Tuas South Incineration Plant - Waste Disposal in Singapore, Nov. 2004.

Tuas South Incineration Plant - Waste Disposal in Singapore.
November 10, 2004

Away from the residential area, TSIP is located within the Tuas Industrial Estate, south west of Singapore

At present, Singapore’s solid waste disposal infrastructure comprises four incineration plants and an offshore landfill. 92% of the 2.51 million tonnes of waste that was disposed of in 2003 was incinerated while the remaining refuse was land filled.

Augustine Anthuvan visited the Tuas South Incineration Plant (TSIP)recently to take a first hand look at Singapore's largest state-of-the-art plant that is not only energy efficient and reliable but has also been hailed as one of the most environment friendly as well.

Have you ever wondered where your garbage ends up after the truck picks it up from the your housing estate or the curb side of your landed property?

Well, here in Singapore, it ends up at one of the four incineration plants located around the island.

And despite the aggressive promotion of waste minimisation and recycling programmes, more than two and a half million (2.51 million) tonnes of refuse was collected and disposed of in 2003.
Of that, a little under 60% (57.3%) was generated from residential premises, food centres and markets, with commercial and industrial premises accounting for the remaining 40-odd percent (42.7%).
Which works out to about an average (in 2003) of one kilogramme (0.94 kilogrammes) of domestic refuse being generated per person per day. And while you mull over those numbers, over the past few decades, it has become increasingly expensive to construct, operate and maintain incineration plants and landfill.

Way back in 1979, it cost only S$130 million to construct an incineration plant while the fourth plant that was completed in 2000 cost about S$890 million.

But for land scarce Singapore, there was no alternative. The volume of refuse had to be reduced and with these four incineration plants together achieving 90% reduction, it made a big difference for a tiny island nation like Singapore.

Which is why, when the government decided to go for its fourth incineration plant, careful planning went into the design - the end product - not only is the Tuas South Incineration Plant the largest refuse incineration facility in Singapore, (the Ulu Pandan Refuse Incineration Plant was built in 1979, the Tuas Incineration Plant was built in 1986 and the Senoko Incineration Plant was built in 1992), it is also one of the largest in the world.

Designed to incinerate 3,000 tonnes of refuse daily, the plant incorporates modern state-of-the-art technology in combustion controls and flue gas treatmen, such as the use of Electrostatic Precipitators and Catalytic Fabric Filters, to control the emission of smoke, dust and other pollutants for compliance with the Environmental Pollution Control (Air Impurities) Regulations. It even has its own Reverse Osmosis (RO) water reclamation Plant, (using continuous micro-filtration and advanced membrane technology) that converts industrial water and rain water (collected in large underground reservoirs) into ultra pure water for boiler use, thus conserving (PUB) potable water usage.

Even the heat generated from the incineration process is recovered from six incinerator-boilers and is used to generate electricity via two steam turbo generators. The Plant consumes about 20% of the 500 million kWh of electricity generated annually to run the Plant and the remaining excess power is sold to the Singapore New Electricity Market.

Augustine Anthuvan visited the Tuas South Incineration Plant recently. Described as one of the largest in the world, it stands on an area of reclaimed land approximately 10.5 hectares. The plant has been built with state of the-art technology and to tell us more about this is Mr Poh Soon Hoong, the General Manager of the Tuas South Incineration Plant which is managed by the National Environment Agency (NEA).

Now usually these plants have heavy truck traffic, how have you gotten around this issue and made it less imposing on the local community? “During the planning stage for Tuas South Incineration Plant, we have together with the Urban Redevelopment Authority deliberately site the incineration plant in Tuas Industrial Estate away from residential areas. The nearest residential area from Tuas South Incineration Plant is Jurong West and it is about 10 km away. Hence, the heavy traffic of refuse vehicles at the incineration plant does not have an impact on the local community”.

What about hazardous wastes and unburnable materials, are they removed before solid wastes are incinerated?

"Tuas South Incineration Plant is designed to incinerate primarily wastes from the households, trade and commercial premises. The incineration plant is not designed to handle hazardous wastes. We would like to inform your listeners that the Pollution Control Department of the National Environment Agency has already put in place legislation and an enforcement regime that require industries to segregate their hazardous wastes and these wastes are disposed of by special dedicated licensed hazardous waste facilities operated by private companies”.

Flue gas from the combustion process is cleaned in the flue gas treatment system and finally dispersed through these tall chimneys

Incinerators release into the atmosphere toxic substances such as dioxins, mercury (mostly from batteries), and easily inhaled fine particles of heavy metals such as lead and cadmium (from plastics). So talking about environmental standards, how do you clean up these gases before they're dispersed into the atmosphere?

