In the world of options, there’s no limit to choose. “Choice” doesn’t matter, right and compatible choice matters. If you choose the incompatible one, you will regret it sooner or later. 

On hearing autoclaves for treatment of biomedical waste what strikes in your mind first? What scenario does it create in your mind?

An image of big machinery with a lot of wastes. That’s true but only to some extent. And do you know about its working process or its efficiency? 

If you have an interest in waste treatment. You will also want to know about its operation, maintenance cost, etc. So, this blog is to answer most of your questions.

In this blog I’m going to cover:-

Topics covered in the blog
Topics covered in the blog
  • When and where were autoclaves invented?
  • What are autoclaves used for?
  • Autoclaves in treatment of Biomedical waste.
  • How Autoclaves Work.
  • Suitable and Unsuitable waste to be treated with Autoclaves.
  • Autoclaves pros and cons.
  • Types of Autoclaves.
  • Companies that sell autoclaves.

When and where were autoclaves invented?

Invention of Autoclaves
Invention of Autoclaves

Charles Chamberland invented autoclaves in 1879. The precursor one was the Steam Digester, invented by Denis Papin in 1679. Autoclave got its name from two ancient languages. From Greek language, auto means automatic and Latin language, Lavis means key. Which means a self- locking device. This reference is for selling doors in chambers.

What are autoclaves used for? 

Infographic for wastes suitable for autoclaves
Wastes suitable for autoclaves

Sterilization is the key purpose of autoclaves. Sterilization is the removing of microbes to maximum extent. Microbial removal is essential in many process like :

  • Testing of samples in laboratory.
  • Culture of specimen
  • Discharge of biomedical wastes.
  • Discharge of wastes that have potent microbes.
  • Biohazardous wastes.
  • Laboratories.
  • Surgical instruments. etc.

Autoclaves in treatment of Biomedical waste.

The rapid growth in biomedical waste creates a lot of concern for all of us. Proper management and handling is one of the most concerning issue. Government has issued many guidelines regarding this issue. By the course of time many advance technology is invented. One of the used biohazardous waste treatment techniques is autoclave. An autoclave consists of a steel vessel/ metal chamber which is sealed by a charging door. Inside chambers are designed accordingly to withstand the elevation of pressures. Steam surrounds on both sides, i.e. outside jacket and inside chamber. Outside chamber heating reduces condensation in the inner chamber, which allows it to employ steam at lower temperature. 

Pathological waste

There is a proper arrangement of pipes and valves for the usher and removal of steam. Air is a key factor and effective insulator in determining efficiency of autoclave. That’s why proper removal of air is essential. Because removal ensures proper penetration of heat into the waste. Removed air at the start of the process, to prevent spillage of pathogenic aerosol. This is performed by passing the air through HEPA (High efficiency Particulate Air) filters before releasing.

How Autoclaves Work

The operating cycle of autoclaves has the following steps:-

Steps in working of Autoclaves

1. Waste collection 

When waste is needed to store in a cart or bin. The bin/ cart is lined with large autoclavable bags or special plastic liners. And then red bags containing hazardous waste are placed into the carts. This two layer coating is done to prevent waste sticking to carts. So the cart or bin can be reused.  

2. Pre-heating

Outer chamber of the autoclave is heated with steam.

3. Waste loading

Containers having waste are loaded into the chamber. Periodically, biological or chemical indicators are introduced in the middle of the waste loads to check disinfection. The chamber is sealed by closing the doors. 

4. Air evacuation 

Air is drawn out from the chamber through HEPA filters. This can be carry on by two ways:-

  • Gravity displacement autoclaves- works on the principle that steam is lighter than air. Steam is forced into the chamber with pressure forcing the air downward to an outlet line in the lower part of the chamber.  
  • Pre-vacuuming autoclaves- These are better as they use vacuum pumps to evacuate air before steam induction. Because of greater efficiency of air removal it needs less time for disinfection. 

