Electrochemical water treatment is a rare but highly effective way to produce clean and germ-free water. However, electrochemical products are currently scarce in the market because of the relative unfamiliarity to the technology as well as the enormous competition of other water treatment methods.

Basically, this type of disinfection is done by passing a current of electricity between electrodes (cathode and anode), resulting to changes in pH levels that in turn encourage pollutant desorption. The technique does not require addition of chemical compounds, but it is nevertheless the action of various chemical substances in the water that does the decontamination. Electrodes made from platinum group metals and their oxides are most suited for this type of process.

There are many reasons why electrochemical water disinfection has only been developed recently. Sufficiently stable electrodes have only been enhanced in the last forty years. Also, the practical interrelationships between chloride concentrations, electrolysis and water quality have been investigated methodically just in the previous decades. Lastly, only a few electrochemists had been engrossed in the topic which resulted to errors in device-making and irrational hypotheses to the mechanism of the process.

How Electrochemical Disinfection Works

The mechanism behind electrochemical disinfection is fairly simple. It is agreed that the cleansing of the water springs from desorption induced regeneration that affects the surface of porous carbons. Simply put, the electrical current allows chemicals to effectively react to microorganisms and kill them in the process.

The cathode, which is the reducing electrode, generates hydroxide ions that increase the alkalinity of the water around it. Through this, desorption of pollutants is promoted and they migrate to the anode for oxidation – hence their destruction.

Pros and Cons of Electrochemical Treatment

The advantages of this type of treatment are obvious. There is no need for the transport, storage and utilization of disinfectants which are otherwise needed for chemical methods of water treatment. The disinfection also has an inherent reservoir effect thereby marking cost-effectiveness and the need for less maintenance. Finally, there is no real need to induce power from an electrical supply grid as the principles of photovoltaic or solar energy can be used.

This is crucial to disinfect water in developing countries.

On the other hand, the major disadvantage comes with the mass transfer limitations between the electrodes. Residual pollutants could not be avoided and thus the cathode has to be cleaned after several cycles. If not, pore blockages and damage to adsorption sites decrease the regeneration efficiency. There is current research though that aims to develop adsorbents that are able to regenerate 100% of their capacity through electrochemical regeneration.

The Bottom Line

The use of electrolysis to chemically treat water has more advantages compared to other conventional techniques. This has been proven with its use in disinfecting drinking water, swimming pools, dental water supplies and industrial cooling water. Although this technology is not in full use today, the cost and performance advantages will eventually pan out to the wider use of electrochemical techniques in the future.

Distilled Water: Uses and Misuses

When you think of distillation, it’s likely your mind wanders to the creation of your favorite single malt whiskey. Fair enough, really. However, when you look beyond the bottle, distillation can also be used as a method of water purification.

Distillation is a fairly simple process. Essentially, unpurified water is boiled to the point of vaporization. Most salts and minerals have a higher boiling point than water, and so while the water vaporizes, most contaminants are separated from the water and remain in the vessel. Once the water has vaporized it is channeled into a condenser where it is cooled down to return to its liquid form and it collected in a clean container. This process is often repeated several times to purify the distilled water as much as possible.

Distilled water is most commonly generated for industrial use. Due to the de-mineralization of distilled water, it is perfect for chemical and biological laboratories, photo and printing stores, lead acid batteries in cars and trucks and for automotive cooling systems. Distilled water definitely has its place in the industrial world, as minerals can be corrosive to machinery and can have undesirable reactions with some chemicals. However, distilled water is not ideal for everyday human consumption.

So why do people opt for distilled water? Well, distillation is a fairly reliable method of removing dangerous bacteria, viruses and heavy metals. In developing countries these contaminants pose a real risk, and so distillation is a valuable process to save people from potentially life-threatening contaminants.

However, in Western countries drinking distilled water usually does more harm than good. In the Western world, most of the extremely dangerous contaminants are filtered out by municipal water treatment facilities, so other forms of water purification are most ecological, efficient and healthy than distillation.

Distillation doesn’t remove synthetic chemicals because their boiling point is lower than water. So pesticides, herbicides, and chlorine solutions remain in the water, which isn’t usually dangerous, but isn’t ideal either.

Another downside is that distillation relies on an energy source kept at a constant temperature. To power the energy source, approximately 5 gallons of tap water are needed to create just one gallon of distilled water. Of course, it is possible to use solar energy as a heat source, but with technology available at present it takes up to five hours and only works for small quantities of water.

