Design of Low-Cost Solar Parabolic Through Steam Sterilization

Introduction

The safe handling and proper treatment of medical waste, tools and equipment is an important part of health care. According to report published by Health Care Without Harm, USA, the regulated medical waste, also called infectious waste, requires disinfection prior to disposal in a landfill. The infectious or regulated medical waste accounts for about 15 percent of total hospital waste (Brannen, L., et al. 2001). One fifth of the patients suffer from post-operation infection, due to, among other causes, the use of improperly sterilized equipment used in the procedure (Pittinger, M., 2010).

There are many technologies available for proper and safe handling, treatment and disposal of medical and surgical equipment and tools; and healthcare waste. The safer disposal techniques which are beneficial for the environment as well as health of the public must be given more importance than other techniques. The cost effectiveness of such techniques can further benefit health care industry.

The steam sterilization of medical waste and surgical instruments through autoclave is considered to be the most dependable and widely used non-incineration technology. Steam sterilization is nontoxic and inexpensive (Rutala, W. A., Weber D. J. & HICPAC, 2008, updated February 15, 2017). The cost, unreliability or unavailability of fuel and electricity in many areas adversely impacts the ability of medical facilities to autoclave medical/surgical instruments and infectious waste. The importance of using solar energy for healthcare has been emphasized by a study conducted by Aditya Ramji & others (2017) and is one of the first evaluations in India of the role of electricity access on health outcomes in the state of Chhattisgarh.

Over the years, different designs and sizes of solar autoclave have been developed by the researchers. A portable solar autoclave with a capacity to sterilize 7.5 kg of medical instruments, consisting of two coaxial cylinders was designed by (Bahadori, 1976). A team of Jones & others (2003) obtained first place in “Health Care Without Harm Competition”, organized by Sydney University, Australia. The team had designed two prototypes of solar powered autoclave, one larger with a capacity of 14 litres per batch and the other portable with a capacity of just 1.5 litres per batch. A solar sterilizer of 76 litres capacity was developed and installed for Holy Family Hospital having 150 beds in rural area of Mandar (Tyroller, 2003). Another researcher tried to design solar autoclave made of aluminium and 25 quarts of capacity, using heat-source based autoclave purchased from All American (Trabia, 2012). Kaseman & others (2012) tested in off-grid settings where electricity is not easily available, the efficacy of solar powered autoclave was tested for wet sterilization. A portable 40 litres autoclave was developed in Maharashtra, India, using the technology of solar cooking (Dravid & others, 2012). Another pressure cooker - based design that is easy to use and has low cost was developed for rural health posts in developing areas (Tao, 2012). Neumann & others (2013), Rice University, tested two types of autoclaves operated by nanoparticle based solar steam generation suited for off-grid settings. One setup was tested for sterilizing medical and dental equipment and another for sanitizing human waste. Another solar autoclave, named as kerr-cole sunflower autoclave design, was designed for using at any altitude (Kerr, 2016). A “Combined Autoclave and Water Purification System Using Solar Energy” was developed which helps to achieve a low-cost sterilization and water purification system (Harikrishnan & others, 2017). Another steam sterilization approach was developed using a solar-driven evaporation system at the water/air interface (Zhang & others, 2017). Most of these designs are suitable for large clinics.

The objective of this study is to design a low cost solar parabolic trough to generate steam for sterilization of medical instruments through autoclave in small clinics where electricity is scarce and expensive. This will help in reuse of sterilized medical instruments. The fabrication of parabolic trough has been done by assembling the ribs and reflector sheet with evacuated tube and heat pipe. Once, the parabolic trough is ready, it has been mounted on a trolley so that it can be moved easily from one place to another, according to the direction of sun light.