Pakistan’s Floating Wetlands: Low-Cost Remedy for Wastewater

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A team of scientists in Pakistan has developed low-cost vegetative mats, which have shown
promising results for the treatment of domestic wastewater, factory effluent streams, and even
pools filled with hydrocarbons and heavy metals. The mats float in polluted reservoirs and
continuously clean wastewater through local plants and vegetation – dubbed as floating treatment
wetlands (FTWs). This technology is developed by Dr. Afzal and his team at the National
Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, under the umbrella of
the Pakistan Atomic Energy Commission (PEAC). Dr. Jochen A. Müller and Dr. Muhammad
Arslan were also collaborators from Helmholtz Centre for Environmental Research in Germany.

For the first time in Pakistan, full-scale FTWs were installed for almost six years at WSPs (waste
stabilization ponds) near Faisalabad. These ponds were filled with 60% sewage from homes,
while 40% wastewater poured from various industries including tanneries, chemical, and textile
factories. Wastewater from both homes and industries turned the ponds into an ideal testbed to
check the importance of floating green patches.

COD (chemical oxygen demand) reveals the amount of both biodegradable and non-
biodegradable substances present in water/wastewater, whereas BOD (biological oxygen
demand) tells the level of only biodegradable matter present in the water/wastewater. So, high
COD and BOD values indicate the presence of a high concentration of pollutants/chemicals in
the wastewater, and lower values indicate that the water is comparatively clean.

The wonders of eco-friendly mats were observed in the second year, and after three years,
almost all water quality indicators were improved. Positive effects were noted in three
categories: physicochemical (reduction in total dissolved solids, oil and grease, and sulfates)
microbiological (coliform and fecal coliform), and heavy metals ( cadmium, chromium, and
nickel, c).

The wetland systems treated 79% of COD, 88% of BOD and 65% of total dissolved solids
(TDS). The locally developed, floating mat is 500 times less expensive as compared to
commercially available solutions. For almost six years, few green mats treated some 57,947,400
cubic meters of filthy water – which can fill more than 31000 Olympic size swimming pools –
treating the water at the cost of a few paise per cubic meter! The data assessment shows that all
wetlands will be further viable for a total period of 15 years.

The Blue Water Crisis
Clean and blue water thirst is increasing in Pakistan. According to the International Monetary
Fund (IMF), Pakistan is the third-most affected country with an acute water shortage. The World
Economic Report also highlighted that water scarcity is one of the major threats to Pakistan's
economic stability. Moreover, the Pakistan Council of Research in Water Resources (PCRWR)
has warned that Pakistan may run out of sufficient usable water by 2025. Apart from the
extensive use of water, the discharge of wastewater into the environment is the main reason for
the depletion of clean water resources in the country.

The toxins and pathogens in the wastewater not only pollute the soil, but also pollute freshwater
resources, hence depleting resources available for human consumption. In Pakistan, masses are
forced to drink unsafe water. According to an estimate, unsafe water contributes to 80% of
diseases and 40% of deaths in the country. In this scenario, floating wetlands are a practical, low
cost and eco-friendly solution to this growing problem. These green systems are easy to use
without any electricity and chemical input.

Pakistan is among the top five countries that account for almost 90% of farmland across the
globe irrigated by sewage water. The findings were published in the Environmental Research
Letters Journal in July 2017. The bad news is that vegetables and fruits grown with this water
contain heavy metals, pathogenic bacteria, and worms – all hazardous for human health.
“Wastewater is rich in nutrients, and it boosts yield, but it also contains traces of heavy
metal which is harmful for human health as well as soil used for agricultural
purposes,” says Rafiul Haq, an ecologist and former consultant to the International Union for
Conservation Nature Pakistan chapter.

In 2013, a study conducted in Sialkot and Wazirabad districts found higher levels of heavy metal
in crops irrigated by wastewater, compared to that of supplied water from tube wells. The study
conducted by Environmental Biology and Ecotoxicology Laboratory at the Quaid-e-Azam
University compared coriander, okra, onion, garlic, capsicum, carrot, brinjal,spinach,mint,
radish, tomato, and wheat crops irrigated by contaminated water from Nullah Aik and Palkhu
streams, and tube well water. Metals like cadmium, lead, and chromium in affected crops,
especially in leafy vegetables, were found to be far above the permissible limits. “Cadmium
causes kidney and lung damage. It also weakens bones, causing frequent fractures in both
children and adults,” says Dr. Zafar Ahmed Fatmi, a professor of Community Health Sciences
at Aga Khan University, Karachi. “Nickel, another metal frequently found in wastewater, has
systemic immunologic, neurologic, reproductive and developmental effects on human
body,” added Fatmi.

In this scenario, Pakistan urgently needs environmentally friendly solutions to clean sewage
pools, and FTWs could be very helpful in this challenge. It is important to mention that
Faisalabad ponds also irrigate some 70% farmland of surrounding areas. Dr. Afzal and his team
designed and fabricated the floating mats, using aluminum frames on the edges, and
polyethylene insulation rolls inside to develop FTWs. Then, four local plants – Common reed
(Phragmites australis), Southern Cattail (Typha domingensis), Kallar grass (Leptochloa
fusca) and Para grass (Brachiaria mutica) – were set in hydroponics system as all plant’s roots
were dipped in sewage water. However, roses and other flowering plants were also grown on the
edges to add beauty to the green mats. All the plants belong to the grass family, and are well
known for biological treatment of wastewater Reference.

The Hydrocarbon Pit

The team also tested wetlands of the same plants in a pit full of heavy metals and toxic
hydrocarbons at Rajian district, Chakwal, which had emerged because of oil and gas exploration.
Collectively, all the floating wetlands reduced COD, BOD, TDS, hydrocarbon content, and
heavy metals by 97.4%, 98.9%, 82.4%, 99.1%, and 80%, respectively, within 18 months. Almost
all the plants survived in the toxic environment and even showed fast growth. Scientists also
observed birds and fishes near the FTWs, which is a plus point for biodiversity and ecology. The
amazing success of environmentally friendly wetlands needs further work, and a web of wetlands
can clean sewage reservoirs from Gilgit to Baluchistan. The floating treatment wetlands consist
of locally available plants and grasses, and pave the way to clean even larger reservoirs of
polluted waters.

Image courtesy: Dr. Muhammad Afzal

Author: Suhail Yusuf is a science journalist and documentary producer based in Karachi,
Pakistan.

The article has been edited by Rabia Nusrat, Anam Riaz and Alizah Gul Memon.

References

https://www.nature.com/natsustain/volumes/2/issues/9

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