TY - JOUR
T1 - 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
AU - Park, Jong Hwan
AU - Kim, Seong Heon
AU - Delaune, Ronald D.
AU - Cho, Ju Sik
AU - Heo, Jong Soo
AU - Ok, Yong Sik
AU - Seo, Dong Cheol
N1 - Funding Information:
This work was supported by the National Research Foundation of Korea grant funded by the Korea Government (Ministry of Education, Science and Technology), [ 2014R1A1A2007515 ].
Publisher Copyright:
© 2015 Elsevier B.V.
PY - 2015/12/1
Y1 - 2015/12/1
N2 - To enhance the nitrate removal in constructed wetlands (CWs) for treating hydroponic wastewater discharged from greenhouses, the effectiveness of HF (horizontal flow)-HF hybrid CWs utilizing a combined sulfur-based autotrophic (based on the optimum conditions from batch experiment) and heterotrophic denitrification was evaluated for treating hydroponic wastewater containing high nitrate and low organic carbon concentrations. The optimum ratio of sulfur: limestone:immobilized bead with Thiobacillus denitrificans (T. denitrificans) was found to be 3:1:4; the optimum initial cell density was above 1×106cells; the optimum temperature was 25-35°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. In the HF-HF CWs utilizing the combined autotrophic and heterotrophic denitrification, the average removal efficiencies of nitrate were higher in the order of T2 (71.5%, thiosulfate treatment-combination of heterotrophic and autotrophic denitrification) >T3 (66.6%, element sulfur treatment-combination of heterotrophic and autotrophic denitrification) ≫T1 (43.0%, control-heterotrophic denitrification only). In the HF-HF CWs, the maximum nitrate removal efficiency by the thiosulfate treatment was slightly greater than that by the treatment with elemental sulfur, whereas the sulfate production influence on autotrophic denitrification by elemental sulfur (SO42-: 89.1mgL-1) was lower as compared to thiosulfate (SO42-: 38.3mgL-1). Because the sulfate production is an important factor to meet acceptable drinking water quality discharge standard (Sulfate concentration in the effluent was below 250 in US EPA, and 200mgL-1 in South Korea), elemental sulfur was a more suitable sulfur source in HF-HF hybrid CWs. Overall, a combined process of using E/L/B (element sulfur/limestone/immobilized bead with T. denitrificans) column in HF-HF hybrid CWs would promote autotrophic and heterotrophic denitrification. Therefore, a combined autotrophic and heterotrophic denitrification process in HF-HF CWs would be more suitable than the heterotrophic denitrification alone (conventional technology in CWs) for treating nitrate in hydroponic wastewater since hydroponic wastewater contains little organic carbon.
AB - To enhance the nitrate removal in constructed wetlands (CWs) for treating hydroponic wastewater discharged from greenhouses, the effectiveness of HF (horizontal flow)-HF hybrid CWs utilizing a combined sulfur-based autotrophic (based on the optimum conditions from batch experiment) and heterotrophic denitrification was evaluated for treating hydroponic wastewater containing high nitrate and low organic carbon concentrations. The optimum ratio of sulfur: limestone:immobilized bead with Thiobacillus denitrificans (T. denitrificans) was found to be 3:1:4; the optimum initial cell density was above 1×106cells; the optimum temperature was 25-35°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. In the HF-HF CWs utilizing the combined autotrophic and heterotrophic denitrification, the average removal efficiencies of nitrate were higher in the order of T2 (71.5%, thiosulfate treatment-combination of heterotrophic and autotrophic denitrification) >T3 (66.6%, element sulfur treatment-combination of heterotrophic and autotrophic denitrification) ≫T1 (43.0%, control-heterotrophic denitrification only). In the HF-HF CWs, the maximum nitrate removal efficiency by the thiosulfate treatment was slightly greater than that by the treatment with elemental sulfur, whereas the sulfate production influence on autotrophic denitrification by elemental sulfur (SO42-: 89.1mgL-1) was lower as compared to thiosulfate (SO42-: 38.3mgL-1). Because the sulfate production is an important factor to meet acceptable drinking water quality discharge standard (Sulfate concentration in the effluent was below 250 in US EPA, and 200mgL-1 in South Korea), elemental sulfur was a more suitable sulfur source in HF-HF hybrid CWs. Overall, a combined process of using E/L/B (element sulfur/limestone/immobilized bead with T. denitrificans) column in HF-HF hybrid CWs would promote autotrophic and heterotrophic denitrification. Therefore, a combined autotrophic and heterotrophic denitrification process in HF-HF CWs would be more suitable than the heterotrophic denitrification alone (conventional technology in CWs) for treating nitrate in hydroponic wastewater since hydroponic wastewater contains little organic carbon.
KW - Autotrophic denitrification
KW - Constructed wetland
KW - Heterotrophic denitrification
KW - Hydroponic wastewater
KW - Nitrate
KW - Thiobacillus denitrificans
UR - http://www.scopus.com/inward/record.url?scp=84940024699&partnerID=8YFLogxK
U2 - 10.1016/j.agwat.2015.08.001
DO - 10.1016/j.agwat.2015.08.001
M3 - Article
AN - SCOPUS:84940024699
VL - 162
SP - 1
EP - 14
JO - Agricultural Water Management
JF - Agricultural Water Management
SN - 0378-3774
ER -