(337) 330-4407
329 Hardware Road, Broussard, LA 70518
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Model AT-20D

AHEAD TANK Type II Marine Sanitation Devices are USCG Certified in accordance with USCG Title 33 Code of Federal Regulations (CFR) 159.16, Subpart C,159.53 (b) Type II, 159.97 Inspected Vessels and approved world wide in compliance with IMO Resolution MEPC.2 (VI) to meet the operational requirements referred to in Regulation 4/1.1 of Annex IV of the International Convention for the Prevention of Pollution from Ships 1973 / 78.


, is the NEXT GENERATION of biological aerobic (bacteria & air) Type II Marine Sanitation Device. Its innovated design, incorporated with Advanced rotational molding technology, has enabled the AHEAD TANK to be the FIRST & ONLY Marine Sanitation Device constructed of LLPE, a Durable Lightweight Corrosion Proof polyethylene material. Its three separate sewage treatment chambers are rotationally molded into the internal structure of one single tank, an innovative State of the Art rotational molding process that no other company has been able to duplicate.

operational functions are identical to that of the traditional larger heavy steel fabricated systems, but with the additional benefits of being rotationally molded from LLPE polyethylene. Its features include durability, smaller footprint, lightweight, simple to install and lower maintenance than the steel fabricated systems and at a fraction of the cost.

will be the LAST Marine Sanitation Device you will ever have to purchase. AHEAD TANK will not RUST nor CORRODE and it’s not affected by HARSH CHEMICALS , UV RAYS or the most EXTREME ENVIRONMENTAL CONDITIONS.

includes the following items at the time of purchase:

Quantity & Description of Items

  • (1) Installation & Operation Manual
  • (1) Hurricane Linear Air Pump
  • (1) Air Hose & Hose Barb
  • (4) Aluminum orange powder coated mounting brackets

Quantity & Description of Items

  • (1) Pail of Sumuhdat  Bio-Activator & Waste Degrader
  • (1) Bottle of Sumuhdat Bio-Enhancer & Odor Controller
  • (1) Chemical Injection Metering Pump


Meets USCG Certification and IMO Standards Worldwide


Durable / Reliable

Simple to Install

Odor Free Operation

Uses Fresh or Salt Water

Gravity Overboard Discharge

Compact / Small Footprint

Corrosion Proof

Easy to Operate

Low Maintenance

Chemical Resistant

No Internal pump necessary


(gallons per day)
BOD (LBS) Bio Chemical
Oxygen Demand
Number of Persons
(per 24 hours)
Inches Length Width Height
Dry Weight
Disinfectant Type
Operating Weight
Coast Guard Approval Number
 AT-20D 110 gallons 5.0 lbs 20 persons 56″ x 23 ” x 30″ 110 lbs Metering Pump 870lbs 159.015/9974/0

NOTE: The treatment capacity of the AHEAD TANK is expressed in the number of persons per 24 hours and depends on the type of toilet used with the system. Ahead Sanitation Systems Inc., recommends using SANIMARIN porcelain macerating toilets that have a normal flushing cycle that uses 0.58 gallons of water and is capable of pumping water 9.8 ft. vertically and 98 ft. horizontally for optimum treatment effectiveness. The SANIMARIN macerating toilets are offered in 110 VAC or 12 VDC.

 is the #1 Choice of Marine Sanitation Devices in the #2 Business 



is a biological aerobic (bacteria and air) Type II Marine Sanitation Device. Liquid and solid waste are removed from the water by bacteria naturally contained in sewage. The AHEAD TANK makes perfect environmental sense by working with nature to accelerate the normal biological process. With the addition of oxygen, the natural occurring bacteria breaks down and digest the solids. A mild disinfectant is added to kill any disease-causing bacteria prior to being discharged. AHEAD TANK has no moving parts that comes in contact with the sewage. This biological aerobic process is simple, effective, and ensures reliable odor free operation.

consist of three treatment Stages: Aeration, Clarification, and Chlorination.

Stage 1: In the Aeration Chamber the bacteria will grow and multiply using the sewage as their food supply. This action reduces the quantity and size of the solid matter.

Stage 2: In the Clarification Chamber the bacterial floc is separated from the treated water. The treated water is clear and free from solids, however, the liquid must be disinfected prior to being discharged overboard to kill any disease-causing bacteria.

Stage 3: In the Chlorination Chamber the disinfectant and final stage of the biological process is completed. The flow through of these three chambers is caused by direct displacement. When new sewage flows into the Aeration Chamber, an equal volume flows into the Clarification Chamber. In turn, displaces an equal volume into the Chlorination Chamber and then gravity flows overboard or into a holding tank. (No Internal sewage pumps are necessary.)


Aeration Chamber

Sewage is aerated as soon as it enters the Aeration Chamber and mixes with the aerated liquid already in the Aeration Chamber. A fine bubble EPDM air diffuser injects air near the bottom of the Aeration Chamber so that the sewage remains in a state of aerobic decomposition. This aerated liquid contains the bacterial sludge that reacts with the sewage to start the reduction process. This movement created by the injected air helps mix the sewage with the bacterial sludge and prevents sludge and sewage solids from settling to the bottom. The air discharged from the surface of the liquid in the Aeration Chamber is vented to the atmosphere through a 1 ½’ FPT connection clearly labeled VENT in black on both sides of the tank.

Clarification Chamber

The liquid displaced from the Aeration Chamber flows through small specially drilled holes at the front bottom side of the Clarification Chamber for further treatment. The suspended material and sewage solids that are too large to pass through the holes remain in the Aeration Chamber to be further reduced in size, as it continues to be mixed with the remaining aerated liquid and bacteria sludge. The liquid sludge and smaller waste material that enters the Clarification Chamber through the small holes is re-moved as the liquid flows upward through some biological filter media located inside the Clarification Chamber. Bacteria will grow on the surface of this biological filter media and produces a sticky, slimy film film that traps small particles of waste. Then the bacteria will consume the trapped particles of waste as their food supply. By the time the liquid reaches the top of the biological filter media it has passed through several layers of bacteria, ensuring that the sludge and waste removal process is completed. Any floating particles of waste that was not trapped and consumed by the bacteria that reaches the top of the biological filter media will be returned to the Aeration Chamber by means of an internal air lift pump. The clean water accumulates here until it is displaced through the crossover pipe connected to the Chlorination Chamber.

Chlorination Chamber

The clean water flowing out of the crossover line is collected in the Chlorination Chamber where a disinfecting chloride solution is injected. In this chamber the water is mixed with a disinfecting chlorine solution for a residence time sufficient to complete the stage of disinfection process. The chlorine disinfecting solution is stored in a plastic reservoir tank and is injected into the chlorination chamber by a chemical injection metering pump through a polyethylene tubing.


The disinfected water is then discharged overboard through a gravity overboard discharge connection. No internal pump is required if the AHEAD TANK is installed above the water line. However, if the AHEAD TANK is installed below the water line of the vessel it will be necessary to install an Automatic Waste Water Discharge System (This unit is sold separately). Ahead Sanitation Systems Inc. recommends the BE-HIND TANK, a fully self-contained Automatic Waste Water Discharge System. The BE-HIND TANK is constructed, and designed to be connected to the discharge of the AHEAD TANK at the same gravity water flow level. The BE-HIND TANK comes complete with a Sump Pump (110 VAC or 220 VAC, single phase 60Hz), a Vertical Float Switch, and Check Valve, all inside a Durable, Lightweight, Corrosion Proof and Compact, 18” X 18” X 18” LLPE polyethylene material tank.