Disposal of laboratory waste

1. Disposal of specimens and contaminated material 

Any clinical material brought into the laboratory and any apparatus used to handle this material must be considered as infectious. To avoid laboratory accidents, make sure that priority is given to correct handling and disposal of specimens and contaminated material. 

2. Incineration of disposable materials 

Making an incinerator (Fig. 3.70) 

An old metal drum is suitable for this purpose. 

1. Fix a strong metal grating (G) firmly about one-third of the way up the drum. 

2. Cut a wide opening or vent (V) below the level of the grating. 

3. Find a removable lid (L) for the drum.

Using an incinerator 

● At the end of each morning’s and each afternoon’s work, place all used stool and sputum boxes on the grating of the incinerator (Fig. 3.71).

Fig. 3.70 Components of an incinerator G: metal grating; L: lid; V: vent.

Fig. 3.71 Using an incinerator

● Always keep the metal drum tightly closed (both lid and vent), except during incineration. 

● Incinerate once a week, or more often if necessary. Fill the bottom of the drum with paper, sticks, wood shavings, etc. 

● Remove the lid. Light the fire and keep it burning until all the infected material has been reduced to ashes. 

● The ash produced is not dangerous and can be thrown on the refuse heap.

3. Burial of disposable materials 

Dig a pit 4–5 metres deep and 1–2 metres wide at a location where neither groundwater nor surface water can enter and where leaching of waste liquids into the groundwater cannot occur (Fig. 3.72). A pit must never be constructed near a water source. 

Make a lid that fits tightly over the pit. It is advisable to strengthen the upper rim of the pit by lining it with bricks or stones. 

● The pit must be protected from animals, birds and humans. 

● Throw stool or sputum boxes and other infected material into the pit twice a day. Replace the lid immediately. 

● Once a week, cover the refuse with a layer (about 10 cm thick) of dried leaves. 

● If possible, instead of using dry leaves add a layer of quicklime (calcium oxide) once a week.

Fig. 3.72 Disposal of materials by burying