Fate of nitrogen in on-site surface application systems
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With the ever increasing suburban growth, the need for expanding currently available public utilities such as wastewater treatment systems become very difficult. An alternative to expanding these public utilities, such as wastewater treatment lines, is to install on-site wastewater treatment and disposal systems. Unfortunately, this can create other problems. First of all, the areas where these systems are usually installed are more rural areas where the source of drinking water is groundwater. In fact, 86 percent of the United States’ domestic water sources come from groundwater and it accounts for 24 and 95 percent of the urban and rural drinking water supplies, respectively. In some cases, these fresh water sources become compromised when on-site wastewater treatment systems either fail or are improperly operated. On-site systems that utilize surface application of the treated wastewater is one area of concern when you consider the nitrogen applied, how the nitrogen cycle is involved, and how uniform this nitrogen gets applied to the surface. The objectives of this research were to investigate the range in uniformity that can occur from using the currently available sprinklers in the various designed systems and how that uniformity affects the application of nitrogen to the surface application system. The potential nitrogen leached to groundwater was calculated and compared between the same sprinkler in systems that use no overlap versus systems that use up to head-to-head spacing. Head-to-head spacing can significantly reduce the amount of excess nitrogen that could potentially leach to groundwater by as much as 58 lb of nitrogen per acre per year, or 22 % of the nitrogen applied for the sprinklers analyzed. It was concluded that proper attention to the design and maintenance of on-site surface applications systems can provide an environmentally sound treatment and disposal system for wastewater.