Solid and Hazardous Waste Management

Different types of waste and their origins

Type of waste	Their origin
Municipal waste	Households and buildings: sewage, garden trimmings, paper, plastic, food, appliances, glass
Commercial waste	Businesses and factories: paper, glass, cans, construction, food, plastics
Hazardous waste	Labs, hospitals and industries: sharps, blood, blood products, laboratory wastes, pathological wastes, isolation wastes, animal carcasses, toxic wastes
Radioactive waste	Hospitals and nuclear plant: radium-226, radioactive nuclear medicine for treating cancer

Waste disposal can be classified according to their disposal methodology - normal disposal, disposal with special treatment, recyclable

Type (classification)	Normal disposal	Disposal with special treatment	Recyclable
description	Can be disposed into normal rubbish chutes A mixture of household items that can be incinerated or land filled	May be toxic, bio- hazardous, bulky, non-incinerable e.g. lab waste, construction waste	Can be sorted and recycled into other products or still be reused in its original form
Example	Floor sweeps, food waste and used cloths Reason: Because they can be disposed directly to landfill/incinerate then landfill or composting then used as soil conditioner	Used battery and used light tubes Reason: Because they contain toxic and hazardous metal and chemical such as Li, Cd, Hg, which is dangerous for environment	Cosmetic container (plastic) and used cloths Reason: Because they can be stored and recycled into other product or still be reused in its original form

The below diagram show a simple breakdown of how waste can be handled according to its characteristics. 

Incineration

• Incineration is able to reduce the volume of the waste by 90%; Waste are incinerable are incinerated before going into landfill, help to reduce the space it take up in the landfill.
• More suitable for waste with high calorific value ( the amount of energy released when object undergo combustion)
• Item such as glass, ferrous iron, which result cannot be incinerated (does not break down in elemental composition, remain as it is, after incineration)
• Waste with lower moisture content will be more likely to be incinerable (more energy released)
• Most waste can be incinerated and dispose into a landfill.

Importance of dealing with waste
Collecting, processing and disposing waste in land-scarce Singapore is expensive and resource intensive. We generate 4 kg/capita/day of waste. If not collected, it will accumulate and give out unpleasant smells, cause diseases, and Singapore will run out of space. Currently, our only landfill available is the Semakau landfill and there’s no other available land area for dumping.