solid waste and e-waste causes and management

solid waste and e-waste

1. VI. SOLID WASTE POLLUTION

2. Solid wastes are the useless, unwanted, or undesirable solid and semisolid substances, discarded by man. They include garbage, trash, rubbish, refuse, ash and residues, waste tyre , sludge from treatment plants, demolition waste, construction waste, dead animals, radioactive substances, and so on. Solid waste pollution depends heavily on the living standards and life styles of human population. It is relatively more severe in industrial towns and cities than in agricultural villages. Solid wastes are of three general categories, namely municipal solid wastes, hazardous industrial wastes and biomedical wastes.

3. (a) Municipal solid wastes Municipal wastes are the non-radioactive and non-hazardous solid or semi-solid wastes from household activities, hotels, restaurants, public places, institutions, vegetable markets, butcher shope , fish markets, automobile workshops, street- sweepings, etc. They include putrescible and non-putrescible wastes, such as gar- bage , rubbish, trash, refuse, ash, paper, discarded appliances, carcasses, construction and demolition wastes, etc. The major sources of municipal wastes are residential centres , commercial complexes and open places (streets, markets, beaches, parks, etc.). Human population explosion, fast progress in urbanization and industrialisation , and rapid changes in the life style of mankind have considerably augmented municipal solid waste pollution.

4. (b) Hazardous industrial wastes Hazardous wastes are the highly dangerous or lethal wastes or mixtures of wastes. They can cause or contribute to mortality, irreversible illnesses, and incapacitating reversible illnesses. Also, they cause potential environmental hazards, when improp - erly handled, treated, stored or transported. So, their handling and disposal require sufficient precautions. In general, hazardous wastes are toxic, carcinogenic, mu- tagenic , teratogenic, ignitable, corrosive, and chemically reactive, or explosive substances, seriously harmful to plants and animals. Their effects may be immediate or belated. Radioactive substances, reactive chemicals, inflammable wastes, explosives, toxic metals and metallic compounds, asbestos, arsenic, etc. are hazardous wastes. The common toxic metals include lead, mercury, manganese, cadmium, chromium, iron, nickel, etc. The major sources of hazardous wastes are industries, nuclear plants, hospitals, research institutes, laboratories, etc.

5. (c) Biomedical wastes Biomedical wastes are the solid wastes generated from health care activities, such as diagnosis, treatment and prevention of diseases, alleviation of disablement, and medical research studies at hospitals, nursing homes, clinics, research centres , blood banks, veterinary institutions, etc. In India, biomedical wastes are classified under ten categories (see box item). Health risks of these wastes include several diseases, such as AIDS, hepatitis Band C, gastroenteric diseases, respiratory infections, skin infections, etc.

6. Major causes of solid waste pollution The major causes for the rapid increase in solid waste pollution include human population explosion, extensive urbanization, social and economic affluence of mankind, technological advancements, etc. ( i ) Human population explosion Perhaps, the major reason for all types of environmental pollution is the rapid growth of human population. Increased utilization of resources by the booming millions simultaneously causes the corresponding accumulation of solid wastes also.

7. (ii) Urbanization Solid waste is mostly an urban product. So, solid waste pollution increases with fast strides in urbanization. In developed countries, the quantity of solid wastes has gone beyond all proportions, making their timely disposal a Herculian task. (iii) Affluence Economic growth of mankind has caused a corresponding increase in per capita consumption also. Consequently, there is a growing tendency among the people to discard usable items for replacing them with new types. This considerably contributes to solid waste pollution.

8. Impacts of solid waste pollution Accumulation of solid wastes and their improper and inadequate management and disposal often cause serious environmental problems and health hazards. Environmental problems include contamination of water supplies, poisoning of the soil and ground water, destruction of habitats and damages to ecosystems. Some of the effect of solid waste pollution are the following: ( i ) Some toxic wastes, especially metallic wastes, are toxic, mutagenic, carcino - genic, or teratogenic agents. So, they may poison living systems, induce abnor - mal mutations, cause cancers and promote abnormal embryonic development ( teratogeny ).

