Wastewater Treatment & Recycling

The 91^st Avenue WWTP Chlorination Improvements project involved the replacement of a 120-ton bulk chlorine system with a system consisting of 32 one-ton chlorine cylinders.  The plant has a treatment capacity exceeding 180 mgd. The existing chlorination equipment and piping was replaced while the plant was in full and normal operating condition. The plant’s treated effluent is used at the Tres Rios Wetlands and as cooling water for the Palo Verde Nuclear Generating Station.

The project also involved the development and coordination of the Maintenance of Plant Operation (MOPO) procedures. The chlorination of the plant effluent had to be maintained at all times during construction. The project also included building structural, electrical, and HVAC modifications. The equipment installed included the following:

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GHD was commissioned to design a new Biological Nutrient Removal (BNR) and membrane treatment system for the Cleveland Bay Wastewater Treatment Facility, with a capacity to cater for an estimated population of 126,000 people.

State-of-the-art biological processes were introduced, by combining an oxidation ditch (to achieve a high level of nutrient removal) with membrane solids separation, to achieve a very high effluent quality. This approach retains the simplicity and flexibility of the oxidation ditch while adding the exceptional solids separation capability of the membranes.

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GHD's ongoing research and investigation into the application of dry composting toilets and separate collection and use of urine provides for a fundamentally different approach to sanitation.

Benefits of dry composting toilet and urine separating technology

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Cox Creek Water Reclamation Facility, Anne Arundel County, Maryland

GHD was retained by Anne Arundel County for the Enhanced Nutrient Removal (ENR) Upgrade of the Cox Creek Water Reclamation Facility (WRF).  The 15.0 mgd (56.7 ML/d)  Cox Creek WRF is the largest of the County’s seven (7) major wastewater treatment facilities and is also the County’s largest single contributor of nitrogen and phosphorus to the Chesapeake Bay. 

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GHD plays a leading role in securing Dubai’s current and future water requirements.

Our team in the Middle East has completed preliminary engineering work on the Jebel Ali Free Zone (JAFZA) Utility project to provide water infrastructure to an area of 8500ha that includes the JAFZA Free Trade Zone, Technopark and downtown Jebel Ali. These precincts comprise both greenfield and existing development with industrial, commercial and residential land uses.

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Perth’s next big waste water treatment plant is being designed to accommodate a potential population of 800,000 people.

GHD has been engaged by the Water Corporation in Western Australia to design the Alkimos Waste Water Treatment Plant. GHD was chosen on the basis of its concept design and joins the Alkimos Water Alliance (AWA) to deliver this AUD$80 million project. AWA comprises Multiplex, McMahon and Zublin.

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GHD designed this 150,000 gpd (570,000 L/d) WWTF using a sequencing batch reactor-activated sludge process, which included nitrification-denitrification to achieve a class A⁺ finished effluent.

Elements of design included influent flow metering, a fully enclosed duplex pump station, fine screens, first and second stage aeration for nitrification and denitrification, clarification, and aerobic digestion.  Sludge handling was accomplished through centrifuge dewatering.  Odor and noise abatement was incorporated through the total enclosure of headworks screens, aeration and clarification elements, sludge processing, air blowers, and electrical system inside a building.  The design included a bulk liquid sodium hypochlorite disinfection system for the final stage of treatment.  Finished effluent is used to irrigate golf turf.

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Sydney Water in partnership with Sydney Water Corporation, John Holland, Thompson Controls, and GHD delivered the $60 million Rouse Hill Recycled Water Plant – stage two amplification project. This is the Southern Hemisphere’s largest residential water recycling scheme.

Initiated in September 2006, the project doubled the capacity of the existing waste water treatment plant to 27 million litres a day and increased the recycled water capacity to 4.7 billion litres a year (this will supply 36,000 homes in the local community at project completion).

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The new Scorpion Bay Marina is located on the west coast of Lake Pleasant.  The marina includes more than 300 boat slips, a boat pumping station, restrooms, showers, and a restaurant.  GHD provided permitting, design, and construction services for the marina’s wastewater treatment plant.  The plant is an activated sludge facility with extended aeration and de-nitrification capability.  It also includes sand filtration, chlorination and de-chlorination, and an aerobic sludge digester.  All of the reclaimed water produced by the plant is stored in an above-ground steel reservoir and pumped through the marina’s irrigation system. 

To enable the marina to open prior to the completion of the treatment plant, GHD also designed a temporary vault and haul system that included instrumentation and controls, secondary containment, an aeration system and an odor control air scrubber.  In addition, GHD provided design and construction support for the marina’s wastewater pumping system, which uses peristaltic pumps to move flows from boats, restrooms, and the restaurant to a common wet well where they are then pumped using grinder pumps off of the marina and to the treatment facility. 

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Following the amalgamation of eight local government boundaries, GHD was commissioned to develop a high-level strategy for the Toowoomba Regional Council for the planning of wastewater treatment plants and effluent reuse.

The study included a review of previous planning studies completed by the former local authorities, a population review and a look at loadings. A brief assessment of the status of the area’s existing sewage treatment plants was undertaken to determine their capacity and if they should remain as a stand-alone system or be integrated with other systems.

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