Page 7 - LN-CH-16

The treated water still contain lots of heavy metals and other toxic pollutants.
– In second step, algae, fungi and bacteria are grown in marsh land through which water
flowed. These life forms neutralise, absorb and assimilate the pollutants and purify the
water naturally.
The marshes also constitute a sanctuary, with a high level of biodiversity.
(b) Ecosan toilets have been developed in areas of Kerala and Sri Lanka for ecological
sanitation. The advantages of ecological sanitation are:
• A practical, hygienic and efficient method of disposal.
• Cost effective approach.
• Human excreta can be recycled into natural fertiliser to reduce need of chemical fertiliser.
5. Solid wastes refer to everything that goes out in trash. The various types are:
(i) Municipal solid wastes contain wastes from homes, offices, schools, hospitals, etc., that
are collected and disposed by the municipality, which generally consists of paper, leather,
textile, rubber and glass, metals and plastic, etc.
(ii) Industrial wastes contain wastes like scraps, fly ash, etc., generated by industries.
(Hi) Hospital wastes contain disinfectants and other harmful chemicals generated by
hospitals.
(iv) Electronic wastes (e-wastes) are the damaged electronic goods and irreparable
computers.
(a) Methods of Solid Waste Disposal
There are various methods of solid waste disposal. Some of them are:
• Open burning involves burning of municipal waste in open dumps but the unburnt piled
waste serves as breeding ground for rats and flies.
• Sanitary landfills are areas where wastes are dumped in a depression or trench after
compaction and covered with dirt. The problem is seepage of chemicals from these landfills
can pollute underground water resources.
• Rag-pickers and kabadiwallas collect and separate out wastes into reusable or recyclable
categories.
• Natural breakdown involves dumping biodegradable materials into deep pits for natural
degradation.
• Incineration is a method of hospital waste disposal.
• E-Wastes
– E-wastes are buried in landfills or in ~inerated.
– About half of the e-wastes generated in the developed world are exported to developing
countries, mainly to China, India and Pakistan, where metals like copper, iron, silicon, nickel
and gold are recovered during recycling process.
– Developed countries have specifically built facilities for recycling of e-wastes.
– Recycling is only solution available for treating e-waste but caution should be taken to
carry out process environment friendly.
(b) A Case Study — Remedy for Plastic Waste
• A plastic sack manufacturer, Ahmad Khan from Bengaluru realised that plastic waste was
a real problem.
His company developed a fine powder, called polyblend of recycled modified plastic.
• This mixture is mixed with the bitumen and used to lay roads.
• It enhanced the bitumen’s water repellant properties and helped to increase road life by a
factor of three.