5. Steam Treatment

Steam is introduced into the autoclave at a temperature of 121° C for a minimum 30 minutes under at least 15 psi pressure. Supplementary air is poured automatically to maintain the temperature for the desired time.

6. Steam Discharge 

Steam is let out of the chamber usually via a condenser to reduce pressure and temperature of the steam. Sometimes the post vacuum cycle is used to remove residual steam.

7.Unloading of waste

Usually, waste is allowed to rest for some time to cool down. After resting, treated waste is removed. The indicator strip is taken out and evaluated. 

8. Mechanical Treatment

Mostly, the treated waste is drawn into a shredder or compactor prior to sending them to the sanitary landfills. 

Suitable and Unsuitable waste to be treated with Autoclaves

Suitable and unsuitable waste for Autoclaving

Every waste cannot be treated with the autoclaves. Each treatment system has some parameters by which suitable and unsuitable waste type is decided. Here is the list of waste that is suitable and unsuitable for treatment through autoclaves. 

Waste suitable for treating with autoclaves Waste unsuitable for treating with autoclaves
Sharps Chemical waste
Isolation and surgery wastes Heavy and huge beddings 
Culture and stock wastes Bulk chemotherapy waste
Materials contaminated with blood or minimal amount of liquids Volatile or semi- volatile organic compounds
Laboratory wastes( except chemical waste)  Sealed heat resistant containers
Soft wastes (gauze, drapes, beddings, gowns, bandages, etc.) from patient care Other hazardous waste
Human anatomical waste Radiological waste
Other waste that hinder heat transfer must be avoided
Large animal carcassess
Sealed heat resistant containers
  • “Human anatomical waste” treatment is possible with appropriate time, temperature, and mechanical system. But ethical, legal, cultural, and other considerations may hinder their treatment. Some states and local authorities have allowed treatment of “trace-contaminated chemotherapy waste”. But facilities should check out the regulations.

Autoclaves pros and cons

Advantages and Dsadvantages of Autoclaves

Everything in this world has some pros and cons. Autoclaves also have many advantages as well as drawbacks. Here is some of the advantages and disadvantages of autoclaves mentioned below:

Pros Cons
Steam technology shows a positive result from dates back. The technology does not make waste unrecognisable.
Low capital costs, compared to other technologies. Waste volume reduction is possible only when a shredder or grinder is attached.
With proper precautions while treatment, emission is minimal. Large and hard objects/metals can damage the shredder or grinder.
Autoclaves come in various sizes, and can treat to some pounds to several tons of wastes. Bad odours are produced around the autoclave unit but can be minimized with proper air handling equipment.
Autoclaves are easily available in the market The resulting treated waste is heavier due to the presence of steam.
Time-temperature relation parameters for high level disinfection are well defined. Barriers to direct heat exposure or steam penetration may reduce the efficiency of disinfection of contaminated waste.
All the states have accepted and approved this technology.

Types of Autoclaves  

There are basically two types of autoclaves for treatment of biomedical waste in the market.

  • Vacuum Autoclaves 

Modern autoclaves use vacuum pumps to evacuate the air from the autoclaves before inducting steams. This ensures safe disinfection of wastes. A very popular example is “Pre-vacuum autoclaves”, which remove air once before steam injection.

Autoclaves for treatment of biomedical waste
Credit- Bondtech

Autoclaves using a fractional vacuum process are the safest option. They evacuate air and convey steam several times to ensure removal of air for better penetration of steam. This results in better steam penetration and uniformity of temperature in the disinfection phase. 

Decontamination takes place at a temperature of 121°C to 134°C for at least 30 min. So, waste bags should be heat resistant and steam permeable. After decontamination bags are considered as non-hazardous, they can be disposed of accordingly. 

Advantages 

Disadvantages

It has low environmental impacts. Authentic and careful solid waste collection is required
It has non- hazardous residues. Dependable electricity and water connection is required.
Some of the treated waste can be recycled. Recognizable residues can cause injury.
It follows the Stockholm convention. Temperature resistant waste bags or bins are needed.

