US EPA

2832401 

Journal Article 

Vertical-flow constructed wetlands treating domestic wastewater contaminated by hydrocarbons 

Al-Isawi, RHK; Sani, A; Almuktar, SAA; Scholz, M 

2015 

1 

Water Science and Technology
ISSN: 0273-1223
EISSN: 1996-9732 

71 

6 

938-946 

English 

25812105 

10.2166/wst.2015.054 

WOS:000352978200019 

The aim was to compare the impact of different design (aggregate size) and operational (contact time, empty time and chemical oxygen demand (COD) loading) variables on the long-term and seasonal performance of vertical-flow constructed wetland filters operated in tidal flow mode before and after a one-off spill of diesel. Ten different vertical-flow wetland systems were planted with Phragmites australis (Cav.) Trin. ex Steud. (common reed). Approximately 130 g of diesel fuel was poured into four wetland filters. Before the spill, compliance with secondary wastewater treatment standards was achieved by all wetlands regarding ammonia-nitrogen (NH4-N), nitrate-nitrogen (NO3-N) and suspended solids (SS), and non-compliance was recorded for biochemical oxygen demand and ortho-phosphate-phosphorus (PO4-P). Higher COD inflow concentrations had a significantly positive impact on the treatment performance for COD, PO4-P and SS. The wetland with the largest aggregate size had the lowest mean NO3-N outflow concentration. However, the results were similar regardless of aggregate size and resting time for most variables. Clear seasonal outflow concentration trends were recorded for COD, NH4-N and NO3-N. No filter clogging was observed. The removal efficiencies dropped for those filters impacted by the diesel spill. The wetlands system shows a good performance regarding total petroleum hydrocarbon (TPH) removal. 

biodegradation; clogging; diesel contamination; Phragmites australis; reedbed; TPH