Design and construction supervision of the bioremediation project in Heglig

Abstract EN

This paper reviews the work by Solar Energy Enterprises Company (SEEC) and its team of Sudanese consultants while under contract with Greater Nile Petroleum Operating Company, GNPOC, over the period January 2000 to August 2002.

A major bioremediation pilot project for the remediation of oil produced water from the Heglig Central Processing Facility (CPF) was designed.

It was constructed by a Sudanese contracting company , under the supervision of SEEC.

The project was conceived as an integrated ecosystem which utilizes and augments the actions and interactions of the relevant natural elements existing in the area, for the remediation of the produced water discharged from the CPF, and for its disposal through evapotranspiration and through its consumptive use for irrigation, with a horizon of 24,000 m3 (150,000 bbl) per day for discharges from the CPF by 2003.

Calculations based on existing data on climatic and other regional conditions, microbial ecology, plant species characteristics plus previous history of the existing treatment system in the CPF have given good indicators as to the size, characteristic times and other properties of the design features.

The project is a basically a 600 hectare constructed wetland.

Produced water from the evaporation ponds at the CPF is pumped, via a pipeline, into a series of “wetland farms” in which earmarked indigenous aquatic macrophytes are planted.

Water then flows to an irrigated area comprising a forest plantation and a reed farm, then to drainage ponds at the tail end of the system.

To mitigate salt and sodium accumulation in the irrigated part of the project, an innovative on-farm continuous “free flow flushing” drainage irrigation system has been incorporated.

Additionally, well-designed management practices are applied.

The rainy season is utilized to flush the forest plantation from accumulated salt and sodium, after irrigation by produced water is diverted to a reserved larger area of the reed farm, not used during normal (dry season) operation.

In this way no discharges of water into the environment are expected.

The system was expected to completely remediate the hydrocarbons and to dispose of 91% of the produced water through evaporation and evapotranspiration in the wetland and irrigated farms, with the remaining 9% (detained in the drainage ponds) disposed of by evaporation before the onset of the succeeding rainy season.

Only salt remains to be disposed of or utilized.

This whole system was to be a pilot experimental project, subject to close monitoring and evaluation for a period of two years.

It was recommended that the Sudanese scientific community be actively involved to further study the multifarious aspects of the project and to eventually have an indigenous version of the technology firmly established in the Sudan.