MSTN EXAM

• Municipal solid wastes in developed countries consists mainly of plastic, metals, and paper, whereas organic matter forms half of the waste generated in developing countries
• Treatment of municipal wastes


  1. Primary treatment

  2. Secondary treatment

  3. Tertiary treatment
• Primary treatment of municipal wastes


  1. Removal of floating materials

  2. Removal of dirt

  3. Sedimentation and sludge removal
• Secondary treatment of municipal wastes


  1. Aeration of water

  2. Breakdown of organic pollutants by aerobic bacteria

  3. Sedimentation of remaining sludge

  4. Methane generation from sludge
• Tertiary treatment of municipal wastes


  1. Removal of highly soluble salts

  2. Precipitation of phosphates

  3. Removal of nitrates and nitrites by electrodialysis

  4. Removal of foul smell and taste by aeration

  5. Disinfection with chlorine or ozone
• Types of process wastes


  • Inorganic process wastes
  • Organic process wastes
• Types of chemical wastes


  • Acidic or basic wastes
  • Wastes high in biochemical oxygen demand
  • Inflammable wastes
• Treatment of inorganic industrial wastes


  1. pH adjustment

  2. Coagulation and flocculation

  3. Heavy metal precipitation

  4. Chemical oxidation of cyanides

  5. Chemical reduction of chromium
• Treatment of organic industrial wastes


  1. Primary treatment

  2. Biological treatment using activated sludge and trickling filters
• Principles of green chemistry for reducing hazardous waste


  • Prevent waste formation rather than treat it
  • Maximize incorporation of raw materials into final product
  • Use substances with little or no toxicity
  • Design products to preserve function while reducing toxicity
  • Avoid use of auxiliary substances like solvents
  • Minimize energy requirements
  • Use renewable raw materials
  • Avoid unnecessary derivatization
  • Use catalytic reagents instead of stoichiometric
  • Design products to degrade into innocuous products
  • Develop analytical methods for real-time monitoring
  • Choose substances to minimize chemical accidents
• Methods for converting hazardous wastes to less hazardous


  • Physical methods
  • Chemical methods
  • Biological methods
  • Incineration
• Methods for disposal of hazardous wastes


  • Adsorption on charcoal or resin filters
  • Distillation
  • Precipitation
  • Immobilization
  • Neutralization
  • Oxidation
  • Reduction
  • Ion-exchange
  • Use of bacteria, microorganisms, and other species
  • Incineration
• Methods for disposal of hazardous wastes


  • Secure landfills
  • Deep-well injection
• Secure landfill


  1. Specially designed pit lined with impermeable membrane

  2. Solid waste carefully placed, spread out, and compacted

  3. Covered with layer of compacted soil

  4. Process repeated until pit is full

  5. Closed by cement concrete
• Biomedical wastes are one of the sources of spreading diseases such as Acquired Immunodeficiency Syndrome (AIDS), hepatitis, septicaemia, and other infections
• Biomedical waste categories and treatment/disposal procedures

  • Category 1: Human body parts - Incineration, deep burial
  • Category 2: Animal waste - Incineration, deep burial
  • Category 3: Microbiology and biotechnology - Autoclaving, microwaving, incineration
  • Category 4: Waste sharps - Shredding, disinfection
  • Category 5: Discarded medicines and cytotoxic drugs - Incineration, secure landfills
  • Category 6: Solid wastes - Incineration, autoclaving, microwaving
  • Category 7: Solid waste - Disinfection, autoclaving, microwaving, shredding
  • Category 8: Incineration ash - Landfills
  • Category 9: Liquid waste - Disinfection, discarded into drains
  • Category 10: Chemical waste - Chemical treatment, secure landfills
• Geological repository for high-level waste


  • High structural strength, good thermal conductivity and heat capacity, low permeability and porosity, high plasticity, low seismicity
• Salt deposits for high-level waste


