ORIGINAL RESEARCH
Aerated Enhanced Treatment of Aquaculture
Effluent by Three-stage, Subsurface-Flow
Constructed Wetlands under a High
Loading Rate
Shi-yang Zhang1,2, Gu Li1, Jun-jun Chang3, Xiao-li Li1, Ling Tao1
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1Key Laboratory of Freshwater Biodiversity Conservation, Ministry of Agriculture of China,
Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, PR China
2Freshwater Fisheries Research Center of Chinese Academy of Fishery Sciences, Wuxi 214081, PR China
3Research Institute of Engineering and Technology, Yunnan University, Kunming, 650091, PR China
Pol. J. Environ. Stud. 2014;23(5):1821-1830
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ABSTRACT
To obtain sustainable aquaculture, developing appropriate treatment processes for wastewater is essential.
In this study, two three-stage hybrid wetland systems were configured to treat aquaculture effluent. The
two systems added with or without artificial aeration were operated under a high HLR (8.0 m/day) with a
short retention time (0.96 h). By the results, COD could be effectively removed by both the systems, and it
had been significantly enhanced by continuous aeration (air:water ratio being 7.5:1). For nitrogen (N) compounds,
NH4+-N concentration of outflow compared to the inflow was elevated in most cases under the nonaerated
condition, but an opposite trend was observed for the aerated state, which indicated that dissolved oxygen
(DO) required for nitrification in the natural bed was more insufficient at the high organic loading rate.
TN mass removal was efficient without aeration, but it significantly declined after enhancement, possibly due
to the resuspension of trapped organic N promoted by the strong airflow. The artificial aeration also significantly
improved the treatment performance on phosphorus. By canonical correspondence analysis (CCA), the
first-order removal rate constants of various pollutants were significantly correlated to the measured environment
of the inflow. Under the high constant HLR accompanied by low DO, pollutant loading rate became the
first dependent factor on removal rate for such a rapid filtration system.