Abstract
The increasing demand for sustainable, robust and cost-efficient wastewater treatment techniques strengthen the implementation of constructed wetlands (CWs) in the agricultural sector. In countries like Belgium (Flanders), the compliance of strict water quality standards and surface area requirements have hindered considerably their application. New wetland designs such as aerated CWs, could help to overcome these challenges. This study evaluated the capacity of artificially aerated mesocosm systems to decrease chemical oxygen demand (COD) concentrations below the 125 mgO2/L limit imposed on installations treating animal manure. The treatment of this high-strength wastewater has been slightly studied via aerated CWs. A three-stage experiment investigated the effect of constant, intermittent and non-aeration regimes on: ammonium volatilisation, the evolution of organic and nitrogen compounds concentrations, and denitrification. The results were assessed through a mixed modelling procedure using SAS 9.4 software. A COD removal between 65% and 58% in constantly and intermittent aerated systems, versus 27% COD removal in the non-aerated system indicated the effectiveness of aeration. However, a dissimilarity was encountered in the removal of nitrogen compounds, resulting in an 82% decrease of nitrate concentrations in the non-aerated system, versus 0.5% and 11% in the aerated ones. Based on the results, this experimental set-up adjusted to field operational conditions can prove that aerated CWs can treat the liquid fraction of piggery manure.
Highlights
In Northwest Europe (NWE), several projects regarding waste management and bio-based resource recovery processes have been interlinked and developed based on circular economy principles, in opposition to the traditional linear economy
This study evaluates the effect of implementing artificial aeration in constructed wetlands (CWs) to reduce chemical oxygen demand (COD) concentrations
Novel technologies and strategies for wastewater treatment have been developed, tested and applied mostly throughout EU northwest countries. This is the case of enhanced CWs, which can be considered as one low-cost and efficient technology able to provide adequate removal of organics and nutrients
Summary
In Northwest Europe (NWE), several projects regarding waste management and bio-based resource recovery processes have been interlinked and developed based on circular economy principles, in opposition to the traditional linear economy. The aims have been to minimise natural resource needs, the emissions of waste, energy leakage, and promote their practice elsewhere. Flanders in Belgium, being part of the NWE area, is classified as a nitrate vulnerable zone (NVZ), where nutrients resulting from the excess of animal manure should be reduced. Nitrate vulnerable zones are restricted on the use of fertilisers and are obliged to reduce nitrate concentrations in water below the mgNO3 − /L. Since the 2000s, manure management activities involve the capture, storage, spread on the field, treatment, and its re-use as a source
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