Multistage Horizontal Subsurface Flow vs. Hybrid Constructed Wetlands for the Treatment of Raw Urban Wastewater

José Alberto Herrera-Melián, Mónica Mendoza-Aguiar, Rayco Guedes-Alonso, Pilar García-Jiménez, Marina Carrasco-Acosta and Ezio Ranieri
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José Alberto Herrera-Melián: Department of Chemistry, Institute of Environmental Studies and Natural Resources (i-UNAT), University of Las Palmas de Gran Canaria, 35017 Las Palmas, Spain
Mónica Mendoza-Aguiar: School of Civil and Industrial Engineering, University of Las Palmas de Gran Canaria, 35017 Las Palmas, Spain
Rayco Guedes-Alonso: Department of Chemistry, Institute of Environmental Studies and Natural Resources (i-UNAT), University of Las Palmas de Gran Canaria, 35017 Las Palmas, Spain
Pilar García-Jiménez: Department of Biology, Institute of Environmental Studies and Natural Resources (i-UNAT), University of Las Palmas de Gran Canaria, 35017 Las Palmas, Spain
Marina Carrasco-Acosta: Department of Biology, Institute of Environmental Studies and Natural Resources (i-UNAT), University of Las Palmas de Gran Canaria, 35017 Las Palmas, Spain
Ezio Ranieri: Department of Biology, University of Bari, 70125 Bari, Italy

Sustainability, 2020, vol. 12, issue 12, 1-15

Abstract: In this study, pilot-scale hybrid constructed wetlands (CWs) and multistage horizontal subsurface flow CWs (HF CWs) have been studied and compared for the treatment of raw urban wastewater. In the hybrid CWs, the first stage was a mulch-based horizontal subsurface flow CW and the second stage was a vertical subsurface flow CW (VF CW). The VF CWs were used to determine if sand could improve the performance of the hybrid CW with respect to the mulch. In the multistage HFs, mulch, gravel and sand were used as substrates. The effect of water height (HF10: 10 cm vs. HF40: 40 cm) and surface loading rate (SLR: 12 vs. 24 g Chemical Oxygen Demand (COD)/m 2 d) has been studied. The results show that the use of sand in the vertical flow stage of the hybrid CW did not improve the average performance. Additionally, the sand became clogged, while the mulch did not. The effect of water height on average pollutant removal was not determined but HF10 performed better regarding compliance with legal regulations. With a SLR of 12 g COD/m 2 d, removals of HF10 were: 79% for COD, 75% for NH 4 + -N, 53% for dissolved molybdate-reactive phosphate-P (DRP), 99% for turbidity and 99.998% for E. coli and total coliforms. When SLR was doubled, removals decreased for NH 4 + -N: 49%, DRP: −20%, E coli and total coliforms: 99.5–99.9%, but not for COD (85%) and turbidity (99%). Considering the obtained results and the simplicity of the construction and operation of HFs, HF10 would be the most suitable choice for the treatment of raw urban wastewater without clogging problems.

Keywords: wastewater; shallow constructed wetland; horizontal flow; substrate; organic mulch; gravel; sand (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (4)

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