RE: Incinerators for hospital waste - Answer

["Emmanuel de Broux" <EMM_DE_BROUX@msn.com>]

Violet, you wrote :
My country "Palestine" is facing a problem with medical waste where hospitals 
and medical centers are getting red of their waste with the municipal waste 
without treatment.  My Institute, The Applied Research Institute-Jerusalem and 
some hospital managers think to solve this problem by providing an incinerator 
to collect and incinerate the medical infectious waste.  I would be very glad 
if somebody send to me information on types, capacity, cost, operation 
expenses of incinerators for this purpose.

Violet : 
There is a clean solution to your problem, infinitely cleaner than 
incineration which you should be forgotten in this case. The solution is 
thermolysis. Adding a small quantity of lime to the waste when pushed into the 
oven will neutralize chlorine by producing relatively inoffensive calcium 
chlorine.
The thermolysis oven would produce activated carbon and a combustible gas 
which can be used to heat the oven at 500 deg C, enough to steamcrack the 
plastic molecules. The activated carbon could then be used as fuel to generate 
power.

If you want to learn more about the process and if you have not saved the 
series of messages having been recently exchanged on the Net about 
thermolysis, I suggest you get in touch with Mr. Paul Olivier at 
100072.3174@compuserve.com. He is living in Belgium and is THE person who can 
supply an adequate solution to your problem.

Here is a description of thermolysis in a nutshell : 

Thermolysis uses a 9m long steel tube, 1.2 m of diameter. The central part of 
the horizontal tube is heated. Waste is ram pushed into the tube with a small 
quantity of lime. Central part of tube brings waste to a temperature of 500 
deg C which provokes a steamcracking of all organic molecules. There is almost 
no combustion inside the tube. Tube produces enough combustible gas at 300 deg 
C to heat tube once process is started. Organic activated carbon accumulates 
in third part of tube, acting as filter for pollutants like mercury, heavy 
metals. Chlorine and fluorine combine with hydrogen to form acids which are 
neutralized by lime. Carbon is then dumped in a water filled quench, with no 
air to avoid combustion. Calcium salts dilute in water. An aluminum can gets 
out of the oven sparkling clean with no trace of paint. Steel rust has 
vanished.

Carbon is filtered to remove metallic waste and large inert materials, can the 
be used as fuel by industry, for instance in blast furnaces. No pollution, no 
carbohalogenated compounds, no PCBs, no dioxin laden dust, no nitrogen oxides, 
no heavy metal in the environment. A very pleasing process indeed.

Here is a comparison between the two process  when applied  to municipal solid 
waste. In your case, there is no fundamental difference between municipal and 
hospital waste. Small size thermolysis plant can be built. There are two 
pilot-plants in France with capacities aqual or close to 500 kg/h.

I hope this helps. With kind regards from Belgium. Manu

Comparison between MSW THermolysis and INCineration
-----------------------------------
** = positive point
~~ = negative point
~ = about
18-wheelers = Large American trucks counting 18 wheels.
INC = Incineration
LHV = Low Heating Value
MSW : Municipal Solid Waste
Nm3 = Standard dry flue gases at 273K, 101.3 kPa, 11 percent O2 or 9 percent 
CO2. 
TH = Thermolysis
USD = US dollar
------------------------------------

## Technique

TH : ** Thermal decomposition by steamcracking of MSW organic fraction in 
absence of air (450 degree C - 550 degree C) during about 20 min. ** Simple 
technology.

INC : MSW incineration by combustion (oxydation) : combustion gases 
temperature : 850 degree C during 2 seconds. ~~ Complex flues gases scrubbing 
system.

## Type of waste

TH : Municipal solid waste, lime added. Hospital waste in specific 
applications. Mixed (sludge, tires, solvents...)

INC : Municipal solid waste.

## Operation

TH : ** Adaptable. Possibility to operate from 25 percent to 100 percent of 
nominal capacity.

INC : ~~ Rigid. Necessity to operate at 100 percent of nominal capacity during 
25 years or more to recover initial and additional investment.

## Air pollution

TH : ** Very low because of the small volume of flue gases generated by 
external heating of oven (800 Nm3 per tonne of MSW). ** No generation nor 
dispersal of nitrogen oxydes, dioxins, furans, PCBs, chlorhydric and 
fluorhydric acids, sulphur dioxydes, dust, slag, soot. ** No dispersal of 
heavy metals.

