GUWAHATI, Jan 22 � While plastic waste has turned out to be a menace because of the popular �throw away culture�, and the failure of the civic authorities in ensuring scientific disposal of the waste, a study has shown that it is the non-recyclable plastic waste that poses an even more serious and long-term environmental hazard.
The threats posed by non-recyclable plastic include clogging of drains, flash flood and water-logging, soil degradation, and expansion of wasteland, as these are not even collected by the rag-pickers and there is no effective recycling mechanism.
ENVIRON, an environmental group, conducted a study on plastic waste and classified plastic waste as recyclable plastic and non-recyclable plastic on the basis of recycling potential which are identified and listed systematically along with the reason of non-recyclability.
As per findings of the study, all multilayered and laminated plastics are non-recyclable whereas all the single-component plastic like PET (Polyethylene Terephthalate), HDPE (High-Density Polyethylene), PVC (Polyvinyl Chloride), LDPE (Low-Density Polyethylene), PP (Polypropylene), PS (Polystyrene) etc., are recyclable.
�Non-recyclable plastic (NRP) includes all the multi-layered plastic, pouch packs and plastic package used for potato chips, tea, coffee, biscuits, snacks, spices, noodles, chocolate, pan masala, shampoo, detergent, lubricants, fruit juice and others made of �metalized PET�, polyester and PE; medicine blister strip made of PE and aluminium foil; various plastic laminated on paper packs made of paper, PET or PE; all the plastic laminated cover page of books, magazines and souvenirs, etc.,� Dr Amarjyoti Kashyap says.
Recyclable plastic (RP), on the other hand, comprise plastic carry bags made of LDPE, HDPE, PP; �plastic glasses� used for tea, coffee, water, ice cream etc., made of PS; plastic bottles used for drinking water, cold drinks, fruit juice, medicine, cosmetics, shampoo and detergent, injectable saline, edible oil, automobile lubricants, mosquito repellent etc., made of PET or PVC; various single-layered plastic pouch-pack used for vegetable oil, salt, milk made of PE, PET, PP; PVC shoe; plastic sheet used for RCC construction, plastic thread, damaged plastic pipes, disposable syringe for injection and other plastic waste made of polyester, PE, PET, PVC, PS, PP, etc.
According to Dr Kashyap, only similar types of plastic can be moulded for recycling, as mixing of a small amount of a different type of plastic can ruin the entire melting process.�For example, in the case of recycling procedure, presence of a small amount of PP (Polypropylene) may hamper the recycling of PET (Polyethylene Terephthalate).
�Non-recyclable plastics are often multilayered, and therefore, cannot be melted for recycling purposes. On the other hand, laminated plastics can be recycled only after the de-laminating process which is costly and not economically viable,� he added.
Dr Kashyap said that the commonly-held belief that non-recyclable multilayered and metalized plastic packs enhances food grade quality was not borne out by facts. �Our study has revealed that enhancement of food grade quality inside the multilayered and metalized-coated plastic is not authentic, as the inner layer where the food remains are always usually LDPE which is used for sealing purposes,� he said.
Dr Kashyap also said that most of the research on plastic waste and its management were based on the research in developed countries. There are four types of plastic waste recycling procedures � primary recycling involving processing of a waste plastics into a product with characteristics similar to those of original product; secondary recycling involving processing of waste plastics into materials that have characteristics different from those of original plastics product; tertiary recycling involving production of basic chemicals and fuels like diesel from waste plastics; and quaternary recycling involving the recovery of the energy content from all types of plastic waste by burning through incinerator.
�The first two processes are popular in India and tertiary recycling processes are just starting and quaternary recycling process is not practised in India. Quaternary recycling is popular in most of the developed countries and for them differentiation of recyclable and non-recyclable plastics is not so important, though it is releasing persistent organic pollutants (POPs) in an alarming manner,� he said.
As per an earlier study of ENVIRON conducted a decade back, total generation of plastic wastes in Assam was 50,000 kg per day.
�As on today, the State is generating nearly 100,000 kg plastic waste out of which 40 per cent is non-recyclable plastic. Given the present scenario, the entire ecosystem of the world is under threat and the day is not far when cultivable land will have loads of plastic waste,� he said.
Non-recyclable plastic also includes battery cases combination of plastic and paper; toothpaste tube and tooth brush, medicine tube, cosmetics tube, pen, comb etc. made of mixed PVC, polyester, PET and others; aseptic packaging or all type of square boxes used for packaging of liquid substances like milk, vegetable oil, fruit juice and soft drink made up from complex layers of plastic, metal and paper, etc.