Separate Treatment of Graywater & Blackwater

Navalis brings a fresh approach to shipboard wastewater treatment. Blackwater (sewage) and graywater (hotel services and galley) are very different in terms of chemical makeup (composition, viscosity), volume, perception by passengers and crew, and how they are currently treated under the law. This realization led Navalis to question the viability and utility of traditional and advanced wastewater treatment systems, which combine these very different waste streams before treatment. The difficult treatment of blackwater is only compounded by a factor of ten or more when graywater is added to the process.

Differences Between Graywater & Blackwater

Treatment Standards
Blackwater must be treated to a higher standard in most operating areas.

Pollutant Concentrations
Most ships are fitted with vacuum flush systems with blackwater pollutant concentrations much greater than those found in graywater.

Associated Costs & Health Risks
Shipboard water production, storage, and management creates costly infrastructure. Graywater reuse onboard ship reduces the freshwater production requirement and is technically possible while upholding current social norms. Reuse of reclaimed sewage bears the risk associated with equipment failure and human health. Combining blackwater and graywater limits reuse potential, introducing high risk to human health.

Advanced Oxidation, Ultra-Filtration

Navalis has studied the treatment of wastewater onboard ships and concluded that although biological based systems produce good quality effluent, they are complicated to operate, have a large footprint in terms of tankage and deck space, are susceptible to periodic chemical upsets, can be expensive to operate due to costs of chemicals, require provisioning of these chemicals, have long start-up times (order days) and produce large amounts of sludge. In contrast, Navalis optimum wastewater treatment systems:

• Are small in footprint
• Produce dischargeable effluent minutes after startup
• Require virtually no chemical additions
• Are simple to operate
• Minimize sludge production from biological activity
• Are constructed from the most durable components
• Produce a high quality effluent exceeding most stringent effluent requirements day-after-day

The Navalis design philosophy is to offer the finest effluent quality possible to those firms that are progressive in their corporate environmental culture. These firms recognize the business advantages of reducing their environmental footprint for continued sustained growth and opportunity.