Victor Luca, 29-Oct-20.
For much of human history our toilet habits have remained extremely primitive. Although there are doubtless many of the more senior members of our district that have fond memories of the long drop, located somewhere remote from the main house, I doubt there are any that experienced the days when corn cobs were used to clean up after a number two.
Today most of us have access to the comfortable white porcelain throne and soft white toilet paper.
At the end of using the dunny these days we simply press a button located on top of the cistern and with a gush of water and a gurgling sound the offending unmentionable material is sent on its way to an often distant location that many are probably not even aware of. Out of site and out of mind!
In the Whakatāne-Ohope ward our unmentionables flow down an intricate reticulated piping network to a centralized oxidation pond facility located near Coastlands or in Ohope. The trick to making a traditional toilet work is an innovation patented in 1775 known as the S-trap. This trap holds water in the toilet bowl to prevent smelly gases from coming back up the pipes and infiltrating the home or building. After the characteristic swish and gurgling sound of this siphon system the problem belongs to the council, although we pay for what happens on its way to and at the oxidation ponds in our rates bill.
At the oxidation pond, the waste is mashed up using grinder pumps and screened and then oxygen and microbes do their job as part of ecosystem services and break down the solids to a sludge which settles out at the bottom of the ponds and is occasionally removed and dumped somewhere. This centralized infrastructure can vary in sophistication.
This waste water infrastructure works well but comes at a significant cost that is simply beyond the reach of much of the developing world.
Some in our district cannot avail themselves of this reticulated sewage system and instead rely on devices known as septic tanks located on their properties below ground.
At the local level, these septic tanks operate in a similar fashion to the centralized oxidation ponds. Again with the aid of microbes and oxygen, the waste matter in the tanks is broken down and the clarified liquid is sent to what is known as a drain field while solids settle at the bottom of the tank and are periodically removed and taken away.
A drain field consists of a series of buried perforated pipes that allow the relatively clear waste liquid to infiltrate into the soil where once again we rely on soil microbes to finish off the job. About 21% of households in New Zealand rely on septic tanks. A modern properly functioning septic tank is a potent device in dealing with our ablutions and as long as it is properly maintained has and continues to do the job adequately. A septic tank however, has its drawbacks among which is the fact that one needs sufficient space in one’s backyard to accommodate the drain field. The cost is not insignificant either and can fall in the range $15,000 - $20,000 depending on site and sophistication.
Those wishing to take their sanitary needs to another technological level might even affix to this indespensable porcelain throne a device known as an electronic bidet toilet seat (see Figure) which obviates the need to use toilet paper and the finger. Instead, one simply presses a button located on a panel on the side of the seat or on a separate remote control and water can be injected toward the site to be cleaned at the desired pressure and temperature. The more sophisticated electronic bidet seats have an auto-open function. A modern electronic bidet can also dry you and perform other functions that I shall not go into. I have been using one of these marvelous ecologically sensible devices for years and will never look back. I say ecologically sustainable because in the United States alone 14 million trees are chopped down each year and turned into toilet paper. Toilet paper production also uses copious quantities of chlorine chemicals. In the end, the not so white paper is flushed and winds up in the septic tank and/or oxidation ponds. A bidet seat is therefore ecologically sustainable and infinitely more hygienic than paper.
Being spoiled by these modern day luxuries most of us probably don’t even realize that there are more than two billion people on our planet that do not experience the luxury afforded us by this bit of engineering infrastructure. These folk often defecate in open sewers which represent a serious health hazard. This lack of adequate sanitation contributes to the spread of diseases like cholera and dysentery, leading to the death of more than 297,000 children under age five every year. As a consequence, it has been calculated that the global economic annual loss in health-care costs and lost productivity is about $200 billion.
Although the modern toilet has come a long way, many improvements are possible.
You may be surprised to know that non-other than Bill Gates, the Microsoft founder, is behind a marvelous initiative to re-engineer the humble porcelain and associated engineering infrastructure most of us don’t see. The Bill & Melinda Gates Foundation’s Reinvent the Toilet Challenge, launched in 2011 with the goal of developing low-cost, off-grid methods to treat human waste. This initiative has involved scientists and engineers all over the world and they are attempting to engineer superior toilets that do not require flowing water or an intricate series of pipes or even electricity. Instead, the idea is to decentralize and miniaturize the entire treatment process. In other words the entire waste disposal and sanitation process is undertaken close to where you sit and do your business. In some cases these toilets can be powered by solar energy and in other cases the waste itself is the power source. Waste volume reduction and disinfection can be achieved by electrochemical systems that generate the powerful oxidizing agent known as ozone or using a heating method known as pyrolysis. In the figure is shown the Sol Char toilet which is but one of the innovative new toilet concepts that has arisen as a result of the Reinvent the Toilet Challenge. One of the products of the pyrolysis-based treatment process is a material referred as biochar which is a type of charcoal that is an excellent adsorbent and soil amendment.
Engineering schematic of the Sol Char toilet prototype used to covert waste into charcoal and fertilizer developed at the University of Colorado Boulder, USA. Market suggested retail price $2,600 – $11,000 USD. See You Tube video at:How the sol-char toilet works.
It is clear that as populations increase, and environmental and sanitary concerns are taken more seriously, increasing attention has to be paid to how we treat our ablutions. Bill Gates has realized this and has put his money where is butt is. That is, in the Reinvent-the-Toilet-Challenge. I can only hope that boost that he has given these developments continues to the benefit of the world’s poor and rich alike.