Scrubber system reducing SOx from exhaust gas to comply with MARPOL Annex VI without using low-sulphur fuel.
In practice
Operator runs the scrubber in compliant mode; chief engineer monitors washwater pH and turbidity continuously. Discharge logs scrutinised at PSC and by some flag states.
Regulatory detail & full definition
Exhaust Gas Cleaning System (commonly 'scrubber') — equipment that reduces SOx emissions from a ship's exhaust to comply with MARPOL Annex VI Reg. 14 without using low-sulphur fuel. The 2021 EGCS Guidelines (MEPC.340(77)) cover open-loop seawater systems, closed-loop fresh-water systems with caustic dosing, hybrid systems combining both, and dry-scrubber alternatives. Operators must monitor washwater pH, PAH, and turbidity continuously. Several ports prohibit open-loop discharge in their waters; the ban list grows as scientific concern about washwater impacts develops.