  • High thermal conductivity, low permeability, high plasticity, but soluble in water so require corrosion-resistant containers
• Deep drill holes for high-level waste


  • Completely devoid of groundwater below 700m, but high temperatures can melt borosilicate glass so require synthetic rock (Synroc) instead
• Environmental Pollution and Waste Management


  The study of different types of pollution and how to manage waste
• Pollution can be natural as well as man-made
• Pollution affects the entire ecosystems where it disrupted marine life, cause a lot of harm to human and animal health, plants and trees and has a major effect on the depletion of the natural flora and fauna
• In Europe, from the Middle Ages well into the early modern era, unsanitary urban conditions favoured the outbreak of population-decimating epidemics of disease, from plague to cholera and typhoid fever
• Through the 19th century, water and air pollution and the accumulation of solid wastes were largely problems of congested urban areas
• The publication in 1962 of Rachel Carson's book Silent Spring focused attention on environmental damage caused by improper use of pesticides such as DDT and other persistent chemicals that accumulate in the food chain and disrupt the natural balance of ecosystems on a wide scale
• Sources of air pollution


  • Gases emitted by vehicles or manufacture exhaust
  • Forest fires
  • Dry soil erosion
  • Building constructions and demolition
• Effects of air pollution include higher rain acidity, increase in smog, crop depletion from in adequate oxygen, as well as higher rates of asthma
• Water pollution is one of the most dangerous as it decreases the amount of drinkable water is available
• Causes of thermal pollution include power plants, urban sprawl, air pollution particulates that trap the earth, deforestation and loss of temperature moderating water supplies
• Sources of industrial pollution include power plants, steel mills, sewage treatment plants, heating plants, and processing and manufacturing companies which release smoke, material wastes, contaminated residues, and toxic by-products
• Industrial pollution can cause ecosystem imbalance, adversely damage plants, and even kill animals
• Effects of environmental pollution on humans


  • Respiratory infections such as allergies, asthma, irritation of the eye, and nasal passages
  • Major factor in the development of cancers
  • Diseases like hepatitis, typhoid affections, diarrhea, and hormonal disruptions
• Effects of environmental pollution on animals


  • Harm to the living environment, making it toxic for them to live in
  • Acid rains can change the composition of rivers and seas, making them toxic for fishes
  • Ozone in the lower atmosphere can cause lung problems
  • Nitrogen and phosphates in water will cause the overgrowth of toxic algae, preventing other forms of life to follow their normal course
  • Soil pollution will cause harm and, sometimes, even the destruction of microorganisms, which can have the dramatic effect of killing the first layers of the primary food chain
• Effects of environmental pollution on plants


  • Acid rains modify the natural environment of the plants
  • Ozone in the lower atmosphere block the plant respiration, and harmful pollutants can be absorbed from the water or soil
• Pollution in its various forms is increasing tremendously which has caused severe damaged to the ecosystems as well as enhances human diseases and death rates of various plants and animals
• Steps to prevent pollution

  • Using smokeless sources of energy
  • Plant trees
  • Industries should be far from residential areas
  • Strict monitoring of automobiles' exhaust emission
  • Adequate sewage and industrial waste treatment
  • Re-use, Reduce and Recycle
  • Proper solid waste disposal
  • Avoid using of fertilizers and pesticides
  • Avoiding polythene bags
  • Proper noise and smoke precipitators should be used to bring down the amount of lethal smoke and noise produced to help protect the environment
• Disposal


  The final stage of solid waste management where associated risks are minimized
• Other categories of waste


  • Ashes or Dust
  • Construction waste
  • Hazardous waste
  • Dead animals
  • Bulky waste
  • Soiled waste
• Types of municipal solid waste


  • Biodegradable
  • Recyclable
  • Hazardous domestic wastes
• The industry generated waste from chemical factories, medical waste from hospitals are considered as Hazardous Solid Waste and they need special settings to dispose of them