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Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Pp. 107-112 in the Ninth International Animal, Agricultural and Food Processing Wastes Proceedings of the 12-15 October 2003 Symposium (Research Triangle Park, North Carolina USA), Publication Date 12 October 2003.  701P1203.(doi:10.13031/2013.15240)
Authors:   T. E. Shearin, J. Cheng, M. M. Peet, and D. H. Willits
Keywords:   Anaerobic digestion, Biofilter, Greenhouse, Nitrification, Swine wastewater, Tomato

Swine waste treatment in North Carolina typically consists of an anaerobic lagoon and sprayfield upon which crops are grown to utilize the nutrients. Currently, swine lagoon effluent must be applied at agronomic rates to satisfy the crops nitrogen (N) needs. The majority of land application occurs in the summer months, when the weather is typically hot and dry. A greenhouse tomato production system has been tested for more efficient utilization of nutrients in anaerobically-pretreated swine wastewater. Two 2,600-m2 greenhouses were constructed on a 4,000-sow farm located in Johnston County, North Carolina. The swine wastewater was first treated in an Ambient Temperature Anaerobic Digester (ATAnD) and the effluent stored in a storage pond. Before being applied to 14,000 tomato plants in the greenhouses, the effluent was treated in a nitrification biofilter to convert the ammonium (NH4 +) into nitrate (NO3 -) because tomato plants prefer the latter as the nitrogen nutrient for their growth. Preliminary data indicated that the tomato greenhouses have used approximately 12 m3 of the effluent per day. Based on an average inorganic N (NH4 + plus NO3 -) concentration of 123 mg/l in the biofilter effluent, the greenhouses have utilized approximately 1.48 kg N/day. At the same time, the greenhouses produced a daily yield of 711 kg of marketable fruit, sold at a gross price of $2.20/kg. The preliminary findings have shown that the utilization of nutrients in swine wastewater for greenhouse tomato production is a viable alternative to the traditional system. In addition to the high daily N utilization rate, the fruit yields are comparable to conventional greenhouse production. Also, the utilization of the treated wastewater during the winter months decreases the possibility of lagoon overflows and/or spills.

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