Ecological approach to water treatment unveiled

A research team from Shanghai Ocean University has developed an ecological approach to water treatment that combines environmental sustainability with economic efficiency.

The team, led by professor Wang Liqing, uses a methodology that mirrors traditional Chinese medicine's diagnostic principles — observation, listening, smelling, inquiry and palpation — to assess and restore ailing water ecosystems.

The process begins with detailed water quality analysis through visual inspection and instrumental monitoring. Subsequent steps analyze water circulation patterns and investigate historical pollution sources and environmental changes. These findings guide the development of tailored treatment strategies.

"We begin by cutting off the pollution source to prevent further pollution input. Then we operate on the water body, engineering underwater topography and creating habitats for selected fishes or plants,"Wang said.

She described water ecosystems as complex networks where material conversion, energy transfer, and information exchange create self-regulating systems with interconnected components.

"We implement complete ecological systems rather than addressing isolated problems," Wang added.

The treatment protocol uses diverse biological agents. In deeper waters, fish populations control algae and absorb excess nutrients. In shallower areas, submerged plants are deployed, particularly vallisneria, which effectively absorbs pollutants.

At their research base in Qingpu district, the team has refined plant cultivation techniques.

For instance, they developed a robust strain of vallisneria through 20 generations of selective breeding, capable of producing two harvests annually and demonstrating enhanced functionality.

The team has also developed specialized equipment, including aquatic plant wrapping machines and automated aquatic plant collection boats, enabling low-disturbance and high-efficiency planting and maintenance.

While the ecological approach appears simple, Wang said its complexity lies in precision. "Each water body requires carefully calibrated, location-specific interventions to maintain balance."

Jinhai Lake in Fengxian district exemplifies the method's effectiveness. "Since its 2011 implementation, the system has maintained remarkable stability," Wang said.

Water transparency consistently reaches two meters, with quality meeting Grade II or III standards. The site now purifies nearly 100,000 metric tons of water daily.

In Zhujiajiao Water Town in Qingpu district, the team established ecological buffer zones to stabilize water quality. Water transparency has improved from under half a meter to over 1.5 meters.

The approach also achieves cost efficiency, reducing treatment expenses from 0.2 to 0.5 yuan per ton with conventional engineering methods to about 0.04 yuan per ton.

"We facilitate natural transformation processes rather than merely removing pollutants," Wang said."Converting dissolved nutrients into harvestable biomass creates a sustainable cycle, with aquatic plants serving as fish feed or organic fertilizer."

The ecological methodology has been implemented in more than 700 projects across 23 provinces and cities in China, treating roughly 90 square kilometers of water area — equivalent to 15 West Lakes.

"Our ultimate vision extends beyond water treatment," Wang said. "We aim to create self-sustaining ecosystems that coexist harmoniously with human activity while delivering lasting environmental and economic benefits."

zhengzheng@chinadaily.com.cn