Located on the "Gold Coast" of China along the Bohai Sea, the city of Tianjin is crucial to the country's economy.
About a third of the 10 million residents living in China's largest port city rely on water from the 104-year-old Jie Yuan Water Treatment Plant (WTP) for drinking and other uses.
The challenges that the plant has faced in the last few years are reflective of the overall water quality situation throughout the Republic.
One of three major plants in the city, the Jie Yuan WTP is tucked away in the downtown area of Tianjin, a major industrial center in China.
Growth of urban areas
Economic growth has spurred the development of urban areas in China. The recent sprawl in Tianjin, one of four municipalities directly administered by the People's Republic of China, is reflective of one of the challenges caused by the overall urbanization of China.
As a result, industrial effluent that is not properly treated is being discharged into rivers, contaminating the fresh water and making it difficult to treat water in these densely populated areas.
At the same time, the Ministry of Health and the Ministry of Construction have raised water quality standards twice during the past two years, placing more pressure on Tianjin's water infrastructure.
"It was becoming clear that the aging Jie Yuan facility lacked the capacity and technological capability to accommodate the escalating situation," said David Chen, manager of Earth Tech's operations in China. "Despite undergoing several renovations over the years, the hands of time were taking their toll on the plant."
Need for action
The need for action became clear in the summer of 2000, when a severe algae problem in the Luan and Yellow rivers strained the plant's ability to produce quality drinking water. The problem is becoming a common one amongst large cities in the republic as pollution in the rivers, the source of water for the treatment facilities, has caused increased organism growth. The large amounts of ammonia and nitrogen in the city's wastewater effluent, in combination with the warm summer temperatures and sunlight, have led to eutrophication and increased algae formation.
Operators at the facility dumped massive amounts of chemicals in the water in an attempt to kill the algae, but the overdosed chemical could produce unwanted byproducts, such as organic chloride and high concentration of residual iron.
The Tianjin Water Works Co., the local, state-owned water utility, turned to Earth Tech, Inc., a global consulting, construction and engineering company based in Long Beach, Calif., for help in dealing with this challenge.
A proposal for the use of a technology that had been used throughout the western world for decades –a customized Dissolved Air Floatation (DAF) filtration system– to clarify the water was recommended.
The technique utilizes compressed air injected into a tank to form fine bubbles that attach to solid particles, such as the algae and other organisms that cause bad odor and taste. The substances float to the surface of the water and form a layer of sludge that can be easily removed and disposed of, leaving behind cleaner water.
Although DAF has been proven to be effective in other areas, the Tianjin Water Works wanted to ensure this would be the right solution for the Jie Yuan WTP.
In 2001, Earth Tech constructed a pilot plant just outside the city to conduct preliminary studies. Following the positive results from pilot tests, the water utility decided to become the first in Northern China to utilize a DAF process.
Largest application in world
The Tianjin Water Works and Earth Tech formed a joint venture to design and construct renovations to the Jie Yuan WTP. With a capacity of 132 million gallons per day (500 million liters per day), the refurbished facility has become of the largest treatment plants utilizing DAF in the world.
An international effort, the preliminary design for the project was completed while the detailed design was performed by the Tianjin Water/Wastewater Design Institute, a local design firm and a subsidiary of Tianjin Water Works.
Modernizing a century-old facility presented its own challenges and surprises.
For example, when construction began in 2002, underground pipes that were not shown on the blueprints were discovered. The pipes were inscribed with markings that showed that they were constructed in England in 1902.
Modifying an existing site also posed some difficulties. Like many urban water treatment facilities, the plant's location in the center of the city left no room for expansion and little room for storing materials or placing debris. In addition, as a vital part of Tianjin's water supply, the Jie Yuan WTP had to remain fully operational throughout the project.
The refurbishment project was done in phases to allow the upgrades to be done in an orderly fashion without interrupting service. The initial phases entailed foundation work, as well as renovating and constructing new facilities on the site.
Testing on the upgraded Jie Yuan WTP began in April 2006, with commissioning in May.
As part of the project, Earth Tech also assumed responsibility for the operation and maintenance of the Jie Yuan WTP and its employees for 20 years. The operations staff needed to be trained to use of the DAF filtration system and the imported monitoring and analysis equipment that was being installed at the facility so they could operate and manage the plant efficiently.
The new monitoring and analysis equipment will allow the staff to optimize the use of chemicals, reducing their use by about 30 percent.
In addition, these tools will minimize unwanted water discharge; prevent the release of toxic chlorine and ammonia gases; and provide online operational data that will allow the employees to analyze and diagnose areas that need maintenance, allowing them to decrease breakdowns and respond quickly using scientific information to respond if they do occur.
Training on the new systems was conducted on-site, however, some key plant operators were also flown to Earth Tech facilities in the United Kingdom and Australia so the Chinese engineers could gain first-hand experience with the technology.
Working together, Earth Tech and the Tianjin Water Works were able to successfully introduce the western DAF technology into China. As a result, the Jie Yuan WTP stands as a model for other urban centers throughout China and the region that are dealing with the same water pollution issues that Tianjin faced just years ago.
