ENVIRONMENTAL STUDIES

Module 5. Environmental pollution

Lesson 18
SOLID WASTE MANAGEMENT

18.1 Introduction

Solid waste includes all discarded solid and semi-solid materials arising from various human activities. Municipal solid waste (MSW), consist mainly of refuse and trash. It predominantly includes food wastes, yard wastes, containers and product packaging, other miscellaneous inorganic wastes from residential, commercial, institutional, and industrial sources.

Trash refers to the bulky waste such as TV, refrigeration goods, broken furniture, etc. Refuse comprises of two components mainly garbage and rubbish. Garbage includes putrescible waste such as vegetables, meats, food wastes and other readily degradable organic wastes. Rubbish consists of the non-degradable material such as glass, rubber, metals, plastics, etc and slowly degradable material such as paper products, textiles etc.

18.2 Sources of Solid Waste

• Residential sources: Waste arising from day to day household activities is a important constituent to the solid waste. Proportion from this source is increasing day by day with rapid increase in population. Household waste includes variety of things such as food wastes, paper, cardboard, plastics, textiles, leather, etc
• Industrial Waste: Solid waste resulting from industries typically includes construction and demolition waste, rubbish, ashes and special waste.
• Community Services: community services such as street cleaning, landscaping, recreational activities, water and waste water treatment plants give rise to solid waste such as wood, dirt, plastic and other general wastes.
• Agricultural activities: Agricultural activities generate spoiled food wastes, agricultural wastes such as straw and sugarcane trash, hazardous wastes such as pesticides and insecticides.
• Construction and demolition activities such as construction sites, road repair, renovation sites, and demolition of buildings generate solid waste like wood, steel, concrete, dirt, etc.
• nstitutions such as schools, hospitals, prisons, government centers generate solid waste like paper, cardboard, plastics, wood, food wastes, glass, metals, etc.

18.3 Effects of Solid Waste Pollution

• Diseases such as diarrhea and dysentery are spread by carriers especially fly which breed on garbage.
• Rubbish and trash can block the drains thus making breeding grounds for mosquitoes, that spread diseases like malaria and dengue.
• Rotting garbage gives out foul smell that can render a locality inhospitable.
• Dumping places are usually also home to stray animals such as abandoned cows that frequently block traffic on roads and occasionally lead to road accidents.
• Seeping of toxic chemicals from factories and garbage waste underground, can render underground water unfit for human consumption.
• Accumulation of construction and demolition waste at places lessens the aesthetic beauty of surroundings.
• Intake of solid non-biodegradable waste such as plastic by scavengers and stray animals like pigs and abandoned cows can choke their windpipes and lead to death.

18.4 Need for Reducing, Reusing and Recycling of Waste

Waste management is necessary because if it is not done the waste may lead to environmental and health problems harmful for mankind. Our planet is going to be filled with waste soon if we don't manage our garbage and trash properly.

• It cuts back on global warming.
• It makes us more energy-efficient. It often takes a great deal more energy to create something from scratch than to recycle it.
• It keeps our landfills from overflowing. We’re fast running out of space for landfills—especially near cities. Seaside cities have been dumping trash into their oceans for decades to circumvent the problem
• It improves the quality of our groundwater.
• It reduces air pollution. Many factories that produce plastics, metals, and paper products release toxins into the air. Recycle these materials, and there will be less need for companies to manufacture new materials—saving on the amount of pollution dumped into our atmosphere.
• It creates jobs. From manufacturing to processing, from collection to invention—it’s no secret that recycling is a growth industry, earning billions of dollars annually.
• It adds to property value. It’s obvious that a landfill near your home can decrease your property values significantly. Recycling reduces the amount of land needed for landfills. This reduces the number of houses near landfills, keeping property values up and homeowners happy.

18.5 Management of Solid Waste

• Best way to manage the problems associated with solid waste is by to reduce wastage itself. With higher standards of living especially in urban areas there is tendency to declare goods outdated and obsolete. This leads to solid waste. Thus, the problem can be checked by promoting efficient utilization and reuse.
• Recycling the trash and refuse greatly reduces the non-biodegradable component of solid waste. Items made up of plastic, glass, paper, metal, etc. can be recycled to form other products, thus saving raw materials and also reducing solid waste.
• Disposing off the solid waste with techniques such as land filling, incineration, pulverization, etc.

18.6 Methods of Solid Waste Disposal

• Land Filling: This is simple and economical method that requires no skilled labour. Method involves dumping the solid waste collected into a low lying area usually at the outskirts of the settlement in layers. The layers are usually 1.5 to 2 meters thick are covered with a thin layer of good earth, before filling another layer of solid waste over it. The layer of solid waste is thus sandwiched between thin layers of good earth. Over time, solid waste breaks and is stabilized. After the site reaches certain height, it can be developed as parks by landscaping and planting trees.
• Incineration: In this method, solid waste is burned in specially designed furnaces. Combustible waste is separated from non-combustible and fed into the furnace. Temperature conditions in furnace are carefully adjusted to burn all organic matter and oxidize all foul smell. If moisture content of solid content is high, some auxiliary fuel such as coal or wood can be added to support burning. Since, this method involves high temperature; all pathogens and pest are destroyed, though, smoke coming from furnace causes air pollution.
• Pulverization: In this method, collected solid waste is powdered by grinding machines, thereby changing its volume and physical characteristics. This pulverized solid waste is further disposed-off by land filling. This is costly technique.
• Composting: This method involves digesting organic matter by anaerobic process, converting it into organic manure and other stable compounds. It solves twin purpose of solid waste disposal and providing manure for farms .Composting by trenching, open window composting and mechanical composting are three widely used composting techniques.
• Disposal into the sea: This method involves dumping the solid waste at sea floor. It can only be applied in coastal areas with strong currents .It is cheap method but tides can bring back some portion of solid waste dumped back to beaches.