Freshly prepared to start the day
No city can survive without a reliable water supply. A new wastewater treatment plant in Singapore supplies up to 190 million liters of water daily. The foundation is a redundant automation solution from Siemens that runs 24/7.
The alarm clock goes off. Out of bed, brush teeth, take a shower, brew the coffee. That – or something like it – is how the day starts for many people all over the world. And that means they need water – a lot of water. And not just for their morning routine. For example, the 5.5 million people in the city-state of Singapore south of Malaysia need 2.3 billion liters of water every day.
To make sure it can keep up with this huge demand, Singapore opened its fifth NEWater water recycling and treatment plant in Changi in early 2017. That makes NEWater the most important pillar of Singapore’s water supply, even ahead of local catchment water, imported water, and desalinated seawater.
This latest plant was realized as part of a joint project between BEWG International (China) and environmental technology company UES Holdings Pte Ltd. (Singapore). At the heart of the automation technology is a turnkey solution from Siemens.
Securing plant availability and quality
“Constructing the NEWater plant in Singapore is subject to very stringent regulations,” says Steven Zhou, Deputy General Manager of BEWG International. “That’s the only way to guarantee the very high quality required of the recycled water. There’s one other way that this plant differs from all others around the world: We have to meet a constant demand and produce about 190 million liters of water per day. And finally, we need to ensure 90 percent uptime for the whole plant.” The solution: a high level of plant automation.
Preventing system outages
The technology supplied by Siemens consists essentially of a variable-speed redundant drive system Perfect Harmony GH 180 for a total of 13 pump units, based on what’s known as cell bypass technology. This makes it possible to replace defective parts in a matter of minutes with no impact on plant availability. For example, five power cells can be switched off for maintenance purposes without compromising plant operation. To do this, the converters bridge the relevant cells to enable the pumps to continue operating at optimal levels.
We have to produce about 190 million liters of water per day. So, we need to ensure 90 percent uptime for the whole plant.Steven Zhou, Deputy General Manager of BEWG International
This redundant solution not only makes maintenance easier, it also increases plant availability to 90 percent. The customer also benefits from substantial energy savings, shorter power-down time, greater flexibility, and faster powering-up again. The modular system also includes a decentralized process control system Simatic PCS 7 based on the standardized Advanced Process Library (APL), Industry Library (IL) as well as integrated magnetic flowmeters to ensure precise measurements and a high level of data transparency. All processes are optimized and the plant is maintained from the central control room.
Better than applicable standards
The Siemens technology drives a complex process for treating the wastewater. The water first passes through a microfiltration stage where membranes filter out larger particles. A semi-permeable membrane then removes dissolved salts and organic molecules in a reverse-osmosis process. Any remaining organisms are removed in a final stage of UV disinfection.
NEWater’s plants have passed more than 65,000 scientific tests to show that they surpass World Health Organization drinking-water standards and that its recycled water is clean enough to be used in the electronics industry and to be bottled as drinking water – or to be used in showers to give Singapore’s residents a fresh start to the day.
Picture credits: BEWG International
NEWater is the brand name under which wastewater is treated in Singapore under the supervision of the Public Utilities Board (PUB, the statutory board of the Ministry of the Environment and Water Resources). The first NEWater plant was completed in May 2000. The latest covers 49,000 square meters and is designed to operate for 25 years. It currently provides about ten percent of Singapore’s daily water needs, and all five NEWater plants together account for 40 percent. The operators plan to increase this share to 55 percent by 2060, partly to reduce the country’s dependence on imported water.
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