Section F Alternate Technologies Section F Alternate technologies

Section F Alternate Technologies Section F Alternate technologies

Bio-medical waste and technology n n Technology is only a fraction of the solution. Major components of waste management are: o Segregation of waste o Waste minimisation o Reducing use of hazardous substances or processes o Waste Audit Section F Alternate technologies F 1

Treatment technologies Treatment technology for bio-medical waste should: n n Disinfect waste Make waste non-reusable Be environmentally safe Should consider worker safety Section F Alternate technologies F 2

Approved treatment methods n n n Autoclave Chemical disinfection Hydroclave Microwave Incineration Any other technology after CPCB approval Section F Alternate technologies F 3

Technologies for bio-medical waste treatment n n Thermal processes o Low heat o Medium heat o High heat Chemical processes Irradiative processes Biological processes Section F Alternate technologies F 4

Biological indicators Suspensions of resistant endospores are used as biological indicators for microbial inactivation: n n n Bacillus stearothermophilus: thermal Bacillus subtilis: chemical Bacillus pumilus: irradiation Section F Alternate technologies F 5

Autoclaves n n Saturated steam acts as the disinfecting agent Pressure, temperature, time combinations o for gravity flow 121 o. C, 15 psi, 60’/135 o. C, 31 psi, 45’/149 o. C, 52 psi, 30’ o for pre- vacuum type (121 o. C, 15 psi, 45’/135 o. C, 31 psi, 30`) Section F Alternate technologies F 6

Types of autoclaves Air is an effective insulator, thus complete disinfection demands removal of air from the chamber. Two methods of removing air are: n n Gravity displacement Pre-vacuum Section F Alternate technologies F 7

Components of an autoclave Major components n n n A metal chamber that can withstand high pressure A steam jacket surrounding the chamber A steam generator A capillary thermometer and 2 pressure gauges to monitor temperatures and pressures respectively Recording mechanism Section F Alternate technologies F 8

Stages in autoclave operation n n n Pre-heating Loading of waste with an indicator Air evacuation Steam treatment Steam discharge Unloading Mechanical treatment Section F Alternate technologies F 9

Types of waste allowed/ disallowed Type of waste allowed category (3, 4, 6, 7): n Microbiological and biotechnological waste n Sharps, soiled waste, solid waste Not to be treated: n Volatile and semi-volatile organic compounds n Chemotherapeutic wastes, mercury and other hazardous chemical waste n Radiological waste, Sealed heat resistant containers n Huge and bulky bedding material Poorly segregated waste can lead to emission of alcohols, phenols, aldehydes, mercury and other toxic contaminants Section F Alternate technologies F 10

Advantages n n Proven technology, with disinfection parameters well established Minimal emissions (with properly segregated waste) Relatively lower capital costs Automated systems Section F Alternate technologies F 11

Disadvantages n n n Waste recognisable after treatment No volume reduction (till a shredder is attached) Odours Emissions (with unsegregated waste) Process gives wet waste, if not subjected to drying Barriers to direct steam exchange may compromise efficiency. Section F Alternate technologies F 12

Points to ponder n n n Segregated waste is a must Air evacuation is necessary Place bags in multi-load trays Proper ventilation to avoid odors Thermocouples and pressure gauges should be checked frequently Section F Alternate technologies F 13

Hydroclave n n Hydroclave is steam treatment with fragmentation and drying of waste It has a double walled chamber with an agitator inside Steam is injected into this wall (jacket) and waste is loaded in the inner chamber The agitator fragments and turns waste Section F Alternate technologies F 14

Hydroclave: treatment mechanism n n The moisture in the waste turns to steam and exerts pressure on the inner walls. If this pressure is not sufficient, additional steam may be injected inside. Cycle runs at 132 o. C for 15’/ 121 o. C for 30’ Finally the steam is vented through a condenser while maintaining heat input, causing the waste to dry Steam is shut off, discharge door is opened and agitator runs in reverse rotation to place the waste on a conveyor belt/ container. Section F Alternate technologies F 15

