Potable Water for All – More Than a Pipe Dream

ORIGINAL: OBR Review
by: Megan Barrett

15th July 2013

Many of us take for granted the availability of a clean glass of water. Yet even at the turn of the second millennium, approximately one billion people still did not have access to a sustainable source of potable water.[1] With water contamination and shortages most prevalent in the remote regions of developing countries (where money and technology can be limited), scientists are faced with a daunting challenge: to develop new ways of treating water to make it safe, using simple, locally sourced and inexpensive processes. Interestingly, the local environment may hold the key. Recent discoveries suggest that naturally occurring products, such as plant seeds and even tomato peel, may be used to help purify water.

Water is essential to our survival and health, with the human body being approximately 70% water. We use water in industry, to grow crops and cook; in sanitation; and for transportation purposes; yet, untreated water sources can contain many hidden threats including toxic heavy metals and dangerous pesticides. According to the World Health Organisation (WHO), approximately 80% of illness in developing countries is known to be associated with contaminated drinking water.[2]

A number of methods for treating water currently exist, mostly involving the addition of chemical substances, such as chlorine or aluminium sulphate (alum), to contaminated bodies of water. The availability, cost and knowledge to ensure the correct dosage of such substances, however, is often lacking in remote communities.[2] Consequently, some scientists are looking for more natural solutions– ones potentially more accessible to people living away from areas of development.

Figure 1: Moringa oleifera pods

The Moringa oleifera (figure 1), a variety of plant found abundantly across rural India, Africa and Cambodia has drawn considerable attention in recent history. Parul Sharma and a team from the Faculty of Science at Dayalbagh Educational Institute, Dayalbagh investigated the ability of M. oleifera seed powder to remove cadmium, a dangerous heavy metal responsible for itai-itai disease, from water sources on a laboratory scale. Cadmium was labelled with a radioactive tracer so its levels could be tracked and the M. oleifera plant seeds were crushed to form a powder. Quite surprisingly, Sharma’s group found that cadmium levels were effectively reduced by the seed powder, suggesting this species of plant may be useful in remote and developing regions of the world to help reduce contamination of the local water supplies.[3]

A second ecologically friendly method of treating water has been developed by a group of scientists from Tshwane University of Technology, South Africa. Recently, Oranso Mahlangu and colleagues tested the ‘Silver Impregnated Porous Pot (SIPP) filter’, a clay-based filtering pot, as a tool to produce safe drinking water at a household level.[4] The SIPP filter is made using certain clay types that naturally remove contaminants (e.g. toxic heavy metals) by a process known as adsorption. This is when particles in a gas, liquid or dissolved solid bind to a surface, and is not to be confused with absorption: when a gas or fluid is taken into a solid (e.g. a sponge soaking up a puddle of water).

Figure 2: Diagram illustrating the set up of Mahlangu and colleagues ‘Silver Impregnated Porous Pot (SIPP) filter’

Mahlangu’s team filtered different river sources through the SIPP filter six times, for 3 hours at a time (figure 2). They then used a method known as atomic adsorption spectrophotometry (AAS) to analyse the level of metal contaminants (such as magnesium, iron and arsenic) in the water samples before and after filtration. What they found was remarkable: the SIPP filter reduced the amounts of magnesium and iron in the water samples by more than 50% to a level below the WHO’s acceptable maximum for these heavy metals (70–100micrograms per litre and 0.2–2micrograms per litre, respectively). Arsenic levels were also reduced, though unfortunately not to within the WHO’s stated guidelines, and the effectiveness of the SIPP filter did lessen with use.[4]

Figure 3: Peeling a tomato

Nevertheless, the search for an affordable and accessible way of acquiring potable water in remote parts of the world has continued. A few months ago, Ramakrishna Mallampati and Suresh Valiyaveettil from the University of Singapore investigated a somewhat unexpected tool for water purification— the tomato peel (figure 3).[5] Remarkably, this fruit‘s “biomembrane” (or cell-covering barrier) also acts as an adsorbent to the toxic heavy metals in polluted water and removes dangerous dyes and pesticides that may have contaminated a natural water source.

