River Treatment as a System in Nanjing

By Feng Jindong, Ji Xinyuan, Kaneko Reimon

In recent years, more companies, organizations, and governments start to focus on environmental protection, especially water protection. Nanjing faced awful water quality in the past, and the situation has been alleviated in the recent 5-6 years. We will focus on how Nanjing “heals” its water bodies as a system, including water sources conservation, remediation and rectification, and Nanjing rivers’ future.

“The freshwater comes from the springhead”

Many people have been discussing the conservation of water sources in their cities. So, what is a water source? Water source is the place where people take water and put it in use.

Water source | Loudoun water, Source water protection

Then, what is the significance of the water source? It should be answered by functions of water sources. Specifically, water sources ensure people’s daily water use, including drinking and washing. It is also necessary for agriculture and industries. For instance, farmers need water from water sources to water crops, and factories need water to cool their machines. A well-protected water source provides people and nature with clean water.

Multiple usages of water from water source | Water Encyclopedia, Uses of Water

The situation in Nanjing is far better than the one in the past. The water quality of the Qinhuai River has been alleviated, during which NGOs play an important role. They conduct research and measurements of several indexes (e.g. COD, BOD, TP, organic matters) in water sources. Discoveries of potential problems in water sources and suggestions to the government are also what they do. Staff and volunteers in Green Stone, an environmental protection NGO devote themselves to measuring the water quality index. They set up a long-term project called “Jinling Shui Yun”. It is composed of measuring water index and discovering environmental problems in a series of water sources, including Xuanwu Lake and Yanziji Lake. What’s more, Green Stone’s employees, experts, and volunteers analyze local environmental issues and offer suggestions to the formulation of Regulations of Jiangsu Province on Environmental Protection.

Although the conservation of water sources plays a vital role in ecological restoration just as the saying goes —- “freshwater comes from the springhead” —- we cannot depend on it entirely.

All creatures live in a harmonic way

Given that the government and other organizations already or plan to take action on water source conservation, these are far from enough to guard the water quality in Nanjing. Different parties also respond in time when pollution occurs.

The reaction towards pollution is divided into two steps. The first step is remediation. To begin with, we need to control the pollution in the sources of water. A technique called diversion of rainwater and wastewater has been used in this process. Rainwater is relatively clean enough to directly go into water bodies, so diversion of rainwater and sewage remit the pressure of sewage treatment plants when dealing with polluted water. “But the construction cannot have a 100% effectiveness,” an employee in the water supply bureau told us “So we need to desilt.” Sludge in water bodies is the accumulation of microbe and organic matters, which makes the river muddy and smelly. Before 2016, Pearl River, a small river in Nanjing with inattentive management, was an awful water body with black sludge stacked in the river. After orders were published by the government, the local bureau took action. Excavators were used to cleaning the sludge up, and the odor disappears with the vanish of sludge. Then we need to fill the river with clean water, which comes from water treatment plants. After the water becomes clear again, ecological restoration starts. Floating beds and aeration machines are used, the former is used to absorb organic matters in water (e.g. P, K, N), and the latter is used to provide microorganisms with oxygen to allow them to “eat” the organic matter in water.

Floating bed & aeration machine   |  Photo by Feng Jindong

However, remediation is just a “palliative”, which controls the pollution but is far from enough to maintain a good water environment. The government also took rectifications as the second step; they planted oriental cherry beside the riverbank, which attracts many people each year and they unintentionally supervise the water quality. Moreover, they also propagandize the history of Nanjing city since the river is near the old site of Nanjing Library, create multiple “duties” to encourage people to supervise the water quality. These actions ensure the maintenance of good water quality and pleasant surroundings.

As the government said, the best environment is an environment that humans co-exist with nature. More companies realize the importance of water supply restoration under the efforts of the government and start to introduce new technologies. Many water treatment plants use an IoT system to supervise water quality in each step of treatment. Chemical engineering companies introduce the “Green Project” to reduce the harmful output to waterbodies.

Cooperate with allies

Though the water quality was significantly improved with remediation and rectification conducted, there are remaining problems toward river treatment. Some common residents have little, or even no sense for the local water conservation. In addition, there is still no solution for the problem of lowered water quality in water sources on rainy days. Moreover, local government faces a hard task when it comes to water treatment. For instance, some small restaurants just “go-for-broke” because they cannot afford the fine for discharge the wastewater into the river. The lack of communication between residents, factories, and government, the difficulty of monitoring all processes of wastewater management, and the imperfect sewage system in the city has created a huge challenge for the government in managing water pollution.

A river’s situation after recent rainfall  |  Photo by Feng Jindong

Fortunately, governments, organizations, and companies start to cooperate on those issues. The local government introduces water protection to companies, and communities to raise people’s attention. They also introduce policies like “333”(3, 3, 3) to eliminate level V water and develop the sewage pipe networks. Organizations like Green Stone communicate with industrial parks, local governments, and nearby residents actively. “We want each side to hear others’ voices.” An employee of Green Stone said. Water treatment plants use an IoT system to supervise water quality in each step of treatment. Chemical engineering companies introduce the “Green Project” to reduce the harmful output to waterbodies.

Some of those actions are already “on the road”, and others are still in the planning. But as the saying goes: “a thousand miles journey begins with a single step.” With the efforts of many allies, river treatment in Nanjing will have a bright future.

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