Key Points

• Rainwater harvesting is a method of collecting and storing rainwater into tanks for different purposes and for future needs as well.
• Surface runoff harvesting and rooftop rainwater harvesting are the methods of rainwater harvesting.
• Collecting and storing rainwater before it lost as surface runoff promotes both water and energy conservation and Improves the quality and quantity of groundwater.

Advantages of Rain Water Harvesting:

• Provides self-sufficiency to your water supply
• Reduces the cost for pumping of groundwater
• Provides high-quality water, soft and low in minerals
• Improves the quality of groundwater through dilution when recharged to groundwater
• Reduces soil erosion in urban areas
• The rooftop rainwater harvesting is less expensive
• Rainwater harvesting systems are simple which can be adopted by individuals
• Rooftop rainwater harvesting systems are easy to construct, operate and maintain
• In hilly terrains, rainwater harvesting is preferred

Need for Rooftop Rain Water Harvesting:

• To meet the ever-increasing demand for water
• To reduce the runoff which chokes storm drains
• To avoid flooding of roads
• To augment the groundwater storage and control decline of water levels
• To reduce groundwater pollution
• To improve the quality of groundwater
• To reduce the soil erosion
• To supplement the domestic water requirement during summer, drought etc.

• Waste is unusable material. Waste comes in many forms.
• Waste can be categorized as:
  • solid waste (vegetable peels, trash cans and other such municipal waste),
  • liquid waste (water discharge from industries, harmful runoff from fields etc),
  • and gaseous waste (harmful gases released from industries).
• Waste management is a burning problem in urban, industrial and rural areas.
• Wastes management involves the following steps:
  • Collection of wastes
  • Segregation of wastes
  • Transportation of waste
  • Treatment of wastes
  • Disposal of wastes

Key Points

Segregation of waste: 

• The wastes are segregated according to their chemical composition, hazard potential and physical nature.
• Waste segregation can occur manually at the household and be collected through curbside collection schemes.
• "Waste segregation" means dividing waste into dry and wet.
• Dry waste includes wood and related products, metals and glass.
• Wet waste typically refers to organic waste usually generated by eating establishments and are heavy in weight due to dampness.
• Waste segregation is the grouping of waste into different categories.
• Segregation of waste ensures pure, quality material. 
• This helps in their eventual disposal.
• Segregation of waste in India is one of the major obstacles in managing municipal solid wastes.
• Segregation of waste in India is only limited to a few urban areas.

Thus, the biggest obstacle in managing municipal solid wastes in India is waste segregation.

Concept:

Composting:

• Biodegradable organic matter of solid wastes is digested aerobically or anaerobically by the activity of microbes.
• This can be used to form fertilizers like manure and also can be used as biogas.
• Earthworms and other worms are used to help in composting.

Explanation:

Eco-San toilet:

• Eco-San or ecological sanitation toilet aims to reuse human excreta in agriculture as humanure.
• This kind of toilet also helps to reduce the use of water.
• It is a kind of dry toilet.
• This toilet helps to minimize the use of non-renewable resources.
• Term Eco-san was first in 1995 in Ethiopia.
• Sometimes this kind of toilet is also called resource-oriented sanitation because its potential resources are human excreta and wastewater.
• Technology that used in the Eco-san system is a vacuum toilet, composting toilet, and urine-diverting dry toilet.
• It is a kind of closed-system toilet that does not need water so places with a scarcity of water and places with risk of groundwater contamination can use this kind of toilet.
• In this kind of toilet by using the principle of recovery and recycling of nutrients from excreta we can use it in agriculture.
• This process is slow and takes feces to change into organic manure can take 8 to 9 months time.

Thus, a design of toilet in which humans excreta is converted to ‘humanure’ is called Eco-San toilet.

 Additional Information

Dry toilet:

• Unlike flush toilets, dry toilets operate without flush water.
• In most cases composting toilets are mainly dry toilets.
• Sewage is not produced in dry toilets.
• Examples of dry toilets- Composting toilet, Arborloo, Treebog, etc.

Incinerating toilet:

• This kind of toilet does not require to be hooked up to a sewer system or inground septic system.
• It is a self-contained waterless system.
• For incinerating human waste to sterile clean ash, this toilet depends upon electricity or gas.
• In this toilet, only human excreta, toilet paper, tampons, and sanitation pads can be incinerated, but urine can not be incinerated here.
• This toilet is an eco-friendly non-contaminating toilet that does not require water.

Concept:

Sewage:

• Sewage is wastewater released by homes, industries, hospitals, offices and other users.
• It also includes rainwater that has run down the street during a storm or heavy rain.
• The water that washes off roads and rooftops carries harmful substances with it.
• Sewage is a liquid waste.
• Most of it is water, which has dissolved and suspended impurities.