INC : ~~ Important thanks to the high volume of flue gases (5,000 Nm3/tonne 
MSW). ~~ Scrubbing of flue gases is costly and complex. ~~ Important air 
pollution (An incinerator with a capacity of 235,000 tonne MSW/year, after 
scrubbing of flue gases, disperses 653 tonne/year of pollutants among which 
dioxins, furans, PCBs, acids, nitrogen oxides, sulfur dioxide, highly toxic 
dust, heavy metals if European Directive no. 94/67 is abiden by which is not 
yet mandatory.)

## Liquid waste

TH : ** Brine containing calcium salts (CaCl2) sold to chemical industries.

INC : Partial treatment and evacuation of largest part in the environment by 
the chimney.

## Solid waste

TH : ~330 kg of semi-coke, containing 30-40 percent of inerts, per tonne of 
MSW, ** to be used in thermal electric plants, in blast furnaces, in cement 
kilns. Heavy metals are trapped by activated carbon. ** No ashes. ** No need 
for a landfill.

INC : Per tonne of MSW, ~~ ~30 kg of highly toxic flue ashes and soot to be 
treated or to be dumped in special class 1 landfills + ~~ ~300 kg of toxic 
slag which cannot be sold. ~~ No depollution of slag containing dioxins, toxic 
gases and heavy metals. ~~ Slag releases its toxic gases without any control 
(an operation called modestly :  “slag maturing”). 

## Toxicity of wastes

TH : ** Negligible. Heavy metals are trapped by the activated carbon. In the 
air : CO2, traces of CO, of NOx and of heavy metals resulting of oven heating 
system.

INC : ~~ Important. Pollutants released in the air and in landfills : heavy 
metals, dioxins, furans, nitrogen oxides, etc. ~~ Lignite coke used to capture 
part of dioxins, furans and mercury is dumped in landfills without prior 
depollution. Calcium salts dumped in landfills without treatment. 
~~ Significant threat to get aquifers and surface waters polluted by leachates 
from landfills.

## Energetic valorisation

TH : ** Obtained from the semi-coke (~330 kg per tonne of MSW) having a LHV of 
17,000 kJ/kg. ** Possibility to differ use of semi-coke in time and space. ** 
Production of excess fuel gas to be used on the spot.

INC : Obtained from mass burn of MSW. ~~ Low efficiency of power production - 
about 15 percent. Power must be produced 24h/24.

## Water and energy supply

TH : ** Self-sufficient (thermolysis fuel gas in excess) ** Very low water 
requirements for cooling hot activated carbon.

INC : Obligation to have ~~ make-up natural gas or LPG burners. ~~ Important 
water needs (150,000 m3/year for 235,000 tonne MSW) for flue gases scrubbing, 
without removal of nitrogen oxides !)

## Plant siting

TH : ** Independent units located close to MSW production areas ** in order to 
limit truck traffic and MSW transportation expenses. ** No need for transfer 
stations.

INC : One unit to treat up to 600,000 tonne MSW/year. ~~ Many transfer 
stations to regroup MSW to transport it to incinerators with 18-wheelers. 
~~ Road damages expected. ~~ Pollution due to flying MSW.

## Investment

TH : ** ~80 MUSD per unit having a capacity of 50,000 tonne/year, that is 
about 125,000 eq. inhabitants. ** Lower investment in the future

INC : ~~ ~1.3 GUSD with neutralization of nitrogen dioxides for a plant with a 
capacity of 235,000 tonne MSW/year.

## Gate fee

TH : ** ~60-70 USD/tonne MSW if semi-coke is used by industry.

INC : ~60 USD up to ~~ 400 USD/tonne MSW (Darmstadt, Germany) depending on 
performances of flue gases depollution system.

## Evolution of gate fee

TH : ** Decreasing because of revenues from sale of semi-coke and calcium 
salts, and of lower investment in the future.

INC : ~~ Increasing thanks to more and more stringent laws about environment 
protection. ~~ High long term financial risk.

## System abide by existing standards ?

TH : ** Easily. ** Pollution is widely lower than requirements of any present 
and future European directives applicable to MSW incinerators.

INC : ~~ Dubious without a permanent control of good incinerator management by 
an independent authority. ~~ No penalty in case of negligence or poor 
management.

## Typical composition of fuel gas produced by thermolysis :

H2 = 11 percent
CH4 (methane) = 15 percent
CO = 20 percent
CO2 = 30 percent
C2H4 (ethylene) = 6 percent
C2H4 (ethane) = 5 percent
other (hydrocarbons) = 13 percent
	+ water vapor
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