Fedler, C. B. and N. C. Parker. 1993. High-Value Product Development Potential From Biomass. Paper No. 936056 presented at the International Summer Meeting of the ASAE/CSAE. Spolcane, Washington. June 2-23, 1993. Fedler, C.B. and N.C. Parker. 1994. Integrated waste treatment systems. Pages 209224 in L.V. Urban and A.W. Wyatt (eds) Proceedings of the Playa Basin Symposium, Texas Tech University Lubbock, Texas. Fedler, C. B., N. C. Parker, H. L. Schramm, Jr., and J. Borrelli. 1991. Integrated production of algal protein, omega-3 fatty acids, and fish in West Texas. Final Report to the U.S. Department of Commerce, Economic Development Administration, Project No. 08-06-02714. Austin, Texas. McReynolds, D. 1994. Ground-water quality near selected South Plains feedlot operations. Pages 175-186 in L.V. Urban and A.W. Wyatt (eds) Proceedings of the Playa Basin Symposium, Texas Tech University Lubbock, Texas. Mullican, III, W.F., N.D. Johns, and A. Fryar. 1994. What a difference a plays lake can make: Defining recharge scenarios, rates, and contaminant transport to the Ogallala (High Plains) Aquifer. Pages 97-106 in L.V. Urban and A.W. Wyatt (eds) Proceedings of the Playa Basin Symposium, Texas Tech University Lubbock, Texas. Oswald, W. J. 1988. The role of microalgae in liquid waste treatment and reclamation. Pages 255-281 in Algae and Human Affairs. Cambridge University Press, Oxford. Parker, N. C., M. C. Bates and C. B. Fedler. 1992. Integrated aquaculture based on Spirulina, livestock wastes, brine and power plant byproducts. Pages 369-372. In: J. Blake, J. Donald, and W. Magette, (eds) National Livestock, Poultry and Aquaculture Waste Management. American Society of Agricultural Engineers Publ. 03-92, St. Joseph, Michigan. Reddell, D.L. 1994. Multipurpose modification of playas - Studies from the 1960's. Pages 37-52 in L.V. Urban and A.W. Wyatt (eds) Proceedings of the Playa Basin Symposium, Texas Tech University Lubbock, Texas. Richmond, A. (Ed.). 1986. CRC handbook of microalgal mass culture. CRC Press, Boca Baton, Florida. Skillicorn, P., W. Spira, and W. Journey. 1993. Duckweed aquaculture: a new aquatic farming system for developing countnes. The International Bank for Reconstruction and Development, The World Bank. Washington, D.C. Sweeten, J.M. 1994. Water quality associated with plays basins receiving feedlot runoff. Pages 161-174 in L.V. Urban and A.W. Wyatt (eds) Proceedings of the Playa Basin Symposium, Texas Tech University, Lubbock, Texas. Stewart, B.A., S.J. Smith, A.W. Sharpley, J.W. Naney, T. McDonald, M.G. Hickey, and J.M. Sweeten. 1994. Nitrate and other nutrients associated with playa storage of feedlot wastes. Pages 187-200 in L.V. Urban and A.W. Wyatt (eds) Proceedings of the Playa Basin Symposium, Texas Tech University Lubbock, Texas. Swaminathan, M. S. 1992. Cultivating food for a developing world. Environmental Sci. Technology, 26(6):1105-1107. Texas Agricultural Statistics Service. 1989. 1989 Texas Agricultural Statistics. Texas D;partrnent of Agriculture and U.S. Department of Agriculture. This page was last revised on Feburary 5, 1999.Comentário

NPI’s integrated food production system uses livestock manure/manure effluent to produce a crop of freshwater microalgae. The algae is used to feed tilapia and or paddle-fish. Surplus algae is harvested with lipids being used for biodiesel and solids used for their varied nutraceuticals, and as a multi-nutrient feed supplement. Fish water and fish manure are used to produce vegetables in an aquaponics system. Water is recycled back to the algal raceway after nutrients are extracted by plants, and water filtered by sand. To improve field crop production, and pasture yields, an algal crop is grown in water from a mineral spring and then mixed with a manure compost to be used as fertilizer. The algae recovers the minerals, and when used in compost fertilizer helps to re-mineralize soils and increase crop yields. The system has consistently increased farm income by 7 to 12 percent.