Special treatment

“It used to drive us crazy, the trash and sewage, the bad smells and children getting sick with dengue fever,” says Gloria Solomon. With her husband and four children, 50-year-old Solomon lives in a tiny, eight sq metre shanty in an informal settlement in Manila. Their home backs on to a small stream, Estero de Paco, a tributary of the city’s Pasig River.

Thanks to a year of intensive restoration of this canalised waterway, the view from Solomon’s home is no longer that of a detritus-filled open sewer, but of an attractive, grass-banked environment where a system of plants and micro-organisms helps to clean the water. “We’re much happier,” she says. “It’s nice to see the estero getting cleaner. Families are now doing business selling snacks by the waterside.”

However improved it may appear, this stretch of water at the head of the Pasig still flows with raw sewage, especially during the rainy season. It has been a problem for decades: Manila’s sewage infrastructure was not designed to cope with the present population of 12m inhabitants.

The Pasig River Rehabilitation Commission (PRRC), a government body, has been working on reviving the biologically dead waterway since 1999. Expensive efforts to dredge the main river have reduced the amount of rubbish and improved the flow, but the tributaries are increasingly choked as informal settlements expand.

After typhoon Ketsana in 2009, which caused havoc in the city, the Metropolitan Manila Development Authority pledged to improve the waterways. It is no small task. The PRRC estimates the 47 major tributaries to total 117km.

The ABS-CBN Foundation, the charitable arm of the country’s largest media company, has also added the city’s waterways to its causes. A year and 40m pesos ($923,000) later, the 2km stretch on which the Solomon family live has been transformed. It is the first phase of what the project’s designers call a “green wave”, which will flow through the city from the headwaters of the tributaries to Manila Bay.

The project has popular support. In October, 116,000 people ran in a sponsored race through Manila at 5am, raising 10m pesos. Those living beside the waterways have been recruited as “river warriors”. Along with police, military and other volunteers, they have mucked in, ladling out sludge and bagging up rubbish. Coir (coconut fibre) has been used to stabilise the banks, in which deep-rooted vetiver grass has been planted. Long used to rats, mosquitoes and cockroaches, residents along the Estero de Paco have welcomed new wildlife. “We now have butterflies,” Solomon says.

The work has caused some disruption. With the assistance of the NGO Habitat for Humanity, more than 1,000 families have been willingly relocated. Because of lack of space in the informal settlements, they had built their homes directly on the banks of the sewers, impeding the flow. Once, they lived in self-built shacks teetering over a stinking drain, or under a bridge, with no room to stand. Now they have brick homes in a purpose-built settlement 70km south of Manila.

The second phase of the clean-up begins this month. Work will start on the installation of technology developed by Biomatrix Water, a Scottish environmental engineering company.

“Although the waterway looks much better, the quality still has a long way to go,” says Galen Fulford, managing partner at Biomatrix, which has been collaborating with Filipino company Coco Technologies and other local public and private agencies. “The water in the Paco has a pollution concentration typically of around 50 per cent of the strength of raw sewage.”

The technology developed by the three-year-old company was spawned in Findhorn Ecovillage in Scotland. This was the first place in Europe to instal a treatment system called Living Machine, similar to a reed-bed purification system but in a greenhouse and covering a smaller surface area. Sewage is treated as it passes through a series of tanks, containing different bacteria, flora and fauna.

Biomatrix’s system for treating polluted rivers develops this idea. The company’s Active Island Reactors are “fully engineered powerful water treatment systems” that float on the water and are filled with water-loving plants such as papyrus and bulrush, and a system of “dynamic media columns”. These, along with the plants’ roots, create a large surface area below the water’s surface, on which bacteria form cleansing “biofilms”.

The idea is to give nature a helping hand. “The fact that all these organisms can clean water is not new,” says Fulford, “But because of the scale of the problem, we need to increase the efficiency using the principles of ecological engineering.” Biomimicry – copying nature’s designs – was a guiding idea in designing the treatment system that, unlike a reed bed, can be installed quickly and needs no land.

The “dynamic media columns”, for example, were inspired by both baleen (the filter feeding system of whales) and cilia (microscopic hairs), providing a vast surface area for many bacteria to thrive. The hexagonal plan shape of the floating islands mimics beehives or coral polyps and gives strength, important when waterways can suddenly become torrents.

Although some electricity will be needed to pump the water, there will be a significant reduction in greenhouse gas emissions: by encouraging aerobic digestion, the amount of methane produced, which is some 23 times more damaging than CO2, will be “greatly reduced”, Fulford says.

To start with, four Active Island Reactors, covering 110 sq metres, are being placed in a section of the Estero de Paco. The work they will do is equivalent to a sewage treatment plant for up to 2,000 people, says Fulford. They will also cope, to some extent, with industrial waste.

Across the world, urban waterways are dying as rural-urban migration results in cities growing faster than the infrastructure can cope. Developed nations are not immune to this. While the River Thames is, on the whole, much cleaner than it was, according to Thames Water, on average, 39m tonnes of untreated sewage overflows into the river each year when London’s Victorian sewers become overloaded.

Water treatment systems that don’t take up any space on land, and that look beautiful too, are clearly the way to go.

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