Solar Syringe Melting Oven
Improper waste management and health risks
The World Health Organisation estimates that worldwide, 8-16 million hepatitis B, 2.3 - 4.7 million hepatitis C and 80,000 -160,000 HIV infections are caused from re-used un-sterilised syringes and needles. Poor management of used syringes puts the health-care workers, waste handlers and the general public at risk.
Proper waste management and waste treatment measures can dramatically reduce such health risks. A variety of measures exist that can minimize environmental hazards. Small health care facilities in less developed countries may not always have funds for environmentally friendly and safe options for waste treatment used in high income countries. Implementation problems may also arise due to the lack the lack of electricity and other infrastructure. Under these circumstances, either burial pits or small-scale incinerators may often be recommended to dispose of used syringes. Whilst this is better than uncontrolled dumping, a solar-powered syringe-melting oven will provide more benign option.
Thermo processing: a solution
The rationale for thermo-processing of used syringes is well summarized in the proceedings of the Technet sub-committee meeting on the disposal and destruction of sharps and other infectious waste, Almaty, Kazakhstan 28–30 April 1999:
“…unless the means for final disposal of waste is immediately available at the point of use, infectious waste should be disinfected, hazardous sharps should be made safe and the volume of the waste reduced as far as possible to facilitate safe and economic transport to the place of final disposal"… Thermal processing, using modified ovens at low temperature, may be an important way to de-contaminate all dry infectious waste and to de-sharp, to disable and to reduce the volume of syringes by melting … High priority should be given to the development and testing of low cost thermal processing products meeting WHO specifications.”
Tests indicate that in high insolation countries it is cost-effective to thermally treat used syringes using a solar concentrator system. The solar-powered syringe-melting oven developed has the potential to provide safe and low-cost thermal processing in accordance with Technet recommendations and WHO specifications.
The solar syringe melting oven
The syringe melter uses reflectors to concentrate the energy in sunshine onto a specially designed receiver (oven). The syringe-melting oven:
- Sterilises the stainless steel hypodermic needles by heating them to temperatures above 171°C.
- Melts the polypropylene syringe body so that the syringes cannot be re-used
- Encapsulates the stainless steel hypodermic needles in a polypropylene block so that they cannot cause injury.
The used hazardous syringes are thus transformed into sterilised plastic cakes, which can be safely stored or transported, disposed off or processed into other plastic products.
Over the past few years, several designs of the ‘Solar Melter’ are fabricated and thoroughly tested.