Lecture 7 bds

• Refuse (Solid Waste)


  Technique for collection, treatment, and disposal of solid wastes of community

  
• Refuse (Solid Waste) disposal system

  1. Collect

  2. Treat

  3. Dispose

  
• Wastes come in 3 states

  • Solid waste
  • Liquid waste
  • Gas waste
• Solid Waste


  All solid /semi solid waste of community
• Each person approximately 1 kg of solid waste every day
• Solid waste must be managed and disposed

  • Protect human environment
  • Prevent spread of diseases
  • Maintain healthy conditions

  
• Three Types of refuse

  • House Refuse or domestic solid waste
  • Trade Refuse
  • Street Refuse

  
• House Refuse or domestic solid waste


  Solid waste from domestic/residential buildings
• House Refuse or domestic solid waste

  • Ashes
  • Rubbish (trash)
  • Garbage
  • Demolition debris structures
  • Vegetables
  • Animal waste (organic)matters

  
• Street Refuse


  Solid waste on streets and roadsides
• Street Refuse

  • Street sweeping
  • Dirty materials dropped from vehicle
  • Tree leaves
  • Empty match /cigarette boxes
  • Fruit peelings
  • Packaging boxes

  
• Trade Refuse


  Solid wastes from factories, business centers, slaughter houses etc.
• Components of Solid Wastes

  • Organic component
  • Inorganic component
• Organic component


  Waste from dead living things that decomposes (rots)
• Organic component

  • Paper, wooden items, textiles, fish, meat, fruits , vegetables, cardboard, dead animals

  
• Calorific value


  Produces heat energy when burned
• Inorganic component


  Does not decompose or rot, includes ashes, dust particles, plastic items, metal items, glass, rubber, concrete or brick demolition debris
• Types of solid waste

  • Highly organic solid waste
  • Moderately organic solid waste
  • Highly inorganic solid waste

  
• The average composition of domestic refuse of a residential community is given
• The average calorific value of total organic constituents of this solid waste is 22kJ/kg
• The population of the colony is 720 and the refuse production in the city is 0.85 kg/capita/day
• Calculation of organic solid waste in a city or town

  1. Calculate weekly production of organic solid waste

  2. Calculate energy (biogas) obtained from organic component

  
• Types of collection system for the refuse

  • Single collection system
  • Double-System or Double collection system
  • Triple bin System

  
• Single collection system


  Single container used for collection of refuse
• Single collection system


  • Garbage can or bins
  • Collection by barges or garbage ships

  
• Double-System or Double Collection system


  2 separate containers used: combustible matter and non combustible matter (organic matter)
• Triple bin collection system


  Separate bins for Garbage, Rubbish, and Inorganic wastes

  
• Methods of Disposal of Refuse

  • Barging out into the sea
  • Sanitary land filling
  • Incineration
  • Composting
  • Pyrolysis
  • Recycling

  
• Barging out into the sea


  Wastes disposed off by throwing it away into the sea depth
• Lighter parts of solid waste float in water causing pollution and sea pollution
• Nuclear and radioactive wastes are dumped into the sea depth by fourteen countries including the USSR and Russia
• Sanitary land filling


  Organic waste is placed in an excavated hole on the ground and covered by a soil layer, microorganisms decompose the organic waste

  
• Land area for landfilling can be used for parks, golf courses and other recreational purposes
• Incineration


  Combustible refuse burnt in incinerators (burning chambers), heat energy produced may be used for useful purposes
• Incineration causes pollution to the environment and health problems to people
• Composting method


  Organic waste converted to compost (or humus) by micro organisms, good manure (fertilizer) for plants
• Composting procedure


  Dig trench, place solid waste, cover with earth layer, bacterial action converts to compost/humus
• Pyrolysis Method


  Waste matter heated at very high temp. in Pyrolysis chamber, produces char, oil or gas, does not produce smoke/fire gases
• Recycling


  Processing used materials into new products which can be used again
• Recyclable materials


  • Bottles, metal, cans, paper