1. Biogas and biomethane in Brazil: what regulation defines in 2026
Biogas comes from the anaerobic digestion of organic residues — vinasse and other agro-industrial residues, animal manure, landfill waste and sewage treatment sludge. Once purified to fuel specification, it is sold as biomethane. Two milestones frame this market. Law 13,576/2017 created the National Biofuels Policy (RenovaBio), under which certified producers and importers issue Decarbonization Credits (CBIOs) according to the Energy-Environmental Efficiency Score calculated in RenovaCalc, the ANP tool.
And ANP Resolution 1,006/2026, published in August 2026, unified the specification and quality control of biomethane from any origin, replacing Resolutions 886/2022 (landfills and sewage plants) and 906/2022 (agro-silvo-pastoral and commercial residues).
For whoever specifies pumps the consequence is practical: gas quality results from purification, not from the pump, but pumps sustain the liquid stages that make purification possible — digester feed and recirculation, digestate separation, gas washing and heating. Each stream needs its own data before selection: composition, solids, viscosity at the real temperature, flow, pressure and classification of the area where the pump will be installed.
2. The three stream families of a biogas plant — separating the problem
The most useful engineering rule is to classify streams by their physical properties, not by the name of the residue. Treating everything as "organic effluent" leads to wrong specifications: the same digestate can be a fibrous slurry before the separator and a turbid liquid after it.
- Stream 1 — raw, with solids: landfill leachate without pretreatment, substrate and digestate with fibers, sand or plastics. Calls for a pump built for solids (progressing cavity, rotary lobe, peristaltic or solids-handling centrifugal). Outside the FB catalog line.
- Stream 2 — liquid after separation: pretreated leachate, liquid fraction of digestate, clarified biofertilizer. Usually aqueous; fine solids, pH, chlorides and H2S come from the analysis. FBCN centrifugal service when the analysis confirms a clean or turbid liquid; suspended solids are assessed by FB case by case (MTEC-03/00, item 2.3).
- Stream 3 — process fluids and utilities: biogas washing water or solution, service water and heating hot water (FBCN); glycerin, oils and fats used as co-substrate or by-product (FBE); thermal oil, when there is a thermal fluid heater (FBOT).
Warning
Do not use a gear pump on a stream carrying fibers, sand or plastics. In the FBE, fluid is carried in the cavities between the teeth and the casing, and gear meshing is what prevents return to suction (FBE 2026 catalog, p.2); manual MTEC-01/01 (item 2.3) asks for FB consultation whenever the fluid carries suspended solids.
3. FBE: glycerin, oils, fats and other viscous fluids
The FBE is an external gear pump developed for viscous fluids (manual MTEC-01/01). In biogas plants this profile appears in co-substrates and by-products that are not aqueous: glycerin, vegetable oils, fats and oily residues added to the digester, provided they arrive without sand or abrasive solids. Clarified aqueous streams, with viscosity close to that of water, are centrifugal service (section 4).
Measure viscosity at pumping temperature and check the size against the FBE 2026 catalogue matrix (p.5). For example, 1,750 rpm at 30–250 SSU is listed for 1/8″, 1/4″, 1/2″, 3/4″, 1″ and 1″D. The 1,150 and 850 rpm bands and lower speeds also have their own model lists; a band must not be extended to the entire series. For products that solidify when cold, assess the heating jacket and startup conditions.
Materials and sealing follow the fluid analysis. The catalog lists casing and covers in ASTM A48 CL30 cast iron, ASTM A536 60-40-18 ductile iron, ASTM A216 WCB carbon steel and ASTM A743 CF8M stainless steel, with shafts and gears in SAE 1045 steel or AISI 316L stainless.
Sealing can be packing, mechanical seal or lip seal; the standard seal in the manual is type 21, with ceramic × graphite faces and Viton elastomer (item 2.5), and it must be reviewed with the seal manufacturer when H2S, methanol or extreme pH are present. For services where leakage is not acceptable — toxic, corrosive or flammable fluids —, the manual provides magnetic coupling sealing (item 2.7).
4. FBCN: clarified liquid fraction, biogas washing and utilities
The FBCN is the FB normalized centrifugal pump, indicated in manual MTEC-03/00 for clean or turbid liquids in applications that include sanitation and the chemical industry. In a biogas plant it covers the already separated liquid fraction, gas washing water recirculation, service water and hot water circuits. The general series data reach 2,200 m³/h and 135 m; these are line maximums, not those of each model, and each size has its own curve.
Purification by washing with water or with an absorbent solution (such as amines) circulates liquid between columns and tanks. Pressure, flow and solution composition come from the purification technology supplier; the pump is selected for that point, with materials and elastomers compatible with the solution and with the H2S and CO2 it absorbs.
The manual offers concrete criteria for these streams: 10 bar maximum suction pressure; minimum flow of 0.1 to 0.15 times the best-efficiency flow, depending on size, and maximum of 1.1 times (Table 1); 3.3 mm corrosion allowance; casing in cast iron, A216 WCB carbon steel or A743 CF8M stainless; and sealing arrangements per application (item 10) — external liquid sealing (S1) for toxic, aggressive or malodorous fluids, S2 for solid particles or small fibers in suspension and external flushing (S3) for abrasive particles or a tendency to crystallize, all three up to 105 °C, or a mechanical seal defined for the application.