9. (ii) Diseases, such as bacillary dysentery, amoebic dysentery, diarrhoea , etc., often result from food and drinking water, contaminated with solid wastes through flies. (ii) Spreading of plague through rats which feed on solid wastes. (iii) Fast spreading of cholera, jaundice, hepatitis, gastrointestinal diseases, etc. through drinking water and vegetables, contaminated with wastes. (iv) Solid wastes sometimes block drains and gully pits and cause water logging. This, in turn, favours the breeding of mosquitoes and thereby promotes the spreading of malaria, filariasis, dengue fever, chikungunya, etc.

10. (v) Decomposition of organic solid wastes produces obnoxious or odourous gases, unpleasant and harmful to human beings. (vi) Burning of some solid wastes, such as plastics, rubber, etc., produces noxious fumes which pollute the atmosphere. (vii) Percolation of decomposed garbage pollutes soil and underground water.

11. SOLID WASTE MANAGEMENT [Disposal of solid wastes] Solid waste management consists of two major areas, namely disposal of munici - pal solid wastes and disposal of hazardous solid wastes. I. Disposal of municipal solid wastes Disposal of municipal solid wastes involves several methods which vary with the accumulated solid material. The common methods include landfilling, recycling, incineration, pulverization, pyrolysis, composting and dumping into sea.

12. ( i ) Landfilling of solid wastes Landfilling is the cheapest and the commonest method of disposal of municipal solid wastes. In this method, solid wastes are dumped in successive layers, one above another, in low-lying land areas. Each layer is nearly 1.5m thick, and is covered by 20-25cm thick soil. It is left out for a week or more, before filling the next layer. Compaction by trucks will cause settlement. Spraying of insecticides is also necessary to prevent the breeding of mosquitoes, flies, etc. In course of time, the solid waste will get stabilized by the decomposition and the subsequent conversion of its organic matter into stable compounds.

13. Hydrolysis of complex organic matter may occur under anaerobic conditions, releasing CO2, CH4, HS and other gases and producing simple, water-soluble organic acids. The whole waste gets stabilized in a few months and settles down by 20-40% of its original thickness. In the non-availability of low-lying areas, 'trenching' is adopted for solid waste disposal. In this method, 4-10m long, 2-3 m wide and 1-2m deep trenches are excavated, leaving 2-3m wide strip in between adjacent trenches. These trenches are then filled with wastes and covered by soil.

14. Landfilling is advantageous in that it is simple and cheap, costly treatment plants, advanced technology and skilled labour are not required, separation of the different kinds of wastes is not necessary, and no residues or byproducts which require further disposal are left out. Also, landfilling is significant it that it enables the reclamation of low-lying areas for better use. Landfilling is disadvantageous in several ways. It requires large land areas and insecticide spraying, causes the continuous evolution of foul smell, and results in the formation of leachate. Leachate is a coloured liquid, formed due to the seepage of rain water into the landfills. In it, some harmful and carcinogenic compounds of the waste dissolve. Contamination of the water with leachate may cause cholera, typhoid, polio,etc .

15. (ii) Recycling of solid wastes Recycling or salvaging of solid wastes is the recovery of some of their components for using as raw materials. It is perhaps the most eco-friendly method of solid waste disposal. In this process, materials that can be recycled are first sorted out, then processed, and finally used as raw materials, for the manufacture of new useful products. Wood, paper, plastics, rubber, metals, glass, paper, clothes, agricultural wastes, slaughter-house wastes, industrial and urban wastes, waste of poultry feeds, etc. are now recycled and used as new products.

16. Currently, recycling is an integral part of solid waste management. In addition to waste disposal, it is advantageous in many ways. Some of its advantages are the following: 1. Avoids wastage, conserves natural resources and energy, and controls or re- duces environmental pollution. 2. Enables the production of many cheaper and useful products to meet the basic requirements of the common man. 3. Generates enough employment opportunities. 4. Directly and indirectly contributes to economic growth.

17. (iii) Incineration or combustion of solid wastes Incineration or combustion is the burning of solid wastes in special chambers, hearths, or furnaces. This method is generally employed when ideal lanfilling areas are not available and dumping into sea is not possible. The minimum temperature for incineration should always be well above 670°C to burn all the combustible organic matter and oxidize the foul-smelling gases. The final products of complete combustion include ashes and cynders . Ashes can be used for filling low laying areas, and cynders can be used as road materials.

