Overview
ARBOK-EFFLUENT is a modular, scalable solution designed to transform biogas digestate — specifically its liquid fraction — from a waste liability into a multi-stream value product. Traditional digestate handling in biogas plants relies on separation, storage, and costly transport of liquid waste. ARBOK-EFFLUENT instead deploys multi-stage membrane filtration to fractionate the effluent into clean technical water (usable on-site or discharged), a concentrated ammonium-nitrate solution (for use or sale as fertilizer), and phosphorus-rich solids reclaimable from the filtration reject. The system significantly reduces environmental load, transport volumes, and regulatory complexity, while unlocking up to $27–38 per ton of digestate in avoided costs and material value. The concept is being modeled and deployed at a reference biogas facility in Turkey, with annual digestate volumes exceeding 16,000 tons/year.
Applications
Agri-, food-, and manure-based biogas plants; on-site technical water reuse; fertilizer production from ammonium concentrate; phosphorus recovery; zero-liquid-discharge (ZLD) strategies.
Operating Principle
The liquid fraction of digestate, taken after mechanical dewatering, is passed through multi-stage membrane filtration (UF/NF/RO) operating in continuous flow. The stream is fractionated into clean water — making up the large majority of the treated volume — an ammonium concentrate, and a solid phosphorus residue from the filtration reject. Chemical use is minimal (anti-scalants, pH control).
Key Parameters
| Parameter | Value |
|—|—|
| Input | Liquid fraction of digestate after mechanical dewatering |
| System type | Multi-stage membrane filtration (UF/NF/RO) |
| Output | Clean water (large majority of volume), ammonium concentrate, solid phosphorus residue |
| Recovery rate | Near-complete liquid-volume recovery |
| Energy use | Moderate specific energy consumption, typical of a multi-stage membrane train |
| Chemical use | Minimal (anti-scalants, pH control) |
| Operational mode | Continuous flow, modular skids |
| Byproduct usability | Compliant with EU fertilizer and discharge norms |
Architecture and Components
Modular filtration skids implementing a multi-stage UF/NF/RO train, fed by the liquid fraction of mechanically dewatered digestate; ammonium concentrate handling; phosphorus-rich solids recovery from filtration reject; clean technical water outlet for on-site reuse or discharge.
Advantages
A substantial reduction in effluent transport volume, among the largest achievable with a single process step. On-site reuse of technical water. Avoided groundwater and nutrient pollution. Enables zero-liquid-discharge (ZLD) strategies. Flexible for agri-, food-, and manure-based biogas plants. Reduces regulatory complexity. Byproducts compliant with EU fertilizer and discharge norms.
Integrations
Outputs feed directly into ARBOK's broader nutrient-recovery and water-reuse portfolio: the ammonium concentrate serves fertilizer-production applications, the phosphorus-rich solids serve soil-amendment use, and the recovered technical water supports zero-liquid-discharge strategies at biogas, food-processing and agricultural sites more broadly.
Deployment & Operation
Continuous-flow operation using modular skids; ready for broad rollout under site-specific adaptation. Reference deployment: a biogas facility in Turkey, annual digestate volumes exceeding 16,000 tons/year.
TRL
TRL 8–9 — Fully operational in controlled environments, validated via pilot deployment; ready for broad rollout under site-specific adaptation. System operational and scalable; key modules tested and optimized in live digestate.
Market Potential
Biogas plants handling agricultural, food-industry, and manure feedstocks; markets where digestate disposal costs $45–70/t. Additional gains from fertilizer sale, water reuse, and ESG credits.
Typical Project Economics
Digestate volume modeled: 16,000 t/year. Baseline disposal cost: $45–70/t (transport, compliance, land cost). ARBOK-EFFLUENT cost per ton: $27–38/t including capex amortization. Net benefit: ~$600,000/year at full scale versus baseline. Break-even period: under 3 years (depending on existing plant infrastructure). Additional gains: fertilizer sale, water reuse, ESG credits.
Risk Factors
Performance depends on digestate quality and feedstock consistency, which vary by plant type (agri-, food-, or manure-based) and by season. Membrane-train maintenance and fouling management are an ongoing operating requirement and affect long-run uptime. Byproduct compliance (fertilizer and discharge norms) is jurisdiction-specific, so market access for the ammonium concentrate and phosphorus residue must be confirmed per country. Economics are sensitive to the local baseline disposal cost, which varies significantly by region, and to the price achievable for the recovered fertilizer streams.
Related Technologies
Related within ARBOK's digestate and nutrient-recovery technology family; connects conceptually to fertilizer-production and zero-liquid-discharge applications elsewhere in the ARBOK platform.