5. Process heating: hot water with FBCN or thermal oil with FBOT
The digester runs in the temperature range defined by the process design, and the heating system replaces heat losses with hot water (for example, recovered from cogeneration engines), steam or thermal fluid. The heating medium is a design decision; the pump follows that decision, and each medium has its own criteria.
In a hot water circuit the selection is a water centrifugal pump (FBCN), and sealing is chosen by the real temperature: with packing and no cooling chamber, manual MTEC-03/00 states −50 to 105 °C; with a mechanical seal, the seal manufacturer recommendation applies.
When the plant has a thermal fluid heater — for example, to supply heat to the reboiler of an amine regeneration unit —, circulation is FBOT service: a back pull-out centrifugal pump sealed with graphite packing and a mechanical seal, with no external cooling (FBOT 2026 catalog, p.2), a 350 °C series limit and maximum discharge pressure that decreases with temperature (Figure 1 of MTEC-16/00).
The catalog requires a fluid free of abrasive particles and of materials that attack pump components.
6. Integrated biodiesel-biogas plant: glycerin, oils and methanol
Crude glycerin in an integrated biodiesel and biogas plant may contain methanol, salts and soaps. Provide batch composition, concentration, viscosity and temperature, plus pH and solids. The catalogue speed matrix guides FBE selection; casing, gear and seal compatibility requires assessing these data together, not pH alone.
Residual or recovered methanol enters the installation’s flammability assessment and area classification. Define sealing pressure, temperature and chemical-compatibility limits; the FBE manual describes magnetic coupling as an option whose configuration and availability require confirmation. This is not a guarantee of no leakage under every condition. Oils and fats that solidify when cold require assessment of pump and line heating.
7. Where FB Bombas is not the choice: raw streams with solids
FB catalog pumps were not developed for raw leachate with plastics and sand, substrate or digestate with long fibers, or sludge with coarse solids. The FBE and FBCN manuals ask for consultation whenever suspended solids are present, and the FBOT catalog excludes fluids with abrasive particles. In these streams the usual technologies are those listed below, offered by specialized manufacturers.
- Progressing cavity: metal helical rotor inside an elastomeric stator; conveys slurries with solids and fibers with little pulsation.
- Rotary lobe: two rotors turning without contact with each other, which accept soft solids and fibers.
- Peristaltic hose pump: the fluid only touches the inside of the hose; used for highly abrasive sludge and for dosing, with periodic hose replacement.
- Solids-handling centrifugal (open, vortex or chopper impeller): free passage for solids in low-viscosity streams.
Engineering note
Identify the separator or pretreatment and characterize the stream that actually reaches the pump. Clarification alone does not prove compatibility: remaining solids, chemistry, viscosity and temperature determine whether the duty fits the FB range or requires another technology.
8. Selection table by application in the biogas-biomethane chain
The table crosses the most common pumping points with the data that must be measured and with the indicated technology. There is no viscosity or H2S range valid for every plant: the values come from the fluid analysis of each project.
| Pumping point | What to measure before selection | Indication |
|---|---|---|
| Raw leachate extraction at the landfill | Solids, sand, plastics, pH | Solids-handling technology (outside the FB catalog line) |
| Raw substrate and digestate | Solids content, fibers, apparent viscosity | Progressing cavity, rotary lobe or solids-handling centrifugal (outside the FB line) |
| Pretreated leachate and liquid fraction of digestate | Fine solids, pH, chlorides, H2S, temperature | FBCN with S2/S3 sealing or mechanical seal; material per analysis; solids on consultation |
| Clarified liquid biofertilizer | Viscosity and solids of the sample | FBCN if aqueous; FBE if viscous and free of abrasives |
| Biogas washing water or solution | Solution composition, process pressure and flow | FBCN with compatible materials and elastomers |
| Glycerin, oils and fats | Viscosity at pumping temperature, pH, methanol | FBE with speed per viscosity (catalog p.5); heating chamber if it solidifies |
| Digester heating hot water | Maximum temperature and circuit pressure | FBCN; sealing chosen by temperature (MTEC-03/00) |
| Thermal oil circuit, when present | Fluid, temperature and circuit pressure | FBOT — series up to 350 °C; discharge limited by Figure 1 of MTEC-16/00 |
9. RenovaBio, ANP biomethane specification and hazardous areas
Under RenovaBio, biofuel lifecycle assessment uses producer data in ANP’s RenovaCalc. The pump is not certified through this process. To assess its contribution to plant consumption, record flow, head, electrical power and hours in each duty; compare the operating point with the curve and evaluate speed control when demand varies. Savings depend on the system and must be measured.
Gas specification: ANP Resolution 1,006/2026 defines the specification and quality control of biomethane; compliance depends on purification, analyses and the producer control plan. Gas washing pumps are part of that stage and must hold the operating point defined by the purification supplier.
Hazardous areas: the zone of each space comes from the area classification study (ABNT NBR IEC 60079-10-1). In Brazil, electrical equipment for explosive atmospheres — motor, panel, instruments — requires Inmetro conformity certification (Inmetro Ordinance 115/2022). When the project specifies an Ex motor, the FB set is quoted with a motor certified by the motor manufacturer; mechanical items, such as the coupling guard in non-sparking material offered as an option in the FB manuals, are defined in the same enquiry.