Problem with plastic bag consumption and its solution

Plastic bag or polythene (PB) is a type of container made of thin, flexible, plastic film, non-woven fabric, or plastic textile. It is used for containing and transporting goods; such as, foods, products, powders, ice, magazines, medicines, chemicals, and wastes etc. Currently, it is a common form of packaging and widely used for its multi-utilities and convenience. However, it was first introduced as a sandwich bag in 1957 and started to be used to carry or transport groceries and goods by hands or otherwise in the 1970s. It was introduced into supermarkets in 1977 and has already replaced conventional biodegradable bags.

Unfortunately, what makes it so useful, such as its durability, light weight, hygiene, water proof, and low cost, also makes it problematic when it comes to its end-of-life phase by generating plastic bag waste (PBW). Further, its life span is very short, estimated average 20 minutes; then thrown away after being used once. In contrast, it is manufactured by using different types of polymers; such as polyethylene (PE), high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), polyvinyl chloride (PVC), polypropylene (PP) and nylon (PA) etc wherein numerous additives; such as, heavy metals and organometallic compounds are encapsulated with polymer matrix to optimize its properties and reduce cost; but not chemically bound to its polymer molecules.

However, its daily consumption is rapidly increasing in spite of associated enormous environmental problems; for example - drainage block, flash floods, soil fertility loss (agricultural), marine pollution (beach litter), carbon footprint (energy and natural resources consumption) as well as health hazards. Further, it is seen that PB consumption is high in countries with top GDP growth or industrialisation compared to developing countries like Bangladesh, India, and Kenya. Hence, it was found that annual per capita PB consumption is 1370 by Hong Kong, 286 by US, 263 by Israel, 252 by Taiwan, 235 by Japan, and 223 by China. Similarly, production and consumption of PBs is rapidly increasing amongst developing countries which indicate upcoming PBWs menace.

Currently, an estimated 500 billion to 1.0 trillion PBs are consumed worldwide every year; that means over 2.7 billion per day and one million per minute. Consequently, approximately 32 million tonnes of PBWs are generated annually worldwide, representing (12.7%) of total municipal solid waste (MSW) volume. Herein, China only consumes 3.0 billion PBs daily while United Kingdom consumes 8.0 billion per year. Similarly, in United States, the average families take 1,500 PBs at home per year and throw away 100 billion, and at least 12 million barrels of oil are used in the manufacture of those bags. On the contrary, in Australia over 6.0 billion PBs are used per year, that's over 10 million new bags are being used every day. An estimated 3.76 billion bags are disposed of in landfill sites throughout Australia annually.

Every year, the average EU citizen uses an estimated 500 PBs, (92.5%) of which is of single-use and around 90 billion such bags are used per year. Similarly, it was found that Ireland consumed 72 million, Taiwan 5.8 billion, Israel 2.0 billion, Hong Kong 9.8 billion, New Zealand 872 million, South Africa 8 billion, Norway 1 billion, Canada 3 billion, Japan 30 billion, and Brazil 12 billion such bags per year. These statistical data indicate the global per year PB consumption as well as PBWs production. Though there is no statistical data of annual PB consumption in developing countries, their cumulative volume is huge.

On the contrary, only 1 out of 200 PBs are recycled in United Kingdom. Thereof, (85%) of the PBWs are sent to landfills and some of the trash ends up as litter on the streets in United States. Australians dump 7,150 recyclabled PBs into landfills every minute or 429,000 bags every hour. Besides, it is estimated that around 50 million bags enter into the Australian litter stream every year. Unless they are collected, they remain in the environment and accumulate at a staggering rate. A similar scenario is seen in almost every country for PBW due to its short life span and light weight.  

