Performance of a constructed wetland treating intensive shrimp aquaculture wastewater under high hydraulic loading rate

Performance of pilot-scale vertical flow constructed wetlands with and without the emergent macrophyte Spartina alterniflora treating mariculture effluent

“…Studies utilizing a natural mangrove wetland (Gautier et al, 2001) and a free water surface flow constructed wetland (Tilley et al, 2002) to treat the brackish effluent from shrimp culture recorded ammoniacal nitrogen increases likely due to dissolved oxygen limitations to effectively sustain sequential processes of mineralization and nitrification (Herbert, 1999;Chen et al, 2006). As confirmed in this study, the artificial wetlands with subsurface flow usually reached high ammoniacal nitrogen removal from aquaculture effluents (Schultz et al, 2003;Lin et al, 2005;Sindilariu et al, 2007). Heterotrophic bacteria have a competitive advantage over nitrifying bacteria, hence the available oxygen is preferentially utilized for organic mater mineralization instead of ammoniacal nitrogen oxidation (Herbert, 1999;Chen et al, 2006).…”

“…Sequential processes of nitrification and denitrification, which occurs by the passage of the wastewater through oxidative and reductive zones, resulting in nitrogen volatilization, are one of the main purification phenomena in wetlands (IWA, 2000). However, in wetlands applied for the aquaculture, these processes have not been easily predicted and optimized (Schulz et al, 2003;Lin et al, 2005;Sindilariu et al, 2007). For example, Lin et al (2005) related the storage of nitrate in a constructed wetland linked with a shrimp culture to a high hydraulic loading rate and scarcity of organic carbon, but it also could be due to high oxygen concentrations preventing denitrifying activities.…”

“…However, in wetlands applied for the aquaculture, these processes have not been easily predicted and optimized (Schulz et al, 2003;Lin et al, 2005;Sindilariu et al, 2007). For example, Lin et al (2005) related the storage of nitrate in a constructed wetland linked with a shrimp culture to a high hydraulic loading rate and scarcity of organic carbon, but it also could be due to high oxygen concentrations preventing denitrifying activities. The present results suggested that the nitrification and denitrification processes could be optimized by the control of oxi-reducing conditions, which was affected by oxygen availability.…”

“…Based on both economic and environmental demands for more sustainable production practices (e.g., Baccarin and Camargo, 2005;Ramos et al, 2009), the aquaculture community has constructed wetlands as a promising option to deal with its wastewaters, which have eutrophic characteristics. However, there is still a lack of knowledge to allow complete understanding and optimization of key processes such as organic mineralization, nitrification, denitrification, and phosphorus removal (Lin et al, 2005;Lymbery et al, 2006;Sindilariu et al, 2007). Studies about the treatment of marine (Sansanayuth et al, 1996) or brackish (Tilley et al, 2002) aquaculture wastewater by constructed wetlands are scarce.…”

Effects of flow speed and circulation interval on water quality and zooplankton in a pond–ditch circulation system

“…Meanwhile, our results support the conclusion of Chen et al (2006), who reported that higher nutrient removal efficiency can be achieved with a longer HRT in the wetland system. On the contrary, previous studies reported that the removal efficiencies of nitrogen and phosphorus increase with the decrease of HRT in a sequencing anoxic/ anaerobic membrane bioreactor process (Cho et al 2005;Lin et al 2005;Song et al 2009). These conflicting results suggest that more investigations are needed to elucidate the role of HRT in remediating wastewater in the PDCS.…”