1 . The government of Singapore has created a highly developed system that turns wastewater into drinking water. The system involves a network of tunnels and high technology treatment centers.

The system helps reduce ocean pollution, as only a small amount of the treated water is sent into the sea. The United Nations estimates that 80 percent of the world’s wastewater flows back into the oceans without being treated or reused.

Singapore has few natural water sources. The island nation has long had to depend mostly on supplies from neighboring Malaysia.

Low Pei Chin, an expert, told reporters, “Singapore lacks natural resources, and it is limited in space, which is why we are always looking for ways to explore water sources and stretch our water supply. One major plan is to collect every drop and reuse endlessly.”

Parts of the water treatment center are underground. Wastewater enters the center through a 48- kilometer tunnel that is linked to sewers. The center contains a large system of steel pipes, tubes, tanks, cleaning systems and other machinery. It can treat up to 900 million liters of wastewater a day.

In one building, a network of air flow systems has been put in place to keep the air smelling as fresh as possible. Waste that arrives at the plant goes through a cleaning process before powerful pumps send it flowing to areas above ground for more treatment. There, the treated water receives additional cleaning. Bacteria and viruses are removed through highly developed cleaning processes and then disinfected with ultraviolet radiation (紫外线).

Singapore is also in the process of expanding its recycling system. The country will add another underground tunnel and a major water treatment center to serve the western half of the island. Officials expect work on the center to be completed by 2025. By the time the expansion is finished, Singapore will have spent about $7.4 billion on its water treatment systems.

3 . On November 7, Lewis Pugh completed a one-kilometer swim in the freezing waters of King Edward Cove, off South Georgia in Antarctica. He was wearing only his swimming glasses, cap and Speedos (速度计).

Pugh is an advocate (提倡者) for our oceans and seas, working to protect these ecosystems (生态系统) with their large diversity of sea life. When asked why he doesn’t wear a wetsuit, Lewis says, “I ask world leaders to do everything they can to protect our oceans. Sometimes the steps they need to take are difficult and unpopular. If I’m asking them to be courageous, I must also be. Swimming in a wetsuit would not send the right message.”

It took Pugh about 19 minutes to complete the one-kilometer swim in Antarctica where the water averaged about 1.6 degrees Celsius. He says that his body can only tolerate about 20 minutes in the freezing waters before it starts shutting down. As he swims, his body temperature steadily drops, which in turn causes his muscle control to drop, slowing him down. When he is done with his swim, his support team rushes him to a hot shower and it takes almost an hour for his body temperature to return to normal.

Doctors and Pugh warn that one must receive months of training to swim in such cold waters. Even expert swimmers who are unused to freezing water can drown within minutes because of the physical shock experienced by the body. Pugh says he trained for six months before this swim.

This is not the first time that Lewis has swum in dangerous conditions. In 2007, he swam one kilometer in the North Pole to draw attention to the melting Arctic ice due to the climate change. In 2015, he swam in the Bay of Whales in Antarctica’s Ross Sea as part of his successful campaign to help set up a sea life reserve (保护中心) there.

5 . Latin America’s first renewable fuel-powered, garbage-trapping wheel is cleaning one of Panama’s dirtiest rivers. It is powered by water and solar energy. It pulls waste out of the Juan Diaz River. Most of the waste comes from the capital area of Panama City where about 2 million people live. Thousands of kilograms of garbage flow down the river into the ocean each year.

As the leader of the project, Robert Getman said, “Cleaning beaches is good, but it is more effective and cheaper to trap garbage in rivers because when it reaches the ocean, the environmental and economic cost becomes too high.”

The Juan Diaz River is one of the most polluted in Panama. Waste systems in the area are poor, and land development is not well supervised (监督). The river also passes through Panama City, one of Central America’s largest cities. Still, the waterway and its mangrove trees are home to wildlife like turtles and birds. According to this situation, the environmental group Marea Verde launched the wheel in late September, which is named Wanda Diaz. By the middle of October, it had gathered 28. 6 cubic meters of plastic bottles from the water. Over five years, Marea Verde projects have slowed the spread of waste along the Juan Diaz River and other Panama’s rivers. Several years ago, the group launched its “Barrier or Trash” technology, a floating device. It captured more than 100 metric tons of waste in the Matias Hernandez River within two years.

The Baltimore Bay “Trashwheel” in the United States is the model for Marea Verde’s machine, Wanda Diaz. However, Wanda Diaz is more advanced and superior in terms of technology, and it even has cameras with artificial intelligence (AI) that can recognize and sort different plastics.

“We want each of us to raise awareness that we can prevent the death of the Juan Diaz River, ”said Marea Verde’s leader Sandy Watemberg. She expressed her hope that the wheel would also help many more other rivers. But she also pointed out that those who accustomed themselves to single-use plastics needed to rethink their behavior.