chapter 5

According to a study completed by the Macao Water Supply Co. Ltd. in 2003, the hotel sector in Macao consumed 4,779,685 m³ of water which was about 9.3% of Macao’s total annual water consumption. Approximately 90% of the consumed water becomes trade effluent discharge. Hotel water consumption depends on many factors, such as location, size, class, occupancy and age of the facility. Guest rooms and in-house laundry operations use the most water in hotels, followed by kitchen and general operations.

Sources of Hotel Wastewater

The following process steps are the main sources of wastewater generation in a hotel:

• Laundry and dry cleaning: laundry schedule, laundry engineering, washing machine operation.

• Kitchen: Food preparation, cooking activities, cleaning cooking and dining utensils, cleaning kitchen, e.g. floor washing.

Why Conserve Water ?

In general, a water conservation programme can help achieve a 25 to 30% reduction in water bills, with no loss of comfort to guests. Many of the water conservation measures have relatively short payback periods. Every litre of water saved means less water is drawn from natural sources and reservoirs, less wastewater is discharged and less energy is required to deliver and process water. Water conservation also helps cut down emissions from power and wastewater treatment plants.

Ways you Can Help

A hotel that has a good water management programme will use as little as half the volume of water per guest per night than a hotel that has a few manual or automated controls on water usage. The most widely tried are listed below :

a. Engineering and Maintenance

• Install water-saving shower heads (<10 litres per minute) in guest baths, public baths, employee baths and pool showers.

• Install low-flush toilets with a maximum flush volume of 6 litres or toilets with 2 selectable water flushing volumes in guest baths, public baths and employee baths.

• Install flow restrictors on water taps of sinks, self-closing faucets or sensor-controlled faucets in guest baths, kitchen sinks, public baths, and employee baths.

• Have an effective system of detecting and reporting leaking toilets and faucets quickly and efficiently.

• Have a preventive maintenance program for routine maintenance of air conditioning and plumbing fixtures, kitchen equipment and laundry equipment.

• Install a flash steam vessel to recover steam condensate and return it to boiler.

• Modify the plumbing installation so that grey water is recovered, treated and then stored in a separate tank for toilet flushing, which may yield water savings of around 30%.

b. Guest Rooms and Other Guest Facilities

• Install push button taps which are timed to give shorter showers in swimming pool changing rooms.

• Consider the feasibility of vacuum toilets, as used on aircraft and trains, that use less than two litres of water each flush.

c. Housekeeping and Laundry

• Provide signs in the laundry to inform the staff of how much laundry can be washed in each machine.

• Have a regular preventive maintenance programme for all laundry equipment, including checking seals on dryer doors and balancing washer drums.

• Minimise the amount of suds, bleach, and rinse operations without reducing quality standards so as to reduce the total cycle time of laundry.

• Consider installing a holding tank to capture the final rinse water from clothes washers to reuse as the wash water in the next wash cycle. Flush the final tank of the day to clean the system.

• Make an all-purpose cleaner by mixing together one third of a cup of ammonia, a third of a cup of soda crystals and 4 litres of warm water, e.g. clean baths and basins.

d. Restaurant and Kitchen

• Design and install grease traps properly to effectively remove the grease and oil from wastewater.

• “Segregate” different streams of wastewater. For instance, wastewater from thawing or cleaning vegetables can be used for floor cleaning.

• Use hot water to pre-rinse dishes before washing, so as to reduce the consumption of detergent. Alternatively, use a dish-washing machine, which can control the use of water and detergent.

• Use removable strainers in washing basins to trap solid grease and other waste.

• Never pour used cooking oil into drains or toilets. Waste oil should be collected in suitable containers and delivered to licensed waste oil recyclers.

• Put oil filters into kitchen drains to prevent grease and oil from entering the sewer. Replace the filters regularly.

• Check for any obstruction in kitchen wastewater drainage and grease trap piping daily.

• Select automatic dishwashing detergent with at least one of the features: products without chlorine bleach; products where NTA (nitrilotriacetic acid) is a component; products with minimal amounts of phosphates; concentrated products.

• Study the feasibility of using “fat-digesting” enzymes in septic tanks, drains and pipes.

e. Landscaping

• Use “recycled” water if possible. Greywater from air-conditioning condensing water, baths, sauna pool and laundry can be used for watering plants and lawns.

• Choose native plants and flowers. They are more adapted to the local environment and require less water, pesticides and other care.

• Sprinkle lawn surfaces with peat moss, wood chips, cocoa hulls, hay or pine needles to cover the ground and reduce evaporation.

• Use slow-watering techniques such as trickle irrigation or soaker hoses. Such devices reduce runoff and are more effective than sprinklers.

• Carry out watering of vegetation in the morning or evening to prevent excess evaporation.

• Moisture sensors located in strategic parts of the grounds will call for water only when the ground needs it. Attach shut-off devices that activate when it rains.

• Use electronic controllers with precise individual timing, multi-irrigation zones and cycles, where appropriate.

Box 5.1 – Conductive Thawing Technique for Kitchen

This technique uses circulating water as the medium for heat transfer for meat defrosting. Meat is pre-packed in plastic bag and is immersed into the thawing tank containing circulating water. After the thawing process, the water is heated up and pumped back into the thawing tank for reuse. This can result in speedy, water-saving and thorough thawing effects.

Advantages:

• Decrease water consumption and greatly reduce wastewater generation - this technique can save 98% of the water and sewage charges when compared to the use of continuous running water for thawing.

