ABSTRACT
174 Typha latifolia planted vertical subsurface flow constructed wetlands (VSF CWs) and an unplanted microcosm constructed wetland were used for treating secondary refinery wastewater from the Kaduna refining and petrochemical company (KRPC, Nigeria). Cow dung was applied to the planted wetlands at the start of the experiment and after three months to enhance plant growth and petroleum degradation. The T. latifolia planted VSF CWs removed 45 - 99 % Total Petroleum Hydrocarbon (TPH), 99 -100 % phenol, 70 - 80% oil and grease, 45 - 91 % chemical oxygen demand (COD) and 46 - 88 % total suspended solids (TSS). The performance of the unplanted control VSF CW achieved lower removal efficiencies: 15 - 58 % TPH, 86 - 91 % phenol, 16 - 44% oil and grease, 24 - 66 % COD and 20 - 55 % TSS. T. latifolia plants had a bioaccumulation factor (BAF) > 1 for phenol, total nitrogen (TN) and total phosphate (TP) suggesting a high removal performance for these contaminants and good translocation ability (TF) for TPH, phenol, oil and grease and TN, with the exception of TP which was mainly retained in their roots (BAF = 47). This study showed T. latifolia is a good candidate plant to be used in VSF CWs for polishing secondary refinery wastewater in developing countries.
