River in Pudong, Shanghai, China

The Problem

     Zhong-Chao Gang is one of the most polluted water body in Pu-Dong (the new developed area) of Shanghai, the biggest city in China. The river is measured at 1.1 km long, 12 meters wide and 1.8 meter deep. For a long while, it has been heavily contaminated by untreated sewage and industrial waste water. Due to its narrow width and particular location (tightly surrounded by structures and lacks spaces for operating heavy machineries), mechanic dredging has been ruled out as an option. Due to low elevation variance and tide movement, water flow is very slow and anaerobic (DO<0.2mg/L). The river is covered with green-blue algae and bottom sludge was measured at 0.7 meter. Water in the river had turned black and emitting offensive odor. It was a dead river with no fish or any other aquatic creature visible.

The Treatment

     In 2001, our company in cooperation with Joinbo Corp., started a bio-treatment project on the river on September 19. Within 3 days, the dissolved oxygen was increased from 0.2 mg/L to 5mg/L. Odor was no longer detectable. Within 7 days, all the algae was eliminated. In 10 days, COD was reduced from 76mg/L to 36mg/L. On the 15th day, the system we built up started to treat nearly 4,000 tons of water per day.

The Result

     Sixty days later, our system had treated a total of 110,000 tons of water. COD was maintained at 36 mg/L, BOD <10mg/L, and DO between 5~6mg/L. The effluent was clear (secchi=0.5 m), colorless, and odorless. The quality of water met all the criteria of China National ground water standard V.


     After more than 8 years, our system continues to function very well on the river. It proves that it doesn’t require expensive equipment and investment to treat polluted water bodies, not even when there is continuous influent. Every day blackish, odorous water entering our treated area, and out goes clear, clean, and odorless water. With just minimum maintenance, the system keeps on working. The lives of people residing in the surrounding area were greatly improved. The effluent from our system is beneficial to all the downstream marine life forms because it has no chemicals and is rich in oxygen and full of creatures that feed the aquatic food chains and nourish more advance forms of lives. The same technology can be applied to any huge water body with or without inflow or outflow.