• Accelerate thawing process and increase production – 6 times faster than the traditional thawing method.

• As the conductive thawing system is equipped with automatic control, it is easy to operate and does not require formal staff training.

Disadvantages:

• If the food does not have its own packaging, additional plastic bags are needed.

Box 5.2 – High-frequency Wave Thawing Technique for Kitchen

This technique makes use of a 13-GHz radio wave to radiate the frozen food placed between two electrodes. The food molecules, polarised by the radio wave, vibrate and heat thus achieving the thawing effect. This method uses the dielectric heating principle; food is heated up evenly and no wastewater is produced.

• Meat can be heated evenly, thereby reducing the chance of contamination and bacteria growth while maintaining the quality of meat.

• Can thaw meat evenly in a short time, and raise the temperature to about -4�C.

• Meat at temperatures around -4�C is easiest to cut and chop. This temperature is also optimal for food processing.

Disadvantages:

Box 5.3 – Ozone Laundry System

This technique uses ozone, in its role as a powerful oxidant and biocide, to assist in the cleaning of a wide range of fabrics and clothes. Ozone is generated on-site at the point that it is to be used. Leftover ozone turns into oxygen.

Advantages:

• Can reduce water and wastewater by 60-75% if rinse water is filtered and then reused in the system.

Case Studies

a. Case Study 5.1 – A Hotel in Seoul, Korea

Since June 1999, a hotel in Seoul, Korea has been saving an average of 100 tons of water a day. An “ultrafiltration wastewater reusing system” enables the hotel to reuse wastewater from guest room baths and basins to flush the toilets in guest rooms and public areas.

The system costs 339,400,000 Won (US$308,545) but it is saving 120,000,000 Won (US$109,090) a year in city water, electricity and other maintenance charges. The hotel expects the payback period to be no longer than four years.

The hotel received the “Water Saving 99” Grand Prize jointly awarded by the Hankuk Daily Newspaper, the Korea Federation for Environmental Movement, the Citizen’s Alliance for Consumer Protection of Korea, the National Council for Consumer Protection of Korea, and the National Council of YMCAs of Korea.

(Source : Green Hotelier, issue No. 19 July 2000)

b. Case Study 5.2 – A Hotel in Hongkong, China

After experimenting with devices such as plastic flow restrictors, a hotel owned by a Japanese company in Hong Kong installed a calibrated water control system, the "Platypus System". The core element of this system is a compact valve, which is inserted into the hydraulic system to control the flow and temperature balance of each tap or shower. The correct type and size of valve is chosen for each tap or shower, depending on factors such as the required water temperature, pressure and flow rate. The advantages of this system are :

• water flow is constant, flow fluctuations from each tap or shower are eliminated;

• changes in water temperature are eliminated;

• water hammer, velocity noise and splashing when taps are turned on, are substantially reduced;

• filters improve the quality of the water delivered to guests.

Despite an average occupancy increase of 4% over the previous year, water consumption per guest decreased by an average of 13%, equating to save HK$13,000 (US$1,688) per month. (Note: This figure could be as high as 30% as it does not include water consumption for laundry).

Since the installation of the water control system, consumption of hot water has fallen and the use of fuel for the hot water boilers has decreased by an average of 4% or 2,000 liters per month, correspondingly. These amounts reduce approximately HK$5,600 (US$724) in fuel costs.

(Source: Environmental Good Practice in Hotels: Hong Kong)

c. Case Study 5.3 – A Hotel in Jiangsu Province, China

In recent years, a hotel in Jiangsu Province, China has built a sewage treatment station with a capacity of 1,500 tonnes per day and uses some of the effluent to irrigate its large gardens.

(Source: A Hotel in Jiangsu Province, China)

d.Case Study 5.4 – Hotels in Macao, China

(Photo 5.12) One hotel in Macau has installed a wastewater treatment system.

One hotel has installed a wastewater treatment system. The system mainly involves a set of rotating biological contactors and other physical-chemical methods to treat the wastewater to meet the required discharge quality. Part of the treated wastewater is reused for lawn irrigation and for fish pond use.

45% of hotels indicated that they installed water-saving features on faucets while 31% claimed they had installed low flush toilets or placed a bottle inside the cistern of the toilet to reduce flushing water volume.

Respondents also reported adopting the following water conservation measures:

• lower the water level of toilet flush tank;

• adopt high pressure water jet for floor cleaning;

• install individual sub-meters to control water consumption;

• reuse pool water for floor cleaning;

• establish policy that washers are used only with full loads.

(Source: Macao Hotel Environmental Survey in 2003)

Chapter 5 : Money Down the Drain

Sources of Hotel Wastewater

Why Conserve Water ?

Ways you Can Help

a. Engineering and Maintenance

b. Guest Rooms and Other Guest Facilities

c. Housekeeping and Laundry

d. Restaurant and Kitchen

e. Landscaping

Box 5.1 – Conductive Thawing Technique for Kitchen

Advantages:

Disadvantages:

Box 5.2 – High-frequency Wave Thawing Technique for Kitchen

Disadvantages:

Box 5.3 – Ozone Laundry System

Advantages:

Case Studies

a. Case Study 5.1 – A Hotel in Seoul, Korea

b. Case Study 5.2 – A Hotel in Hongkong, China

c. Case Study 5.3 – A Hotel in Jiangsu Province, China

d.Case Study 5.4 – Hotels in Macao, China