You might be surprised to know that in bustling cities like Delhi alone, over 3,800 tonnes of waste remain untreated. This staggering volume poses a serious challenge for urban waste management systems, highlighting the urgent need for sustainable solutions. However, in recent times, digestate management has emerged as a transformative strategy in addressing these issues. Digestate is the nutrient-rich by-product produced during the anaerobic digestion process in biogas plants. Anaerobic digestion breaks down organic matter, such as agricultural waste, food waste, and manure, without oxygen to generate biogas (a mixture of methane and carbon dioxide). The remaining material after biogas production is called digestate. It contains valuable nutrients like Carbon, nitrogen, phosphorus, and potassium, making it a useful biofertilizer for improving soil health and supporting sustainable agriculture. By using digestate as a biofertilizer, CBG plants help recycle these nutrients back into the soil, reducing the need for synthetic chemical fertilizers. Digestate typically consists of two fractions: a solid part and a liquid part, which can be utilized in different applications.
Advanced techniques like stripping or filtration can extract concentrated nutrients such as ammonia, phosphate, and potash from both liquid and solid digestate. These recovered nutrients can be used to produce commercial fertilizers, reducing reliance on synthetic alternatives. By applying digestate in agriculture, the nutrients from organic waste are recycled back into the soil, contributing to a circular economy and reducing the need for chemical fertilizers, thus minimizing environmental pollution and resource depletion.
As technology evolved, India emerged as a leader in this field, with the potential to generate 62 million metric tonnes of compressed biogas (CBG) and 370 million metric tonnes of bio-manure annually from various feedstocks. Organic waste inputs are transformed into valuable outputs—biogas for energy and digestate for agriculture—creating a closed-loop system. This not only reduces environmental harm but also supports local economies by providing renewable energy, organic fertilizers, and sustainable waste management solutions, explains Mr Prince Gandhi, CEO & Director of CEID Consultants & Engineering Pvt Ltd.
Innovations in digestate management are playing an important role in maximizing the value of nutrient-rich by-products of anaerobic digestion. These advancements are reshaping how digestate is utilized. Here is a key innovation driving this transformation. The CBG plant manufacturers such as CEID have pioneered innovative solutions in digestate management, ensuring that this valuable by-product of anaerobic digestion is efficiently processed and utilized. One of the key innovations is the development of advanced Separation Technologies, specifically through the use of in-house designed and built Solid-Liquid Separators (SLS). This technology plays a critical role in transforming digestate into distinct, usable products with significant environmental and economic benefits. The SLS operates by pressing the digestate through a series of filters and screens, separating it into two distinct products FOM and LFOM. The company’s SLS is designed to be adaptable, allowing for adjustments in the separation process to meet the specific requirements of different feedstocks and end-use applications. This flexibility is particularly useful when dealing with different types of digestate from diverse organic inputs like agricultural residue, food waste, or manure.
In India, the soil usually has a lower percentage of carbon than what is needed for growing crops effectively. For optimal crop yield, soil organic carbon (SOC) content should generally be between 1.5% to 3%. This level of carbon ensures that the soil has good structure, nutrient retention, and biological activity, all of which are essential for healthy plant growth and high yields. The current soil organic carbon content in Indian soils is worryingly low. Studies show that in most agricultural regions of India, the SOC content ranges between 0.1% and 0.4%, which is significantly below the recommended levels for sustaining healthy crop production. This decline is largely due to intensive farming practices, deforestation, overuse of chemical fertilizers, and erosion.
Fertilizers, especially those derived from digestate, can naturally enrich the soil’s carbon content while providing essential nutrients like nitrogen and phosphorus if needed. When integrated into the soil, digestate-based fertilizers foster a dynamic ecosystem. The nutrients are gradually released, ensuring that when plants require them, the soil is well-equipped to provide them, thus enhancing productivity. Furthermore, digestate promotes healthy microbial activity, which is crucial for supporting plant growth. This is especially important in regions where agricultural productivity is directly linked to soil health and nutrient availability.
Additionally, the economic potential of digestate management is significant. CEID’s CBG plants in Barnala and Vadodara have already demonstrated the potential for dual revenue streams by selling various digestate-based products, including solid compost and liquid bio-fertilizers. These plants are generating double the revenue from FOM & LFOM compared to CBG sales alone. This underscores the opportunity for businesses to treat digestate as a valuable resource rather than waste.
EPC companies like CEID Consultants are successfully generating double the revenue through effective digestate management. In addition to CBG production, CEID Consultants are promoting digestate-based fertilizers by highlighting their financial viability. The economic potential of digestate is becoming increasingly evident as more businesses adopt innovative management practices, contributing to both environmental sustainability and profitability.
CEID is continuously innovating in the field of digestate management. The company is investing in research and development to further enhance nutrient recovery systems, improve solid-liquid separation efficiencies, and explore new uses for both the solid and liquid fractions of digestate. Future innovations may include the integration of digital monitoring systems into the SLS, allowing for real-time adjustments in separation processes based on the composition of the digestate.
Under the Market Development Assistance (MDA) scheme, the Indian government provides financial support to encourage the marketing of organic fertilizers produced as by-products from bio-gas and CBG plants. The scheme, particularly aligned with the GOBARdhan initiative, offers Rs 1,500 per metric tonne (MT) to support the marketing of the organic fertilizers i.e CBG plant digestate (FOM & LFOM)
Innovations in digestate management at CBG plants present significant environmental benefits, particularly for sustainable agriculture. By converting waste into valuable biofertilizers, farmers can decrease their reliance on chemical fertilizers, which often lead to negative environmental impacts such as soil degradation, water contamination, and loss of biodiversity. The use of digestate-based fertilizers not only enhances soil health but also lowers the carbon footprint associated with agricultural practices.
Furthermore, the nutrient-rich digestate generated from CBG plants supports the long-term vitality of agricultural lands by replenishing essential nutrients such as nitrogen, phosphorus, and potassium. This sustainable approach aligns with global sustainability goals, promoting practices that enhance food security while safeguarding the environment.
Moreover, integrating digestate management into CBG operations contributes to a circular economy, where waste is continuously repurposed for beneficial uses. This not only maximizes resource efficiency but also encourages agricultural resilience by fostering healthier ecosystems. As CBG plants adopt innovative digestate management strategies, they play a crucial role in advancing sustainable agriculture and environmental stewardship, ensuring a more sustainable future for both farmers and the planet.
Mr. Prince Gandhi is CEO & Director of CEID Consultants & Engineering Pvt Ltd.
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