Reconcile petrochemical production and environmental protection in Chengdu

Capital of the Chinese province of Sichuan, Chengdu is a city experiencing strong economic and demographic growth, resulting in an ever-increasing consumption of natural resources. Preserving the environment and water resources is a crucial issue for PetroChina, which has to meet increasingly stringent standards specific to the petrochemical industry. China's largest oil company therefore tasked SUEZ with the design and build of an industrial wastewater treatment plant for its Chengdu refinery.
1/3
of Chinese watercourses are extremely polluted.
10
million tonnes
The quantity of oil processed each year by PetroChina's refinery in Chengdu.

Optimise the wastewater treatment process to promote reuse

In October 2009, SUEZ signed a contract with PetroChina for the design and build of a wastewater treatment plant with two main objectives: bring petrochemical industrial effluents into compliance with the most demanding standards; and recycle part of these effluents.

In 2010, SUEZ began built on the petrochemical site of a treatment plant combining the best available technologies, with several benefits:

Wastewater treatment without any risk for a sensitive environment

The Chengdu refinery discharges its treated wastewater into the Tuo River, a tributary of the Yangtze. It is therefore vital that PetroChina comply with all sanitary and environmental standards in force, in particular the level of Chemical Oxygen Demand (COD). Thanks to the combination of ozonation and biofiltration, SUEZ obtains high quality treated wastewater.

Stormwater and wastewater converted into process water

The new treatment plant comprises no fewer than five treatment processes on the same site, two of which concern the recycling of effluents and stormwater. This is the first installation of this size in China to use a wastewater and stormwater recycling system. It allows PetroChina to conserve water resources, the recycled water produced on site being used for the operational requirements of its refinery.

The results

In operation since end of 2013, the Chengdu water treatment plant is a benchmark for the implementation of the treatment and recycling of wastewater in China. 

SUEZ implemented state-of-the-art technology, Oxyblue®, which requires much less ozone and consumes less energy than traditional treatment processes. The plant produces treated wastewater of optimal quality thanks to the combination of two techniques: 

  • ozonation to oxidise organic matter;
  • biofiltration to complete the treatment. 


The treatment process removes more than 65% of non-biodegradable COD and allows the reuse of more than two thirds of the treated wastewater. 

Oxyblue for COD removal
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70
%
of wastewater is reused as make-up water in the plant's cooling towers.
67,000
m3
The daily wastewater treatment capacity of the Chengdu treatment plant.
2,500
m3
of recycled water produced every hour from the industrial effluents of PetroChina's Chengdu refinery.