Using a compact combined constructed wetland system to treat agricultural wastewater with high nitrogen.
The objectives of this study were to find appropriate conditions for nitrogen removal by a compact combined constructed wetland system and to evaluate the removal rate constant in a tropical climate. This study will present suitable operating conditions for a combined system to treat pig farm wastewater containing high ammonia-nitrogen. Four laboratory-scale combined constructed wetland units (0.5 x 1.0 x 1.0 m3): vertical flow vegetated bed over horizontal flow sand bed, were operated under an average temperature of 24 degrees C. Pig farm wastewater with COD and NH4-N concentration of 1034 and 448 mg/L in average was fed to the system at different HLR from 2 to 8 cm/day. The performance of the system when operated with a vertical flow bed followed by a horizontal flow bed or vice versa did not show a significant difference but under high HLR, nitrogen removal efficiencies were clearly reduced. Nitrobacter and Nitrosomonas were found in a large number in vertical flow beds and the same for denitrifier bacteria in a horizontal flow beds. Removal rate constants for nitrification (kNH4+ -N) were 0.0413 m/d for H-Vmode and 0.0339 m/d for V-H mode. Removal rate constants for denitrification (kNOx-N) were 0.0979 m/d for H-Vmode and 0.0399 m/d for V-H mode, respectively.
Kantawanichkul
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Department of Environmental Engineering, Chiang Mai University, Chiang Mai 50200, Thailand. suwasa@eng.cmu.ac.th
Somprasert
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D000383:Agriculture; D000818:Animals; D001673:Biodegradation, Environmental; D017753:Ecosystem; D004779:Environment Design; D009576:Nitrobacter / Q000254:growth & development; D009584:Nitrogen / Q000302:isolation & purification / Q000378:metabolism; D009606:Nitrosomonas / Q000254:growth & development; D011157:Population Dynamics; D013552:Swine; D014329:Tropical Climate; D014865:Waste Disposal, Fluid / Q000379:methods*
D009584:Nitrogen