Water characteristics and microbial flora in a lagoon system for wastewater from a paddock of dairy cattle
1999
Nakai, Y. (Tohoku Univ., Sendai (Japan). Faculty of Agriculture) | Abe, T. | Kohda, C. | Ando, T.
Water qualities and microorganisms in a lagoon which was used for the treatment of the wastewater from a paddock in a dairy farm were investigated seasonally. Biochemical oxygen demand, suspended solid and total nitrogen were decreased by the lagoon treatment to meet the general requirements for the wastewater discharge in Japan year-around. Ammonium nitrogen was also decreased by the treatment; however, concentrations of nitrite and nitrate were very low in any basin of the lagoon. The levels of microbes aerobically and anaerobically cultured tended to be decreased by the treatment; however, the levels of these microbes in each basin of the lagoon were relatively stable year-around. Spore-forming bacteria such as bacilli and clostridia were relatively large in number in the lagoon. The levels of enterobacteriaceae and streptococci tended to be decreased by the treatment, which suggested that these fecal bacteria were eliminated in the lagoon. Fungi and actinomycetes were small in number. Ammonia- or nitrite-oxidizing microbes were almost less than the detectable level, which agree with the low concentrations of nitrite and nitrate in the lagoon. This suggested that a limited amount of ammonia was nitrified, and ammonia in the wastewater was removed not by nitrification but by assimilation of microbes. Microbial assimilation of ammonia may be one of the important processes in the wastewater treatment by the lagoon
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