Closing the Water Loop at Biogas and Ethanol Plants

Biogas plants and ethanol facilities generate high-strength wastewater and process water that often contains dissolved organics, suspended solids, salts, and residual nutrients. These streams can overwhelm biological treatment systems, challenge membrane and filter technologies, and create costly brine discharge and disposal burdens.

Aqua Fission offers a thermodynamic distillation-based approach that recovers clean water directly from digestate, process residuals, and high-COD effluent, without producing continuous toxic brine. The result is a closed or near-closed water loop with minimal waste, lower operational costs, and improved environmental performance.

Treating biogas digestate, ethanol stillage, and process wastewater

These streams can be difficult to manage because of:

• High chemical oxygen demand (COD) and suspended solids that foul membranes
• Dissolved salts and nutrients that create secondary wastewater
• Large volumes that strain biological treatment and disposal capacity
• Regulatory pressure to reduce discharge and nutrient loading

Aqua Fission separates water from contaminants at low temperature using deep vacuum. Because the system is not membrane-based, it is not impaired by organics, suspended solids, or high TDS. The recovered water can be returned to the process or reused elsewhere, while concentrated residuals are retained for controlled handling.

Building water resilience

Many biogas and ethanol facilities depend on external water supplies, which may be seasonal, restricted, or expensive. By closing the water loop, Aqua Fission reduces reliance on fresh intake and minimizes discharge obligations. The system can be scaled modularly to match site capacity and integrated into existing treatment infrastructure.

This approach is particularly useful at sites where water availability is a constraint on production or expansion, or where discharge regulations are tightening.

Managing solids and nutrients

Digestate and stillage contain concentrated organics, nutrients (nitrogen and phosphorus), and other solids that can be valuable when properly managed. Aqua Fission retains these non-volatile substances in the concentrate, which can be:

• used as soil amendment or fertilizer
• processed for further nutrient extraction
• integrated with composting or biochar production
• managed via controlled dewatering and disposal where appropriate

The modular design allows each site to determine how the residual concentrate is best used, depending on local agricultural practices, regulation, and business opportunities.

Supporting near-zero liquid discharge

Where appropriate, Aqua Fission can be operated to approach zero liquid discharge (ZLD) or near-ZLD, dramatically reducing the volume of liquid waste requiring disposal and improving site permit compliance. This is particularly valuable at plants facing discharge constraints or high disposal costs for wastewater.

Cost and operational benefits

Closed-loop water management with Aqua Fission can reduce costs related to water intake, wastewater treatment, discharge fees, and disposal logistics. The low-temperature distillation process requires less energy than thermal evaporation and avoids membrane replacement and fouling issues common with reverse osmosis. System uptime can be high, and modular scaling allows capital to be deployed incrementally.

Supporting ESG and regulatory objectives

Reducing water consumption and wastewater discharge supports environmental, social, and governance goals and can enhance a facility's license to operate, particularly in regions sensitive to water scarcity and nutrient pollution. Closing the water loop can also improve public perception and stakeholder relations.

Scalable, modular, and deployable

Aqua Fission units can be deployed as skid-mounted modules or in containerized form, making them straightforward to integrate at existing biogas or ethanol plants. Each module can be sized to match digestate flows, and additional modules can be added as capacity expands.

The system is well suited to decentralized sites and can operate on renewable power or waste heat from the biogas or ethanol process itself, creating a synergistic circular system.

AQUA FISSION BENEFITS