Keeping seawater intakes, pipelines and screens free of mussels, barnacles and biofilm — chlorination strategy, dosing-point design and monitoring that protect SWRO pre-treatment without breaching marine discharge limits.
Seawater is alive. Left untreated, an intake pipeline becomes a reef: mussel and barnacle settlement restricts the bore, biofilm raises head loss and seeds downstream fouling, and the resulting debris and organics drive up SDI and shorten membrane life. The art of biofouling control is to suppress settlement and growth reliably, at the lowest chemical dose, with the residual fully managed before discharge so the plant stays compliant. Reynolds & Bauhm designs the dosing strategy, injection points and monitoring around the specific organisms, temperature and residence time of the intake.
A low free-chlorine residual (typically 0.2–0.5 mg/L) held through the intake suppresses settlement and biofilm — the workhorse strategy for most intakes, dosed at the screen or intake head.
Periodic higher-dose shocks dislodge established growth and break biofilm — effective where continuous dosing is undesirable, and useful against larval settlement peaks.
Pulse-chlorination timed to mussel behaviour (they close valves transiently) can control macrofouling at a fraction of the continuous chemical load.
Electrochlorination generates hypochlorite from the seawater itself — no bulk chemical storage, ideal for remote or large intakes.
Disinfectant DosingFree chlorine destroys polyamide RO membranes, so residual is removed (SBS dosing or carbon) ahead of the membranes — and managed to the marine discharge limit at outfall.
Copper-nickel or non-metallic surfaces, velocity that discourages settlement, and pig-launch / clean-in-place provisions reduce the chemical burden in the first place.
Materials| Parameter | Typical basis | Note |
|---|---|---|
| Continuous residual | 0.2–0.5 mg/L free Cl | Suppresses settlement & biofilm |
| Shock dose | 1–5 mg/L, intermittent | Dislodges established growth |
| Injection point | At intake head / screen | Full-bore contact through the line |
| Dechlorination | SBS or activated carbon | Protect polyamide RO membranes |
| Residual at outfall | To consent limit | Marine-discharge compliance |
| Monitoring | ORP / free-Cl analysers | Closed-loop dose control |
Share the intake length, seawater temperature and the organisms present — we’ll design the dosing strategy, injection and monitoring to keep it clear and compliant.
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