Operation requirements

Installation of vacuum autoclaves have some proper requirements. Some main requirements are listed below:-

  • Water connection
  • Waste water drain connection
  • Electricity requirements: 380/400 Volt (smaller ones might require 220/230/240 Volt)
  • Compressed air
  • Demineralized water is needed for steam production 

Capacities and Consumption

Waste treatment vacuum autoclave capacity can be in a range of 5 to 3000kg/hour. The cycle time includes time required for waste loading, air evacuation, steam introduction, steam exposure and waste removal.  

  • Autoclave with integrated shredder 

Autoclave
Credit- Tuttnaeur

Autoclaves with integrated shredders or grinders are developed to increase the heat transfer into the waste. This provides uniform heating to the waste. These systems of autoclaves are sometimes referred to as advanced steam autoclaves or hybrid autoclaves. 

Increment of steam penetration and better efficiency is the result of pre shredding. At the end of the cycle waste is considered as non- hazardous and can be disposed of accordingly. Some waste can be recycled after treatment. 

Advantages

Disadvantages 

Shredding results in more uniform heating. Dependable electricity and water connection is required.
Make the waste unrecognisable. Water quality should be checked to maintain the equipment.
Great reduction in waste volume reduction. High cost for maintenance.
It has a low environmental impact.  Requires a skilled operator.
No hazardous residue.
It follows the Stockholm convention.

Operation requirements

Installation of shredder autoclaves have some proper requirements. Some main requirements are listed below:-

  • Water connection
  • Waste water drain connection
  • Electricity requirements: 400 volts
  • Compressed air
  • Demineralized water is needed for steam production 

Capacities and Consumption

Waste treatment shredding autoclaves capacity can be in a range of 5 to 3000kg/hour. The cycle time includes time required for waste loading, air evacuation, shredding, steam introduction, steam exposure and waste removal.

Companies that sell Autoclaves 

Now-a-days there are many companies that manufacture and sell autoclaves. Here I’m mentioning some of the well known companies that sell autoclaves.  

Autoclave
Credit- mcf.com
  • Bondtech
  • Environmental Tectonics Corporation (ETC)
  • Mark-Costello
  • Sierra Industries
  • Steri Tech
  • Tuttnauer
  • San-I-Pak
  • Tempico Rotoclave
  • STI Chem-Clav
  • Hydroclave
  • Sciencetech
  • Unident

Conclusion

Autoclaves for treatment of biomedical waste are highly effective and have good efficiency. They are inexpensive and durable if properly handled. Direct contact of steam with waste is essential as it prohibits growth of spores and bacterial cells. Effectiveness can be easily checked through indicators. Pros are more than cons. It is widely accepted for biohazardous waste treatment. It’s easy to handle.

So, it’s a good alternative against incineration. Environmental issues because of incineration can be prevented. We can’t handle more polluted air. It’s high time to choose alternative techniques. Autoclaves are highly capable and can be helpful.Choose for your betterment and our next generation. Let’s leave some earthly beauty for our coming generation and try not to hand over a toxic and garbage bag to them in the name of the planet. If you want to say something on this topic. Please message me in the comment box or say hello. I love to hear from you all. And if you want more informational blogs related to waste management please subscribe with us and follow our page.  

Stop polluting earth and make it a better living planet
Stop polluting earth and make it a better living planet
andleep zahra
Author

She is a biotechnologist and received her master degree in biotechnology from V.B.S. Purvanchal University. Being a biotechnologist she loves to do research and write articles on the same. She’s best known for writing articles and blogs on environmental issues. Through her writings she likes to provide more information on environmental conservation and provide knowledge on how to address the issue, mainly focused on waste management. She looks for ways to get involved and also attended several conferences, workshops and webinars. “Increasing waste around the globe that is affecting our ecosystem and reducing our biodiversity is the most critical issue we humans often overlook and it will be the greatest challenge our younger generation will ever face,” she says.

Write A Comment