LAGOON PRE-TREATMENT AND MANAGEMENT
Lagoon systems are series of pond-like structures designed to treat livestock wastewater over time. Typically, they are lined with clay or synthetic lines to prevent leakage into soil or groundwater (Miller et al., 2011). Lagoons utilize biological, physical, and chemical processes to treat wastewater during a storage period before dispersal onto crops or pasture land (Miller et al., 2011).
Over a period of time, wastewaters separate into layers, with oils on top and heavy sludge on the bottom. Through a variety of anaerobic or aerobic processes, bacteria treats wastewater and starts a process of purification that is later completed by chemical or physical purification (Miller et al., 2011). While lagoon systems are relatively simple to maintain and produce water suited to irrigation purposes, they can create odor problems. Also, nitrogen is lost in during anaerobic or aerobic processes, which reduces the fertilizer value of waste.
Lahav et al. (2013) developed a new process, based on ion-exchange and electrochemical regeneration, for removing ammonia from anaerobic lagoons treating swine waste. Findings suggested that zeolite removed ammonia from wastewater with an adsorption stage of 12.5 bed volumes and 14.5 min hydraulic retention time (Lahav et al., 2013). The method proved to be cost effective over a prolonged period of time.
Venglovsky et al. (1999) examined the adsorption properties of natural zeolite and bentonite in pig slurry. After 28 days of contact with a sample of slurry, zeolite had removed 98.9 percent of psychrophilic and mesophilic microorganism respectively. Also, fecal coliform microorganisms were not detected after 14 days of treatment of slurry (Venglovsky et al., 1999). Researchers also noted a decrease in concentrations of ammonium nitrogen, total nitrogen, and phosphorus (Venglovsky et al., 1999).
To measure the effectiveness and optimal rates of addition of zeolite and alum to dairy slurry, Lefcourt and Meisinger (2001) measured ammonia emissions and resulting chemical changes in slurry. The results demonstrated that an addition of 6.25 percent of zeolite to dairy slurry reduced ammonia emissions by 50 percent respectively (Lefcourt & Meisinger, 2001). Also, because zeolite is a cation exchange medium, it effectively adsorbed ammonium, reduced dissolved ammonia gas, and reduced soluble phosphorus by over half (Lefcourt & Meisinger, 2001).