Descaling Naval Sewage and CHT Systems Supports Fleet Readiness

CBM+/Predictive Maintenance

Problem Statement:
Shipboard sewage, black water, grey water, and Collection, Holding, and Transfer (CHT) systems are critical to manned ship sanitation and ships force habitability. Scale and organic build-up can restrict or stop sewage and water flow through those systems which may adversely affect readiness. The maintenance community have historically improved reliability by remediating these blockages pier-side via corrective, often intrusive, maintenance actions including component and sub-system replacement. Existing responses can be disruptive, resource-intensive, and dependent on maintenance availability scheduling and need to address HAZMAT issues.

Description of the Innovation Solution:
Envirofluid’s ActiveEco SX Descaler is a low-pH acid-replacement descaling technology that enables onboard restoration of scale-affected sewage and CHT pipework. It is formulated to dissolve scale and build-up without relying on traditional acidic chemistries. For naval sewage, black water, grey water, and CHT systems, the descaling chemistries can be dosed through onboard access points, moved through affected pipework, and followed by fresh-water flushing and inspection.

Benefits to the DoW:
ActiveEco SX Descaler is a cost-effective sustainment capability that can reduce maintenance burden, minimise downtime, extend system life, and improves morale by improving ships’ force living conditions. Since remediation can occur while the system is in use it imposes no additional burden on operational schedules supporting on-time ship deployment and does not require pier, port or dry-dock access.

Innovation Challenges:
The key innovation challenge will be to tailor, if necessary, the chemistries to be compatible with onboard materials and CHT processes. Key implementation challenges include identifying dosing points, adapting application to ship-specific layouts and complying with discharge requirements.

Technical Maturity / Demonstration Results:
The technology was demonstrated onboard HMNZS Canterbury providing direct relevance to the removal of black water scale in a naval sewage-system. ActiveEco SX Descaler was injected into toilet locations every half hour while the black water system remained in use during dosing. The trial used 80 litres (21 US gallons) over three days, followed by fresh-water flushing. Post-treatment observations documented cleaner pipework where the chemical reached, while untreated pipework retained dense scale build-up. These results support a practical, onboard, and cost-effective alternative to more disruptive maintenance pathways.

Laboratory efficacy of ActiveEco SX Descaler was assessed independently by Sharp & Howells. Dried crushed scale was placed in a bath of descaler at concentrations of 10%, 20%, and 50% v/v for periods of 2, 4, and 6 hours. Across these test conditions the descaler dissolved between 95% to 97% of the scale. The most effective result was 97.0% after 2 hours at 50% concentration.