Managing quality and utilisation of compost is long standing challenge in handling biodegradable waste

India, with its burgeoning population, faces a colossal challenge in managing municipal solid waste. Rapid urbanisation and changing consumption patterns have led to a substantial increase in the generation of waste, overwhelming existing waste management systems. 

As per the Union ministry of housing and urban affairs (MoHUA), urban India generates around 156,000 tonnes of waste per day, out of which we consider about 50 per cent wet (biodegradable) in nature. However, the amount of wet waste that accumulates at dump sites on a daily basis remains a major concern in India. 

Despite the fact that infrastructure to treat wet waste exists, it is frequently underutilised due to the traditional convenience of dumping. 

Of course, this is exacerbated by the practice of collecting mixed waste at the source, which ultimately reduces the possibility of treating wet waste for products such as compost or biogas.  However, dumping is environmentally unsustainable and causes a variety of problems, including groundwater pollution, soil degradation and the release of harmful greenhouse gases.

There are currently two methods for processing wet biodegradable waste: Composting and biomethanation. In terms of processing percentage, composting is the predominant method. According to MoHUA, there are a total 2,507 plants designed to handle wet biodegradable waste and possessing a collective capacity of 117,112 tonnes per day (TPD). 

The contribution includes 2,390 waste-to-compost plants with a combined capacity of 113,113 TPD, along with 117 bio-methanation plants of 3,999 TPD capacity.

%  distribution of wet waste processing technology

Source: SBM urban dashboard

Despite having processing infrastructure, we can only handle 76 per cent of total waste generated, according to the SBM urban dashboard. However, the recent Swachh Survekshan 2023 indicates poor performance by Urban Local Bodies (ULB) in waste processing, with only Chhattisgarh, Gujarat, Kerala, Maharashtra and Odisha achieving a 50 per cent processing rate, raising concerns and the need for a reassessment of claimed processing data. 

Notably, Arunachal Pradesh stands at 0 per cent processing, followed by Assam at 2.61 per cent, Tripura at 1.05 per cent, Mizoram at 2.35 per cent,and Nagaland at 5.78 per cent. The Central Pollution Control Board’s Annual Report for 2020-2021 further underscores this issue, revealing that the ULBs in cities process only 50 per cent of the total waste collected.

Composting as a suitable method of processing

Composting, a sustainable alternative to traditional waste disposal methods, involves the controlled decomposition of organic matter by microorganisms like bacteria and fungi. The resulting compost is nutrient-rich, improves soil structure and supports plant growth. 

However, the present soil health is adversely affected by chemical fertilisers, with estimates indicating a decline in soil organic carbon content in India from 1 per cent to 0.3 per cent over the past 70 years. Utilising compost from municipal solid waste can serve as a valuable nutrient resource for the soil and contribute organic matter.

Despite the widespread adoption of waste-to-compost methods, the marketing of compost faces challenges in ULBs for several reasons, including:

• Limited awareness among consumers regarding its applications
• Contamination of the byproduct due to non-segregated waste processing
• Absence of a uniform policy for the promotion and marketing of compost.

How contaminated compost affects soil system

Contaminated compost can have a variety of negative effects on soil properties, vegetation and plants and may be caused by the presence of harmful substances such as heavy metals, pathogens, pesticides or other pollutants in the compost. The introduction of such contamination into the human body via the consumption of such food may disrupt a variety of biological and biochemical processes.

Here are some potential ways in which contaminated compost can disturb soil and vegetation:

Photo: iStock

Heavy metal contamination: Some compost may contain high levels of heavy metals like lead, cadmium and mercury, which can accumulate in the soil over time. The introduction of such metals into the human body via food consumption may disrupt a variety of biological and biochemical processes and damage the functioning of the brain, lungs, kidneys and liver. 

Pathogen introduction: Contaminated compost may introduce harmful pathogens that can cause diseases in plants. If contaminated soil is used to grow food crops, there is a risk of pathogens entering the food chain and causing foodborne illnesses in humans.

