Composting is the natural process of turning organic matter in waste into a beneficial fertilizer that can benefit both soil and plants. Composting converts organic waste such as food waste, manure, leaves, grass trimmings, paper, wood, feathers, agricultural residue, etc. into beneficial organic fertilizer by using various microorganisms such as bacteria and fungus. Farmers can use this to increase their harvests. This article will explain to you about Composting for the disposal of solid waste which will be helpful in preparing the Environment syllabus for the UPSC Civil service exam.

Composting - Concept

• Composting is a biological process that allows the organic element of waste to decay under carefully controlled conditions.
• The organic waste material is decomposed by microbes, which reduces its volume by up to 50%.
• Compost or humus is the name for this stabilized product. It has the texture and odor of potting soil and can be used as a soil conditioner or mulch.
• Composting allows for the simultaneous digestion and recycling of waste and sewage sludge.
• Composting is projected to become increasingly popular as more rigorous environmental regulations and site constraints limit the use of solid-waste incineration and landfill options.
• Sorting and segregating the waste, size reduction, and waste digestion are all processes in the process.

Compostable Wastes

• Compostable materials include anything that can be consumed or cultivated in a field or garden.
• Compostable materials include fruits, vegetables, dairy products, cereals, bread, unbleached paper napkins, coffee filters, eggshells, meats, and newspapers.
• Plastics, grease, glass, and metals, such as plastic utensils, condiment packages, plastic wrap, plastic bags, foil, silverware, drinking straws, bottles, polystyrene, and chemicals, cannot be composted.
• Red meat, bones, and small bits of paper can be composed, but they decompose more slowly.

Composting - Phases

Composting goes through three main phases under optimal conditions:

• Mesophilic Phase: It is an initial phase where mesophilic bacteria such as Listeria monocytogenes, Staphylococcus aureus, and Escherichia coli decompose the material at moderate temperatures.
• Thermophilic Phase: As the temperature rises, a second, thermophilic phase begins, in which diverse thermophilic bacteria such as lactobacilli, Streptococcus thermophilus and bifidobacteria carry out breakdown at higher temperatures (50 to 60 °C).
• Maturation Phase: In the maturation phase, when the supply of high-energy molecules diminishes, the temperature begins to drop, and mesophilic bacteria once again take the lead.

Composting - Procedures Involved

Sorting And Shredding

• Sorting and separating procedures isolate decomposable materials from glass, metal, and other inorganic components in trash.
• These are done mechanically, based on variances in the refuse's physical features such size, density, and magnetic properties.
• The size of the waste items is reduced by shredding or crushing, resulting in a homogenous mass of material.
• Hammer mills and rotary shredders are used to accomplish this.

Digesting and Processing

• Composting crushed waste can be done in an open windrow or in an enclosed mechanical facility. Windrows are long, low rubbish heaps.
• Every few days, they are flipped or stirred to allow air to reach the bacteria that are digesting the organics.
• It may take five to eight weeks for the waste to be completely digested, depending on moisture conditions.
• Temperatures in an active compost pile reach around 65 °C (150 °F) due to the metabolic action of aerobic bacteria, destroying harmful organisms that may be present in the waste material.

Composting - Various Methods

• Passive Composting or Piling: Simply stacking the materials and allowing them to degrade naturally is passive composting or piling.
• This process is simple and inexpensive, but it is slow and may produce unpleasant odors.
• Aerated Static Piles: Air is added to the stacked pile via perforated pipes and blowers in aerated static piles.
• This approach does not involve any labor to change the compost, but it is weather-dependent and can result in unpredictable pathogen elimination due to poor mixing.
• Windrows: Windrows are long, narrow piles that are turned when temperature and oxygen requirements dictate.
• This process generates a consistent output that can be remotely tracked .
• Turning the compost, on the other hand, might be time-consuming or expensive.
• Windrows are commonly utilized for huge volumes that take up a lot of space. Windrows can also cause odor issues and leachate concerns if they are exposed to rain.

• Bins: Small amounts of food waste are usually composed in bins. Bins with wire mesh or wooden frames allow for adequate air circulation and require little labor.
• Three chamber bins speed up compost output by allowing for different stages of decomposition.

• In-vessel System: In-vessel systems, which use perforated barrels, drums, or specifically manufactured containers, are easy to use, turn, require little effort.
• They are not weather sensitive, and can be used in urban and public settings.
• The initial investment can be expensive, yet handling volumes are usually minimal.
• Vermicomposting: Vermicomposting involves feeding food waste to worms and then using the worm castings as high-quality compost. Containers, bins, and greenhouses are commonly used for this.
• 1 pound of worms can eat 4 pounds of garbage every week on average. This kind of composting is used in many schools as an environmental education tool.

