Picking the Right Technology for Medical Waste Treatment

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Batch and continuous are the two Platonic ends of the process design spectrum. “Batch” means all processing and treatment is done to a given mass of waste together. No new waste introduced until the process is complete. The batch process may take place at one physical location or the waste mass may be moved between process steps. "Continuous" means new waste is entering the process as treated waste exits; each bit of waste in the process has received a different amount of treatment from the other bits. Very large industrial processes are often continuous - oil refineries, sewage treatment, paper plants. These can be very efficient processes. Batch processes are more often employed for smaller quantities of materials and for which continuous operations are not feasible. Of course, no process is purely continuous and often a system is "fired up" to create, modify, or treat a given mass of material; this is sometimes called "batchwise continuous" processing.

Medical waste treatment is usually batch.

Efficiency

Is medical waste treatment inefficient?

Yes, probably, but mostly because too much waste is classified as infectious. This is caused largely because the people who manage medical waste err on the side of safety The process of treatment – usually heat treatment/incineration is not necessarily inefficient.

Condensers

Upsides

• Can recover condensed material that might be useful
• No need to add material to waste stream

Downsides

• Hard to get pollutants down to very low levels just by condensing
• Coolant system cost (capital and operating) and complexity

Combustion

Upsides

• Simple, can destroy a lot of chemical compounds
• Really efficient destruction of organic contaminants if operated correctly
• Generation of heat which can be useful.

Downsides

• High operating costs - fuel, personnel
• Hazards of playing with fire
• Potential for incomplete combustion and production of carbon monoxide and other hazardous chemicals such as dioxins

Evaporators

• Rising film evaporators - liquid enters at bottom of tube, goes up, like coffee percolator
• Falling-film evaporator - liquid flows down on inside of heated tubes or outside of heated plat
• Forced circulation evaporators - uses flash evaporation and forced circulation

See also air pollution control for medical waste incinerators.

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