"In all our four refuse incineration plants at Ulu Pandan, Tuas, Senoko and Tuas South, we have installed sophisticated combustion control and flue gas treatment systems to scrub the flue gases. Flue gases are gases that are formed whenever we burn any substances and the flue gas are passed through the chimney before releasing to the atmosphere. The systems remove dust particles, acid gases, dioxins and other pollutants before the flue gases are emitted from the incineration plants into the atmosphere via tall chimneys. We also monitor the emission of the flue gases continuously and the monitoring results had so far shown that they are within the limits for air pollutants prescribed in the Environmental Pollution Control Regulations”. Could you tell us what sort of training do the supervisors and operators have to go through before handling such sophisticated equipment?

The plant's processes are monitored and controlled by the Digital Control System (DCS) in the Central Control Room

“Our operations staff are all from the engineering and technical background, with qualifications such as engineering degrees, technical diplomas or ITC / NTC certificates. They have to undergo on-the-job training (OJT) for 6 months to a year before they are able to operate the equipment
By the way, we are also one of the ITE Certified Centres for On-the-Job-Training".

What does this incineration plant actually run on?

“Refuse is actually the fuel for incineration plants. We only use a small amount of diesel to heat up the furnace for a short period during start-up of the incineration process. Once the refuse is ignited, they will burn continuously by itself. The incineration is non-stop operation on 24 hours daily”

Right so the heat from combustion is used to generate steam in boilers, which in turn drives the steam turbines to produce electricity. And this electricity that's being produced, I understand the plant consumes part of it and actually sells the surplus?
“The heat from the incineration of refuse is recovered to operate turbo generators to produce electricity. Tuas South Incineration Plant generates about 80 MW of electricity, 20% of which, is consumed by the plant and the surplus is sold to the Singapore National Electricity Market. All in, the four incineration plants supply about 2% of the total electricity consumption in Singapore”.
Even though its intense heat and all, I'm sure there is still some scrap metal that’s going through this process, do you remove that from the incineration process and if so, does this get recycled in some way?
“Yes we do recycle scrap metal. Now the combustion temperature at 1000 degrees C is not sufficient to melt ferrous metal. The metal is recovered by electromagnets for sale to a steel mill in Singapore. Last year, for example, the four incineration plants recovered a total of about 23,000 tonnes of scrap metal for recycling”.

From my research, I understand incinerators produce residues that include about 90% less toxic bottom ash and then there is a small percentage of fly ash. Perhaps you can explain to our listeners the difference between the two and what happens to this ash?

"The incineration plants produce incinerated bottom ash or in short we call it IBA and fly ash. Bottom ash are ash and slag that remain after the main burning in the furnace. Fly ash are dust particles as well as the lime that we inject into the flue gas to remove acidic gases, together they form the fly ash. These ashes are not considered toxic and they are currently disposed of at Semakau Landfill. We have successfully processed IBA and used the processed IBA to construct a trial 150m stretch of road in Jalan Buroh as a pilot trial project. Currently, some private companies are exploring the commercialization of processing IBA as road paving material. Studies are also being carried out to use IBA for land reclamation projects. As for fly ash, these are only about maybe three to four percent of the ash generated, tests are also being conducted to process the fly ash into paving blocks as well as bricks”.

As Singapore reconciles with the fact that one island - Pulau Semakau - has already been set aside as an offshore landfill site to meet Singapore's needs till 2030, it is nevertheless a stark message that this island nation has its limits. So what would you like to say to our listeners in closing on the issue of waste management?

“For long term sustainability in our waste management strategy, we need to strive towards "Zero Landfill" and towards "Zero Waste" - that is minimising wastes that end up in the landfill and reducing waste generation. Everyone, both residents and the industries, can play their parts in recycling, reusing and reducing wastes at source”.

When the Tuas South Incineration Plant was officially opened in 2000, there were already plans for the fifth incineration plant to come on stream by 2006.

It is worth pointing out that if the amount of waste that Singapore continues to produce everyday continues to increase, then Singapore by the year 2030, would need ten incineration plants to dispose of its daily waste.

As each plant takes up about seven hectares of land and costs about a S$1billion to build, it may not be the best use of Singapore’s limited land and resources.

Which is why for a city state like Singapore, there is a limit to its long-term capacity in waste disposal. In the end the best option would be to minimize the generation of waste and maximize the reduction, reuse and recycling of waste.

Only then can Singapore succeed in sustaintaining itself as one of the most environmentally friendly nations in the world for a long time to come.