Seasonal production
Large quantities of bagasse, press mud and other residues arise during the processing campaign, while the energy supply must remain reliable throughout the year.
Sugarcane waste, vinasse and biomethane
Biogas and biomethane from sugarcane processing residues
Anaerobic digestion and biomethane engineering concepts convert vinasse, filter cake or press mud, bagasse, sugarcane straw, molasses and yeast wastewater into biogas, biomethane, process energy and organic NPKS fertilisers, with storage and pretreatment for year-round operation.
Initial challenge
Seasonal residue volumes, high energy demand and unused nutrient potential
Fibrous residues
Sugarcane straw, cane tops and bagasse contain high levels of lignocellulose and are only partly accessible to conventional digestion.
Liquid residues and wastewater
Molasses, vinasse, condensates and yeast wastewater require substantial treatment and disposal but also contain recoverable organic matter.
Losses of nutrients and energy
Combustion, open storage or insufficient wastewater treatment can waste energy and plant-nutrient potential and cause emissions.
Process concept
Year-round sugarcane waste digestion through storage and pretreatment
Combined ensiling
Surplus bagasse, press mud and other solid or liquid residues are combined into a storable mixture with a suitable dry-matter content and ensiled, allowing operation outside the harvest campaign.
Size reduction and biosuspension preparation
Solid residues and silage are reduced to short fibre lengths. Together with press mud, vinasse, molasses, yeast wastewater and recycled biofiltrate, they form a pumpable, solids-rich biosuspension.
Spatially separated hydrolysis
The biosuspension is hydrolysed under aerobic or semi-aerobic conditions. This opens up fibrous structures before anaerobic digestion and relieves the digesters.
Mesophilic main digestion
The hydrolysate is treated in culture-retaining digesters with mixed cultures adapted to lignocellulosic materials. Sufficient minimum retention time supports stable and high biogas yields.
Thermophilic post-digestion
A downstream thermophilic stage increases degradation, produces additional biogas and improves the hygienic quality of the digestate.
Gas, water and nutrient cycle
The biogas is biologically desulphurised and used for energy. Digestate is separated; biofiltrates are recycled after inhibitor removal, while solid NPKS fractions and ammonium sulphate solution are available as fertilisers.
Suitable feedstocks
Residues from sugar, ethanol and yeast production
Sugarcane straw and cane tops
Lignocellulosic harvest residues from the plantation that can be used for energy after size reduction and pretreatment.
Bagasse
Fibrous pressing residue from sugarcane processing that can be partly or fully biotechnologically recovered depending on the site.
Filter cake (press mud)
Nutrient-rich residue from raw-juice clarification with strong potential for biogas and fertiliser recovery.
Molasses, vinasse and distillery spent wash
Liquid residues and by-products from sugar and bioethanol production that can serve as organic and liquid components of the biosuspension.
Yeast wastewater and condensates
Organically loaded liquids that can reduce fresh-water demand and provide additional energy input.
Biofiltrates from digestate separation
After ammonium reduction, they serve as microbially active process medium and the main liquid component for renewed suspension preparation.
Client benefits
Greater energy autonomy, lower disposal costs and closed nutrient cycles
Year-round plant operation
Ensiling balances seasonal volumes and enables continuous biogas and process-energy production outside the sugarcane campaign.
Electricity, steam and heat from residues
Biogas can be used in CHP or combined-cycle systems to generate electricity, process steam, hot water and warm water.
Reduced wastewater and disposal burden
Vinasse, yeast wastewater, press mud and other residues are used as feedstocks instead of being costly to treat or dispose of.
Organic NPKS fertilisers
Solid digestate fractions and ammonium sulphate solution return nitrogen, phosphorus, potassium and sulphur to sugarcane plantations and can partly replace mineral fertilisers.
Lower environmental impact
Closed-loop recovery reduces emissions, residue transport, ash generation, fossil-fuel use and chemical-fertiliser demand.
Additional revenue potential
Potential revenue can come from surplus electricity, fertiliser products and, depending on applicable programmes, recognised emission reductions.
Engineering scope
Sugarcane biogas and biomethane plant engineering
Domogalla Engineering develops integrated concepts for sugar mills, ethanol distilleries and yeast plants, from residue characterisation and feasibility studies to process design and energy integration.
Vinasse biogas feasibility study
Site-specific mass, COD and energy balances assess biomethane or biogas potential from vinasse, distillery spent wash, molasses and organically loaded wastewater.
Filter cake and press mud digestion
Filter cake, also known as press mud, can be evaluated as a nutrient-rich anaerobic digestion feedstock and integrated with liquid residues and process-water recycling.
Bagasse and sugarcane straw pretreatment
Size reduction, ensiling and hydrolysis improve the accessibility of lignocellulosic bagasse, cane tops and sugarcane straw for stable biogas production.
Biomethane and process-energy integration
Produced gas can supply electricity, steam and heat or be upgraded to biomethane, while digestate treatment supports nutrient recovery and reduced disposal demand.
Related solutions: bioethanol residue recovery and digestion of lignocellulosic feedstocks.
Technical background
The presented process solution is based on the published international patent application WO 2018/091004 A1. A specific design requires a site-specific material and energy balance and an assessment of the existing sugar, ethanol, yeast, steam and wastewater facilities.
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