1. What contributions have the authors mentioned in the paper "Carbon and nitrogen dynamics and greenhouse gas emissions in constructed wetlands treating wastewater: a review" ?
Previous research on nutrient removal in CWs did not consider the dynamics of pollution swapping ( the increase of one pollutant as a result of a measure introduced to reduce a different pollutant ) driven by transformational processes within and around the system.. This paper aims to address this knowledge gap by reviewing the biogeochemical dynamics and fate of C and N in CWs and their potential impact on the environment, and by presenting novel ways in which these knowledge gaps may be eliminated.. A conceptual model highlighting the current state of knowledge is presented and experimental work that should be undertaken to address knowledge gaps across CWs, vegetation and wastewater types, hydraulic loading rates and regimes, and retention times, is suggested.. The authors recommend that further research on process-based C and N removal and on the balancing of end products into reactive and benign forms is critical to the assessment of the environmental performance of CWs.
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2. What are the future works mentioned in the paper "Carbon and nitrogen dynamics and greenhouse gas emissions in constructed wetlands treating wastewater: a review" ?
Mixed contami- nants entering CWs and those formed within and underneath CWs during transformational processes must be considered in future studies.. Further research is also needed to investigate the im- pacts of hydraulic retention time on nutrient dynamics.. At this time the authors can not suggest any design optima in terms of nutrient removal and GHG mitigation be- cause empirical information is not yet abundant.. Reducing the saturated hydraulic conductivity below the wetland bed will help reduce nutrients leaching to groundwater.
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3. What are the main factors controlling the purification capacity in CWs?
Soil physico-chemical properties, such as permeability(Dzakpasu et al., 2014) and cation exchange capacity (Drizoet al., 1999) are important factors controlling the purificationcapacity in CWs.
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4. What is the effect of aeration on NH+4 removal?
In vertical subsurface flow (VSSF) CWs, aeration can increase NH+4 oxidation to NO − 3 , which can be denitrified or converted to NH+4 by dissimilatory NO−3 reduction to NH + 4 (DNRA).
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