Wastewater Project of the Year: Shortlist
Shortlisted Nominees
Al Methneb Zero Waste Project, Saudi Arabia
What is it?
A project reusing brine water and treated sewage effluent (TSE) to irrigate more than 85,000 newly planted trees and seedlings and a major park in the Qassim province. The project’s wastewater treatment plant and purification plant have capacities of 3,500m3/d and 1,400m3/d respectively, producing TSE and brine for irrigation. The project also involved the construction of irrigation networks from TSE underground tanks.
Who is involved?
The SAR2 million project was carried out by Qassim’s Water Directorate, supervised by the National Water Company, the Al-Methneb Governorate and Saudi Arabia’s Ministry of Environment, Water and Agriculture. Alkhorayef operates and maintains the purification plant, the water and sanitation networks and the inside of the WWTP.
What makes it special?
Al Methneb is the first city in the kingdom of Saudi Arabia to make extended use of brine water and TSE to water trees, helping to increase vegetation cover. This project will greatly benefit the Al-Qassim province, known as the country’s breadbasket, as it combats the ever-present risks of desertification that could jeopardise its agricultural assets.
The reuse of brine water from purification plants, which has been tested to determine its agricultural suitability, helps reduce the environmental impact of stagnant waters that may cause pollution, infestation and airborne weeds. It also addresses the problem of evaporation ponds overflow and prevents the need to create additional ones.
The project presents an alternative to groundwater use for irrigation and reduces the creation of TSE ponds which would frequently be discharged into the valley. It is a crucial step towards kick-starting a country-wide plan to reuse brine water and TSE to help fight the country’s dual challenges of water scarcity and desertification.
Mel Leong Treatment Plant upgrades, USA
What is it?
Upgrades to the San Francisco International Airport’s (SFO) Mel Leong Treatment Plant (MLTP) that include a new industrial wastewater treatment plant (IWWTP) with a capacity of 5,300m3/d, a new laboratory and administration building, along with investigating repairs for the existing sanitary wastewater treatment plant and several sitework upgrades.
Who is involved?
SFO and the Airport Commission of the City and County of San Francisco signed a $63 million design-build contract with the Walsh Group, which undertook the majority of the IWWTP work. Carollo Engineers was subcontracted by Walsh as engineer of record. The laboratory and administration building was designed by MWA Architects.
What makes it special?
The upgraded MLTP is one of the first in California to use an industrial water source to produce Title-22 grade recycled water, ably meeting SFO’s sustainability goals, and dramatically reducing pollution in the water to which it discharges. The new IWWTP also significantly reduces MLTP’s overall footprint, since the previous dewatering process made use of sludge drying beds that required a larger footprint.
The secondary treatment stage consists of an ozone generation and contactor system that facilitates the assimilation of small molecules by the biological activated filters. The ozone process is considered the best at breaking down hydrocarbons, an essential feature since the plant experiences fuel spills, as well as handling blue dye from the airplane’s bathroom disposal. The new IWWTP can treat both sanitary and industrial flows, accommodating existing and future needs. Plans are in progress for the further introduction of an advanced water treatment plant, already designed by the Walsh Group and Carollo Engineers.
Instead of upgrading the IWWTP piece-by-piece, the careful construction of a replacement allowed the plant operations to continue running apace during its construction and commissioning stages, in one of the busiest airports in the US.
Riviera Utilities WWTP upgrade, USA
What is it?
An advanced secondary treatment upgrade at a wastewater treatment plant in Wolf Creek, Alabama, that marks the first installation in the US of the AquaNereda aerobic granular sludge technology. The WWTP treats an average flow of 13,248m3/d and can handle a peak flow of 22,710m3/d.
Who is involved?
After a competitive bidding process, Riviera Utilities contracted Goodwyn, Mills and Cawood Inc. to design the upgrades in a $20 million project. Aqua-Aerobic Systems provided the AquaNereda systems, as the local supplier for technology developer Royal HaskoningDHV. It also provided AquaDisk cloth filtration media, while Hidrostal supplied the main lift station. Other key contractors involved were water and wastewater specialists Automation Control Service and Max Foote Construction.
What makes it special?
Instead of taking the straightforward approach of increasing the treatment capacity, this project also future-proofed the plant in anticipation of more stringent effluent limits for nitrogen and phosphorus, which are expected to be enacted in the future. In addition, the solution offers advanced biological nutrient removal without requiring multiple tanks, pumps, and mixers.
The upgrades provide smart aeration control, reduced equipment needs, and an improved substrate and oxygen utilisation through the use of granular sludge, transforming the plant’s operating capabilities. The adoption of the AquaNereda technology also led to huge energy cost savings of between 40% and 50% with an energy consumption rate of less than 0.3kWh/m3 registered in the first months of operation. The high operating mixed liquor solid suspension level, exceeding 8g/L, reduces settling time, producing a higher quality effluent with a vastly reduced plant footprint.
The improved capacity of the plant has meant that it can treat higher flows of effluent, including stormwater from tropical storms and hurricanes, which are very common in the region. In the midst of these challenging conditions, there is no subsequent decrease in discharge quality or degradation of the plant’s performance.
Sydney Harbour stormwater management, Australia
What is it?
An A$50 million project aimed at separating the last remaining combined stormwater and wastewater systems in Sydney, part of the huge Refresh Woolloomooloo legacy programme. It included laying 4.2km of wastewater pipes and 650m of stormwater pipes in a dense urban area, connecting over 200 properties, as well as the construction of 140 maintenance manholes, and repair to vent shafts. Full completion was achieved in March 2020.
Who is involved?
Sydney Water took an integrated team approach, taking on GHD to lead planning and design, and Diona Civil Engineering for the construction stages. Pezzimenti and UEA Australia were responsible for the trenchless pipe installation and technology, and Rocla supplied the prefabricated manholes.
What makes it special?
This was an extremely high-impact project as a result of the densely populated location, affecting more than 30,000 customers in the Woolloomooloo, Potts Point and Darlinghurst areas. The location challenges led the team to adopt advanced technologies like prefabricated manholes, that reduced installation times from 21 days to 3-5 days. State-of-the-art trenchless construction techniques such as bed bores, stitch boring and micro tunnelling were deployed, reducing noise impacts and minimising the impact on the environment.
The improved system now captures and transfers wet weather wastewater overflows in the Woolloomooloo catchment into the Bondi treatment plant. It has also eliminated wafted odours during the dry weather, which were a main cause of complaint for the surrounding community. The new separated system ameliorates the liveability of the area, minimises the contamination of the Sydney Harbour and bay, enhances its water quality and improves marine life.
The integrated team approach meant that a wide variety of stakeholders were involved in the planning and designing from the beginning of the project. It ably facilitated the community’s cooperation and involvement and led to exceeded public expectations.
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