Recently a local citizen filed a complaint to the Government Environmental Protection Department (EPD) regarding the white foam along the shore of our campus. This person was obviously concerned about the adverse impact to the environment, and suspected that the foam was originated from discharge of our swimming pool.

Those of us who have been around long enough may remember quite a while ago, to explain an apparent increase in shark attack/spotting incidents at Silver Strand Bay and nearby areas, the local media published a postulation that due to "wastewater discharge from HKUST campus", there was a nutrient-enriched marine environment around Port Shelter, causing marine organisms to flourish, and eventually attracting more top predators—sharks to frequent this part of the coast.

Of course, both the suspicion and postulation were proven to be not true. The foam is due to discharge from our seawater cooling system. Using seawater for cooling is a common practice both locally and in other countries, and foaming has frequently been a "by-product" that is associated with this type of operation. A few months ago, a team of technical personnel from a power plant in Malaysia visited our campus and other local organizations, precisely to learn about our practices and experience in controlling foaming of cooling seawater discharge. Since the purpose of seawater used for cooling is only to carry heat away, it is not in contact with any pollutants or chemicals, except for a small amount of biocide and chlorine to prevent marine microorganisms from growing inside and clogging the inlet, outlet and heat exchange piping system. The biocide was approved by EPD, and the amount of biocide and chlorine allowed in the outgoing seawater are controlled by a discharge license issued to HKUST by EPD.

The foam is mainly a result of agitation of water, which contains protein and other naturally occurring and foam-generating substances. This is a picture of the Niagara Falls, and the extensive amount of foam downstream from the waterfalls. In our case, before the cooling seawater leaves our Sea Water Pump House, where the heat exchange takes place, it also passes through a substantial drop, similar to a water fall, although it is within a pipe. Therefore when the seawater reaches the outfall on the seawall, a considerable amount of foam is formed. The foam will naturally dissipate with time, but it does create an eye sore, and an occasional misunderstanding as mentioned above. The bottom line is, and to quote EPD in their reply to the recent complaint, the foam is "normally short-lived and non-toxic."

Different control measures have been applied by Facilities Management Office (FMO) since the early days to reduce this foam. These included various devices to retain or break up the foam, a more successful attempt was an underwater retention chamber made of metal plates. For an extended period of time, the foam was well under control. Unfortunately with the aging of the outfall, the submerged plates that were attached to the concrete outfall were repeatedly pulled off by forceful current, especially during typhoon seasons, and it was afraid reattaching the metal plates again may damage the aged and weakened concrete structure of the outfall itself.

The latest attempt by FMO was a metal mesh at the mouth of the outfall, which has been proven to be effective in retaining the bulk of the foam, but it leaves a thin, yet still very conspicuous, layer of fine bubbles. FMO colleagues are still working to improve on the current foam containment measure. It is hoped that with the additional work, the foaming situation will see substantial improvement by the end of this year.