Biogas engineering vs O&M: the three asymmetries of the EPC
Engineering and biological O&M answer different questions at different times. EPC engineering delivers a plant that is sized, built and commissioned, with a typical process guarantee of 12-24 months. Biological O&M maintains operational control over the following 15-25 years, against a diet that changes, a consortium that evolves and supply contracts that are renegotiated. Three […]
Slurry biogas: stabilisation against inhibitors
Slurry biogas carries three specific operational pain points that do not appear with other substrates: low energy load per unit of mass, free-ammonia inhibition derived from the ammoniacal nitrogen of the manure, and erratic input of veterinary antibiotics and disinfectants that harm the methanogenic consortium. The profitability of livestock biogas does not depend on how […]
Biogas in WWTP: maximisation with OFMSW co-digestion
Biogas in WWTP is the most underused operational opportunity in Spain’s water sector. Most plants with anaerobic digestion operate with VS removal of 35-50% digesting only primary and secondary sludge, when they could reach 45-65% by co-digesting with the organic fraction of municipal solid waste (OFMSW). Well-managed co-digestion raises biogas production, reduces the dewatered sludge […]
Agro-industrial co-digestion biogas: seasonal variability
Agro-industrial co-digestion in biogas is the main strategy for diversifying the digester diet and increasing productivity above a single substrate. But it is also the main source of operational instability. For example, the seasonal variation of VS in alperujo can reach ±25%, silage loses BMP with storage time, and fruit and vegetable waste concentrates peaks […]
Scaled biogas pilot: 5 quantitative success criteria
A correctly scaled biogas pilot starts with quantitative success criteria defined before the pilot, not after. Five KPIs underpin the technical decision: minimum increase in specific productivity (≥7%), operational stability measured by FOS/TAC (<0.35 during 80% of the pilot), H₂S reduction (≥30% when applicable, relative to the initial value), reproducibility sustained for 60 days with […]
BMP biogas VDI 4630: ISR, acclimation and kinetic fitting
BMP tests that do not comply with the VDI 4630 protocol introduce biases of 20-40% in the results. The critical points are the inoculum-to-substrate ratio (ISR ≥ 2 on a VS basis), inoculum acclimation, the inclusion of triplicates and endogenous blanks, the termination criterion (daily production < 1% of the cumulative) and kinetic fitting with […]
Biogas plant diagnosis: a 14-KPI dashboard
Operating a biogas plant without a technical dashboard turns every biological shutdown into a mystery. The Smallops Operational Excellence Diagnosis assesses 14 variables grouped into 4 blocks — load, performance, stability and inhibitors — and classifies each inefficiency into its real category: a criterion failure, a methodological error or a physical limitation. With that classification, […]
Anaerobic digestion additives: a 5-step technical protocol
Applying additives or catalytic nanoparticles to an anaerobic digester without a prior diagnosis is a serious mistake: the effect is marginal or nil and is unfairly attributed to the product. The Smallops operational rule is sequential and non-negotiable: Problem · Diagnosis · Process understanding · Plan · Necessary actions and optimal catalyst addition (decision-making with […]
Free ammonia in biogas: calculation, thresholds and mitigation
Co-digestion multiplies profitability but introduces dynamic uncertainty. The first risk is not total ammoniacal nitrogen (TAN): it is the free NH3 fraction. It is governed by the pKa 9.25 equilibrium, modulated by pH and temperature. A digester that incorporates pig slurry, WWTP sludge or poultry by-products without auditing the mixture works with an inhibition variable […]
Anaerobic digester stabilisation: sentinel variables, FOS/TAC thresholds and predictive control
Managing an anaerobic digester by looking only at pH and biogas production is operating while looking in the rear-view mirror. When pH drops you may already have severe acidosis: the operational damage runs 5 to 14 days ahead in the variables you should be measuring. Robust control is built on sentinel variables with defined operational […]