18. Current incineration technique involves the mass burning of solid wastes in hot furnaces at temperatures above 1000°C. The heat energy from this process is used to generate steam from water which, in turn, is used to drive turbines to generate electricity. Incineration of solid wastes is advantageous in several ways as follows: 1. Incineration serves two purposes, namely waste disposal and generation of uti - lizable energy. 2. Serves as a sanitary measure to destroy harmful and pathogenic organisms in the waste. 3. Does not produce dust and foul odour . 4. Produces useful substances, such as ashes and cynders . Incineration of solid wastes is disadvantageous in that it incurs high initial expenditure, and causes air pollution by smoke and ashes.

19. (iv) Pulverization of solid wastes Pulverization is the process by which solid wastes are crushed and powdered in specialized grinding machines to reduce their mass and modify their physical character. Pulverization makes the waste odourless and unattractive to insects. The powdered waste is then disposed by landfilling. Pulverization is very costly and so it is not commonly employed for waste disposal.

20. (v) Pyrolysis of solid wastes Pyrolysis is the conversion of solid organic wastes to useful liquid fuels. It involves the recovery of the chemical constituents and the chemical energy of some solid organic wastes by a process called "destructive distillation." In pyrolysis, the combustible components of the solid waste are subjected to thermal decomposition; they are heated in a specially designed chamber, called pyrolysis reactor, at a temperature of 650-1000°C, under oxygen-free or low-oxygen conditions. This produces useful petrochemicals and some amount of char. Pyrolysis differs from incineration in that it is an endothermic process. The advantages of pyrolysis are the same as those of incineration. Often, the residual char, produced in pyrolysis, is made to react with CO2 and steam. The gas produced by this reaction is used in gas turbines or internal combustion engines to generate electricity.

21. (vi) Composting of solid wastes Composting is the biological decomposition of the putrescible organic constitu - ents of solid wastes into stable mineral compounds and a humus-like material, called compost. The organisms involved in composting include bacteria, fungi, earthworms, insects and some soil organisms. Composting of solid wastes is significant in three major respects as follows: 1. Serves as an eco-friendly method of solid waste disposal with minimum financial expenditure. 2. Provides compost which is a valuable natural manure. 3. Is a most hygienic method without environmental pollution and health risks. There are four major methods of composting, namely trench composting, open window composting, mechanical composting and vermicomposting.

22. (a) Trench composting In this method, 4-10m long, 2-3m wide, and 0.7-1.0m deep trenches are excavated. Solid waste is spread in these trenches in successive 15cm thick layers, sandwiched by 5cm thick layers of semi-liquid cattle dung, until the waste heap rises to 30cm or more above the ground level. Then, a 5 -7.5 cm thick layer of soil is spread over the top of the heap. This prevents wind-blowing of the waste and the entry of insects. In about 4-5 months, decomposition is completed and the humus-like compost gets stabilized. It is removed, sieved and used as a manure.

23. (b) Open window composting In this method, the solid waste is dumped on open ground as 5-10m long, 1-2m wide, and 0.5-1.0m high piles. The top of each pile is covered with cattle dung. After a few days, the piles are raked and turned upside down for cooling and aeration. In about 4-6 weeks, the compost gets stabilized.

24. (c) Mechanical composting In this method, putrescible solid wastes are converted to compost by mechanical devices in composting plants. The whole process is completed in about 3-6 days. Mechanical composting involves segregation, shredding (pulverization) and stabilization of the waste, and the preparation of the stabilized mass for marketing.

25. (d) Vermicomposting Vermicomposting is the composting of solid organic waste using some species of earthworms. It is much faster than trench composting and open window composting. The compost, produced by the breakdown of the organic debris by earthworms, is known vermicompost. The earthworms commonly used in vermicomposting include Perionyx excavates, P. sansibaricus , Dendrobaena veneta , Dichogaster spp , Eudrilus eugeniae , Eisenia fetida , E. andrie , Lumbricus rubellus , etc. Vermicomposting can be carried out in bins, tanks, or other suitable containers. The solid waste is first allowed for natural primary decomposition. Then, it is filled in vermicomposting containers.

26. Now, earthworms are released to the containers. They gradually bring about composting. The whole process is completed in about 60-75 days. Vermicomposting is a technology for the disposal of domestic garbage, solid municipal waste and non-toxic solid and liquid industrial wastes, for the production of non-chemical and non-synthetic manure, and also for keeping the environment clean and healthy.

