Instructions for the Use of Glutaraldehyde

Glutaraldehyde is a broad-spectrum, non-oxidizing biocide. Its use instructions vary significantly by application scenario (industrial water treatment, oilfield, or medical disinfection). Given your previous questions focused on oilfield chemicals, the instructions below focus on oilfield water injection and industrial water treatment systems, with brief notes on medical use.

Core Safety Warning (Must Read First)

Glutaraldehyde is a respiratory and skin sensitizer; once sensitized, even minimal future exposure can trigger severe asthma or allergic reactions. Concentrated solutions are corrosive and toxic to aquatic life. Mandatory requirements: Always wear chemical splash goggles, appropriate gloves (nitrile/neoprene), and respiratory protection (organic vapor/P100 respirator) when handling; use only in well-ventilated areas.

Oilfield Water Injection System Usage

1. Dosage and Frequency

According to EU ECHA authorized use specifications, for preserving oilfield injection water (targeting anaerobic bacteria such as SRB):

Preventive continuous/intermittent dosing: 150 – 1000 g of glutaraldehyde per cubic meter of injection water (i.e., 150–1000 ppm). Typical frequency is weekly batch dosing, with each dosing lasting 1–5 hours.

General reference: Some sources indicate continuous dosing at 50–200 ppm, with shock dosing at 200–500 ppm for 6–12 hours when SRB exceed standards (e.g., H₂S > 0.5 mg/L).

Note: Exact dosage must be determined through laboratory tests based on water quality, bacterial load, and residence time.

2. Dosing Point and Compatibility

Dosing Point: Inject via metering pump at a location with good mixing, ideally before the injection water enters the wellbore.

Separate Dosing: Glutaraldehyde must be dosed separately from other oilfield chemicals (such as defoamers, oxygen scavengers, flocculants, or oxidizing biocides like hypochlorite) to prevent cross-reactions. If the system uses a deaerator with oxidizing biocides, glutaraldehyde should be dosed downstream of the deaerator.

Incompatibility: Avoid contact with primary amines and ammonia, as they react with glutaraldehyde and reduce its efficacy.

3. Discharge Limits

If produced water is discharged to the sea, glutaraldehyde concentration must not exceed 0.2 mg/L. This can be achieved through extended retention (natural degradation), dilution, or addition of sodium bisulfite (pH 5) or sodium hydroxide (pH 12) to accelerate degradation.

Industrial Circulating Cooling Water Systems

Routine Control: Typical dosage is 50–100 mg/L (based on system holdup).

Biofilm/Cleaning: When stripping slime or heavy biofouling is required, increase dosage to 150–200 mg/L.

Advantages: Unlike quaternary ammonium salts, glutaraldehyde does not foam, has good compatibility with corrosion inhibitors, and is suitable for systems sensitive to foaming.

Medical/Disinfection Applications (Brief)

If the intended use is medical device disinfection (typically 2% alkaline glutaraldehyde):

General instruments: Immerse for 20–30 minutes (disinfection).

Items contaminated with bodily fluids: Immerse for 60 minutes or more.

Sterilization (including spores): Requires 10 hours or longer.

Note: Must thoroughly clean and dry instruments before immersion; after removal, rinse thoroughly with sterile water.