Sewage treatment:

• Cleaning of water is a process of removing pollutants before it enters a water body or is reused.
• This process of wastewater treatment is commonly known as sewage treatment.
• There are mainly three types of sewage treatment stages primary, secondary or biological, and tertiary sewage treatments.

Explanation:

Secondary or biological sewage treatment:

• It is the removal of biodegradable organic matter from sewage or similar types of wastewater.
• This is usually done with the help of microorganisms, hence it is called biological treatment.
• The microorganisms feed on the organic matter present in the wastewater thereby reducing the organic load of the wastewater and purifying the water.

Thus, secondary sewage treatment is mainly a biological treatment.

Additional Information

Primary treatment (Physical process):

• It is the process of physically removing small and large particles from sewage.
• The floating debris is first removed by filtration through wire mesh screens in a sequential filtration.
• Then, the grit is removed by sedimentation in settling tanks.
• The sediment is known as primary sludge, and the supernatant is known as effluent.
• The effluent is taken for secondary treatment.

Tertiary treatment (Chemical process):

• The biological treatment precedes chemical treatment in the treatment process.
• Chemical treatment is now considered as a tertiary treatment that can be more broadly defined as “treatment of wastewater by a process involving chemical treatment”.
• The most implemented chemical treatment processes are: chemical precipitation, neutralization, adsorption, disinfection (chlorine, ozone, ultraviolet light), and ion exchange.

Concept:

DEWATS:

• The full form of DEWATS is the 'Decentralized Wastewater Management System'.
• It is a type of treatment designed and constructed using organic and natural water treatment processes.
• The objective of this project is to get rid of foul smells and waterlogging problems, especially during monsoons.
• The wastewater is collected from homes, industries, hospitals, and markets place.
• It is collected in covered or open drains to a central treatment plant.
• The BOD of water is reduced and processed.
• Wastewater is used for irrigation and safe disposal into water sources.
• DEWATS is a community management plan and is built using local labour.
• It is a natural treatment system using bioremediation put together in different conditions according to specific requirements.
• The objective is to improve the quality of the environment.

• Provide the best treatment for domestic and industrial wastewater.
• The system can easily handle organic wastewater.
• Systems are built to be reliable, long-lasting and tolerant of inflow and fluctuations in loads.
• Reliable and long-lasting construction, design and application.
• Low operation maintenance cost.
• Wastewater is treated at an affordable cost with limited space requirements.
• Resouces recovery through wastewater reuse and biogas generation.

Concept:

Water scarcity:

• When storage of something is in short supply or being scarce then this kind of state is known as scarcity.
• So, when an imbalance happens between demand and supply of water, along with a shortage of water, then it is known as water scarcity.
• In today's world, human carelessness and shortage of perfect planning increase the water scarcity level day by day.
• By 2025, it is predicted that large parts of India will join countries or regions having absolute water scarcity.
• Therefore we need to save all usable water present on earth in order to live a healthy sustainable life without water scarcity.
• Even though the earth's surface is covered with 71% of water all of it is not consumable.
• The amount of fresh water on the earth is very small thus accessibility to potable water on earth is limiting.

Explanation:

Causes of water scarcity:

• Overpopulation on earth causes water scarcity by overusing and wasting it.
• The consumption of water is increasing hugely due to urbanization and industrialization.
• The supply of water is decreasing although the demand for water is very high due to overpopulation.
• Water scarcity in most cases is caused by over-exploitation, excessive use, and unequal access to water among different social groups.
• Some other causes of water scarcity are human carelessness like:
  • Left a tap open after use.
  • Excessive use of water during washing.
  • Leakage problem.

Thus, water scarcity is mainly caused due to excessive use and unequal access to water.

 Additional Information

Water pollution:

• Whenever harmful substances such as sewage, toxic chemicals, silt, etc., get mixed with water, the water becomes polluted.
• The substances that pollute water are called water pollutants.
• Sources of water pollution:​
  • Industrial effluents.
  • Urbanization.
  • Deforestation.
  • Use of Detergents and Fertilizers.
  • Social and Religious Practices.
  • Agricultural run-offs- Use of insecticides and pesticides.

Water management:

• Water management is the process of controlling and moving water resources in order to limit damage to people and property while maximizing their efficient and beneficial usage.
• Dams and levees with good water control lessen the risk of floods.

• Waste is unusable material. Waste comes in many forms.
• The term “energy recovery” often is applied only to a narrow number of methods for converting wastes into energy.
• It applies to a broad range of technologies used to create heat, electricity, or fuel.
• Energy recovery gives governments and businesses another way to reduce their waste streams.
• After recyclable materials have been removed, the remaining waste can be treated to release energy.
• There are two types of technologies used generally for converting waste streams into energy: thermal and biological.
• Thermal waste-to-energy is created by burning trash, while biological processes are typically centred on anaerobic digestion.

