The future of wastewater

November 2010 » Columns » BEYOND WORDS
Stephanie Hildebrandt

As the global population approaches 9 billion in 2050, the same life-threatening water issues we’ve been facing will only continue to get worse. That is, unless we come up with some solutions.

Luckily, for as many questions as there are about the future of water, there are just as many answers. Seventeen of these “answers” were awarded at the International Water Association’s (IWA) Project Innovation Awards, which recognizes excellence and innovation in water engineering projects throughout the world. The projects are judged based on originality and innovative application of technology; future value to the engineering profession; social, economic, and sustainable design considerations; complexity of the situation addressed; and degree of meeting clients’ needs and expectations.

One of the largest concerns regarding water relates to energy and climate change. Within the next generation, 60 percent of the world’s population will live in cities or urban areas requiring massive water and energy services and infrastructures, according to the IWA. Plus, potable water and wastewater management remain crucial issues in developed and developing countries. One of the biggest questions regarding our future becomes: How can we use every part of wastewater to our advantage?

“Energy and nutrient recovery are the big issues related to wastewater collection in the developed world,” said David Garman, Ph.D., president of the IWA. “Wastewater sludge can be a great source of sustainable energy and the nutrients, when extracted from sludge, provide a source of fertilizers. Effective wastewater collection also provides water for reuse and protects public health.”

A project focusing on decreasing sludge production comes from Institut National de la Recherche Scientifique, Centre Eau, Terre & Environnement (INRS-ETE), Université du Québec. The project offers two ways to decrease sludge production: reduce sludge at the source by improving the existing wastewater treatment plants, and reuse the sludge for value addition. INRS-ETE, in partnership with the U.S. Environmental Protection Agency, is carrying out a scientific project to develop and commercialize low-cost technologies for the production of value-added products (bio-pesticides, bio-plastics, bio-fertilizers, and bio-inoculants) using wastewater and wastewater sludge as a raw material. The project would provide a significant contribution to sustainable waste management, produce alternative value-added products, and reduce greenhouse gas emissions by recycling the carbon contained in wastes. Plus, the cost of production is 40 to 60 percent lower than conventional processes.

A question countries with large populations face is: How can we provide our citizens with enough water during a severe drought?

The answer to this question for South East Queensland in Brisbane, Australia, came in the form of the Western Corridor Recycled Water (WCRW) project. The largest water recycling project in the Southern Hemisphere, the WCRW project provides a new source of pure water to power stations and in the future, will provide water to industry, agriculture, and Wivenhoe Dam to supplement drinking supplies when needed. To do so, the project consists of more than 200 kilometers of large-diameter underground pipeline, three advanced water treatment plants, 12 major pumping stations, and nine balance tanks. The system has the capacity to produce as many as 232 megaliters of purified water a day — around 40 percent of the region’s daily water needs. The project also aids in improving the health of waterways and the environmentally significant Moreton Bay by reducing the amount of nutrients that would otherwise have been released into rivers.

At the other extreme, what can high-population, high-rainfall areas do to retain water for its residents?

Singapore, for example, is 700 square kilometers in size with a population of 4.9 million and a limited catchment area. To solve this problem, PUB, Singapore’s national water agency, built three estuarine reservoirs and introduced alternative sources such as high-grade reclaimed water branded as NEWater and seawater desalination. This expanded the country’s local catchment from half to two-thirds of its land area.

Conventionally, constructing dams across small canals can only support the continuous operation of very small water treatment plants because of low storage capacity. On the other hand, building high-capacity plants to harvest the large quantities of runoff whenever it rains increases the yield, but the plants will be idling 85 percent of the time, resulting in extremely low plant utilization. To balance these two extremes, PUB created a variable salinity plant to harness water from estuarine catchments. The plant treats the surface runoff that is stored in the canal behind an inflatable rubber weir when available and switches to treating seawater when the canal is dry, thus affording high plant utilization. Because it’s a hybrid plant, it has a lower operating cost than a conventional seawater desalination plant.

The civil engineers awarded by the IWA offer a glimpse into the future. With ideas like these, we can be sure there are even more exciting innovations to come.


Upcoming Events

See All Upcoming Events