The difficulty in replicating Dora Akunyili’s Legacy
Part IV: Evaluating Water Treatment Technologies
If you had a public enemy perhaps a liar whom you hoped to decimate his influence, what will you do? Educate the public or confront the liar? Most African leaders will choose the latter. Experience shows the former will produce long-lasting results than the latter. Dora Akunyili (remember her?) undertook both approaches. She fought the liars but also educated the public. In this piece, I intend to bring an end to the series and show why a non-chemical approach to water treatment is promising. I hope you will be able to see why following her would be a tough call.
So far, we have established some (3) guidelines for drinking water. We have also shown the need for water treatment. Lastly, we have seen why chemical oxidation and filtration are the most effective options so far. Now I will want us to delve into the effectiveness more by considering cost, advantages and disadvantages. The term I like to use is “cost-efficiency”. Firstly, I would like to replace the three guidelines with three problems common to water quality experts. In other words, let us assume the three guidelines and treatment objectives target these three things. They are:
· Pathogens
· Total Dissolved Solids
· Solids
So the objective of the treatment is:
· Pathogen inactivation
· Total Dissolved Solids removal
· Solid particulate removal
To help understand how I have ranked these technologies, I am going to proceed to define or elucidate some parameter.
1. Effectiveness
Effectiveness for TDS and particle removal are easy to gauge. You observe the water or taste it. However, effectiveness in terms of pathogen inactivation is not very easy to measure. Now because the objective of pathogen inactivation is disinfection (reduction of pathogens), not sterilization (complete elimination of pathogens), we use Log Reduction Value (LRV) of the water treatment technology to measure effectiveness. Secondly, we also consider the risk of recontamination for example from distribution or temporary storage. As a result, we have merits for residual protection.
From the table above we can see that boiling and filtration offer the best LRV but offer no residual protection so recontamination might be likely if it is not adequately stored. On the other hand, oxidation has a good LRV. Moreover, Chlorination offers residual protection (recall the excellent value proposition of water guard sellers). However, protozoans like Cryptosporidium and Giardia resist chlorination. Additionally, there are several emerging issues associated with oxidation that cast doubt over their overall effectiveness which we shall discuss in the next paragraphs.
2. Emerging Concerns (or Associate Problems)
So like I pointed out earlier, we now know of potential problems associated with most water treatment technologies.
3. Robustness/Flexibility of Operation
Here I will consider if the technology can be standalone i.e. used independently. We shall also consider how durable (I prefer the word robust) it is and how much expertise would be required for its operation.
Considering the two parameters we have earlier outlined, we can see that none of these technologies is capable of being standalone. This is the basis of a multi-barrier approach to water treatment. This approach simply means combining a range of these technologies to achieve optimal water quality. This approach is what most sachet and bottled water companies in Nigeria employ. Boiling appears to be very effective and honestly, I wonder why most families have abandoned it. But let's say you intend to boil 100 Litres of water, then boiling becomes less attractive. For this reason, membranes are the most robust even though they might require ancillary technologies.
Regarding ease of operation, UV, boiling, and filtration are preferable. This is because, after the installation of these technologies, the operator requires minimal input to operate them. In addition, the operator does not require a lot of technical training to operate them. This is not the same for the use of chemicals such as coagulants or oxidants as there are so many variables such as the volume of the water, concentration of the substances you want to eliminate relative to the volume and objective of treatment. So you would need to require complex calculations to determine an adequate dose or a sensor to monitor these. Can a normal household do this?
A perfect illustration of this is as follows:
Let's suppose you are dosing 2 ppm of chlorine into your tank of water to oxidize iron/manganese oxides, inactivate microbes and offer residual protection, how will you know if this is enough? By investigating. Let's assume you found 10 ppm to be fine for 10000 Litres. How about when there is variability in water quality as we experience after a heavy flood? You would need to determine a new dose. So many variables. Can a normal household do this?
So you see that chemical dosing requires strict monitoring and complex calculations and analysis that make it difficult if not impossible for a normal household to perform. For this reason, I think you need to express caution when purchasing a water guard. What beats my imagination about these products is that there is even no caveat on them. This is why late Professor Dora fought so hard to confront both the liars and educate the populace. For this reason, too I suspect water treatment plants based on chemical dosing-very soon you would hear they are out of chemicals.
4. Cost
The last parameter I will consider is cost. In terms of cost, we shall look at it as CAPEX and OPEX. CAPEX refers to Capital Expenditure-money you spend on setting up, buying your equipment, installation. OPEX refers to Operating Expenditure-money you spend on operation and maintenance. Cost of buying chemicals, electricity, paying a staff etc.
The first point is most technologies have an OPEX-CAPEX trade-off. That is low OPEX means high CAPEX and vice versa. Simply put, if you buy a cheap tokunbo car you must befriend a mechanic. However, some things that have a high CAPEX and OPEX like iPhone, Mercedes Benz, Rolls Royce. So never believe that any technology has low CAPEX and OPEX. Never! Expecting a low CAPEX and OPEX is hypocrisy according to my Grad school lecturer who said
We, humans, are hypocrites. We expect our drugs to be very cheap and yet very safe at the same time.
Little wonder drug peddlers still have a field day in spite of Professor Dora’s efforts. The implication of this is if it appears too good to be true, it probably is.
The second point is we don’t have any literature available in Nigeria. So I won’t give objective information. However, from experience, we know conventional filtration like membranes have high CAPEX and a lower OPEX compared to have a conventional combined technology (multi-barrier approach). Chlorine is cheap but not effective against protozoans, ozone is but unlike chlorine offers no residual protection. Moreover, it is expensive. UV is like an iPhone. It has both high CAPEX and OPEX which is why most households never dare it. Boiling is the same but you cannot boil the ocean as they say.
To sum up, I would like to reiterate the points again. Nothing beats boiling and filtration, However safe storage is key. This is because while chemical oxidation looks attractive, no one tells you the following caveats:
-There is a growing risk of disinfectant byproducts (DBPs)
-Protozoans like Cryptosporidium and Giardia resist chlorination
-Chemical dosing requires expertise
I hope that by this series, I have been able to inspire you to return to the basics: Boiling and filtration that were so effective against Dracunculiasis aka Guinea worm (remember our last series)! Thanks for reading.
(1) In Guidelines for Drinking Water Quality; WHO, 2011; Vol. 65, pp 117–153.
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