High Quality Treated Effluent at Doha Sewage Treatment Works

December 6, 2017 in Infrastructure

Doha North Sewage Treatment Works are expanding their wastewater (sewage) treatment plant (STP). The developments, carried out by Ashghal, the Public Works Authority of Qatar, will use up-to-date technologies to treat raw sewage of non-potable use, such as irrigation for public parks. The STP will be the first facility of its kind with comprehensive odour control system, minimising the impact on the surrounding environment.

Much of the work is taking place at the Doha North STP site. Although Doha North STP was completed in December 2015, and was fully operational by July 2016, Ashghal remain in their final stages of landscaping works in the plant’s surrounding ‘buffer zone’.  The buffer zone will contain nature-reserve style areas for birdwatching, and it will feature up to 50 picnic spots.

The buffer is being carefully curated to form a green oasis, with approximately 95,000 trees that have arrived from different parts of the world. 28 species in total have been selected, chosen for their abilities to withstand the harsh local climate. So far, around 30,000 of the trees have been planted and the lakes have been dug and filled, according to the Operations Director at Nakheel Landscapes Rafi Ohanian. Senior Project Manager at Doha North, Mr. Rajendran Balasubramanian said:

“Even as the buffer zone is about half done, we are already welcoming our first visitors. We see many migratory birds perched on the trees or near the lagoons,”

The landscaping part of the project includes the installation of interconnecting roads. These remain under construction, with the irrigation pipe work and planting still a work in progress.

Public works authority Ashghal said the construction of the TDP is “substantially completed and is currently going through final commissioning”. Ashghal won multiple regional awards for the Doha North Sewage Treatment Works Project, gaining the ‘GCC Award for Sustainability’ and the ‘GCC Water Project of the Year’ trophies.

It is not just sustainable practices that have been commended. On site safety, measured by a low accident rate and a high commitment to health and safety standards, has been praised at the plant. A certificate was presented to the representatives of the contractor for completing 7.7mn man hours without any accidents.

The achievements of the project attracted the attention of Minister of Municipality and Environment Mohamed bin Abdullah al-Rumaihi. Mr al-Rumaihi visited the Doha North Sewage Treatment Plant (STP) in 2016, accompanied by Infrastructure Affairs Director Jalal Yousef al-Salhi.

The Minister was briefed on the project and the rate of the plant’s expansion, alongside the engineering and construction techniques involved in its implementation. He was also shown the components of the build, advised about the advantages of the new treatment plant and thermal drying plant, and he was able to take a tour of the plants’ advanced systems.

Much of the treatment processing is happening at a plant located in the Umm Slal Ali area, North Doha. The catchment covers all of Umm Slal Ali, and it includes Al Kheesa, Al Khariatiyat, Al Duhail and the Pearl and Lusail developments to the east of the city.

The modern facility features advanced biological treatment processes as well as an ultra-filtration membrane, which separates large particles and small granules from the water. Then, it uses ultra-violet technologies to produce high quality reclaimed water, successfully reducing waste effluent from the Umm Slal Ali area.

The first project phase focused on increasing capacity to treat wastewater of up to 244,000 cubic metres per day. This will serve a projected population of over 900,000 by the year 2020.

The second project phase is the construction of a Thermal Drying Plant (TDP) to process sludge from the sewage treatment plant. This phase involves the construction of three electricity substations, six pump houses, one stormwater lagoon and one treated sewage effluent lagoon. Waste water runs through a network of 15km of plant piping in order to be treated. The TDP will also receive and treat sludge generated by other sewage treatment works. The sludge is dewatered, and then it is processed through thermal dryers to produce dried pellets. Public works authority Ashghal said the construction of the TDP is “substantially completed and is currently going through final commissioning”.

The third phase includes the establishment of largest pumping station in the state to receive sewage and pump it to the treatment plant.

The fourth and final phase includes the implementation of lines of treated water for irrigation.

In October 2007, Keppel Corporation was appointed as Design Build and Operate (DBO) contractor for the first phase of the project whose scope of work includes the construction of 439,000m3/day. They have since handed their solids stream and sludge treatment facilities to Ashghal. On speaking to the press, Dr Ong Tiong Guan, Chief Executive Officer of Keppel Infrastructure, said:

“With the handover of the solids stream and sludge treatment facilities, we have reached another significant milestone for the Doha North project, which plays a crucial role in ensuring clean, liveable environments for Qatar and supports the country’s sustainable economic and social development. We will continue to work closely with the client on ensuring the smooth operation of the Doha North Sewage Treatment Works.”

The handover of the solids stream and sludge treatment facilities is not expected to have a material impact on the net tangible assets and earnings per share of Keppel Corporation Limited for the current financial year.

Doha North STP is not Doha’s only sewage infrastructure that is enjoying developments. The plant south of Doha is being redesigned with 11 new shafts in order to excavate a 16km-long main tunnel, or ‘trunk’. The trunk will channel the sewage flows to the existing Doha South treatment works. It is divided into three segments: Eastern, Northern and Western. The sewage will enter pumping stations, which have the capacity to treat 241mn litres of sewage water per day.

The project also includes the construction of seven lateral interceptor sewers with a length of about 24 kilometers, which will convey flows from areas in the centre of Doha to the main tunnel. This is designed to serve areas in the south of Doha and the expected population growth. The project can be linked to future infrastructure projects, and when completed, it will enable the decommissioning of more than twenty old pumping stations currently located in the residential and commercial areas in the south of Doha.

The gravity based main trunk sewer will reduce environmental impacts through the full control of odours in sewage treatment works and conveying system. It will also reduce other environmental problems arising from sewage overflow, relieving excess hydraulic pressure on the existing drainage network where sewage flows exceed its capacity.

The last large-scale extension project within the Doha STP network is the extension at Doha West. Doha West STW is located in Al Sailiya area. The extension aims to increase the capacity of the treatment plant from the current processing rate of 175,500 m3/day to 280,000 m3/day. The increase will be able to serve a total population of 1,040,000.

The Preliminary and Biological Treatments will be extended to accommodate the increase of flow. The Treated Sewage Effluent a Tertiary Treatment Stage: a stage of quality control, entirely facilitated by the new extension. The UV and Chlorination Systems will be extended for the new flow capacity and will be upgraded for the existing flow capacity. A final Pumping Station for the additional 104,500 m3/day will be built for the distribution of the TSE to the final consumers.

Ashghal will continue their work with sustainable environmental practices. The public works authority hope that they can play a role in the “greening” of Qatar’s desert landscape.