Full-Scale Experiment on Domestic Wastewater Treatment by Combining Artificial Aeration Vertical- and Horizontal-Flow Constructed Wetlands System

Seasonal Variation of Nutrient Removal in a Full-Scale Artificial Aerated Hybrid Constructed Wetland

“…However, in aerated treatment units (OT and MA-VBFW), variations of DO concentrations in summer and winter seasons were almost similar, suggesting a stable aeration throughout the year and maintenance of a suitable condition for nitrification in these aeration steps. This performance was slightly different from the results reported by Pan et al [7] in a similar type of hybrid system, where authors reported that outflow DO values of the AA VF and HF were below 1 mg/L during winter and concluded that AA was less effective in the cold season. Although authors found that overall annual average DO values significantly increased from 0.…”

“…The average removed COD, NH 4 + -N, TN, and TP loads in the studied hybrid system were estimated to be 35 ± 19, 7 ± 2, 6 ± 2, and 1 g/m 2 per day, respectively. The current carbon and nutrient removal efficiencies were much higher than the previous results obtained from a similar type of full-scale hybrid CW consisting of a storage tank, a AA VF, a HF, and a landscaped ecological pond, used to treat domestic wastewater [7]. Pan et al [7] reported that the annual average COD, NH 4 + -N, TN, and TP removal efficiencies were 34.1%, 58.4%, 31.1%, and 41.6%, respectively.…”

“…The current carbon and nutrient removal efficiencies were much higher than the previous results obtained from a similar type of full-scale hybrid CW consisting of a storage tank, a AA VF, a HF, and a landscaped ecological pond, used to treat domestic wastewater [7]. Pan et al [7] reported that the annual average COD, NH 4 + -N, TN, and TP removal efficiencies were 34.1%, 58.4%, 31.1%, and 41.6%, respectively. The performance of our AA hybrid system was also comparable with the same type of full-scale hybrid CW without AA with similar COD inflow concentrations but lower hydraulic loading rates of 27-36 cm/day [17].…”

“…CWs performances are frequently reported to be satisfactory (over 80%) for suspended solids (SS) and organic matter [6]; however, for nutrient removal, high variations in removal rates are often observed. Previous studies reported that total nitrogen (TN) and total phosphorus (TP) removal efficiencies are reported to be varied between 40%-55% and 40%-60%, respectively, in different CWs [6][7][8], suggesting the need to improve nutrient removal in order to obtain more reliable treatment performances.…”

“…Furthermore, AA improves the resistance of CWs to the fluctuating influent loads [13] and intensifies mineralization of solids to prevent clogging of the system, and thus increases the lifespan of CWs [13,21]. Studies on AA in CWs have been conducted mostly in short-term laboratory-scale and pilot scale experiments, but very few experiments focused on long-term full-scale systems or its integration in hybrid CWs [7,13,22]. Moreover, seasonal variations of nutrient removal in aerated full-scale hybrid systems still remain unclear.…”