Vertical flow constructed wetland as a green solution for low biodegradable and high nitrogen wastewater: A case study of explosives industry. (June 2021)

• Record Type: Journal Article
• Authors: Madeira, Luís; Carvalho, Fátima; Teixeira, Margarida Ribau; Ribeiro, Carlos; Almeida, Adelaide
• Is Part Of: Chemosphere. Volume 272(2021)
• Publication Date: 2021-06
• Subjects: Explosives wastewater -- Vertical flow constructed wetland -- Flooding level -- Nitrogen and organic loads -- Vetiveria zizanioides; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2021.129871
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: The removal of nitrogen compounds from a pretreated explosives wastewater in vertical flow constructed wetland planted with Vetiveria zizanioides (0.24 m 2 × 0.70 m), filled with light expanded clay aggregates (Leca®NR 10/20), was studied. Experiments under constant hydraulic load, 50 ± 4 L m −2 d −1 and 83 ± 5 L m −2 d −1 without and with flooding level (25%), respectively, were made at different ammonium (3–48 mg NH4 + -N L −1 ), nitrate (56–160 mg NO3 − -N L −1 ) and nitrite (0.3–1.1 mg NO2 − -N L −1 ) concentrations. Results indicate that without flooding level (unsaturated) the removal efficiencies obtained were 30 ± 9, 7 ± 1 and 96 ± 2%, respectively to NH4 + -N, NO3 − -N and NO2 − -N. When using flooding level and an external carbon source (C/N ratio from 1.3 ± 0.19 to 2.5 ± 0.20), the organic matter (COD) removal efficiencies were above 90%, 75% for NH4 + -N and 55% to NO3 − -N. Increasing the C/N ratio from 2.9 ± 0.21 to 4 ± 0.22 did not contributed to upgrade the efficiencies of COD, NH4 + -N and NO3 − -N removal. The denitrification process was occurred in aerobic conditions and nitrite production have ben occurred, probably due to the presence of aerobic conditions that inhibited partially denitrification. Graphical abstract: Image 1 Highlights: VFCW with Vetiveria zizanioides for low biodegradable wastewaters is a treatment option. Nitrogen removal was worse in unsaturated conditions than saturated conditions. Nitrification, denitrification, and aerobic biodegradation can occur simultaneously. The highest nitrate removals (55%) were obtained at 30 g m −2 d −1 COD and low C/N. Denitrification was observed even at 10 mg L −1 O2 in influent.