Pesticide residues: Compost derived from organic waste treated with pesticides may contain pesticide residues. These residues can persist in the soil and affect non-target plants, insects and soil microorganisms, disrupting the natural balance of the ecosystem.

pH imbalance: Some compost materials may alter the pH of the soil. If the compost is too acidic or alkaline, it can affect nutrient availability for plants and influence soil microbial activity.

Nutrient imbalance: Contaminated compost may have imbalances in essential nutrients. Excessive amounts of certain nutrients can lead to nutrient imbalances, affecting plant growth and potentially causing toxicity.

Affecting soil microbial communities: Harmful substances in contaminated compost can negatively impact the diversity and activity of soil microorganisms. This can disrupt important soil processes such as nutrient cycling and organic matter decomposition.

Bioaccumulation in plants: Plants grown in contaminated soil may absorb and accumulate harmful substances from the compost. This bioaccumulation can lead to food safety concerns, especially if the plants are consumed by humans or animals.

To mitigate these risks, it’s crucial to ensure that composting processes follow Fertilizer Control Order (FCO), 2009 standards. Regular testing of compost for contaminants, monitoring composting conditions and using quality source materials can help minimise the negative impacts on soil, vegetation and food crops. Additionally, regulations and guidelines for compost quality and application should be followed to safeguard environmental and human health.

How to sustainably utilise compost

Compost quality depends on the waste quality received at the facility, which requires high-quality composting through source segregation. Onsite composting is more manageable, but centralised plants face challenges with city waste, leading to compromised waste and, subsequently, compost quality.

Unfortunately, our ULBs struggle with waste management, collecting mixed waste. It’s crucial to reevaluate the claimed 90 per cent waste segregation on the Swachh Bharat Mission Dashboard and implement penalties to enforce city-wide waste segregation by ULB authorities.

Composting is widely acknowledged as an effective method for managing biodegradable waste, aligning with waste-to-wealth initiatives. Sustainable plant operations rely on efficient marketing of by-products, especially compost. Unfortunately, the discontinuation of the compost policy in September 2021 has left its implementation unattended.

To sustain the success of composting initiatives for municipalities, individuals and entrepreneurs, it’s crucial to prioritise the revival of this policy. Government subsidies are essential for incentivising the utilisation and marketing of compost, ensuring its continued impact.

Compost consumption is particularly high in agriculture. Adherence to quality standards outlined in FCO is critical for preventing contamination during land application. When revising policies, quality control and testing must be prioritised in order to effectively market compost.

Growing need for compost minimum sale price

Effective product marketing is vital for the sustainability of composting plants and requires active promotion of compost marketing, which is essential to sustain these plants and leverage the “waste to wealth” concept.

Despite maintaining quality, compost underutilisation is recognised, prompting the need for a minimum price for compost sales and a government-led supply chain to promote city-compost among farmers and the fertiliser industry.

These measures aim to ensure composting plant sustainability by establishing a structured marketing framework and addressing current utilisation challenges essential to actively promote the marketing of compost.

Presently, compost produced by ULBs is either provided to consumers at a fee or remains stockpiled within the plant, occupying valuable space. However, there are instances where policies have facilitated compost marketing.

An example of effective policy implementation can be seen in the state of Odisha, renowned for its decentralised waste management practices that provide livelihood opportunities to self-help groups (SHGs). The state has a comprehensive policy for the marketing of compost.

Compost produced at various decentralised facilities, named Mo-Khata, is marketed through outlets directly from the facility, both for individual consumers and bulk buyers facilitated by the agriculture and horticulture departments. To support the livelihoods of SHGs and sustain composting plants, Rs-10-20 per Rs 20 per kilogramme for marketing has been decided by the state.

There is a growing need for a centralised minimum sale price for compost and creating a supply chain within the government promotes city-compost among the farming community and fertiliser industry.

This would contribute to ensuring the sustainability of composting plants by creating a structured framework for the marketing of compost, thereby addressing the current challenges in its utilisation.