Enhancement of nitrate removal in constructed wetlands utilizing a combined autotrophic and heterotrophic denitrification technology for treating hydroponic wastewater containing high nitrate and low organic carbon concentrations

Bacterial community and nitrate removal by simultaneous heterotrophic and autotrophic denitrification in a bioelectrochemically-assisted constructed wetland

“…Thus, it is often difficult to maintain high nitrate removal efficiency when organic carbon in wastewater is insufficient. To date, numerous studies have been undertaken to enhance denitrification in CWs when treating low chemical organic demand to nitrogen (COD/N) ratio wastewaters, which mainly include looking for cheap and abundantly available alternative carbon sources (e.g., various plant materials) (Hang et al, 2016) and incorporating autotrophic denitrification into CWs (Park et al, 2015;Song et al, 2016a). However, directly adding plant carbon source into CWs is increasingly unfavorable because of its low effective utilization compared to soluble substrates (e.g., methanol), need for optimization of plant biomass dosage and dosing position, as well as potential risk of secondary pollution resulting from excessive organic carbon (Hang et al, 2016).…”

Wetlands for Wastewater Treatment

“…One study showed that a HSSF-VSSF CWs system achieved over 95% of organic matter removal and over 90% of nitrogen removal, where HSSF-CW mainly reduced organic matter and supported denitrification while VSSF-CW provided nutrient removal (Ayaz et al, 2015). HF-HF CWs utilizing a combined sulfur-based autotrophic and heterotrophic denitrification improved the nitrate removal compared to the conventional CWs with only heterotrophic denitrification process (Park et al, 2015). Substrate material palm kernel shell in twostage VFCWs was more effective than sand in nitrate removal (Jong and Tang, 2015).…”

“…CWs are also efficient in the removal of nutrients in water. For example, Park et al (2015), evaluated the effectiveness of horizontal flow hybrid CWs utilizing a combined sulfurbased autotrophic and heterotrophic denitrification. The optimum ratio of sulfur: limestone: immobilized bead with Thiobacillus denitrificans was found to be 3:1:4; initial cell density of above 1 × 10 6 cells; the optimum temperature was between 25 and 35°C; and the optimum sulfur sources were thiosulfate and elemental sulfur to effectively treat hydroponic wastewater utilizing autotrophic denitrification with T. denitrificans in batch experiments.…”

Effects of C/N Ratio on Nitrate Removal from PU Synthetic Leather Wastewater Treated by Anoxic Moving Bed Bio-film Reactors

“…Then, some innovated biological ways, such as deep-bed filters and etc., are continuously investigated to be used for deep nitrogen removal that is much more preferred than physical-chemical ways for some advantages, such as low operating cost and no secondary pollution [11].…”