Ammonia Volatilization from Marsh–Pond–Marsh Constructed Wetlands Treating Swine Wastewater

Abstract

Ammonia (NH3) volatilization is an undesirable mechanism for the removal of nitrogen (N) from wastewater treatment wetlands. To minimize the potential for NH3 volatilization, it is important to determine how wetland design affects NH3 volatilization. The objective of this research was to determine how the presence of a pond section affects NH3 volatilization from constructed wetlands treating wastewater from a confined swine operation. Wastewater was added at different N loads to six constructed wetlands of the marsh-pond-marsh design that were located in Greensboro, North Carolina, USA. A large enclosure was used to measure NH3 volatilization from the marsh and pond sections of each wetland in July and August of 2001. Ammonia volatilized from marsh and pond sections at rates ranging from 5 to 102 mg NH3-N m(-2) h(-1). Pond sections exhibited a significantly greater increase in the rate of NH3 volatilization (p < 0.0001) than did either marsh section as N load increased. At N loads greater than 15 kg ha(-1) d(-1), NH3 volatilization accounted for 23 to 36% of the N load. Furthermore, NH3 volatilization was the dominant (54-79%) N removal mechanism at N loads greater than 15 kg ha(-1) d(-1). Without the pond sections, NH3 volatilization would have been a minor contributor (less than 12%) to the N balance of these wetlands. To minimize NH3 volatilization, continuous marsh systems should be preferred over marsh-pond-marsh systems for the treatment of wastewater from confined animal operations.

Denitrification in Marsh‐Pond‐Marsh Constructed Wetlands Treating Swine Wastewater at Different Loading Rates

“…These wetlands had sloped bottoms, and denitrification was higher at the upper slope area where oxygen was more available to facilitate nitrification of the ammonia in the wastewater. These apparent high losses via denitrification are in agreement with the recently reported very high N removal by constructed wetlands in Ontario, Canada (Kadlec and Bishay, 2005).At the higher N loading rates, gaseous losses were also the major N removal pathway for N on MPM wetlands (Poach et al, 2003(Poach et al, , 2004a. Whereas Poach et al (2003) measured the volatilization of ammonia at various N loading rates, it was also important to assess denitrification at these varying loading rates.…”

“…The wetlands were constructed at the swine facility of the North Carolina A & T State University farm in Greensboro, NC, in 1995 and consisted of six sets of MPM wetland cells (Poach et al, 2004a(Poach et al, , 2004b …”

“…Their research indicated that the continuous marsh wetlands were able to treat higher loads of N than the MPM wetlands. Furthermore, the continuous marshes were subject to less ammonia volatilization than the MPM wetlands (Poach et al, 2002(Poach et al, , 2004a.While soil accumulation and plant uptake of N were important at low N loading rates , they were responsible for smaller portions of the removal at higher N loading rates ($10 kg ha 21 d …”

Sustainable Production of Algal Biomass and Biofuels Using Swine Wastewater in North Carolina, US

“…As shown in Table 3, the results of diluted and non-diluted wastewater showed that there is no significant inhibition effect when using original swine wastewater. Compared with the compositions reported in the literature, the swine wastewater collected from the uncovered lagoon has a lower COD value of 2050-2600 mg/L [27] and a lower ammonia content (<180 mg/L) [28], representing a low-strength wastewater that might be used directly as the algal medium. In addition, algal biomass yield in diluted wastewater is similar to that of proteose medium, which might be limited by the nutrients available.…”

Sustainable manure management.

“…51 % total N and 26% total P from swine wastewater (Poach et al, 2004). Constructed wetlands can also release N as NH 3 • although this has been shown to be a relatively small portion of total N loss (Poach et al .. 2002). The main limiting factor for denitrification in these systems is the conversion of N to nitrate (Hunt et al.…”