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Rain bank planned to offset water shortage

EAST China Normal University is working with an ecological high-tech company to develop a “rain bank.”

The aim is to collect and purify rainwater during wet times and use the stored purified water for irrigation in dry seasons, the university announced as the two parties set up a research center.

How to best use rain is a topical issue as China suffers from a serious shortage of high-quality water resource while its annual water consumption has gone beyond 600 billion cubic meters, the university said.

“It is estimated that Shanghai receives about 2.4 billion cubic meters of rainwater each year, valuing it at nearly 10 billion yuan (US$1.45 billion) according to the current water price in the city,” said Lin Tuo, director of the new center. “But the resource is not only wasted, but it also brings pollution to rivers, lakes, farmland and forests as acid rain.”

The core technology of the green rain recycling system — developed by the university and Shanghai Shifang Landscape and Ecology Co. — is not to let the rains infiltrate to underground water directly, but to collect them and purify them into high-quality and recyclable water via two ecological filtration procedures.

The first step is to use a specially constructed greening slope and roots of special plants, while the second is to purify the water via a filtration trench with minerals, according to Lin.

“Take a piece of 10,000-square-meter public green space for example,” he said. “We only have to build a 560-cubic-meter rainwater collection pool and a 140-cubic-meter reservoir for clean water so as to achieve the ecological balance for irrigation.”

The technology was also helpful in promoting the construction of a “sponge city” with high ecological and economic value, Lin said. “The maintenance and operation fees are lower than irrigating plants with tap water, while the effect is better as the recycled water is better for survival and growth of botany.”

He added that the technology will be used in the green belt area along Huangpu River in the Pudong New Area. Lin added the center would tackle more problems in ecological city construction, such as ecological treatment, household waste, and silt in rivers to improve water quality in rivers and lakes.

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