Table 6.1 Shipboard Compatibility Attributes for Long-Range Technologies

ATTRIBUTE

ULTRAFILTRATION

BIOTREATMENT

SEMICONDUCTOR PHOTOCATALYSIS

ELECTROHYDRAULIC CAVITATION

Status of technology

  • Widely used in commercial industry

  • Navy waste stream applications being studied

  • Used on luxury cruise ships

  • Commercially available

  • Commercial suppliers available

  • Current used for hazardous waste remediation

  • Will be used on future space stations

  • Numerous manufacturers of ultrasonic equipment are producing equipment that can be modified for waste treatment applications

Process versatility

  • Any liquid waste stream requiring concentration, i.e., oily water, gray water, black water

  • Black water

  • Portions of gray water

  • Suitable mainly for waterborne dissolved wastes and hazardous wastes at medium to low concentration. BOD and TOC should be ≤ 3000 mg/L

  • Suitable mainly for waterborne dissolved wastes and hazardous wastes at medium to low concentration. BOD and TOC should be 3000 mg/L

Process density

  • 2 lb/h/ft2

  • Low

  • Not now available but could be determined

  • Not now available but could be determined

Ship system demands

  • Low-pressure pumping only

  • Fresh water for cleaning

  • Concentrated cleaned effluent is hazardous waste–small volume

  • Space (potential use of holding tanks)

  • Electric power for mixing and aeration

  • Vacuum and/or low- pressure pumps

  • Source of UV photons which could be derived from the sun or from artificial sources

  • Most convenient sources are simple black lamps

  • Forced aeration is necessary

  • Electrical power

  • Dissolved oxygen

  • Ventilation

Installation flexibility

  • No constraints

  • Medium to large surface ships

  • Surface ships only

  • Surface ships

Energy requirements

  • Not significant

  • Vacuum and/or low-pressure pumps

  • Aeration

  • Mixing

  • Requires power for black lamp operation

  • Solar operation requires power for pumping and filtration

  • 1.0 kW/L per liter at 500 kHz frequency

Ship motion effects

  • Not significant

  • Not significant with enclosed reactors

  • Could impact gravity setting

  • Minimal effects on process

  • Minimal effects on process

Process sensitivity

  • Relatively insensitive

  • Microbial activity is sensitive to toxic contaminants

   

End products

  • Concentrate of feed stream

  • Flush residual soaps, etc.

  • Water

  • CO2

  • H2O

  • Oxidized organic compounds

  • Sludge

   

Process safety

  • Low risk

  • Low risk

   

Projected reliability

  • Highly reliable simple system

  • Dependent on membrane selection

  • Reliable with close monitoring

   

Projected maintainability

  • Membrane cleaning and replacement within ship's force capability

  • Can be maintained by trained crew

   

Projected controllability

  • No concerns

  • Rapid startup not possible (needs acclimation time)

  • Requires periodic monitoring of solids (biomass) inventory

  • Continuous process with some automation

   

Costs

  • $0.50 per 1,000 gallons

  • $1 to $3 per 1,000 gallons

   

Note: BOD, biological oxygen demand; TOC, total organic carbons.



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