MUSCAT Two presentations for the public and for students regarding the current state of selected wastewater treatment plants and the challenges faced in rural Oman were given by Dennis K. Alexandersen, Regional Sales & Business Development Manager from BAUER Nimr LLC at the German University of Technology in Oman (GUtech) recently. During the talk, Mr Alexandersen addressed the operational and maintenance challenges and gave an overview of effluent reuse practices. "Some mechanical treatment plants face certain operational and maintenance challenges including lack of financial support and proper maintenance," said Alexandersen. During a previous visit to Saham it was observed that the effluent water is being pumped into a lagoon area in the neighboring wadi where it is left to evaporate and infiltrate. Previously, these effluent lagoons were flushed away with the winter rain generating nuisance to the downstream community settlements.
In the past years the Sultanate has invested in the modernization of wastewater treatment systems and sanitary drainage networks, mainly in Muscat, Sohar and Salalah. "Although rural Oman has seen improvements in wastewater management, these areas still rely on cesspits or holding tanks with around 50 conventional treatment plants using tanker services for the transport of wastewater," said Alexandersen.
According to the expert, pond systems have historically been used in the rural and remote locations of Oman, for example in Khasab ,whereas in Duqm a kind of lagoon system is still in use. However, a shift towards mechanical activated sludge treatment has been realized by the authorities.
To improve wastewater management, constructed wetlands could be used to further polish the effluent water from mechanical plants with minimal or no electricity consumption and can also be used to demineralize the sludge." When sludge is transferred to a reed bed it will settle on the surface and turned into compost," said Alexandersen. As a result, the sludge will reduce to around 10 per cent of its original volume. "I think there is a lack of awareness about the potential reuse of sludge as fertilizer. There also seems to be a need to establish constructed wetlands as environmental buffer zones between the mechanical sewage treatment plants and the natural environment," said Alexandersen to mitigate the risk of polluting the groundwater resources. Wetlands would provide a way to re-introducing the excess treated water that is not reused back into the environment whilst providing habitat for birds and a potential for recreational park lands.
The life expectancy of a reed bed varies between 25-30 years, whereas a mechanical package plant will only be operational for 7-10 years before significant re-investment is needed to replace mechanical equipment and parts. "The optimal goal to handle effluents would be to establish constructed wetlands," said Alexandersen. In Muscat Haya Water has set-up the Al Ansab wetlands and in the South of Oman BAUER Nimr has set-up a huge area of constructed wetlands - one of the world's largest commercial wetland , which has received international awards. Currently, 95,000 m3 of produced water are treated in Nimr every day in a 700ha gravity flow wetland-pond system that use no electricity. And as a result a new habitat for different animals was created; More than 100 species of birds have been identified using the wetland to date" For each barrel oil brought to the surface, 9 barrels of contaminated water are generated at the same time." According to the expert between 80-95% of the hydrocarbons in the water are recovered using hydrocyclones and with a further polishing in the reed beds the system can achieve a treatment efficiency of 99.9%. We have started biosaline crop research to understand the environment and to find out which crops can be introduced to further reuse the treated saline water. Reed bed wastewater treatment will also be integrated in the upcoming GUtech Eco Haus project that will be built at the GUtech campus.
© GUtech/Manuela Gutberlet
© Press Release 2013
