Pollution of waterbodies and the environment by petroleum industry is of particular concern in Nigeria. This problem can be addressed by the application of constructed wetlands (CWs) which is a nature-based system that is simple to construct, have low operational and maintenance costs in terms of supply of energy and its periodic maintenance.
The application of CWs in Nigeria for polishing of petroleum refinery wastewater is an unprecedented research. This PhD thesis focused on some specific objectives which were characterization of treated secondary refinery wastewater, design, construction, operation and monitoring of planted (T. latifolia, C. alternifolius and C. dactylon) and unplanted vertical subsurface flow, horizontal subsurface flow and hybrid CWs for the removal of suspended solids, nutrients, heavy metals, organic matter and organic pollutants. The CWs effectively treated the petroleum contaminated wastewater to effluent compliance limits.
In this study, T. latifolia planted CWs had consistently higher removal efficiencies for all the measured parameters than C. alternifolius and C. dactylon planted CW systems. Therefore, in order to improve the wastewater quality discharged by Kaduna Refining and Petrochemical Company (KRPC) Nigeria, meet stringent guidelines and protect the recipient streams, installation of CWs at the effluent discharge point of KRPC is strongly recommended.
Ch. 1. General Introduction
Ch. 2. Constructed wetlands to treat wastewater generated in conventional petroleum refining industry: a review
Ch. 3. Characterization of secondary treated refinery effluent
Ch. 4. Vertical subsurface flow constructed wetlands for polishing secondary Kaduna refinery wastewater in Nigeria
Ch. 5. Optimization of petroleum refinery wastewater treatment by vertical flow constructed wetlands under tropical conditions: plant species selection and polishing by a horizontal flow constructed wetlands
Ch. 6. Fate of heavy metals in vertical subsurface flow constructed wetlands treating secondary treated petroleum refinery wastewater in Kaduna, Nigeria
Ch. 7. Vertical subsurface flow constructed wetlands for the removal of petroleum contaminants from secondary refinery effluent at the Kaduna refining and petrochemical company (Kaduna, Nigeria)
Ch. 8. Performance evaluation of duplex constructed wetlands for the treatment of diesel contaminated wastewater
Ch. 9. General discussion and outlook
IHE Delft PhD programme leads to a deepening of a field of specialisation. PhD fellows do scientific research, often with conclusions that directly influence their region. At IHE Delft, PhD researchers from around the world participate in problem-focused and solution-oriented research on development issues, resulting in an inspiring research environment. PhD fellows work together with other researchers from many countries dealing with topics related to water and the environment.
PhD research is often carried out in the ‘sandwich’ model. Preparation and final reporting – the first and last portion of the programme – are carried out in Delft, while actual research is done in the fellow’s home country, under co-supervision of a local institute. Regular contacts with the promotor are maintained through visits and long-distance communication. This enables researchers to employ solutions directly to problems in their geographical region.
IHE Delft PhD degrees are awarded jointly with a university. The degrees are highly valued and fully recognised in all parts of the world.