His revolutionary treatment concept, which stood out among 39 international nominations, enables industrial-used water to be purified cost-effectively and produces renewable energy, fertilizers and soil conditioners. Professor Lettinga has chosen not to patent this invention so that his water treatment technology can be universally available.

As a result, his technology has been widely adopted in industrial as well as municipal use. Today, the technology is in use in almost 3,000 reactors, representing about 80% of all anaerobic used water treatment systems in the world.

Energy-efficient, cost-effective process

Professor Lettinga pioneered the widespread use of anaerobic technology, which uses micro-organisms in an oxygen-free environment to purify used water. Although anaerobic technology has been around for over 100 years, his invention proved that it could be operated as an energy-efficient, cost-effective and self-sustaining process.

The anaerobic reactor can pre-treat polluted used water from industries such as breweries, beverage, paper and pulp manufacturing and sugar, starch and alcohol distilleries. The used waters produced by these industries contain a large amount of organic contaminants. Some of these contaminants cannot be efficiently removed by conventional aerobic processes, while others are toxic.

With energy-efficiency concerns becoming more pressing, this technology is being increasingly applied, not just to industrial-used water, but also to municipal used water in countries like Brazil and India. The anaerobic system is a simpler system compared to aerobic systems as it does away with the use of oxygen, generating energy savings of 30% to 40%.

Before Professor Lettinga’s breakthrough, highly contaminated industrial used water was treated mainly by aerobic biological processes, which were expensive and energy intensive due to the use of oxygen. In countries which could not afford the aerobic process, the untreated, highly contaminated water would have polluted the environment, affected aquatic life, and even endangered public health.

Self-sustaining system

At the same time, the process also produces methane which is the principal component in natural gas and can be used as a fuel to generate electricity. Treatment plants using Professor Lettinga’s technology are able to offset part of their plants’ operating costs by generating this renewable power. Other by-products are fertilizers and soil conditioners.

“I believe that innovative technologies for treating used water, waste and gas, especially those that focus on closing the loop and recovering resources, will contribute to more sustainable living, which the world urgently needs,” Professor Lettinga says.

“Professor Lettinga’s invention has played an important role in addressing the world’s growing concern over finding environmentally sustainable solutions. In choosing not to patent his Upflow Anaerobic Sludge Blanket Reactor, many developing countries now have access to a low-cost, sustainable used water treatment system,” chairman of the Lee Kuan Yew Water Prize Mr Tan Gee Paw says.

“Besides contributing to water management with his technological breakthrough, he has also imparted his knowledge to young water engineers and professionals all over the world so that they can apply the knowledge in their countries. His altruism is indeed highly commendable.”