Abstract
One of the largest industrial constructed wetland systems in the world was commissioned by Janurary 2011 to sustainably manage 45,000 m3/day of produced water from the Nimr oilfields in Oman. Further to which, an extension to the wetland system (additional 120 hectares) is being constructed & commissioned by November 2012 to increase the capacity of the plant to 95,000 m3/day. This natural treatment system consists of a passive oil-water separator, 354 hectares of surface flow wetlands and 300 hectares of evaporation ponds and has been instrumental in reducing the amount of hydrocarbon polluted produced water being disposed to the deep well aquifers. The Nimr Water Treatment Plant (Nimr WTP), being a gravity flow system uses minimal fossil fuel for its operation and therefore results in an enormous saving in energy consumption compared to the conventional, energy-intensive disposal method of pumping the water using DWD pumps. Maximizing the use of locally available and naturally occurring materials for construction, treating and reusing oil contaminated soil from the oilfields and minimizing electricity consumption has decreased the carbon footprint, greenhouse gas emissions and environmental impacts of the oilfield, thus helping to protect people and the environment. The average operational power consumption for running the NWTP was only 0.06 kWh per m3 of produced water treated, compared to 3.6 – 5.5 kWh/m3 for the deep well disposal that has traditionally been used. This equates to an energy saving of 98.3 – 98.9% for managing the produced water and represents a huge saving in energy costs, fossil fuel consumption and subsequent green-house gas emissions making the project not only environmentally friendly but also economically successful for the oil producer. The wetlands and ponds also provide a valuable habitat for migratory birds, with close to 100 different bird species having been identified at the site to date.
