Where should waste water from restaurants be discharged into – public foul sewers or storm drains ?
Waste water from restaurants must be discharged into public foul sewers and not into storm drains as the discharge of restaurant waste water into storm drains is illegal. According to the Water Pollution Control Ordinance, restaurants should be granted valid Discharge Licence. Licence application forms are available free of charge from various offices of the Environmental Protection Department or can be downloaded from the EPD website. Submission of forms must be accompanied by the photocopies of applicants' business registration certificates or certificate of incorporation and recent water bills or information for the assessment of water consumptions. The validity of licence is normally 5 years.
What is Sewage Charge? What is Trade Effluent Surcharge ? How are they calculated ?
The sewage charge is calculated by multiplying a unit rate and the number of cubic metre of water supplied by the Water Supplies Department. Occupants of all premises connected to public foul sewers are required to pay sewage charges.
The trade effluent surcharge is determined by the quality and flow rate of waste water discharged. Specific trades (including the restaurant trade) need to pay trade effluent surcharges in addition to sewage charges as the pollution level of their discharged waste water far exceeds that of the domestic premises. The pollution level is indicated by the Chemical Oxygen Demand (COD) values (i.e. CODtotal and CODsettled).
For the restaurant trade, the sewage charges are based on 70% of the water supplied to them, water used for flushing purposes being excluded from the calculation (Note 1). Furthermore, the calculation of the trade effluent surcharges are based on 80% of the water supplied to account for the water consumed in the production process and therefore is not discharged into the public sewers (Note 2).
Note 1 : Sewage charge for restaurant = Water supplied in cubic metre x 70% x Sewage charge rate.
Note 2 : Trade effluent surcharge for restaurant trade = Water supplied in cubic metre x 80% x Trade effluent surcharge rate.
What are the measures and methods for the effective improvement and control of waste water?
Waste water discharged by most restaurants contains an excessive amount of oil and grease, leading to water pollution problems. To effectively control water pollution, it is essential to reduce water consumption and properly handle food waste and waste oil, such as to use hot water to pre-wash bowls and dishes, minimize the use of detergents, avoid using excessive cooking oil and handle food waste and waste oil separately. Furthermore, the installation and use of grease traps can also help. Grease traps can effectively separate oil and grease from waste water, allowing the lighter oily substances to be afloat and the heavier substances to remain in the grease trap. (For details on grease traps, please refer to the "Grease Traps for Restaurants and Food Processors" booklet published by the Environmental Protection Department.
Other control methods : By electrolytic means, electroflocculation introduces coagulants into waste water to remove suspended solids and emulsified oil droplets; Biochemical solutions are mixtures of enzymes and micro-organisms which multiply under suitable environment, feed on oil and grease and turn them into water, carbon dioxide and other harmless substances.
How can cooking fume and odour emissions be effectively controlled and reduced?
| (1) | Grease Filters (Metallic wire mesh or fine polymer fiber mesh grease filters) |
| Both can remove relatively larger oily droplets in fumes and can be used as preliminary treatment. | |
| (2) | Electrostatic Precipitators (Hood type and duct type) |
| Electrostatic precipitators employ static electric fields to remove fume. They are ideal equipment for the control of fumes as they can effectively collect minute oil droplets with the removal efficiency of up to or above 90%. | |
| (3) | Hydrovents (Also called water spray hoods or water curtains) |
| Hydrovents are usually used with air washers. When fumes come into contact with water curtains, the oil droplets in them are carried away by the water flow. | |
| (4) | Venturi and Packed Tower Scrubbers |
| Venturi scrubbers operate by accelerating fumes and scrubbing liquid stream through a constricted throat where the high velocity of the streams causes a violent turbulent contact between them, capturing the oil droplets within the scrubbing liquid. Packed tower scrubbers remove fume by absorption as stream of scrubbing liquid is sprayed on the fume laden gas stream. The packed tower scrubber is filled with specially design packing materials to increase the contact surface area between the scrubbing liquid and the kitchen exhaust gas stream. | |
| (5) | Activated Carbon Filter |
| Activated carbon filters contain activated carbon particles with very large surface areas capable of adsorbing odorous compounds. They are very effective in eliminating organic volatile compounds and odour. |
For details, please refer to the "Control of Oily Fume and Cooking Odour from Restaurants and Food Business" booklet and Cooking Fume Emission Control for Restaurant and Catering Trade (Leaflet), published by the Environmental Protection Department.
How can noise problems be addressed?
Cooling towers and air-cooled chillers should be installed away from domestic premises and schools. As far as practicable, exhausts of ventilating systems (such as exhaust fans and etc.) should avoid directing at domestic premises and should be fitted with silencers.
For details, please refer to the "Good Practices on Pumping System Noise Control" and " Good Practices on Ventilation System Noise Control" booklets published by the Environmental Protection Department.
How to handle wastes from restaurants?
The restaurant trade is one of the major sources of massive amount of wastes. Wastes from the restaurant trade can be categorized into paper, cans, food waste and so on. The proper treatment of restaurant wastes requires the adoption of correct waste reduction measures : (1) reduce waste volume, reduce consumption of water, detergent and paper napkins; (2) select re-useable products, properly collect food waste and used cooking oil for re-cycling; (3) practise waste separation – segregate different kinds of wastes for recycling. Restaurant can consider collect food wastes for treatment into fertilizers (i.e. composting) using a composter to provide a suitable environment for bacteria to decompose and ferment food wastes into organic fertilizers.
How to handle grease trap waste?
For small grease traps (eg. those installed under individual sinks), the grease trap waste can be removed manually by scooping it into watertight plastic bags and disposed of together with other kitchen refuse. For large grease traps(e.g. centralized underground grease traps), restaurants and food processing factories should employ reputable collectors to collect the grease trap waste for proper disposal and maintain record of the services.
Enquiry and hotline numbers for the restaurant trade:
| Compliance Assistance Help desk: 28383111 (press “5” after language selection) Please click here to download the leaflet |
| Restaurant complaint hotline: 1823 Citizen's Easy Link of the Government |
| Enquiries and appeals to the the Drainage Services Department about sewage charges and trade effluent surcharges: |
| Customer Service Hotline of the Environmental Protection Department (Pollution Complaints) : |
| Enquiries about waste reduction and recycling: |
| Restaurant Licences (Food and Environmental Hygiene Department) Hong Kong & Islands Licensing Office: |
| Restaurant Licences(Food and Environmental Hygiene Department) Kowloon Licensing Office: |
| Restaurant Licences (Food and Environmental Hygiene Department) New Territories Licensing Office: |
| Restaurant Licensing Resource Centre (Food and Environmental Hygiene Department) : |
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