Mallampati and Valiyaveettil treated their local shop-bought tomato peels by boiling them, washing them with propanol (an alcohol that removes pigment, i.e. the red colour of the tomato) and drying them. These peels were then added to different solutions containing known water contaminants and were found to effectively lower the levels of chemicals such as arsenic, alcian blue and neutral red (two dyes) and phenol which is used in pesticides. Moreover, the effectiveness of the tomato peels to help remove the water pollutants did not seem to deteriorate over time, suggesting that the easily accessible and inexpensive tomato peel may be a useful material for treating drinking water.[5]

The availability of sustainable water sources for the more isolated communities around the world; (especially in developing countries) is a serious problem facing scientists and society today. Many of the current chemical processes for treating drinking water are not obtainable or affordable for remote populations, such as those in rural India or Sub-Saharan Africa. Yet scientists have made some bio-friendly breakthroughs. The recent findings that certain heavy metals and other contaminants toxic to human health can be reduced by natural materials, such as plant seeds, clay and tomato peel, is a significant achievement in the fight to provide safe potable water for all— a battle I will definitely be thinking about the next time I turn on my tap.

References

1. Rush EC. 2013. Water: neglected, unappreciated and under researched. Eur J Clin Nutr. 1-4. http://www.ncbi.nlm.nih.gov/pubmed/23361160
2. Yongabi K, Lewis D, Harris P. 2012. Natural materials for sustainable water pollution management. In Prof Nuray Balkis (Ed). Water Pollution. InTech. http://www.intechopen.com/books/water-pollution
3. Sgarma R, Kumari P, Srivastava M, et al. 2006. Removal of cadmium from aqueous system by shelled Moringa oleifera Lam. seed powder. Bioresour Technol. 97:299-305. http://www.ncbi.nlm.nih.gov/pubmed/15949938
4. Mahlangu O, Mamba B, Momba M. 2012. Efficiency of Silver Impregnated Porous Pot (SIPP) filters for the production of clean potable water. Int J Environ Res Public Health. 9:3014-3029. http://www.ncbi.nlm.nih.gov/pubmed/23202668
5. Mallampati R, Valiyaweettil S. 2012. Application of tomato peel as an efficient adsorbent for water purification— alternative biotechnology? RSC Advances. 2:9914-9920. http://pubs.rsc.org/en/content/articlelanding/2012/ra/c2ra21108d

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What Would Suburbia Look Like If It Had The Same Water Resources As Africa?

A cadmium lining

ORIGINAL: The Economist

Jan 26th 2013

Growing mounds of electronic scrap can mean profits or scandals

A worker dismantles electronic waste in Guiyu, southern China. Over 100,000 people are employed there to recycle discarded computers and other gadgets. EYEVINE 

Recycling e-waste can be lucrative. But low safety standards cause serious health hazards, ranging from burns to cancer and miscarriages. EPA 

Most of the waste comes from rich countries. Crude techniques like burning off plastic parts release toxins, leading to dangerously high lead levels

Those who do not handle e-waste may suffer too; from contaminated water, for example. Studies have found high rates of miscarriage in local women. EPA

5,500 workshops in Guiyu recycle 1.5 million tonnes of e-waste a year, making $75 million. Techniques are improving, but labour standards are lax. GETTY IMAGES

Chinese policemen guard confiscated gadgets. The Basel Convention, which governs the waste trade, wants to ban shipments to poor countries. REUTERS

Guiyu's thriving e-waste industry is hard on the environment too. Cleaning it up, without closing it down, will be difficult for regulators. EYEVINE

POOR countries have long been a popular destination for the rich world’s toxic trash. In 1987 an Italian importer sparked international outrage by dumping 8,000 leaky barrels in the Nigerian village of Koko. On January 9th Nigeria fined importers $1m for trying to bring in two 12-metre containers full of defunct televisions, computers, microwaves and stereos, aboard a ship from Tilbury in Britain—the fifth such incident in three years.

Waste consisting of dead electronic goods, or e-waste, is growing at three times the rate of other kinds of rubbish, fuelled by gadgets’ diminishing lifespan and the appetite for consumer electronics among the developing world’s burgeoning middle classes. In 1998 America discarded 20m computers; by 2009 that number had climbed to 47.4m. China alone retired 160m appliances in 2011, 40% of America’s haul. A 2011 report by Pike Research, a consultancy, estimates that the volume and weight of global e-scrap will more than double in the next 15 years.

International efforts to regulate the trade in waste revolve around the Basel Convention, passed in 1989 following the Koko row. It aims to stop the rich world dumping its harmful detritus in poor countries. But e-waste is not just poisonous: it contains precious metals, too. Processors, chips and connecting pins (known as “gold fingers”) contain seams of silver, gold and palladium; these “deposits” are 40 to 50 times richer than dug-up ores, according to a study conducted by the United Nations University. Other less valuable and more troubling lodes for “urban miners” include cadmium, lead and mercury.

