80–95% (80–95% moisture)
Also known as: raw digestate water content
The moisture content of raw (unseparated) digestate leaving an anaerobic digester — mostly water, requiring mechanical separation before practical transport or fertilizer use.
Last updated
Beyond definitions
Planning to start a CBG business?
Get the full business understanding — capex, regulations, machinery, vendor questions, and risk checks before you commit capital.
What is 80–95%?
80–95% is the moisture-content range for raw, unseparated digestate as it leaves an Indian anaerobic digester operating under wet conditions (8–15% Total Solids feedstock). The number is the inevitable consequence of how wet digestion works: feedstock is diluted with water or recirculated process liquid to a pumpable slurry before entering the reactor, microbial breakdown of solids further increases the moisture fraction, and the output stream is therefore 4–5× more water than solid by mass.
The implications for downstream handling are large. At 90% moisture, 1 tonne of digestate contains only 100 kg of dry matter and 5–10 kg of NPK — a fertilizer value of ₹150–250 per tonne. Yet the same tonne weighs as much as a tonne of high-grade urea (₹26,000–30,000) for the purposes of trucking, pumping, and storage. The economic case for mechanical separation is therefore immediate: a screw press or decanter centrifuge can split raw digestate into a 50–70% moisture solid fraction (25–35% of mass) and a 95–98% moisture liquid fraction (65–75% of mass), with capex of ₹30 lakh–1.5 crore depending on throughput.
Raw digestate at 80–95% moisture is workable only for very specific applications. Direct land application through tanker spreaders within a 5–15 km radius of the plant is viable if local farmers will accept it, particularly for liquid-tolerant crops like sugarcane, banana, and pasture. Fertigation through low-pressure surface irrigation is another option, though emitter clogging requires pre-filtration. Long-term storage in lined lagoons is feasible but emits methane and ammonia, complicating air-emission compliance under SPCB Consent to Operate. Most Indian SATAT CBG plants now treat the 80–95% moisture stream as an intermediate, with separation built into the design from day one.
- Typical moisture content of raw digestate from Indian wet anaerobic digesters.
- 1 tonne at 90% moisture = 100 kg solids = ₹150–250 fertilizer value but full tonne of freight cost.
- Screw press or centrifuge separation produces a 50–70% solid fraction and 95–98% liquid fraction.
- Direct application viable only within 5–15 km of the plant for liquid-tolerant crops.
Common questions about 80–95%
Plain-English answers to what people most often ask.
Why is raw digestate so wet if the feedstock was only 8–15% water?
Can raw digestate be applied directly to fields?
Want the full picture, not just the term?
Adhāra Viveka gives you structured clarity on capital-intensive recycling and renewable-energy sectors — before you commit money or engage vendors.