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ChemEngineering 2018, 2(1), 3; doi:10.3390/chemengineering2010003

Effectiveness and Temporal Variation of a Full-Scale Horizontal Constructed Wetland in Reducing Nitrogen and Phosphorus from Domestic Wastewater

1
High School of Agriculture, Polytechnic Institute of Castelo Branco, Quinta da Senhora de Mércules, Apartado 119, 6001-909 Castelo Branco, Portugal
2
Department of Civil Engineering and Architecture, University of Beira Interior, Bloco II das Engenharias, Calçada do Lameiro, 6201-001 Covilhã, Portugal
3
Depart Sciences and Environmental Engineering, Faculty of Sciences and Technology, New University of Lisbon, 2829-516 Caparica, Portugal
4
Institute for Sanitary Engineering and Waste Management, Welfengarten 1, 30167 Hannover, Germany
*
Author to whom correspondence should be addressed.
Received: 13 November 2017 / Revised: 13 December 2017 / Accepted: 3 January 2018 / Published: 5 January 2018
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Abstract

Cultural eutrophication stimulated by anthropogenic-derived nutrients represents one of most widespread water quality problems worldwide. Constructed wetlands (CWs) have emerged as an aesthetic, sustainable form of wastewater treatment, but, although they have shown adequate levels of organic matter removal in wastewaters, the effectiveness of nutrient removal has been less successful. An eleven-month monitoring program was undertaken in a horizontal subsurface flow CW (HSSF-CW) treating domestic wastewater from a village in Centre Region of Portugal, to evaluate the influence of climatic conditions (Continental-Mediterranean Climate region) and seasonal variations on removal. This CW uses gravel and sand as substrate and Phragmites australis as wetland plants. Samples were collected at the inlet and outlet from wetland bed and analyzed for pH, TN, Org-N, NH4+-N, NOx-N, TP and DP. The removal efficiencies (RE) of nitrogen and phosphorus compounds were relatively poor, but the results allow us to conclude that season had a significant (p < 0.05) effect on the RE of TN, NH4+-N, NOx-N, TP and DP, with higher values in warmest period (10.4%, 10.4%, 3.4%, 27.5% and 26.1%, respectively) than in coldest period (0%, −7.7%, −9.8%, 12.9% and 0%, respectively). Although lower hydraulic loading rate (HLR) generally resulted in better RE of all N and P compounds analyzed, no significant linear relationship was observed between these two variables. TN and NH4+-N concentrations in the effluent tend to significantly (p < 0.05) decrease with increasing respective incoming mass load rates for whole monitoring period and during spring–summer period, while the correlation between outlet TP concentrations and the inlet loading rate are not significant. The results indicate that the system is not effective for removal of nutrients, probably because it operated on overload and with a low hydraulic retention time (HRT) (average = 2.4 days). The results also showed that the RE of N and P followed seasonal trends, with higher values during spring–summer period. View Full-Text
Keywords: constructed wetland; horizontal subsurface; nitrogen; phosphorous; removal efficiency; seasonal variations constructed wetland; horizontal subsurface; nitrogen; phosphorous; removal efficiency; seasonal variations
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Mesquita, C.; Albuquerque, A.; Amaral, L.; Nogueira, R. Effectiveness and Temporal Variation of a Full-Scale Horizontal Constructed Wetland in Reducing Nitrogen and Phosphorus from Domestic Wastewater. ChemEngineering 2018, 2, 3.

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