Refinery cooling-tower biocide program (oxidiser + non-oxidiser rotation)
Programme outline, dosing range, feed points, target parameters, and lead times for the AAS cooling-tower biocide program into the refineries segment in Pakistan. Sole Pakistan agent for Shaanxi Ande Technology (China) and Innovative Water Technology (Pakistan). Karachi office, same-business-day technical response.
Same-day Karachi visit · CoA per drum · Engineering autopsy on request
Refinery-tower biocide programs are the most contested line in utilities chemistry — KW&SB or well-water makeup shifts biofilm pressure week to week. AAS sites a biocide rotation on the customer's HPC + ATP trend, not on a fixed recipe.
Dosing programme outline
Programme outline below is the AAS default for refineries applications. Final dose is set against the customer's source-water analysis, equipment metallurgy, and operating cycles. Every drum ships with a Certificate of Analysis; SDS is shipped pre-shipment for HSE-document review.
- Oxidising biocide
- ClO₂ on-site generation OR sodium hypochlorite 12% w/v
- Non-oxidising biocide
- UN-611 (isothiazolone family) + DBNPA shock
- Oxidiser feed
- Continuous to 0.2–0.5 ppm free residual at return
- Non-oxidiser feed
- Weekly slug, 50–100 ppm, 4–6 hr contact
- Target ATP
- < 100 RLU on swab sample
- Target HPC
- < 10⁴ CFU/mL bulk water
- Legionella program
- Quarterly Legionella spp. PCR + ATP trending
- THM management
- Switch to ClO₂ if THM > 80 µg/L on tower blowdown
- Lead time
- Ex-Karachi stock on UN-611, DBNPA; on-call ClO₂ generator skid
Why oxidiser-only fails on a refinery tower
Refinery cooling towers sit downstream of hydrocarbon-process leaks, which preferentially feed biofilm-forming Pseudomonas and Legionella. Oxidisers alone — hypochlorite or ClO₂ — burn out fast against process hydrocarbon demand and never penetrate established biofilm. The standard answer is rotation: continuous low-level oxidiser to keep planktonic counts down, plus a weekly non-oxidiser slug (DBNPA for fast-kill / fast-degrade, isothiazolone for residual penetration) to break biofilm. Anti-legionella programs at PRL / PARCO / ARL all read this pattern.
Read deeper into the programme.
Request a technical proposal for cooling-tower biocide program.
Send the unit you're trying to protect (site, loop or train, symptom or KPI, volume, deadline) plus a source-water analysis if you have one. Same-business-day Karachi reply with a programme outline, dose range, and the relevant CoAs / SDS attached.
Karachi office · Sole Pakistan agent · Shaanxi Ande & Innovative Water