Phoenix Public Facilities Application Guide


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Our acclaimed planning guide helps maintenance professionals determine capacity, choose a site, optimize building design, and devise an efficient maintenance schedule.

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Choosing a Composting Toilet: Eight Key Questions

Composting is a familiar process to many people. Organic materials, such as leaves, lawn clippings and food waste, are placed in a pile or enclosure. Over time, in the presence of oxygen, heat and moisture, biochemical processes convert the waste to stabilized compost, which resembles rich, dark, potting soil. Pathogens are nearly eliminated and the volume of the organic material is reduced by 90 percent or more.

The same biochemical processes are employed by composting toilets to treat human waste. A composting toilet is a system that provides an environment within a container for aerobic (in the presence of oxygen) decomposition and stabilization of waste. It is a miniature, on-site sewage treatment plant. It is not a dehydration system that uses heat to dry waste; not a “waste reduction” system that circulates large volumes of air over the waste to evaporate liquid; not a “recycling system” that merely stores the waste for periodic removal and composting at a remote facility.Not all composting toilets are created equal. They vary in size, materials, features, effectiveness, maintenance, energy requirements and safety. In choosing a composting system, we recommend considering the following questions:

1. What are the durability, suitability and longevity of the materials used in manufacturing?

2. Does the size and shape of the composting vessel make sense?

3. Does compost removal require a pumper truck or climbing into the tank?

4. Can you remove compost without also removing fresh waste?

5. What are the energy and ventilation requirements?

6. What are the long term operating costs?

7. Would you personally be willing to perform the required maintenance?

8. Do the specifications make sense?

At Advanced Composting Systems, we manufacture the Phoenix Composting Toilet, a large and very rugged composting system that provides for the safe and effective stabilization of human waste on site. The insulated tank, efficient ventilation system and automatic controls assure the lowest possible heat and electrical requirements. Most often, these requirements can be met with solar energy. The Phoenix’s built-in rotating tines and vertical design assure higher quality compost and easier, safer maintenance.

The Planning Procedure 

The process for planning and designing a Phoenix composting toilet facility for a specific application requires several important steps. The following application guide will help in this process. If you need further information for a unique situation, please contact us. ACS designs, supplies, and installs complete turnkey facilities satisfying a wide range of criteria. We also perform site visits to help select a building location.

An outline for the planning process follows. Some steps will be easy, others will require research, design decisions and tradeoffs. All are important to guarantee a successful project. Our application guide follows this outline. Refer to it to assist with each step.

Phoenix considerations

1. Is a composting toilet appropriate for this application considering the type of user, environment and maintenance commitment?

2. Determine the amount, type and season of use expected for the design life of the facility.

3. Determine the capacity of the Phoenix, model and quantity of systems needed for the expected environment (temperature, maintenance and use). Will supplemental heat be required to facilitate composting?

Facility considerations

1. Accessibility for the handicapped. Is formal ADA accessibility compliance required?

2. Sunlight availability for solar heat and electricity. What, if anything, will obstruct direct sunlight?

3. Sloped ground to provide a daylight basement.

4. Avoid confined space problems!

5. Does the leachate require a holding tank or evaporator for zero discharge or is an on site leachfield possible?

Operational considerations

1. Maintenance! Maintenance! Maintenance!

2. What will you do with the removed compost?


When does a Phoenix make sense?

Employing a Phoenix does not always make sense; certain management and site conditions suggest a composting toilet while others are inimical to its success. A better alternative may be a conventional system, vault toilet or pit privy.

What circumstances exploit the Phoenix’s unique characteristics?

At heavily used backcountry sites where access and transportation are limited the Phoenix needs only simple manual maintenance.

In environmentally sensitive areas such as lakeshores, the Phoenix offers zero discharge.

Where no utility electricity is available, a photovoltaic system can be used to supply the Phoenix’s minimal electrical needs.

Where water scarcity precludes flush toilets, the waterless Phoenix will operate. To facilitate maintenance, provide a small amount of pressurized water from a rain water cistern.

Winter freezing conditions which may damage pipes and fixtures in a conventional flush system will not damage the Phoenix. As long as the tank is in a heated space, the composting process continues. A drain-back water supply for sink faucets offers the same freeze protection.

In high density campgrounds, a Phoenix facility’s odorless toilet room and aerobic decomposition are more aesthetic than a vault toilet’s penetratingly offensive odor.

When does a Phoenix not make sense?

Consistently cold conditions that reduce the Phoenix’s capacity below use requirements will result in incomplete stabilization of end product and unhealthy and unpleasant maintenance.

If sewer and water connections are available, a flush system often will be less expensive.

Severe vandalism could destroy a composting system. A concrete vault and toilet building offer more immunity.

Inconsistent or improper maintenance will reduce tank capacity and composting efficiency resulting in poorly decomposed end product.

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Capacity PlanningSizing the facility. How many tanks and how many toilets will a facility need? The answers depend on total annual use, and peak daily use. “Uses” should not be confused with the number of people in an area: “uses per person” varies depending on the nature of visitor activities in an area.

