How wet gas scrubbers from Semian eliminate acid, alkali and toxic fume hazards from laboratory fume hoods, semiconductor process tools and industrial exhaust streams — and what Bangladeshi institutions need to know about installation, maintenance and regulatory compliance.
Every laboratory fume hood, semiconductor wet bench and industrial process tool that handles acids, alkalis or toxic gases generates an exhaust stream that must be treated before it reaches the atmosphere. In Bangladesh, the Department of Environment (DoE) enforces emission standards under the Environment Conservation Rules 2023, and international accreditation bodies (ISO 17025, IEB/BAETE) increasingly require documented exhaust treatment as part of laboratory safety management. Vvon Technologies Limited supplies Semian SBW-series wet gas scrubbers (confirm exact model designation — SBW 200-C/200-CE — with OEM before publishing) — compact, high-efficiency units designed specifically for laboratory and light-industrial exhaust treatment.
A wet gas scrubber passes the contaminated exhaust stream through a packed tower or spray chamber where it contacts a liquid reagent — typically water, dilute NaOH (for acid gases) or dilute H₂SO₄ (for alkali gases). The pollutant dissolves into the liquid phase and is neutralised, producing a safe aqueous effluent that can be discharged to drain after pH adjustment. Semian's MIDAS series uses a counter-current packed-bed design with polypropylene packing media, achieving removal efficiencies above 99% for HCl, HF, HNO₃, H₂SO₄, NH₃ and NaOH mists at typical laboratory concentrations.
| Model | Airflow Capacity | Inlet Concentration | Key Feature |
|---|---|---|---|
| MIDAS-I | Up to 500 m³/h | Up to 500 ppm | Single-stage, compact — ideal for single fume hood |
| MIDAS-II | Up to 1,500 m³/h | Up to 2,000 ppm | Two-stage packed bed — for multi-hood or process tool exhaust |
| SBW 200-CE | Up to 2,000 m³/h | Up to 5,000 ppm | CE-certified, recirculating reagent — for industrial exhaust |
| SBW 200-C | Up to 2,000 m³/h | Up to 5,000 ppm | Continuous reagent feed — for high-load industrial applications |
University chemistry and materials labs: A single MIDAS-I unit handles the exhaust from one or two fume hoods handling HCl, H₂SO₄ or HNO₃. For a multi-hood teaching lab (6–12 hoods), a MIDAS-II or SBW 200-CE provides the required capacity with a single exhaust fan and scrubber stack. Semiconductor and MEMS research: Wet-etch processes using HF, BOE (buffered oxide etch) and piranha solution require dedicated acid scrubbers on each process tool. The MIDAS-II is the standard choice for university cleanrooms. Pharmaceutical manufacturing: Solvent recovery and acid neutralisation in API synthesis require high-capacity scrubbers with reagent recirculation — the SBW 200-C is designed for this duty. Textile and dyeing: Chlorine and SO₂ from bleaching and dyeing processes are efficiently removed by the SBW 200-CE.
Semian scrubbers are supplied as complete packaged units with integral sump, recirculation pump, level control and pH probe connection. Installation requires a concrete plinth or steel frame, a drain connection for sump blowdown, a mains water supply for reagent make-up, and an exhaust fan sized to overcome the scrubber pressure drop (typically 100–300 Pa). Vvon Technologies provides the full installation scope including ductwork design, fan selection, civil works specification and commissioning. We also supply pH controllers and chemical dosing systems for automated reagent management.
Vvon Technologies provides a commissioning report including stack emission test results, scrubber efficiency data and a maintenance schedule — the documentation package required for DoE environmental compliance certificates and ISO 17025 / ABET laboratory accreditation audits. Annual service contracts include packed-bed inspection and replacement, pump overhaul, pH probe calibration and reagent system cleaning. Request a scrubber sizing consultation →