Nitrous oxide emissions from surface flow and subsurface flow constructed wetland microcosms: Effect of feeding strategies

Optimization of organics and nitrogen removal in intermittently aerated vertical flow constructed wetlands: Effects of aeration time and aeration rate

“…Moreover, artificial aeration was applied in hybrid HF CW systems to enhance the treatment performance, which showed that aeration greatly improved organics and nitrogen removal than typical HF CW . Several studies have also focused on the effects of aeration mode, aeration period, aeration position, hydraulic loading rate and C/N ratios on the pollutants removal in aerated CWs (Jia et al, 2011;Fan et al, 2013b;Dong et al, 2012;Wang et al, 2015;Wu et al, 2015c). Nevertheless, considering the concept of sustainability based on costebenefit analysis, CWs using artificial aeration requires additional energy input and increases the lifecycle cost, even though this approach can greatly improve treatment performance (Wu et al, 2015c).…”

“…microbial processes) play an important role in the removal of organics and nitrogen (Saeed and Sun, 2012). Oxygen availability was recognized as the crucial influencing factor for organics and nitrogen removal (Jia et al, 2011;Li et al, 2014). However, limited oxygen supply and transfer capacity in traditional VF CWs cannot generally meet the requirement for the complete removal processes of organic matter and nitrogen, particularly for treating high-strength wastewaters (Saeed and Sun, 2012;Wu et al, 2015c).…”

Soil Media CO2 and N2O Fluxes Dynamics from Sand-Based Roadside Bioretention Systems

“…Søvik [54] observed CO 2 -C fluxes in the range of −35 to 3875 mg m −2 h −1 in constructed wetlands in several northern European countries, where even though the fluxes varied between sink and source, the maximum flux was orders of magnitude higher than found in our study ( Figure 5, Table 4). High fluxes in the constructed wetlands could be attributed to variable flowrates/volumes of the influent [64] and fluctuating water levels bringing intermittent oxygen into the system, increasing CO 2 efflux via decomposition, and affecting both nitrification (increasing the rates) and denitrification (interrupting the last biochemical step conversion to N 2 ) in a way that contributes to more N 2 O release [65,66]. Søvik [54] [53]) from constructed wetlands should also be considered when evaluating the overall tradeoffs of these systems.…”

A combined application of different engineering and biological techniques to remediate a heavily polluted river

“…2 that after 21st August, the reduction of COD Cr , NH 4 + -N and TSS reached ∼85%. This phenomenon can be explained by following processes: (1) the hydraulic retention time was prolonged by constructed dams, which enhanced the sedimentation of pollutants and suspended solids in the river water; (2) the artificial aeration increased the DO level in the water body, which provided stronger oxidation to degrade the pollutants (Albuquerque et al, 2012); (3) after one month, the microbial community in the water body, BAF and artificial biofilms will have built up, enhancing the removal of pollutants (Cao et al, 2012;Sheng et al, 2012); (4) the plant roots of the ecological floating bed began to consume the C, N, P as nutrition (Hadad and Maine, 2007;Jia et al, 2011). In this work, filter materials (coal cinders) used in BAF and artificial biofilms (Beier Film) have specific surface area for biofilm production, providing living space for PSB, B. subtilis and nativeborn microorganisms.…”

“…In order to enhance the purification by ecological floating beds (Hadad and Maine, 2007;Shan et al, 2011;Jia et al, 2011), local hydrophytic plants were used to set up ecological floating beds along the riverbank at different locations. In order to recover the river ecosystem and also improve its esthetic appeal, mechanical aeration, biological aerated filters, artificial biofilms and ecological floating bed were all combined.…”