27. (vii) Dumping of solid waste into sea In this method of waste disposal, solid waste is dumped into the deep open sea, 16 to 20 km away from the sea shore. Though this method is simple and cheap, it has the following disadvantages also. ( i ) Lighter components of the waste float, drift and spread and often return to the shore along with high tide. This pollutes the beach. (ii) During monsoons and stormy weather, when the sea is dangerously rough, off- shore transportation of the waste is very difficult.

28. II. Disposal of hazardous wastes The disposal of hazardous wastes is a highly expensive affair. It involves an appropriate combination of several methods and requires maximum precautions. Some of the methods used in it are the following: ( i ) Safe landfilling and deep-well injection. (ii) Solidification, chemical oxidation, incineration, pyrolysis, etc. (iii) Preliminary neutralization of acidic, alkaline, oxidizing, or reducing wastes, prior to final disposal. In India, the management of hazardous wastes is regulated by the Hazardous wastes (Management and Handling) Rules (1989) and Amendment Rules, 2000 and 2003.

29. III. Disposal of biomedical wastes The disposal of biomedical wastes is to avoid their dispersion in the environment and also to avoid human exposure to them. It mainly involves the transformation of the waste into non-hazardous residues by appropriate treatment. Prior to storage, transportation and treatment, the wastes have to segregated in separate containers taking into account their nature and the existing statutory regulations. The loaded containers must be labelled and then transported for treatment and disposal only in those vehicles which are authorised for the purpose by competent authorities.

30. The waste treatment methods include incineration, chemical disinfection, auto- claving , microwave irradiation, shredding, etc. The disposal may be done by sanitary landfilling or burying inside the premises. The criteria for the selection of the method include availability of technology, qualified personnel and sufficient space, prevail- ing regulations, nature and quantity of the waste, environmental aspects, and so on. The Govt. of India have promulgated the Biomedical waste (Management and Handling) Rules 1988, stipulating some guidelines for biomedical waste manage- ment . As per this law, it is mandatory that any health care activity, which may generate biomedical waste, should get the prior legal sanction from the Pollution Control Board.

31. E-WASTE MANAGEMENT E-Wastes, or electronic wastes, are the wastes generated from the broken, defective, unwanted, or outdated electronic devices, appliances and accessories which are no longer useful for their intended purposes. Hence, they are left for disposal, or for recycling, recovery and reuse. They include a wide range of obsolete articles, such as computers, laptops, UPS, printers, CDs, pen drives, connecting cables, hand-held cellular phones, radios, stereos, battery cells, electronic toys, refrigerators, air conditioners, telephones, music systems, and so on.

32. E-wastes are the by-products of electronic revolution and the spectacular and mercurial growth of electronics and electrical industries. In these industries, new gadgets and sophisticated models ap- almost every day and the old ones are discarded as junk. These industries ensure their steady and rapid growth by making their existing products obsolete as fast as possible. Some of the old ones may still be in good working condition, but they cannot be used for want of spare parts. This results in the piling of e-wastes, putting a growing menace and major challenge to the environment.

33. The composition of e-wastes is highly diverse and product-specific. They include both toxic and useful materials. In general, the major toxic components in- clude ferrous and non-ferrous metals, flame retardants, plastics, glass, wood, ply- wood, printed circuit boards, ceramics, rubber, and the like. The non-ferrous hazard- ous metals include copper, zinc, aluminium , silver, gold, platinum and palladium. The presence of mercury, arsenic, cadmium, selenium, chromium, etc is also common.

34. The toxic materials in the e-wastes contaminate air, soil and ground water and pose serious health hazards. The hazardous materials of e-wastes can have harmful effects when they are burnt or buried. Landfilling of e-wastes may lead to the leaching of some of them, such as lead, to the ground water. Their crushing or burning may release toxic fumes to the atmosphere. Some developed countries export their e-wastes to developing countries. Countries like China and India import e-wastes and recycle them.

35. Environmental impacts of e-wastes It has been roughly estimated that nearly 56 million tonnes of e-wastes have been generated world wide in 2010. In 2012, it rose to around 65 million tonnes . At this rate of increase, it might have crossed the 160 million tonnes mark by this time. This trend is on steady increase in the digital revolution era, with a corresponding in- crease in environmental risk. It is a shocking revelation that nearly 40% of the lead and 60% of the heavy metals (copper, iron, aluminium , gold, chromium, mercury), found in landfills, come from e-wastes and 30% of the e-wastes consists of non- degradable or very slowly degradable plastics.

