Why digestate decides CBG economics
A CBG plant processes far more tonnes of feedstock than it produces in gas. Most of the mass leaves the plant as digestate. Handled as waste, it is a cost and a compliance problem. Engineered properly, it becomes organic fertilizer and value-added products that improve project returns and support India's soil health.
- Digestate
- Solid–liquid separation
- FOM
- LFOM
- Biochar
- Pellets / Briquettes
FOM plants
Indian-technology FOM plants that convert dewatered digestate into value-added Fermented Organic Manure through processing, enrichment and bagging.
LFOM processing
Purpose-designed machinery and processing systems that turn the liquid fraction into Liquid Fermented Organic Manure.
Biochar
Solutions for converting suitable digestate-derived material into biochar, a carbon-rich product with soil and carbon-market applications.
Pellets & briquettes
Drying, crushing, material handling and pellet plants for suitable processed digestate and biomass fractions.
Digestate processing: from slurry to saleable manure
- Digestate
- Solid–liquid separation
- Drying / curing
- Enrichment
- Granulation / screening
- Bagged FOM
| Step | Equipment options | Selection depends on |
|---|---|---|
| Solid–liquid separation | Screw press, decanter centrifuge, filter press, or screw press followed by filter press | Digestate solids and fibre content, target cake dryness, power use |
| Drying / curing | Paved sun-drying yards, windrow curing, or mechanical dryers (rotary or paddle) using plant waste heat | Land, climate, monsoon storage, and the moisture limit for sale |
| Enrichment | Blending with rock phosphate, bio-inoculants or other permitted additives (for example to make PROM) | Target product and applicable fertilizer standards |
| Granulation & packing | Crushers, granulators, screens, bagging machines | Market preference for powder or granules, and dealer network |
| Liquid fraction (LFOM) | Settling and storage tanks or lagoons, filtration, and part recirculation as process water | Volume, field-application demand and water balance |
Plan the water balance: part of the separated liquid is usually recirculated to prepare feedstock slurry. This reduces fresh water demand and the volume of LFOM to be managed.
Selling FOM & LFOM: FCO compliance
To be sold as fertilizer, FOM and LFOM must meet the specifications notified under the Fertilizer (Control) Order (FCO). These cover moisture, total organic carbon, N-P-K content, C:N ratio, pH, electrical conductivity and heavy-metal limits. Build regular lab testing and batch records into plant operations from day one.
Plan for the monsoon and crop seasons
- LFOM buffer lagoon: farmers don't take liquid manure every day, and in the monsoon field application stops. Size a lined lagoon for several weeks of output (often around 30 days).
- Command area: identify enough farmland nearby to use the LFOM every year. Napier-based plants can recycle it to their own grass fields.
- Windrow composting yard: a low-cost way to turn surplus digestate into solid compost, with tractor-drawn turners and temperature logging. The active stage typically takes 4–8 weeks, depending on season.
- Covered storage for finished FOM, so that monsoon rain doesn't wash out nutrients or block sales.
Government support for organic manure from CBG plants
The Government of India supports organic fertilizers produced from CBG and GOBARdhan plants: eligible FOM, LFOM and PROM receive Market Development Assistance of ₹1,500 per tonne under the applicable MDA scheme. The GOBARdhan unified scheme also covers organic-manure value addition. See scheme details.
Designing the post-CBG section
- Digestate quantity and characteristics from the mass balance
- Separator and dewatering selection
- FOM processing, curing, enrichment and bagging capacity
- LFOM storage, treatment and dispatch
- Market linkage and quality standards for fertilizer sale
- Optional drying, biochar or pelletisation routes
The complete circle: Waste → CBG → Organic fertilizer → Agriculture → Waste → Energy. See our full turnkey EPC scope.
Frequently asked questions
FOM (Fermented Organic Manure) is the solid organic manure produced by dewatering and processing the digestate left after anaerobic digestion in a CBG or biogas plant. It adds organic carbon and nutrients to soil.
LFOM (Liquid Fermented Organic Manure) is the liquid fraction of digestate from a CBG/biogas plant, processed for use as a liquid organic manure.
Yes. Eligible FOM, LFOM and PROM produced from CBG/GOBARdhan plants receive Market Development Assistance (MDA) of ₹1,500 per tonne under the applicable scheme, subject to its conditions.
Where technically and commercially suitable, dewatered and dried fibre-rich fractions can be pelletised or briquetted, or converted into biochar. Suitability depends on the feedstock, moisture and market, and is evaluated project by project.