Making Refinery Wastewater Clean

About four years ago, I visited Ordos, Inner Mongolia, to work on a project. When I arrived, all I saw was desolation. Rivers were dried up, lakes had shrunk, wetlands were destroyed, grasslands were shriveled. Yellow sand was ubiquitous, even within lake water. I had heard about the devastation in the arid region in China. Upon seeing all of this with my own eyes, however, I was still greatly affected and incredibly shocked.

It’s hard to imagine how life goes on in such a rough environment, let alone how industry can move forward. I realized that some drastic changes must take place to enable development in this bleak environment. Making the best use of the existing water resources would be a breakthrough.

Refining water to produce fresh water
Petroleum refineries are complex systems involving multiple operations that depend on the type of crude oils refined and the desired products. Refineries also can generate a significant amount of wastewater that has been in contact with organic materials. With a shortage of fresh water in most areas of the world, and the requirements for relatively high volumes of raw water in a refinery, refinery wastewater treatment and reuse are becoming an important option as water cost increases.

We are facing major challenges in refinery wastewater treatment and reuse: (1) MBR permeates COD concentration for reuse (<30/50ppm), especially for recalcitrant COD removal; (2) shock loading on the performance of biological system and its recovery; (3) stability of membrane performance and membrane fouling. These organics have become an obstacle to more stringent discharge regulation and water reuse.

A solution lies in figuring out an economical and effective way to reuse industrial wastewater, especially in developing cities.

Lei_Wang_photo1
Engineers working at the pilot site at PetroChina Changqing Refinery

Thanks to years of dedicated effort, we have the capability to face these challenges by industrializing and commercializing technology that is based on GE’s product line. Our team successfully launched the MACarrier*  to solve the most challenging problems of recalcitrant organic removal for water discharge and reuse. MACarrier has a huge bacteria-friendly surface area on which dense and strong biofilm can quickly form. In addition, MACarrier can adsorb and pre-concentrate the residual recalcitrant organic compounds in the mixed solution. The pre-concentrated organic compounds can be much more effectively biodegraded by the biofilm, thanks to its higher organic concentration and longer contact time. Self-bioregeneration occurs constantly on the MACarrier surface, where it can continue to adsorb and pre-concentrate the recalcitrant organic compounds. It also helps to attenuate the toxicity of the wastewater to the biological system.

The pilot test of the MBR with MACarrier included different phases to enhance COD removal. In more than two years of continuous studies in China, Russia and Brazil, MBR with MACarrier further reduced the recalcitrant COD in the effluent by more than 50% over the conventional MBR. It also demonstrated better tolerance to shock loading and maintained stable membrane performance under various upset conditions with attenuated membrane fouling. This proactive effort of the technology team is paying off.

Lei_Wang_photo2
Pilot equipment arriving at the site

In short, our idea derived from an old military concept— a team effort is better than an individual struggle, and “group think” is better than any single solution.

 

*A trademark of General Electric Company. May be registered in one or more countries.

 


2 Comments

  1. Atoosa Hosseini Nejad

    Dear Mr.Wang
    How can we use your expertise to reduction of COD in gas refineries.

  2. Berdj Rassam

    Wastewater reuse continues to be researched and improved; hopefully one day they can refine the process to one much safer than it is today so the use can be expanded.