Animal Waste Containment in Anaerobic Lagoons Lined with Compacted Clays

The practice of animal waste containment has recently drawn much interest from public and regulatory agencies in agriculture-oriented states such as Kansas and North Carolina. In this paper, the debate surrounding the practice is outlined, and results from a research investigation pertinent to the state of Kansas are presented. The research investigation involved two phases. In the first phase, compacted specimens of Kansas soils were tested with animal waste as the influent. The key objective of this phase of research was to assess the range of seepage quantities and the transport characteristics of nitrogen in the ammonium form (NH4-N) through the compacted soils. Results from this phase indicated a steady increase of microbial counts in the liquid effluent. However, biological clogging did not appear to be prominent during the NH4-N breakthrough time period. The results indicate significant differences in microbial uptake of NH4-N among samples of the same soil type. In the second phase, analytical and numerical solutions were used to simulate ammonium transport in the field-scale liners and to estimate upper-bound travel times and final concentrations of NH4-N in the underlying soils. Results from this phase showed drastic differences in travel times and end concentrations of NH4-N among liners prepared from the same soil type. The potential for significant retardation, decay, and saturation levels of NH4-N in clay liners suggests that liner thickness is an important parameter. It is concluded that mass transfer characteristics of liner material, cation exchange capacity and microbial uptake in particular, should be important considerations in the design of animal waste lagoon liners.