Modular biogas treatment systems
EnviroBox Biogas Systems, a division of Municipal Tank Works, LLC, delivers full-facility anaerobic digestion using our proven modular steel tank platform. From feedstock receiving through energy generation and digestate management — engineered for the renewables industry.
Complete biogas system
The EnviroBox Biogas System is a complete anaerobic digestion facility built from ASTM A572 Gr. 50 modular steel tanks with high-performance 3-coat epoxy interior lining (20–30 mils DFT). The system processes 1,300–5,300 GPD of feedstock, produces 3,600–10,600 ft³/day of biogas, and generates 90–540 kWh/day of electricity plus 100–600 kWh(th)/day of recoverable heat.
Whether developing a greenfield anaerobic digestion facility or expanding an existing operation, EnviroBox provides a modular, standards-compliant platform that scales with your production requirements.
Gallons total liquid
Day hydraulic retention
Process stages
Every stage of the biogas production process is housed in purpose-built EnviroBox modular steel tanks. All units are constructed from ASTM A572 Gr. 50 steel with 3-coat HP epoxy interior lining per NACE SP0108 / AWWA D103.
Raw material intake and storage buffer. Gravity or pump-fed up to 2,500 GPM with ultrasonic level transmitters and SCADA-integrated high/low alarms.
pH adjustment, dilution, and feedstock homogenization. Auto-controlled NaOH/H₂SO₄ metering via in-line pH probe with 1–3 day equalization buffer at 1,300–5,300 GPD to primary digesters.
Main anaerobic digestion at mesophilic (95–99°F) or thermophilic (126–131°F) temperatures. 20–30 day HRT with OLR of 0.06–0.19 lb VS/ft³/day producing ~1,800–5,300 ft³/day biogas per unit.
Extended hydraulic retention time with +15–35% additional biogas recovery. Dual-purpose secondary digestion and biogas buffer providing 2–6 hours uninterrupted CHP runtime per unit and 55–72% system-wide VS reduction.
Peak-shaving gas storage providing 4–8 hours of CHP runtime. HDPE double-membrane dome rated −40°F to +165°F with automated pressure management and full gas conditioning train.
60+ day liquid digestate holding for nutrient management. Class B or Class A biosolids with valuable biofertilizer content of ~200–400 lb N/acre-ft. Screw press separation produces low-odor compost at ~0.5–2 tons DM/day.
CHP power generation
The integrated combined heat and power (CHP) system converts biogas into 50–250 kW of electrical output and 100–600 kWh(th)/day of recoverable thermal energy. Jacket water at 160–180°F feeds back into all four digester heating loops, driving overall CHP efficiency to 78–85%.
90–540 kWh/day at 120V/240V/480V 3-phase. Net of ~8–15% parasitic load. Grid-tie with IEEE 1547 utility disconnect.
100–600 kWh(th)/day from jacket water plus additional 30–50 kW from exhaust flue gas heat exchanger.
NSPS 40 CFR §60 Subpart JJJJ; CARB compliant; NOx <1.0 g/HP-hr. Acoustic enclosure <70 dBA at 50 ft.
Automatic transfer switch with island mode capability. CAT/Cummins biogas-flex engine; skid-mounted.
SCADA & controls
An Allen-Bradley ControlLogix PLC with 15″ color touchscreen HMI manages all process variables across 100+ analog/digital I/O points. 4G LTE and Ethernet connectivity enables web-based remote HMI, SMS/email alarms, and ISA-99 cybersecurity compliance.
Performance
The complete EnviroBox Biogas System is designed to achieve the following performance targets across all operating modes and feedstock types.
65–68%
CH₄ Conversion Efficiency
55–72%
System VS Destruction
33–38%
CHP Electrical Efficiency
78–85%
CHP Combined Efficiency
>99.99%
Pathogen Reduction (Thermo)
330–880 tCO₂e/yr
Carbon Offset Potential
4–8 hrs CHP
Biogas Buffer Coverage
~498,754 gal
System Liquid Capacity
>95% annual
Target System Uptime
100% spark-tested
Epoxy Coating Integrity
| Parameter | Feedstock In | Biogas Out | Electricity | Thermal | Digestate |
|---|---|---|---|---|---|
| Daily | 1,300–5,300 GPD | 3,600–10,600 ft³/day | 90–540 kWh/day | 100–600 kWh(th)/day | 1,100–4,800 GPD |
| Weekly | 9,000–37,000 GPD | 25,000–74,000 ft³/wk | 630–3,780 kWh/wk | 700–4,200 kWh(th)/wk | 7,700–33,600 GPD |
| Annual | ~3.3–13.5M gal/yr | ~1.3–3.9M ft³/yr | ~33K–197K kWh/yr | ~36.5K–219K kWh(th)/yr | ~400K–1.75M gal/yr |
| Quality | 6–12% TS; pH 5–8 | 55–75% CH₄ | 3-phase output | 160–180°F jacket water | Class B or A; 40 CFR §503 |
Project economics
Revenue streams include on-site electricity generation, RNG premiums ($15–$30/MMBtu + D3 RINs), gate fee income ($15–$55/ton food waste tipping), and carbon credit monetization (LCFS / voluntary markets). Payback periods shorten with IRA §45Z incentives.
2 primary + 2 secondary
4 primary + 2 secondary
4 primary + 4 secondary
Services
Whether you need a complete turnkey facility for a greenfield site, modular expansion tanks for an existing anaerobic digester, or individual components and replacement parts — EnviroBox has you covered.
Complete facility design from feedstock receiving through energy generation and digestate management. Site-specific engineering, permitting support, and full turnkey delivery for new anaerobic digestion projects.
Add EnviroBox modular tanks to existing biogas operations. Each secondary expansion pair adds ~101,496 gallons and +15–35% additional biogas recovery with 4–8 weeks to stable gas production per unit.
Individual EnviroBox tanks, HDPE dome membranes, epoxy coating systems, heat exchangers, gas scrubbers, and SCADA control packages available as standalone components for self-integration.
Safety & compliance
Every EnviroBox Biogas System is designed, constructed, and commissioned in accordance with an extensive framework of US codes and standards including ASTM, NFPA, OSHA, EPA, ASME, AISC, NACE, and ANSI requirements.
NEC/NFPA 70 Art. 500 · NFPA 69 · NFPA 820
UL 2075 · NFPA 72 · ISA-84 / ISA-99
ASME Sec. VIII · API 2000 · IBC 2021 · AISC 360-22
OSHA 29 CFR 1910 · EPA 40 CFR · ANSI Z358.1
Referenced standards include: AISC 360-22 · AWS D1.1 · ASTM A572/D7407/D4541 · NACE SP0108/SP0188 · AWWA D103 · API 652/520/2000/RP 2003 · NFPA 69/70/72/77/780/820 · OSHA 29 CFR 1910.119/.138/.146/.147/.1000 · EPA 40 CFR §60/§98/§112/Part 503 · ACI 318-19 · ASME B31.3/Sec. VIII · ASCE 7-22 · IBC 2021 · GRI-GM13 · UL 2075/499/844 · ANSI Z358.1 · ISA-84/ISA-99 · AGA Report No. 9 · IEEE 1547 · NRCS Practice 313/632
Full tank specifications, process diagrams, safety systems, project economics, and retrofit parameters.
Contact
Reach Municipal Tank Works, LLC for complete biogas system design, retrofit engineering, component supply, and project-specific technical requirements.
Open Monday–Friday 09:00 AM – 05:00 PM
