Water. Desalination + reuse
Issue link: https://fhpublishing.uberflip.com/i/867173
22 In Site September 2017 Water. desalination + reuse Eskom is currently working on three projects: two brackish groundwater desalination plants to meet its own process water needs, and a pilot seawater desalination plant in partnership with the City of Cape Town that could lead to a bigger municipal supply project. "We began in January with an ambition to install a plant around July 2017. That was our first attempt to go to the market for a solution for our own water needs. Unfortunately the market didn't respond well. Most of them indicated that the timelines were very tight to make it to a permanent solution," says Velaphi Ntuli, manager of Koeberg Nuclear Power Station. The utility is now taking a two-phase approach on the groundwater project. The first phase is for a temporary desali- nation installation that does not interface with the power plant's processes, and the second phase will be a permanent solution that does integrate into the plant. Tenders for both the temporary and permanent solutions went out in spring 2017, and are now closed. Eskom has a groundwater permit to draw water from an aquifer within its site, and both the permanent and temporary plants, which will provide water for the power station's cooling process, will provide for capacity of around 1,400 m3/d. The per- manent plant will have flexibility to scale up, should the City of Cape Town want to increase the capacity of water that Eskom can draw from the aquifer and to take off the excess desalinated water for municipal use. "For that we would need a review of the water permit," says Ntuli. "For the temporary plant, we had a good response to the ten- der. We have evaluated the sub- missions and are about to com- plete the process. The successful applicant has been identified. We are still in the commercial phase and we have not yet awarded the contract," explains Ntuli. The submissions for a temporary plant suggest a timeline of thee to six months for installation, and Eskom is hoping that a solution will be operational before the end of this year. The tender for the permanent groundwater desalination project received 10 submissions, which are currently in evaluation. "The response was much better than the first time," Ntuli says. Eskom wants to have the permanent plant operating by June or July 2018, and in the meantime to rely on the temporary installation. The third project at Koeberg is for a seawater desalination pilot plant project in partnership with the City of Cape Town, known as the Data Monitor and Collection Plant. The site has been identified as a good one, partly because using the existing water intake and out- fall infrastructure would help to reduce the cost of a desalination plant project, and also because of its ease of connection to the city's water network. "The City of Cape Town and Eskom have done a huge amount of work together on this pilot project. As this point we know the site where we want to locate it, and under- stand what the timings would be," Ntuli says. Additionally, the water discharged by the plant is warmer than seawater by several degrees, which could improve the efficiency of the desalination process. The challenge now is to understand what may be possible in terms of building a bigger, integrated desalination project. "We have done some theo- retical modelling based on our samples that we collect at Eskom and the data that is available. The next step is for the city to go out to the market to find a suitable supplier to develop this plant. When that's done, we can specify it and begin installing it." The ambition is to have the pilot project installed by the end of 2017. ReSIlIence ReSponSe city outlines plans for emergency, tactical, and strategic phases • city sought help from international experts in drought response • rapid procurement and commissioning process is largest and most complex expenditure programme in the city's history • capex for the first tranche of projects is estimated at ZAR 2 billion ($150 million) Until May 2017, the City of Cape Town's response to drought was based principally on driving down demand, and supplementing supply with limited new augmentation schemes. As the drought took hold, this approach was no longer proving sufficient. Over 11 weeks from June to August, a new Water Resilience Task Team developed a portfolio response to the crisis with help from professional consultants with experience of responding to droughts in places like Australia and California. A number of programmes have been established for the emergency and tactical phases that run until end of June 2018, and for the strategic phase which begins from July 2018. A part of the response is to drive down collective usage to 500,000 m3/d, and to ensure that at least 500,000 m3/d of water is always in production. While the city has historically relied on its dams for water supply, a variety of technologies will now to be introduced to augment the drought-ravaged system. The information provided through the RfI has been used to plan an extensive rapid procurement programme that will be rolled out, starting from 16 August, in three phases: the immediate and first tranche; the second tranche; and the extreme tranche. This rapid procurement and commissioning process will be the largest and most complex expenditure programme in the history of the City of Cape Town. The city has appointed engineering consultants to assist the process, and has begun to develop bid specifications, and register bids. The capex for the first tranche of projects is estimated at ZAR 2 billion ($150 million), and opex from ZAR 1.3 billion upward. Water tariffs are set for 2017-18 and will not be adjusted, and the city aims to fund projects by reprioritising existing water projects, loans, and cutting expenditure elsewhere. However the cost of the new water sources will begin pushing up prices for consumers from July 2018. Koeberg nuclear power Station brackish water project key requirements • refurbish an existing borehole system • design and install an RO desalination plant, including pre-treatment and post permeate water treatment, producing cooling process and potable water • use existing water pipes and electrical supplies • achieve water recovery rate of 75 per cent • produce a minimum of 1,440 m3/d • provide 14 months' operations and maintenance from the time of handover, and train personnel on operations, troubleshooting and maintenance continued from p21