Let’s poka-yoke lives of STP operators

Asia's largest sewage treatment plant at Bharwara, near Lucknow. (Source: IWP Flickr photos; photo for representation only)
Asia's largest sewage treatment plant at Bharwara, near Lucknow. (Source: IWP Flickr photos; photo for representation only)

Poka-yoke* is a simple Japanese quality principle from the 60s--the use of any automatic device or method that makes it impossible for an error to occur. It is a simple idea. 'Simplicity' always wins! 

Now, let's switch to STP operators and poka-yoke! 

Manual scavenging is still widely prevalent in India.The recent Tehelka article, Dalits still sent to die in gas chambers was condemned by many for its headline but the fact is, hundreds die in septic tanks, gutters and sewers. Movies like Kakkoos and Lesser Humans have exposed the atrocities they face. 

In the western world, the entire sewer cleaning exercise is 'mistake proofed'; they wear Dupont bunny suits with respiratory kits, the sewers are well lit, mechanically aerated with huge fans and therefore not so oxygen-deficient. In Hong Kong, a sewer worker needs to have at least 15 licences and permits in order to enter a manhole and of course absolutely no alcohol consumption before entering! These are mandatory mistake-proofing tactics which simply save lives. 

The lives of sewage treatment plant operators are worse as they live in STPs day in and day out. As you all maybe aware, three STP operators died in an apartment STP recently in Bangalore. There is panic among residents' associations now as, after the incident, the managing committee members were arrested and put behind bars--many of them have no clue on STP operations. 

Apart from other issues like being power-intensive, heavy on maintenance, difficult to manage etc, the conventional motor-based STPs relies on labour to enter the tanks to clean up regularly, most of whom enter without sufficient protection.  

We have seen hundreds of STPs. The fact is that none of us can stand in an STP room for more than two minutes without feeling suffocated. We would like to share some guidelines for apartment associations that will prevent such mishaps from happening. 

1. Buy an alcohol tester and keep it handy: You can get them at less than Rs 1000 at online stores. Ensure that the personnel undergo the test especially if they are cleaning the tanks. The very presence of the tester will serve as a deterrent. 

2. Educate operators about carbon monoxide: If one breathes in a lot of CO, it can make one nauseous leading to loss of consciousness, even death. People who are sleeping or drunk can die from CO poisoning before they even have symptoms. Alcohol and CO is a deadly cocktail. Many look at odour as an 'STP quality' yardstick. As carbon monoxide is an odourless gas, STP operators jump into STP tanks to clean or fix the clogged diffusers without knowing the risks involved. They should be educated about CO poisoning. In other words, the STP may not stink but that does not mean it is safe. 

3. Ensure safety is part of the training: Ensure all personnel are trained in safety precautions with regular random tests or quizzes. Yes, this may not sound practical but safety training is perhaps the most important mistake-proofing action to save lives. CPR training should also be mandatory. Usually, we never discuss the safety aspects--it’s time to change that! 

4. Ensure emergency information and first aid box are kept handy: A clear visual poster of what to do in an emergency should be put up. For example, If you inhale chlorine, blood pressure can drop drastically. At this point, the affected person should be given fresh air as soon as possible. Going to the highest possible ground to seek fresh air is helpful because chlorine is heavier than air. In addition to the usual first aid items, STP specific items should be added to the first aid box. For example, activated charcoal for chlorine poisoning. 

5. Ensure exhaust fans are working: There should be backup exhaust fans. Also, a good practice followed by some is to put a nice air exchange: one fan to let the STP air out, and one to let fresh air in by blowing a forced stream of air inside the STP room. The test is simple--one should be able to stand inside the room for two minutes at the least! If there is a power failure, the operators should be instructed not to go into the STP cabin and after the power resumes, operators should enter the room only after exhaust fans are operational for a while. 

6. Ensure safety gear is used: Gloves and masks should be worn at all times. Sludge pathogens may be present and are of four major types--bacteria (Salmonella, E-coli etc.), viruses (Hepatitis A virus, Rotavirus etc.), protozoa (Entamoeba histolytica, Giardia lamblia etc.), and helminths (Ascaris suum, Necator Hookworm etc.) Also present in STPs are drug-resistant variants. The recent research at the Indian Institute of Technology, Delhi shows how STPs spread antibiotic-resistant bacteria as well as resistant genes in the environment. So it is very important that STP Operators wear gloves and mask at all times. 

7. STP area should be designed for safety: Fire extinguishers, anti-slip zig-zag pattern floorings, ladders with handles, fire exit paths etc. are examples. As the area is very noisy, earplugs also should be supplied. Many vendors sell low-cost earplugs which are also available online. These are small investments that go a long way. 

8. Stop tinkering with STP equipment: There is a tendency to continuously repair STP equipment beyond their end of life. If they are gone faulty, please let them go. For example, many STP operators go inside the STP tank to clean the air diffuser pores. You need to treat air diffusers as consumables and replace them. Some blowers get very loud due to usage--stop oiling them and replace them instead. Usually, we put pressure on the STP operators and they are forced to do the tinkering. 

9. CCTV in STP areas: The most effective mistake-proofing intervention ever is the simple camera. Now they are very economical and placing one in the STP room does not cost much. The above safety guidelines can be easily enforced if there is a camera as it serves as an effective mistake-proofing tool. 

10. Legal contracts in place: Technical measures can help but it is best underpinned by legal contracts indemnifying residents if STP mishaps happen. The STP contractor has to ensure all the safety measures are in place including the health of the STP operators. Note that eventually, this boils down to higher costs of operations but this should be treated as a non-negotiable item. 

Outside of this, we would highly recommend that real estate developers, pollution control board, RWAs and citizen groups keep themselves informed about STPs that run without power or machines, without risks and issues of maintenance. There are a few, but good players in the market that treat sewage through bioremediation. It is up to them to make the shift and adopt these technologies for a safer, healthier, cleaner future. 


*Poka-yoke: As per Wikipedia, poka-yoke is a Japanese term that means "mistake-proofing" or “inadvertent error prevention”. The key word in the second translation, often omitted, is "inadvertent". A poka-yoke is any mechanism in a lean manufacturing process that helps an equipment operator avoid (yokeru) mistakes (poka). The concept was formalised by Shigeo Shingo as part of the Toyota Production System. 

Some examples are the Antilock Braking Systems (ABS) for drivers who stomp on the brake, 'Beware of Dog' signs or the railway tap which gives water only when pressed. One crazy example is a patient about to undergo surgery for a problem on his right arm has 'wrong arm' written with a marker pen on his left arm as he is worried about any potential mistakes by surgeons. Similarly, once a bank mandated their tellers to record eye colour on bank transaction form to ensure eye contact! Rumour has it that they were looking for some poka-yoke ideas to make tellers smile too! 

About authors 

Dr E.Muralidharan is passionate about researching on hydrology. He is an M.S. and Ph.D.- IIT, Madras, post-doctoral fellow–NIH Georgia Tech and Inoue Research Fellow–visiting professor–(cellular physiology, Ehime U. Medical School, Japan). His research papers are published in more than 50 international journals and conference proceedings. He can be reached at dremurali@ecostp.com 

Tharun Kumar has over 20 years of experience in the field of sustainability and information technology. He has a rich mix of experience in technical as well as business leadership positions with global corporations. Tharun has done advanced management programme from IIM Bangalore and is a BS50001 energy auditor. He is passionate about sewage treatment and can be reached at tharun@ecostp.com 

The views and opinions expressed in this article are those of the author/s and do not necessarily reflect the policy or position of India Water Portal.

Post By: arathi