Compressed biogas plants
Upgrade biogas to Bio-CNG for vehicles and city gas.
- SATAT plants
- City gas injection
- Vehicle fuel
RESEARCH PARTNERSHIP / 03
Developed withIndian Institute of Technology Bombay#3 in engineering, NIRF 2025
Field validatedDelivered by Rispri Labs
Biogas upgrading.
No compression. No chemicals.
Rispri Labs delivers modular water scrubbers, developed with IIT Bombay, that strip CO₂ from raw biogas at near-atmospheric pressure. A lower-cost route to Bio-CNG and compressed biogas for plants of every size.
RESEARCH TO REALITYRispri Labs × IIT Bombay
IIT Bombay
What it means for you
Biogas upgrading with just water.
No compressor
Raw biogas is cleaned at normal air pressure before any compression.
Just water
No amines, no caustic, no chemicals to buy or handle.
Small plants too
Modular units sized for a gaushala, dairy or STP digester.
Performance
Upgrading that pays at any scale.
Conventional water scrubbers compress biogas to several bar before they can remove CO₂, and chemical scrubbers need amines or caustic. A rotating-disk contactor does the job with water at near-atmospheric pressure.
- TRL 8
- System proven in operating conditions
- ~1atm
- Scrubbing pressure; no compression step
- ~3m
- Pump head for water circulation
- <10Pa
- Gas-side pressure drop per stage
Figures are from the research team's field validation in operating conditions. Performance on your stream is confirmed in our laboratory before design.
Challenge and response
The problems this solves.
- 01The challenge
Water scrubbers compress raw biogas to several bar before upgrading.
How we solve itScrub at near-atmospheric pressure and compress only the clean methane.
- 02The challenge
Amine and caustic scrubbers add chemical cost and handling risk.
How we solve itPlain water absorbs the CO₂; no chemicals are dosed.
- 03The challenge
Small digesters cannot justify a large upgrading plant.
How we solve itModular units match the gas flow of dairies, gaushalas and STPs.
- 04The challenge
High power use eats into Bio-CNG margins.
How we solve itLow pump head and very low pressure drop keep running power down.
How it works
The process, step by step.
- 1
Contact
Raw biogas flows across disks wetted with a thin film of water.
- 2
Absorb
CO₂ dissolves into the water far faster than methane does.
- 3
Deliver
Methane-rich gas moves on for drying and compression to Bio-CNG.
- 4
Regenerate
The water releases its CO₂ in air and is circulated again.
Use cases
Where biogas upgrading and CO₂ scrubbing delivers.
Dairy and gaushala digesters
Turn cattle-dung biogas into saleable fuel.
- Gaushalas
- Dairy cooperatives
- GOBARdhan plants
STP digester gas
Upgrade sludge digester gas for on-site use or sale.
- Sewage treatment plants
- Faecal sludge plants
- Municipal digesters
Food and agro-industry
Upgrade gas from press mud, distillery and food waste.
- Sugar press mud
- Distillery spent wash
- Food processing waste
Municipal solid waste
Upgrade gas from organic fraction biomethanation.
- Wet-waste plants
- Bulk waste generators
- Market waste
Captive fuel
Replace LPG, diesel or furnace oil on site.
- Boilers and kitchens
- Process heating
- Gensets
Comparison
How it compares.
| Factor | Pressurised water or amine scrubber | Rispri solution |
|---|---|---|
| Scrubbing pressure | Several bar; raw gas compressed first | Near-atmospheric |
| Chemicals | Amines or caustic in chemical scrubbers | Water only |
| Scale | Economic mainly at large flows | Modular; suits small and mid-size digesters |
| Energy | Compressor on the full raw-gas flow | Low-head pump; compress only the upgraded gas |
| Operation | Skilled operation of pressure vessels | Simple, low-pressure equipment |
Standards and regulations
Designed around the rules that apply to you.
We design each system to meet your consent conditions and the regulations for your sector, and our laboratory reports against them.
- IS 16087:2016Specification for biogas (Bio-CNG) for automotive and stationary use.
- SATAT initiativeOfftake framework for compressed biogas from new CBG plants.
- GOBARdhanNational programme for biogas from cattle dung and organic waste.
- PNGRB and PESO normsSafety and quality rules for compressed gas storage and dispensing.
Industries served
Built for the sectors that need it most.
- Waste-to-energy and biogas
- Dairy
- Sugar and distilleries
- Municipal STPs
- Food processing
- Gaushalas
Why Rispri
Institute science. Industrial delivery.
Institute-developed technology
Built on patented and peer-reviewed research from our partnership with IIT Bombay.
Tested on your stream
Our accredited laboratory characterises your water or waste before design and verifies results after.
Engineering since 1999
The team that builds ETPs, STPs and ZLD plants across India takes each solution from pilot to full scale.
One accountable partner
Design, supply, installation, commissioning, operation and testing under one contract.
Questions
Frequently asked questions.
How can CO₂ be removed without compressing the gas?
The rotating disks create a very large, constantly renewed water film. That gives the gas enough contact time with water to absorb CO₂ at near-atmospheric pressure, instead of relying on high pressure to push it into solution.
What size of plant does it suit?
Units are modular, so they suit small and mid-size digesters at dairies, gaushalas and STPs as well as larger CBG plants, which usually find conventional upgrading hard to justify.
Are any chemicals used?
No. Water absorbs the CO₂ and is regenerated in air for reuse.
How ready is the technology?
The water-based scrubber has reached TRL 8, which means the system has been proven in operating conditions.
Can Rispri build the digester as well?
Yes. We design and build complete waste-to-energy plants, from feed handling and digestion to upgrading and testing.
Research partnerships
More solutions from our partnerships.
THE NEXT STEP
Prove it on
your own stream.
Send us a sample or tell us about your site. We will test it, recommend a configuration and set up a pilot.
Request a pilot