Although PBs are modern conveniences for carrying goods, they have also very hazardous negative impacts on environment. Environmental impacts range from litter, to a danger to wildlife, to the use of non-renewable resources but societal use of PB creates an unnecessary consumption of an unsustainable product, while provided at no visible cost to the consumer. Thus, consumption of PBs is leading to unsustainable development with serious economic, social, and environmental repercussions. Therefore, many countries have already banned PBs due to public concern over the serious negative impact on the environment and agriculture; especially, in agricultural countries, such as Bangladesh, India, Pakistan, South Africa, etc.

These disposed PBs have now found their way to everywhere including the remote areas, like the Pacific Ocean, thus not only posing a threat to aquatic life, but also the landfills, urban environment and agricultural lands which have now posed a great threat to our environmental and agricultural development. There had been cases where large turtles of the endangered species had been found to have suffocated due to mistakenly swallowing plastic sheets mixed with seaweeds. These petroleum based products contain toxic additives such as endocrine disruptors and carcinogens, which can migrate into marine environments and enter the food chain via marine fauna. Accidental death in children from respiratory obstruction by bags made from thin plastic sheeting is well known.

On the contrary, the production and transportation of PBs not only consume energy, but also deplete resources and generate global warming emissions. Production of PB emits toxic chemicals and fumes such as methane, ethane, and ketones. The Nolan-ITU (2002) report assessed some environmental impacts from PB use; such as, for every 520 single-use HDPE bags, it resulted in 3.12 kg of materials consumed, 210 MJ of energy use, and 6.08 kg of CO² greenhouse gas emitted. Similarly, the same number of single-use LDPE bags resulted in 11.77 kg of materials consumption, 957 MJ of energy use, and 29.8 kg CO² greenhouse gas emitted (ibid).

Though all types of plastic wastes are recycled, PBW is neither recycled nor treated due to its light weight or being thin. Due to several uncaring factors, around 96% such PBWs are dumped into landfills along with MSW and some are littered in agricultural lands, streets and sea beaches. According to the report by Tweed (2008), during the International Coastal Cleanup in 2006, over 750 million pieces of PB litter were found in over 60 countries, which accounted for 9% of all the litter found during the clean-up. On the contrary, it is estimated that PBWs take up to thousands of years for partial degradation in natural way, but are ultimately never completely degraded.

However, the industries for PB production emerged in Bangladesh in early 80's and within a decade it reached such a level that the jute bag production was forced to be almost closed. Survey report showed that about 10 million PBs were used every day and every year about 3000 million bags were dumped in Dhaka City alone before banning (2001). The steadily growing use of PBs posed an ominous environmental problem in the city as well as in rural areas. The worst example of adverse effect caused due to PBWs was the delaying process of recession of flood water in Dhaka city during 1998. In spite of banning PB consumption in Bangladesh since 2002, still a large volume of PBs are consumed and discarded throughout the country every day.

One of the effective ways to manage PBWs is recycling or reuse of post-consumer PBs for other useful purposes. But the state of recycling in Bangladesh again posed some other environmental hazards and some means of transmission of diseases. The burning of PBWs in open air produces the threat of poisonous gas like CO, CO2 and HCN that cause health hazards to the people. The people who are involved in collection of PBWs are the most vulnerable group namely tokai.

On the contrary, all types of PBWs have HHV ranging from 18 to 47 MJ/kg almost equal to conventional fuel. Hence, PBWs can be treated to recover energy by using thermal treatment technologies such as incineration and pyrolysis. Thereby, it will save disposal cost as well as meet local energy demand partially by providing alternate of source of renewable energy. On the other hand, biodegradable PBs can be introduced by using green polymers extracted from inexpensive and abundant sources. But the alternate of synthetic PBs which have been suggested by many researchers aren't getting popularity being costly and heavy in weight.

The author is a student of Master of Environmental Engineering in UNEP-Tongji Institute of Environment for Sustainable Development (IESD), and research student in Institute of Waste Treatment and Reclamation (IWTR), College of Environmental Science and Engineering, Tongji University, Shanghai, China.

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