BalClor® Ballast Water Treatment System (BWTS)

Advanced Filtration and Disinfection for Marine Vessels

The BalClor® ballast water treatment system (BWTS) — also referred to as a ballast water management system (BWMS) — keeps vessels compliant with international ballast water regulations while protecting marine ecosystems. Developed by SunRui and supplied in Norway by Eiken Maritime, BalClor® combines filtration, electrolytic disinfection and neutralization in a system that is type approved by both the IMO and the US Coast Guard.

What Is a Ballast Water Treatment System (BWTS)?

A ballast water treatment system removes and inactivates the organisms — bacteria, plankton and larvae — that ships would otherwise carry between ecosystems in their ballast water. Under the IMO Ballast Water Management Convention, which entered into force in 2017, vessels must meet the D-2 discharge standard, and ships trading in US waters additionally require a US Coast Guard type-approved system.

Most systems pair mechanical filtration with a second treatment stage. The two most common second-stage technologies are ultraviolet (UV) disinfection and electrochlorination (electrolysis). BalClor® uses the electrochlorination approach, which stays effective where water clarity and turbidity vary — a useful characteristic in mixed coastal and brackish conditions.

Key Features

• Comprehensive treatment: combines filtration, electrolytic disinfection and neutralization in one automated process.
• Regulatory compliance: type approved by both the IMO and the US Coast Guard (USCG), with multiple class approvals.
• Versatile operation: unaffected by variations in temperature, salinity and turbidity.

How the BalClor® BWTS Works

The BalClor® BWTS integrates filtration, disinfection and neutralization into one automated process. During ballasting, incoming seawater is filtered and then disinfected by electrolysis; during de-ballasting, the system neutralizes any residual oxidants before discharge. Its operation is unaffected by variations in temperature, salinity and turbidity, ensuring compliance with the IMO D-2 standard and USCG requirements.

Automatic Back-Flushing Filter Unit

The automatic back-flushing filter unit removes large plankton and solid particles exceeding 50 microns from the ballast water. This self-cleaning filter operates without interruption, ensuring minimal pressure drop and reducing the oxidant consumption generated by the system. As filtration progresses, the system monitors pressure differences, triggering a self-cleaning cycle when necessary and discharging dirty water overboard.

Electrolytic Disinfection Unit

The electrolytic disinfection unit processes a small portion of filtered seawater to produce oxidants (mainly sodium hypochlorite) and by-product hydrogen. The oxidant is injected back into the main ballast pipe, effectively sterilizing marine organisms. By-product hydrogen is safely separated and diluted with air before release. The unit typically draws seawater from the filter outlet or a seawater booster pump, and can use alternative seawater sources for fresh-water voyages.

Automatic Neutralization Unit

During de-ballasting, the automatic neutralization unit adds a Na₂S₂O₃ solution to neutralize residual oxidants (TRO) in the treated ballast water. This ensures compliance with IMO D-2 and USCG requirements. The neutralization reaction produces only mild chemicals (NaCl and Na₂SO₄) that pose no risk to receiving waters.

Monitoring and Control System

The monitoring and control system oversees the entire BWTS operation, automatically managing the working status of all components and providing both local and remote control for efficient, secure operation.

Approvals and Compliance

BalClor® holds a comprehensive set of international approvals. In 2017 it became the first Asian-built BWMS — and the fourth worldwide — to receive US Coast Guard Type Approval, widely regarded as the industry's most demanding certification. It was subsequently the first system globally to be certified to the revised IMO G8 standard, certified by DNV on behalf of the Norwegian Maritime Authority. BalClor® also carries class approvals from ABS, BV, CCS, DNV, KR, LR, NK and RINA, and its neutralization stage ensures discharge complies with the IMO D-2 standard and USCG requirements.

Proven Technology at Scale

BalClor® is a mature, widely deployed system rather than a newcomer. SunRui reports more than 4,000 orders and over 3,000 systems delivered, with a leading market share for medium and large vessels. Available across a wide capacity range — from 170 up to 8,500 m³/h — BalClor® suits everything from smaller vessels to the largest tankers and bulk carriers, in both newbuild and retrofit projects.

Get BalClor® BWTS from Eiken Maritime

As a certified sales agent and distributor for SunRui, Eiken Maritime helps vessel owners select, specify and source the right BalClor® system for newbuild or retrofit projects, backed by after-sales support and genuine spare parts — held in stock in central Europe — throughout the system's service life. SunRui additionally provides service for vessels in operation. With a base close to Nordic operators, we help you find a solution that keeps your vessel compliant with ballast water regulations.

Frequently Asked Questions

What is the difference between a BWTS and a BWMS? "Ballast water treatment system" (BWTS) and "ballast water management system" (BWMS) are used interchangeably in the industry. Both describe equipment that treats ballast water so it meets discharge standards such as the IMO D-2 standard.

Is the BalClor® system USCG type approved? Yes. BalClor® received US Coast Guard Type Approval in 2017 — the first Asian-built system and the fourth worldwide — and is also certified to the revised IMO G8 standard.

Can BalClor® be retrofitted to an existing vessel? Yes. With a capacity range from 170 to 8,500 m³/h, BalClor® is suitable for both newbuild and retrofit projects across a wide range of vessel sizes. Eiken Maritime supports specification, installation and service.

What technology does BalClor® use? BalClor® uses filtration followed by electrochlorination (electrolysis) during ballasting, and neutralization during de-ballasting — an approach that remains effective across varying temperature, salinity and turbidity.