Hydroclave n n Advantages o Shredded, dry waste o Internal mixing improves transfer of heat Disadvantages o Clogging of agitator blades with waste o Mixed shredded waste makes recycling difficult Section F Alternate technologies F 16

Microwave: action mechanism n n n Disinfection by moist heat and steam generated by microwave energy Magnetrons convert high voltage electrical energy into microwave energy The microwaves create an electromagnetic field Water and other molecules in waste try to align in the field and in the process they vibrate Vibration of the molecules produces heat Section F Alternate technologies F 17

Microwave: action mechanism Microwave kills by two mechanisms: n n By heat energy from the steam generated Changing the biological molecular structure of proteins Section F Alternate technologies F 18

Microwave: operating parameters n n Microwaves are high frequency (2450+50 mhz) radio waves capable of creating electromagnetic field Temperatures reached are around 97100 o. C. In some new systems, steam under pressure is passed, to achieve temperatures>135 o. C. Cycle time is around 25’ Typically, around 2 -6 magnetrons are used with an output of about 1. 2 KW each Section F Alternate technologies F 19

Stages in microwave operations n n n n Waste loading Steam injection in the hopper Internal shredding Microwave treatment Disinfection cycle Optional secondary shredding Discharge Category of waste that can be and cannot be treated is similar to the autoclave. Emission parameters are also similar Section F Alternate technologies F 20

Advantages and disadvantages Advantages n In use for more than a decade n Minimal emissions if no hazardous waste fed n Automated system n No liquid effluent Disadvantages n Relatively high capital cost n Toxic emissions if hazardous waste fed n Any large metal item can damage shredders n Odour problems n Probability of microwave energy leakage Section F Alternate technologies F 21

Points to ponder n n Properly segregated waste is a must. It becomes necessary to ensure: o absence of large metal blocks o absence of hazardous or radiological waste: Workers to be trained for monitoring leakage of microwave energy and handle it Section F Alternate technologies F 22

Othermal technologies n n n Low heat (dry) technologies (<350 o. F) o high velocity heated air Medium heat (350 o. F-700 o. F) o reverse polymerization or thermal depolymerisation High heat technologies (1, 000 o. F 15, 000 o. F) o pyrolysis Medium and high heat technologies also produce dioxins and furans and other toxic pollutants, require pollution control devices, and are fairly expensive. Section F Alternate technologies F 23

Chemical methods n n n n (Na. OH/ KOH: For treatment of pathological and cytotoxic waste): Sodium hypochlorite Glutarladehyde Peracetic acid Ozone gas Calcium oxide Sodium hydroxide: alkaline hydrolysis Section F Alternate technologies F 24

Evolving technologies Irradiation (ionising radiation): n X rays/gamma rays n Electron beam Biological: n Enzymes n Composting, vermiculture Section F Alternate technologies F 25

Choosing an alternate technology n n n n Throughput capacity Types of waste treated/not suited Microbial inactivation efficiency Environmental emissions and water residues Regulatory acceptance Space requirements Utility and other installation requirements Section F Alternate technologies F 26

Choosing an alternate technology n n n n n Reduction of waste volume and mass Occupational safety and health Noise and odour Automation Reliability Manufacturer background Cost Recurring cost and maintenance After sales service Level of operator training, other manpower requirement Section F Alternate technologies F 27

Centralised facilities Guidelines on common facilities n Treatment facilities: 90% non-burn, 10% burn n Limits incineration to Categories 1&2 n At least 1 Km from residential areas. Acceptable in industrial area n One operator allowed to cater upto 10, 000 beds, situated within 150 km radius n Segregation is the role of generator; operator can report mixing of waste to the prescribed authority Section F Alternate technologies F 28

Chemical Disinfection Section F Alternate technologies

Hydroclave Section F Alternate technologies

Microwave Section F Alternate technologies

Autoclave Section F Alternate technologies

Incinerator Section F Alternate technologies