Aircraft toilets
Happy landings in Hong Kong

By Sally Tse
     Public toilets are often dirty, malodourous places. Some people might rather postpone answering the call of nature than to visit public toilets.
     However, this situation may change in the future.
     Vacuum toilets, which have been used only on aeroplanes in the past, are now being installed on land.
     The first and only vac-uum toilet in Hong Kong has been placed in Ta Kwu Ling in the New Ter-ritories.

     Sally Tse
 
    Aircraft toilet (above), and its cousin, adapted for Hong Kong.
     The in-stallation of this vacuum toilet can be traced back to December 1996. After a year’s free trial provided by its German supplier, the system was approved the Provisional Regional Council in November last year.
     Mr. Law Kai Chung, staff officer of the Regional Services Department’s cleansing unit, explained the purpose these “aircraft toilets”.
     “The system was selected to improve the condition of public toilets in areas where there is a lack of flushing water due to the absence of a government sewer,” said Mr. Law.
     Vacuum toilets work like those installed in aircraft.
     An electronic sensor is installed near the entrance of the toilet. Whenever it senses the presence of a user, it goes into stand-by mode. After each use, water is released from the rim to rinse the contaminated toilet pan.
     A valve in form of a sliding gate opens automatically and the contents are sucked by a vacuum pump into an intermediate tank. Upon the closing of the valve, the intermediate tank is pressurized.
     Soon after, a second valve opens and the contents are expelled through pipes to septic tanks for biological disintegra-tion.
     The whole process is triggered by a simple step on the foot pedal in front of the toilet pan.
     Apart from the environmentally friendly benefits of saved energy and water, vac-uum toilets are credited for min-imizing odours and the growth of insects and bacteria.
     Not only do users benefit from the new toilet system; the crew who clean the toilets also benefit.
     “The clean-up work is much easier because toilet pans are rinsed automatically each time after use,” said Mr. Law.
     Technicians are required to service vacuum toilets, which cost $39,500 each.
     “Maintenance requires expertise in electronics and mechanical engineering,” said he. “The Electronical and Mechanical Services Department has been giving professional advice to us on the system.”
     However, 30 complaints were received within the first 10 months of the trial period.
     Mr. Cheung is the owner of the Man Fung Store at Ta Kwu Ling.
     “It was out of order for nearly 29 days each month,” said Mr. Cheng.
     “Not every user knows what ought and ought not to be thrown into the toilet pans,” he said.
     “Technicians from the Regional Services Department asked us not to wet the machinery and avoid using three out of the existing five toilet pans at the same time,” he said. “These are all ridiculous.”
     But Mr. Cheung said the situation has been greatly improved.
     “Inspectors from the department check the toilet pans every day. Whenever problems arise, the case is soon looked into and repair work is done quickly.”
     Mr. Kwong Sik Chiu of the Kwan Ti Vegetable Marketing Co-operative Society is a frequent user of the vacuum toilets.
     “The government is paying much attention to the toilet now because it is the first one. Complaints and break downs are therefore handled swiftly.”
     Though he appreciates the improvement, he is doubtful the maintenance in the future will be as efficient as it is now.



 Breathless in HK




January 1998

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