Executive Summary
A remediation site had two multi-million-gallon runoff tanks filled with high-pH groundwater containing dissolved sulfur compounds. Draining required neutralization to pH 6–9 for discharge, but acid addition liberated massive H₂S (up to 60,000 ppm in headspace) and VOC vapors — creating both odor and safety risks.
Envent delivered a turnkey, dual-phase system in <72 hours**:
- Acid injection + recirculation loop for fast, uniform neutralization
- Recirculating caustic H₂S scrubber + EMTOS thermal oxidizer for 100% vapor capture & >99.9% destruction
Result: Both tanks neutralized and emptied on schedule, zero odor complaints, zero H₂S exposure, full NPDES & RCRA compliance.
Project At A Glance
- Location: U.S. Remediation Site
- Challenge: Neutralize millions of gallons of high-pH water while controlling 60,000 ppm H₂S vapors
- Solution: Acid injection + recirculating caustic scrubber + EMTOS thermal oxidizer
- Outcome: Neutral pH achieved, zero emissions, tanks ready for reuse
The Challenge: High-pH Water + Massive H₂S Liberation Risk
- Several million gallons of alkaline groundwater (pH >11)
- Dissolved sulfur → 60,000 ppm H₂S released upon acidification
- Must meet NPDES discharge limits (pH 6–9) and EPA RCRA air standards
- Site surrounded by workers and nearby community — zero odor tolerance
Envent’s Turnkey Dual-Phase Treatment System
| Phase | Equipment & Envent Service Link | Purpose |
|---|---|---|
| pH Neutralization | Acid injection skid + recirculation loop + inline static mixer | Fast, uniform pH reduction to 6–9 |
| Primary H₂S Capture | Recirculating Caustic Scrubber | Neutralized up to 60,000 ppm H₂S |
| Final Destruction | EMTOS Mobile Thermal Oxidizer | >99.9% DRE of residual VOCs & H₂S |
| 24/7 Monitoring | pH, H₂S, LEL, flow | Real-time data & auto-shutdowns |
System ran continuously during recirculation and discharge with Envent operators on site.
Proven Results – Safe, Fast, Zero Emissions
| Benefit | Delivered Outcome |
|---|---|
| Neutralization | Both tanks to pH 6–9 in days — ready for discharge |
| H₂S Control | 60,000 ppm → 0 ppm at stack |
| Odor Elimination | Zero complaints — even during peak off-gassing |
| Compliance | 100% NPDES, RCRA, and local air permit compliant |
| Tank Availability | Tanks emptied and returned to service on schedule |
This remains one of the largest mobile pH-neutralization + H₂S vapor control projects ever executed.
Have high-pH water or H₂S risks blocking your tank or pond discharge? Get your Free NPDES-Compliant Treatment Plan & Quote today. Call Envent’s Water Team at 888-997-9465 or Request a Quote → — we make contaminated water discharge-ready, safely.