The worst part of all is that distillation removes trace elements that are naturally present in water. Removing elements from water through distillation makes hydrogen a greater percentage of the distilled water’s composition, thereby making the water acidic.

Although drinking acidic, demineralized water is better than ingesting harmful contaminants, long term consumption of distilled water can lead to mineral deficiencies

How effective are ceramic filters at generating potable water?

ow effective are ceramic filters at generating potable water?

Although the technology they use is extremely simple, ceramic filters are increasingly popular water filtration devices. Ceramic filters trap bacteria in tiny pores like a sieve, allowing potable water to filter through.

So, how effective are ceramic filters? Ceramic filters are effective at catching cryptosporidium and giardia, the two primary causes of diarrhea from drinking dirty water. However, volatile organic compounds and chlorine will remain in the potable water as the microns are small enough to pass through.

There are several issues with ceramic filters. One common concern about ceramic filters is that one cannot know exactly how effective any particular ceramic filter is. The effectiveness of ceramic filters is dependent on their pore size. The pore size of a ceramic filter is dependent on two main variables: the ceramic material used and the temperature at which the kiln is set when the ceramic filter is vitrified. Although the composition varies from filter to filter, most ceramic filters are made of diatomaceous earth, a fine silica powder found in certain types of algae.

Ceramic filters must be vitrified in order to work effectively. When struck, a properly vitrified ceramic filter should ring like a bell. When vitrified, ceramic filters should not retain black specks, as this means the carbon hasn’t broken down during the firing process.

Effective ceramic filters are relatively slow to work. Most have a slow flow rate, passing water through the ceramic element at a rate of two liters an hour. For this reason, ceramic filtration is one of the least time-efficient methods of water filtration. However, in developing countries, ceramic filters are adequate as they are low-maintenance and don’t require batteries or electricity to run. For this reason, ceramic filters have been used to increase the standard of living in many areas throughout Asia and Africa.

Ceramic water filters are more effective if used in conjunction with other forms of water filtration. In areas where ceramic filters aren’t entirely effective, they can still be helpful as a pre-treatment before reverse osmosis water treatment systems.

The main disadvantages with ceramic water filters are the limited volume of potable water one can produce from a single filter and filtration in areas with dangerous chemicals such as arsenic in the water. Ceramic filters are slow to produce a small amount of potable water, so they aren’t the best option for large NGOs trying to provide potable water for whole communities. Any organization planning to use ceramic filters as the primary source of water filtration would need to thoroughly research the water quality and do extensive testing to ensure that ceramic filters provide sufficiently potable water.

As with many filtration devices, it is essential to avoid touching the vessel catching the purified water from the ceramic filter. Often, your hands come into contact with contaminated water while you are filling the filter, so it’s important not to contaminate the water you have just gone to all the effort of purifying. However, if in doubt, simply pour the water through the ceramic filter a second time.

Before You Buy, What Kind of Water Filter Do You Need – Reverse Osmosis or Microfiltration?

Reverse osmosis is basically the process of separating contaminated water into clean and unclean water using a semi-permeable membrane to filter out waterborne bacteria and contaminants.

Ideal for purifying seawater and brackish water, it has been extensively used in industry and smaller units for boating or fishing trips. Purification is achieved by forcing the water, under pressure, through the membrane and effectively dividing it into a pure waterside and a contaminated waterside.

For best reverse osmosis water purification results, several stages are required – 2 levels of sediment filter, 1 activated carbon filter (it’s essential to remove chlorine as it damages the unit), the reverse osmosis cartridge filter, ideally followed by an ultra-violet lamp to disinfect any remaining microbes.

The reverse osmosis membrane needs to be flushed reasonably regularly to stop the formation of scale, and very often, pre-filtering by a water softening agent, as well as a carbon-based product to reduce chlorine, may be required. While reverse osmosis drinking water systems are effective against most microorganisms, they may not filter out protozoa such as Cryptosporidium.

In independent testing, on a scale of 1 to 5, where 1 is the most effective, ( see comparison chart) the microfiltration membrane scored a 1, while the reverse osmosis water filter scored a 2. That one place could mean the difference between allowing a small amount of contamination through or none at all.

As a point of vital interest – alongside the results for reverse osmosis, bottled water purchased in developing countries scored a 3, possibly due to two critical risks with bottled water purchased overseas

1. the risk the water has come from local water supplies, either newly bottled or an old bottle refilled, and
2. the proven build-up of bacteria in water bottles that have been transported long-distances and in high temperatures.