High-tech recyclers—such as Umicore in Belgium and Xstrata in Canada—can recover up to 95% of the metal using furnaces and solvents. But dirtier methods are cheaper. In the Guiyu area of southern China 100,000 people work in e-waste recycling. It is “ground zero for the e-waste trade,” says Jim Puckett of the Basel Action Network, a green group. Standard practice is to separate the plastic by boiling circuit boards on stoves, and then leach the metals with acid. Workers risk burns, inhaling fumes and poisoning from lead and other carcinogens. A study by the nearby Shantou University found high miscarriage rates in local women.

So far, manufacturers are doing little to make their products easy to dismantle and recycle cleanly. Mr Puckett and his allies want a blanket ban on e-waste shipping to stop the West “exporting harm”. The Basel signatories took a big step in October 2011 towards a general ban on the export of hazardous waste—which would include electronic scrap. But poorer countries already produce a quarter of the world’s e-waste pile; they could overtake rich ones as early as 2018. Choking off the trade will not stop the acid cauldrons bubbling.

Adam Minter, a Shanghai-based journalist and author of a forthcoming book, “Junkyard Planet”, says that China’s wages and location give it a comparative advantage. “It’s no accident that Guiyu is so close to where iPads are being made,” he says. Feng Wang, an e-waste expert at the UN University, notes that the authorities in Guiyu are supporting safer, high-tech recycling plants. Mr Minter says other recyclers there have been using heated centrifuges to dislodge the valuable bits from circuit boards; they have charcoal filters to absorb the fumes. Guiyu would not meet Western health and safety standards, but, he says, “it’s progressed from the medieval era to the 1970s.”

Those endorsements ring hollow for Mr Puckett. He cites the dearth in developing countries of enforceable safety rules, health care for workers and courts to redress grievances when things go wrong. While poor countries lack these arrangements, he says, rich countries should not send them e-waste. And many countries do not recycle at all: most televisions and computers that end up in Nigeria are dumped. Nigeria’s parliament is currently considering a bill to prohibit traffic in e-waste altogether. The Chinese may be cheering for that.

A Heavy Metal Filter with a Sustainability Twofer

ORIGINAL: Clean Technica

Just in time for the final installment of the Twilight vampire saga, a team of researchers from the University of Delhi is developing a filter made of garlic and onion, to clean up arsenic, cadmium, iron, lead, mercury, and tin. The process could be used to treat industrial effluent at factories, and it could also join the growing bioremediation toolkit for cleaning up polluted sites. As for its application as a discouragement to vampires, that looks fairly promising, though apparently some vampires harbor more disaffection for garlic than others.

Image (cropped): Garlic by photofarmer

Researchers are already beginning to look into food-related substances like lactate, bananas and vitamin B12 as a sustainable means of neutralizing toxic substances in soil, also known as “green remediation.”

Green remediation presents a marked improvement over conventional “remediation,” which used to involve either capping a site and letting the contaminants fester under the cap, or digging out tons of contaminated soil and trucking it to a landfill where it would also fester.

The Delhi University process is of particular interest because it involves a double dose of re-use.

The filter itself consists of waste biomass — namely, the leftovers from processing garlic and onions at food canneries. The biomass absorbs as much contaminants as it can handle, and then nitric acid is applied to separate the metals into another vessel. The filter can then be reused all over again.

The process depends on achieving an efficient pH of 5, and so far the researchers have found that this can be achieved under a relatively low temperature of 122 degrees Fahrenheit.

Using food production waste to make a reusable filter is good enough. To ice the cake, once the filter has outlived its usefulness as a contaminant-trapper, it can be slipped into the food waste stream as feedstock for biofuel refineries.

Commercial scale food waste biofuel is still in the development phase, but a pilot food waste biorefinery in Germany looks promising. So, let’s call this a sustainability threefer.

More and Better Green Remediation

The Delhi team isn’t alone in its quest to turn a vampire remedy into a bioremediation tool. In Bulgaria, a team of researchers is experimenting with on-site plantings of garlic and grasses to absorb contaminants.

The use of plantings in green remediation is a whole ‘nother ball of wax, since it can involve perennial grasses, shrubs and fast-growing trees like poplar, all of which can double as biofuel crops.

If garlic joins the green remediation/biofuel club, that gives you the fuel of the future: it’s sustainable, and it keeps vampires off your car, too.

Follow me on Twitter: @TinaMCasey

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