Course : Fundamentals of Safe Handling for Healthcare Waste LECTURE : TREATMENT TECHNOLOGIES ? ?

Hazardous waste Waste for exploitation Waste for disposal Chemicals „Stock market“ Silver- Recycling Treatment Techniques Xylol- Recycling Formalin- Recycling Amalgam- Recycling Before starting : Ways of final treatment /disposal

Fixing bath recycling Xylol re-distillation Alcohol re-distillation Formalin recycling Paraffin recycling Amalgam recycling Example : Chemicals - Reprocessing and reuse Large Scale Smaller Scale

- Types /quantity of wastes requiring treatment - Performance considerations eg Biological efficacy / volume and mass reduction - Health, environmental and safety considerations - Operation and maintenance considerations - Location and surroundings of treatment facility - Investment and operating costs - Regulatory requirements DECIDING FACTORS FOR SELECTION OF TYPE OF TREATMENT ENVIRONMENTAL LAW

TREATMENT METHODS & TECHNOLOGY Incineration Chemically, incineration is high temperature dry oxidation process. Organic and combustible waste is reduced to inorganic, incombustible matter. As a result the waste volume will be reduced about 70 %. The main residue is slag (300 kg per ton of waste incinerated)and smaller amount of fly ash (20 kg per ton of waste incinerated),

Kinds of Incinerator : - Pyrolytic / Double chamber - Rotary kilns - Single – chamber furnaces with static grate Summary Features for Pyrolytic / Double Chamber Incineration Temperature : 800 – 900 C Incinerator capacity : from 200 kg/day to 10 tonnes / day Exhaust gas cleaning equipment needed Capital, operation and maintenance costs relatively high Summary Features for Rotary Kilns Incineration Temerature : 1200 to 1600 C – for PCB‘s Incinerator capacity from 1 tonne / day to 21 tonnes/ day Exhaust gas cleaning equipment is needed Capital, operation and maintenance costs relatively high – ie cost of refractory relining etc Summary Features for Single Chamber Incinerators Incineration Temperature : 300 – 400 Incineration capacity from 100 kg/ day to 200 kg / day

The Problem of PBTs Persistent Bioaccumulative Toxic Chemicals Persistent: The constituent does not generally break down into other substances once they are released into the government. Bioaccumulative: The constituent accumulates in plant and animal tissue Toxic: The constituent found in hazardous waste has the potential to harm the environment or adversely impact human health. - Pressurised gas containers - Large amounts of reactive chemical waste - Silver salts and photographic or radiographic wastes - Halogenated plastics such as PVC - Waste with high mercury or cadmium content, - Used batteries - Sealed ampoules or ampoules containing heavy metals Wastes not to be Incinerated

Scheme of a five-step filter in a modern healthcare waste incineration plant A Modern Incineration Plant Control and monitoring of performance and operating parameters

Treatment Methods and Technology ; Wet Thermal Treatment ( Steam Autoclave ) Wet Thermal Treatment – Steam Autoclave The reacting tank for the wet thermal process may be a horizontal steel cylinder, connected to a steam generator ( to presssure of 6 bar, 160 C ) the process is usually batch - At the start of operation, the waste is initially shredded – vacuum conditions are established in the tank to increase the partial pressure of the steam and hence the effectiveness of contact between steam and waste – superheated steam is then introduced and a minimum temperature of around 120 C and pressure of 2 to 5 bar is maintained for a contact time of between 1 to 4 hours. Since the disinefction efficiency depends on the extenct of contact between the steam and surface of the waste the system should not be overloaded The effectiveness of the system should be checked using the Bacillus subtilus or bacillus stearothermophilus 4 log 10 efficacy kills Disadvantages : The shredder is prone to mecahnical failure and breakdiown The efficiency of disinfection is very sensitive to the operational conditions Advantages : Relatively low investment and operationg costs and low environmental impact

Treatment Methods and Technology ; Screw Fed Technology Screw Fed Technology Screw fed technolgy is a relatively new technology. It is the basis of a non burn, dry thermal disinfection process in which the waste is shredded and heated in a rotating auger. Continuously operated units, also called continuous feed augers are commercially available and used in hospitals. In brief, the principle steps of the process are : -The waste is shredded to particles about 25 mm in diameter -The waste enters the auger, which is heated to a temperature of around 110 to 140 C by oil circulating through its central shaft -The waste rotates through the auger for about 20 mins, after which the residues are compacted The waste is reduced by around 80 % in volume and 20 to 35 % in weight.

Treatment Methods and Technology ; Microwave Irradiation Microwave Irradiation Most microorganisms are detroyed by the action of microwaves of a frequency of about 240 MHz and a wavelength of 12 cm. The water combined within the wastes is rapidly heated by the microwaves and the infectious compoenebts are destryed by heat conduction In a microwave unit a loading device transfers the wastes into a shredder where it is reduced to small pieces. The waste is humidified, transferred to the irradiation chamber and irradiated for about 20 minutes. The efficiency of microwave disinefction should be checked routinely through bacteriological testing. The disadvantages of the system is its high costs and unique operation and maintenace problems

Treatment Methods and Technology ; Chemical Disinfection Chemical Disinfection The speed and efficiency of chemical disinfection will depend on various operating conditions eg : - The kind and amount of chemical used - The contact tiome betwen disinfectant and waste - The extent of contact betwwen disinfectant and waste - The organic load of thewaste - Operating temperature, humidity, pH etc etc The major problems of the system is the handling and safety of the disinfectants being used – ie formaledhyde, ethylene oxide, sodium hypochlorite, chlorine dioxide ( in situ or out of situ )

Treatment Methods and Technology Land Disposal Disposal means final storage of untreated healthcare waste on landfills. There are two main types of landfills  Open landfills: area without special installations; the risk of uncontrolled and scattered is high  Sanitary landfills: area which fulfills the following criteria geological isolation from the environment, engineering preparation of the site (drainage system), staff present on site, regular coverage of deposited waste.

Investment cost per ton treatment capacity: Incineration including flue gas control – US$ / ton / day Irridation (Microwave) – US$ / ton / day Autoclaving (steam disinfection) only – US$ / ton / day Autoclaving (steam disinfection) only – US$ / ton / day Th Problem: Investment cost

Advantages / Disadvantages of Healthcare Waste Treatment & Disposal Systems ( refer to page 18 of notes )