Key Points

Pelletization:

• Pelletization of municipal solid waste involves the processes of segregating, crushing, mixing high-and low-heat value organic waste material.
• It involves solidifying it to produce fuel pellets or briquettes, also referred to as refuse-derived fuel (RDF).
• The process condenses the waste or changes its physical form and enriches its organic content through the removal of inorganic materials and moisture.
• The calorific value of RDF pellets can be around 4000 kcal/ kg depending upon the percentage of organic matter in the waste.
• Pelletization enriches the organic content of the waste through the removal of inorganic materials and moisture.
• It can be a very effective method for preparing an enriched fuel feed for other thermochemical processes like pyrolysis/gasification, apart from incineration.
• Pellets can be used for heating plant boilers and for the generation of electricity.
• It is a waste to energy recovery method.

Biomethanation:

• Biomethanation is a process by which organic material is microbiologically converted under anaerobic conditions to biogas.
• Anaerobic digestion (AD) is a bacterial fermentation process that operates without free oxygen and results in biogas containing mostly methane (~60%), carbon dioxide (~40%) and other gases.
• Biomethanation has dual benefits. It gives biogas as well as manure as the end product.
• This technology can be conveniently employed in a decentralized manner for the biodegradation of segregated organic wet wastes such as wastes from kitchens, canteens, institutions, hotels, and slaughterhouses and vegetable markets. 
• The biogas generated from the Biomethanation process can be burned directly in a gas boiler/burner to produce heat for thermal application industries and cooking or burnt in a gas engine to produce electricity.
• Alternatively, the biogas can be cleaned to remove the carbon dioxide and other substances, to produce BioCNG.
• This can be injected into the national gas grid to be used in the same way as natural gas, or used as a vehicle fuel. 
• It is a waste to energy recovery method.

Pyrolysis:

• It is a process of chemically decomposing organic materials such as plastic and rubber at elevated temperatures in the absence of oxygen.
• In general, pyrolysis does not involve reactions with oxygen, water or any other reagents.
• It is a waste to energy recovery method.

Composting:

• Composting of refuse is a biological method of decomposing solid waste.
• If the organic materials excluding plastics, leather and rubber are separated from the solid wastes and are subjected to decomposition either aerobically or anaerobically, the remaining end product is called compost or humus.
• The entire process involving both the separation and bacterial conversion of the organic solid wastes is known as Composting.
• It is not a waste to energy recovery method.

​Thus, composting is not an energy recovery method of solid waste management.

Concept:

Curitiba:

• It is a city in Brazil comprised of 26 municipalities.
• Curitiba in Brazil has attracted global attention for innovative urban plans using low-coast technologies.
• The city shows us that inclusive development models for urban renewal are workable.
• In coordination with the master plan, five arterial structural roads were laid to form a structural growth corridor and growth pattern in the city.

Explanation:

Hierarchical transportation system:

• This city involves creating a road hierarchy and land control system along with a pedestrian network in the centre of the city.
• In Curitiba, the central road had two restricted lanes dedicated to express buses. 
• The central roads have two restricted lanes dedicated to express buses.
• Local traffic travels onto local roads running in opposite directions parallel to express bus lanes.
• The structural corridor had interdistrict and feeder lines and zoning laws were set in place to structure the growth of the city.
• Payment ware made through transfer token.
• Later a two fare payment separating express fare from feeder fare was installed.
• An integrated transportation network along with a unified fare was installed later.
• Buses are constructed with three, two doors for exit and a front door for entrance. 
• These buses had turbo engines, low floor levels, and wider doors for mass transit.
• The present system of transportation has three complementary levels service feeder line, express line, and inter-district routes.
• Feeder lines are connected to lower density which is later connected to the express system along with a structural corridor. 
• City circle lane has white minibuses that circle major transport terminals and the downtown area.

Thus, Curitiba is a city in Brazil known for its hierarchical transportation system.

The correct answer is 8 November.

Key Points

• World Urbanism Day is observed every year on 8 November.
• It is also known as World Town Planning Day.
• It promotes the role of planning in creating livable communities.
• The day was founded in 1949 by the late Professor Carlos Maria Della Paolera of the University of Buenos Aires.
• It is organised by the International Society of City and Regional Planners (ISOCARP).

Additional Information

Concept:

Urbanization:

• Urban areas are characterized by high human population density and vast human-built features.
• Urban areas are like cities or towns, developed by the process of urbanization.