Composting - Advantages

• Reduction in Methane: Methane, a strong greenhouse gas, is produced by organic waste in landfills. Methane emissions are considerably decreased when discarded food and other organics are composted.
• Reduction in Chemical Fertilizers: Chemical fertilizers are reduced, and in some cases eliminated, by compost.
• Boosts Crop Yields: Compost encourages agricultural crop yields to increase.
• Aids in Rejuvenation: By rehabilitating contaminated, compacted, and marginal soils, compost can help with reforestation, wetlands restoration, and habitat rejuvenation projects.
• Rehabilitate Soils: Compost can be used to rehabilitate soils that have been contaminated by hazardous waste at a low cost.
• Money Saver: Wherever applicable, compost can save money over traditional soil, water, and air pollution remediation solutions.
• Improves Moisture Dispersion: Compost assists with water absorption and penetration into the soil by reducing soil crusting. According to new research, adding compost to sandy soils can help with moisture dispersion by allowing water to travel laterally from its place of application.
• Aids Carbon Sequestration: When compost is added to the soil, the soil's health improves as microbes multiply and become more abundant. From photosynthesis, these microorganisms sequester carbon in the soil. Thus carbon sequestration is a great benefit of compost.

Composting - Challenges

• Availability: This compost's availability is solely dependent on suitable distribution systems, which are now lacking in India.
• Functions of Government Schemes: Because of its administrative complexity, government schemes for composite have not functioned well.
• Great Volume: Compost's great volume but low value makes it less appealing to fertilizer marketing businesses to promote its use.
• Compliance With Government’s Requirement: Compost producers are finding it more difficult to meet the Fertiliser Control Order's quality requirements (FCO).

Conclusion

Plant pathogens such as Fusarium oxysporum, Rhizoctonia sp., and Pythium debaryanum, which can cause crop illnesses, have been reported to be inhibited by compost products such as compost tea and compost extracts. By reaching temperatures exceeding 50 °C, composting can kill some pathogens and undesirable seeds. Stabilized compost (composted material in which microorganisms have finished digesting the organic materials and the temperature has reached 50–70 °C) provides very little risk because these temperatures kill pathogens and even render oocysts unviable.

FAQs

Q1: What is composting?

Q2: What are the benefits of composting?

Q3: What materials can be composted?

Q4: What is vermicomposting?

Q5: How long does the composting process take?

MCQs

1. Which of the following can be composted?

a) Plastic bags

b) Food scraps

c) Glass bottles

d) Metals

2. What is the purpose of composting?

a) To dispose of hazardous waste

b) To convert organic waste into fertilizer

c) To increase landfill space

d) To produce industrial chemicals

3. Which of the following organisms are used in vermicomposting?

a) Earthworms

b) Bacteria

c) Algae

d) Fungi

4. Which of these benefits is directly associated with composting?

a) Increased pollution

b) Soil enrichment

c) Fossil fuel production

d) Waste burning

5. How does composting help reduce greenhouse gas emissions?

a) By burning organic waste

b) By reducing methane emissions from landfills

c) By producing carbon dioxide

d) By increasing water use

GS Mains Questions and Model Answers

Q1: Explain the role of composting in sustainable waste management.

Answer: Composting contributes significantly to sustainable waste management by converting organic waste into a valuable resource. This process reduces landfill demand, curbs methane emissions, and provides natural fertilizers for agriculture. By promoting composting at community and household levels, we can effectively manage waste and improve soil health, aligning with sustainable environmental practices.

Q2: How does composting impact soil quality?

Answer: Composting improves soil structure and fertility by adding essential organic nutrients. It enhances soil moisture retention, supports microbial activity, and reduces the need for chemical fertilizers. This enriches the soil, promoting healthier plant growth and increased agricultural productivity, while maintaining ecological balance.

Q3: Discuss the importance of vermicomposting as a composting method.

Answer: Vermicomposting accelerates composting by using earthworms to break down organic matter rapidly, producing nutrient-rich compost known as worm castings. This method is efficient, eco-friendly, and ideal for urban composting setups, offering a high-quality fertilizer. Vermicomposting also enriches soil with beneficial microbes, making it an important alternative for sustainable waste processing.

Previous Year Questions on  Composting

1. UPSC CSE Prelims 2020

Question: Which method of composting uses worms to decompose organic waste?

Answer: Vermicomposting is a method that uses earthworms to decompose organic waste. Earthworms consume the organic material and produce nutrient-rich castings that enhance soil fertility. This process is highly efficient and produces compost faster than traditional methods. Vermicomposting is particularly suitable for small-scale, urban composting due to its low-maintenance requirements and high-quality output, making it a preferred method for waste management in various settings.

2. UPSC CSE Mains 2018

Question: Evaluate the environmental benefits of composting as a waste management solution.

Answer: Composting is a beneficial waste management solution that reduces landfill use, minimizes greenhouse gas emissions, and promotes soil health. By diverting organic waste from landfills, composting decreases methane emissions—a significant contributor to climate change. Compost improves soil structure, fertility, and water retention, aiding sustainable agriculture and reducing reliance on chemical fertilizers. Implementing widespread composting practices can support waste reduction, environmental sustainability, and healthier ecosystems, making it an essential component of eco-friendly waste management strategies.