Water. Desalination + reuse
Issue link: https://fhpublishing.uberflip.com/i/604344
PROJECTS | 22 | Desalination & Water Reuse | November-December 2015 PROJECTPROGRESS GREEn GROuPS PlEdGE TO dROP HunTinGdOn aPPEal ... Environmental groups have pledged to drop their appeal against the award of a permit for the proposed Huntington Beach desalination plant after California state water officials confirmed that the plant developer, Poseidon Water, will have to reapply for one of its permits if state regulatory amendments go into effect. Orange County Coastkeeper, the Coastal Environmental Rights Foundation, the Surfrider Foundation, and Residents for Responsible Desalination said they would withdraw their three-year-old appeal of the permit were Poseidon required to reapply for its discharge permit. The State Water Resources Control Board informed the groups that Poseidon would need to resubmit or revise its permit application with the Santa Ana Regional Water Quality Control Board regarding how the plant would discharge brine effluent. Assistant chief counsel for the state water board, Philip Wyels, said the permit – which was approved by the regional board in 2012 - was not being revoked or deemed invalid. But Poseidon would need to update its intake and discharge plans with the regional board to comply with yet-to-be implemented amendments to the state's ocean regulations that were approved in May. The amendments rule on: salinity limits; taking from and discharging to the ocean; monitoring and reporting; and which sites and technologies should be used. The state board has to submit the changes to the state Office of Administrative Law. Poseidon vice president, Scott Maloni, said the developer will not be required to reapply until the AES power station, next to the Huntingdon plant site, ceased using its water cooling system, which Poseidon plans to use for the desalination facility. Maloni said the company had known this since the permit was approved. According to Maloni, AES has proposed switching to an air-cooled system and plans to have the upgrades finished by 2024, around the time Poseidon would revise its permit with the regional water board. Poseidon has changed its operational plans to comply with the proposed state standards. Its new plans include a rotating screen in front of the water intake pipe to reduce the likelihood of marine life becoming trapped in the pipe and a diffuser on the outflow pipe to disperse the brine leaving the facility. Although the application has been submitted, it could be months before the commission determines whether the company gets the green light to build its project. Environmentalists demanded that Poseidon uses subsurface intakes but a draft report by an expert panel concluded recently - after 20 months of investigation - that such intakes would not be economically viable (see below). ... aS ExPERTS diSmiSS ECOnOmiCS Of SEabEd inTakE Sub seafloor intake pipes were "not economically viable at the Huntington Beach location within a reasonable time frame" according to a recent expert report. The findings sparked controversy over the the Huntingdon project because sub seafloor technology was considered pivotal to regulatory approval. The Independent Scientific Technical Advisory Panel, convened by the California Coastal Commission and the plant developer, Poseidon Resources, found that two construction options for a seafloor infiltration gallery (SIG) were viable technically. But in its report it concluded that a SIG was "not economically viable at the Huntington Beach location within a reasonable time frame due to high capital costs and only modest reduction in annual operating costs." The advisory panel said the economic viability of the technology at Huntingdon was "highly uncertain" and that it was "unlikely that the unit price for produced water from a seawater reverse osmosis plant with the SIG intake technology would find a buyer under current and likely future estimates of alternative waters sources through 2033." The panel calculated that Poseidon's favoured open ocean intake would have a unit cost 40-50% less than the sub seabed technology. It proposed that Orange County Water District "might be willing to pay these water costs in 2018." A sub seafloor approach was favoured on environmental grounds by the coastal commission whose approval is required before construction can begin so the findings. STW finiSHES bRinE COnCEnTRaTOR PROJECT aT HORizOn Texas-based water management firm, STW Resources, has completed a US$ 2.2 million contract for the design, engineering and construction of a reverse osmosis (RO) concentrator for the Texas city of Horizon. STW Resources subsidiary, STW Water, was the manufacturer and technology integrator for the Horizon project and will maintain the system under a contract with Horizon City Municipal Utility District. An existing 13 year-old municipal RO plant in Horizon City could produce processed water at only 28-36 Ml/d. The Texas Commission of Environmental Quality (TCEQ) recorded that the facility discharged brine effluent at about 4 Ml/d into evaporation ponds that failed to evaporate at their expected rate. And land costs made the construction of more ponds uneconomical. STW and its engineering partner, TRE & Associates, proposed and subsequently built the RO concentrator to deal with evaporation pond shortfall while allaying environmental concerns. The new set up makes about 50% of the effluent usable with the concentrator reclaiming the rest back into the distribution system to be blended with permeate from the other RO systems into the final tanks. The concentrator is, as a result, an economical option compared to buying land for additional ponds. STW Resources said the concentrator RO trains were recovering fresh water from the concentrated brine stream of the existing RO facility in Horizon City at 4Ml/d. It said the system was running at a rejection rate of 99%. STW Water president Alan Murphy said the company was anticipating other projects in the US's dry south west: "This is the second concentrator project in the state of Texas that we designed to recover the maximum amount of fresh water from brackish water. We look forward to continue to work with Horizon City and we are currently in negotiations throughout Texas and California."