Collaboration between science, engineering and a sympathetic bureaucracy is mimicking nature to address wastewater problems in Indonesia using sunlight, gravity and plants to create a molecular filter that transforms wastewater into oxygen-producing gardens.

Based on naturally occurring wetland filtration systems, Professor Denny Kurniadie of Bandung's Padjadjaran University and engineer Heru Tarjoto have developed a miniature constructed wetland system that can be applied to domestic and industrial wastewater, cleaning wastewater of heavy metals, oils and septic waste via water gardens.

"I had read Dr Denny's books on the constructed wetlands that he applied in Germany and was hooked on this environmentally friendly way of dealing with wastewater. I took his ideas and added a settling tank that allows for the rapid breakdown of waste so the constructed wetland technique could be scaled down for domestic applications," said Tarjoto of a system that not only cleans wastewater, but creates a garden at the same time.

Tarjoto says he developed the b-wet constructed wetland, "which is a gravel bed hydobotanical garden where wastewater is purified through self-sustaining biological molecular filters formed by the roots of water-loving plants."

He added that constructed wetland technology had been used for decades with the United States NASA team using the system to clean up heavy metals in ground surrounding rocket launch sites.

"The concept is not new, but in the past large areas of land were needed for surface-flow constructed wetland filtration area. The system we have come up with is a sub-surface flow wetland that traps odors and toxic waste below ground level in the roots of water plants. This allows the system to be placed in schools, hotels and restaurants and in domestic homes," Tarjoto said.

He explains water plants form a gel-like substance in their roots that traps and breaks down waterborne toxins at the molecular level, releasing the cleansed water back to the surrounding wetland environment. Tarjoto says the system is the way forward in wastewater treatment.

His viewpoint is supported by the head of Bali province's Environment Assessment Agency (EPA) and engineer, Ni Wayan Sudji, who has implemented the constructed wetland system in her offices and in Bali's governor's offices.

"In Bali we have built this system we call the Wastewater Garden in schools and government buildings in the public arena and we are pushing for all new commercial buildings, such as hotels, restaurants and industrial utilities to use this system for their wastewater," Sudji said.

She pointed out that the constructed wetland wastewater system had first excited her because it was so similar to the traditional Balinese tebe or community waste zone that has been used in villages for centuries.

"I have a keen interest in pursuing the system because we have a traditional practice called tebe, which is an ancient approach to managing wastewater and solid waste that drains into the tebe where the waste was processed by plants. This has happened for hundreds of years, generation to generation. People have always cleaned up their village environment by recycling waste," Sudji said.

The low cost and maintenance of the self-sustaining system was also an important factor in EPA's support of the project, which Sudji says is "low budget, good for the environment, simple to construct and can be applied anywhere".

She added that officers from all of Indonesia's provinces had visited Bali to see the system in use and the Home Minister had endorsed the constructed wetland technique across the country.

Tarjoto and Kurniadie's constructed wetland system answers the problem of raw sewerage pouring into Indonesia's rivers and seas.

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