Water. Desalination + reuse
Issue link: https://fhpublishing.uberflip.com/i/640467
February-March 2016 | Desalination & Water Reuse | 23 | Projects _________ Dr trevor Loveday, editor D&WR ___ Oasys Water's chief executive officer, Jim Matheson, talks about the context of the Changxing project and the Chinese market generally in the global appetite for more stringent water stewardship. China's outstanding economic growth and its recent deceleration have had enormous impact not just on the world's economies but also on the environment. Its enormous expansion of power production to feed its former double-digit growth has placed huge demands on the country's water resources for plant coolant and in flue gas desulphurization (FGD). "China is emblematic of the rest of the global market," says Matheson. "There is a rising awareness of the importance of environmental stewardship in China as there is globally. They are a bit out in front in being thoughtful about how to use regulation and technology together to find the right path forward to continue industrializing but more sustainably," he adds. Matheson sees abundant opportunities in China for Oasys' ZLD technology not only in new-build plant like the 1.2 GW Bullish in China Changxing power station (see case study) but also the installed base – all using water coolant and many fitted with FGD. China has responded to its place as a major emitter of greenhouse gases with increased stringency in its environmental regulations. This is pushing greater efforts by power producers to improve their water management says Matheson. But there are economic imperatives in play too, adding momentum to improvements in water and discharge management. "Regulation is meant to articulate a problem set. I think economically, many industrials are seeing that not only do they want to be in compliance but they want to manage their sustainability programme and environmental risks and their water supply security risks. So over time it is becoming more clear that there is a very strong economic argument to be thoughtful about water management and to adopt Going forward at Changxing: "China is emblematic of the rest of the global market," says Oasys' chief, Jim Matheson. A case study of the Changxing zero liquid discharge system Oasys Water's forward osmosis-based zero liquid discharge technology has made its debut in a new coal-fired power plant at Changxing, China. In China, power generation growth has increased national dependence on coal for meeting a large portion of power needs and has in turn driven regulations surrounding environmental controls and water treatment. Regulation of power plant wastewater discharge, to the level of zero liquid discharge (ZLD) for streams such as the wastewater from coal power plant flue gas desulfurization (FGD) and blowdown from recirculating cooling systems, has become the norm. Amid these new stringent discharge and water reuse requirements, the Huaneng Group, China's largest power producer, finalized plans for the construction of a state-of-the-art ultra-supercritical coal-fired power plant at the Changxing Power Station in Zhejiang Province. A new wastewater treatment plant was included for treatment of a combined waste stream, including the FGD blowdown wastewater stream and cooling tower blowdown. To meet water intake and discharge limits the new water plant would be designed for ZLD and complete liquid recovery for reuse as boiler makeup water. Process FLoW DesIGN Changxing Power Plant selected Oasys Water and its Chinese partner, Beijing Woteer, to deliver the world's first commercial application of forward osmosis-based ZLD. Oasys Water has provided its membrane brine concentrator (MBC) system and pre-concentrating reverse osmosis (RO) while Beijing Woteer supplied physico-chemical, filtration and ion exchange pretreatment. The guiding philosophy in designing the ZLD process flow for Changxing was for the pretreatment and MBC sections of the system to be able to absorb the wide swings in wastewater flow and water quality arising from variations in the FGD scrubber process. Because the wastewater treatment plant was built with the new facility and not a retrofit, the ZLD process flow design was based on projected water quality data. Ability to treat a variety of waters across a wide range of hardness, alkalinity and total dissolved solids (TDS) was therefore planned for in the design of the system.