36. E-wastes pollute air and ground wa - ter and contribute to the acidification of soil. They may inflict severe damages on vital organs, nervous system and immune system. Radiation effects from e-wastes and exposure to heavy metals pose serious health hazards. The contamination of air, soil and water, with severe impact on human health is mainly by the following agents. ( i ) Lead and cadmium from circuit boards. (ii) Lead oxide and cadmium from monitor cathode ray tubes. (iii) Mercury from switches and flat screen monitors. (iv) Cadmium from computer batteries. (v) Lead and antimony oxide from the brominated flame retardants of plastic cas - ings , cables, etc. (vi) Dioxins and furans, released during the burning of cables and casings.

37. Management and disposal of e-wastes E-waste management is very difficult and highly expensive due to the wide range and high complexity of their component materials. So, profitable recycling and the safe disposal of e-wastes are very serious problems in most countries, especially in developing countries. The issue is further complicated by the export of e-wastes from developed countries to developing countries in the name of free trade for the recycling of the valuable materials contained in e-wastes. Thus, for the developing countries e-waste is a burning environmental problem, and for developed countries it is a business opportunity.

38. Crushing and landfilling are not safe methods for the disposal of e-wastes. Currently, reduction and re-cycling seems to be the most appropriate strategy for deal- ing with e-wastes. It involves the decontamination, dismantling, pulverization, shred- ding or density separation, and re-cycling of e-wastes. The bulk of accumulating e-wastes can be reduced by prolonging the life of the products through eco-friendly designing, best-suited for repair, re-use, recycling and upgradability. Product designers should ensure that the products are repairable, re- usable, re-cyclable, re-furnishable and upgradable.

39. They must also ensure that the materials used are less toxic and easily recoverable for their easy recovery and close- loop recycling. Recovery of metals, plastics, glass, and other materials from e-wastes considerably reduces the potential hazards of e-wastes. For the successful imple - mentation of this e-waste management strategy, manufacturing companies must com- pulsorily adopt the policy of product take-back from the end users for replacement, repair, recovery, or recycling.

40. Components of e-waste management E-waste management consists of the following two major components. (a) E-waste collection, sorting and transportation. (b) E-waste recycling which involves the dismantling and recovery of valuable materials and the disposal of the unsalvageable dismantled parts. The collection systems should collect e-wastes from the right places in the right time. The collected wastes should be dismantled and recycled only at authorised centres that are provided with the required facilities to deal with the wastes in an environmentally sound manner as per national and international guidelines.

41. The recovery of metals, plastics and other valuable materials from e-wastes en - ables to bring them back to the production cycle. This makes e-waste recycling a profitable and lucrative business. Perhaps the best way of e-waste management is the adoption of the principle of "extended producer responsibility (EPR)". By applying this principle, all the links of the producer-product-user chain, namely the producers or manufactures, suppliers and consumers, are made to share the responsibility of minimizing or neutralising the environmental impact of a product.

42. The manufacturer has to decide or influence the product design, select the ideal raw materials, choose the most appropriate manu-facturing process or technology, and buy back the product after its end use for safe recycling or disposal. All these are aimed at making the process and product least harmful and most environment-friendly. Suppliers should see that they provide the manufacturers only with non-toxic and environment-friendly materials and components. Consumers has to very carefully choose and purchase only environment- friendly products, opting out the others. They must also see that the products are used and are finally disposed in a most environmentally ideal manner.

43. E-waste laws in India It has been roughly estimated that India generates nearly 350,000 tonnes of e- wastes and imports about 50,000 tonnes every year. To regulate all the processes related to e-wastes, E-Waste Rules came into effect from 01.05.2012 onwards, empowering the State Govts. to grant licences . According to these rules, manufactures are accountable for the quality and safety of their products throughout the produc - tion -distribution-consumption-disposal cycle.

44. A producer has to manage the end of the life of his products in a safe and environment-friendly manner. The local self government institutions are authorised to collect non-branded "orphan" e-wastes and send them to authorised dismantlers or recyclers. Manufacturing companies have to organize their own buy-back or take-back mechanisms and machineries for the final environment-friendly disposal of their products to reduce e-waste accumu - lation .