Science Target Conference Systems, Ajman 4th International Environment Conference 2016

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Long-term Performance of Vertical-flow Constructed Wetland Systems Treating Domestic Wastewater Contaminated by two Dosages of Diesel Spills
RAWAA AL-ISAWI, Miklas Scholz

Last modified: 2015-10-29

Abstract


Wetlands are a sustainable and cost-efficient technology to treat large quantities of oil-contaminated water, particularly in regions where land costs are low. 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 performance of vertical-flow constructed wetland filters operated in tidal-flow mode contaminated withtwo diesel spills (20 g/l and 159 g/l) on September 2013 and September 2014, respectively. The objectives were to (i) assess the performance of the wetland filters after diesel contamination; (ii) compare the effect of high and low doses of diesel concentration on the performance of the wetland filters; and to assess (iii) the impact of design and operational variables on the removal of diesel and other water quality variables between September 2013 and September 2015. For the first dosage of diesel contamination, all wetland filters showed high diesel removal efficiencies (more than 90%) and compliance with secondary wastewater treatment standards was achieved by all wetlands regarding ammonia-nitrogen, nitrate-nitrogen and suspended solids, and non-compliance concerning biochemical oxygen demand and ortho-phosphate-phosphorus. While for the second period of diesel contamination,wetland filters showed a high variation in the hydrocarbon component removal efficiency with time.Moreover, filters contaminated by diesel performed worse in terms of COD, but considerably better regarding nitrate-nitrogen removal. This work will contribute to better understanding of the performance of constructed wetlands in terms of hydrocarbon pollution control.