The number of total annual uses determines how many tanks are needed. The peak daily use determines how many toilets must be installed (a tank can accommodate two toilets).

When calculating rates of use, planners should account for the accelerated rates of use that can occur following the opening of a new facility (if you build it, they will come and go).

The Phoenix’s capacity is rated in average uses per day and varies according to the tank’s temperature, the type of use, and the frequency and quality of maintenance.

Predicting facility use. The total annual use for a facility can be inferred (with varying degrees of accuracy) from a surprising variety of data. Here are a few common situations:

Highway rest areas. The Federal Highway Administration has quantified toilet use as a function of traffic counts. Thus historical traffic count data can be used to estimate current use and project future use.

Existing facilities. The amount of use at an existing toilet facility can be calculated from:

Water consumption, provided that the water is metered. This is true even when water is used only for washing, as in the case of a facility equipped with pit toilets.

The volume of waste pumped from a vault or portable toilet (20 uses per gallon, or 5 uses per liter).

The consumption of toilet paper. For example, 90 uses per roll seems to be the norm for restricted delivery holders.

Door counters. We sell an automated door counter that can be retrofitted to any facility with a toilet room door. This, obviously, is the best method for ascertaining the amount of use.

Campsite capacity and occupancy. In campgrounds, the daily per capita use of toilet facilities is a function of access, recreational opportunities, and the amount of time spent in the area:

At campgrounds accessible by vehicles, daily per capita use ranges from 3 to 5. The average group numbers 3 persons, but may be larger in campgrounds that attract a high percentage of family use. Campgrounds offering close-at-hand recreational opportunities, such as swimming or fishing, experience longer stays and higher per capita use than sites that are used mostly for overnight stops.

At backcountry campgrounds, daily per capita use ranges from 2 to 3. Tallies from trailhead registers, and the number of campsites, can be used for estimating backcountry facility use.

At facilities for day hikers, daily per capita use is between zero and one. Tallies from trailhead registers, and/or vehicle traffic counts, can be used to estimate the amount of day use.

Parking areas. The number of parking spaces, visitor turnover rates, and remoteness affect the rate of toilet use.

Determining the Phoenix’s capacity. Capacity is the amount of use (expressed as “uses per day”) the Phoenix can sustain while producing stabilized, non-offensive, liquid and solid end products with low coliform counts; solids with a moist but not saturated texture; liquids with a high proportion of nitrate nitrogen. Removing compost from a Phoenix that has been (a) properly maintained, and (b) used within its capacity rating, will not be an unpleasant operation.

Our ratings are conservative, and are derived from operational experience. We have equipped representative facilities with data loggers to record key parameters. We visit many Phoenix installations to retrieve use data (the Phoenix is the only system that includes door use counters and has done so since its inception), and to assist with removing the compost. Our extensive hands-on experience with the capacity-environment-maintenance relationship has allowed us to quantify the rate of composting as a function of maintenance and ambient temperature. We continue to refine our numbers by monitoring existing facilities, and through an ongoing research and development program.

Temperature. The rate of decomposition within a Phoenix, and all other composting systems, primarily depends on the internal temperature of the compost pile. The higher the pile’s temperature, the more rapid the decomposition, and thus the higher the capacity of the tank. Moreover, a relatively small increase in compost temperature results in a relatively large increase in the rate of decomposition.

Proper temperature management is critical to successful composting. Two temperatures affect the composting process:

Ambient temperature is the temperature of the tank’s surroundings and ventilation air supply. This temperature can differ significantly from the out-of-doors air temperature, and/or from the temperature of the ground. A low ambient temperature increases the heat loss from the Phoenix and depresses the compost temperature.

Compost temperature is the temperature of the compost pile. When significant composting activity occurs, the compost temperature almost always will be higher than the ambient temperature. Conversely, a low compost temperature indicates a cold tank and a lack of significant composting activity.

Compost self-heating. The biochemical reactions of the composting process produce carbon dioxide and water, and release energy, heating the compost pile. The rate of the biological and chemical processes involved in composting approximately doubles for every 18 degrees F (10 degrees C) of increase in compost temperature. Self-heating occurs when the pile has sufficient mass and oxygen, and when the ambient temperature is high enough that the reactions can be sustained. The Phoenix’s low ventilation rate and insulated tank hold the heat generated by the compost pile.

Composting activity is very slow at ambient temperatures below 55 degrees F (10 degrees C), but accelerates rapidly as the ambient temperature rises. Our target minimum ambient temperature is 65 degrees F (19 degrees C).

Ventilative and evaporative cooling. The Phoenix is kept odorless by drawing air through the toilet and tank, and expelling it through a vent in the roof.

Air flowing through the Phoenix accelerates evaporation of the liquid, cooling the pile. In addition, heat from the pile is lost when the temperature of the ambient air drawn into the tank is lower than the temperature of the pile. The Phoenix minimizes these losses by ventilating at the lowest rate necessary to control odors and supply oxygen for aerobic decomposition. It is better to use an external evaporator when liquids must be evaporated on-site.

Cold composting conditions. At ambient temperatures below 55 degrees F (13 degrees C), heat loss through the tank wall prevents significant self-heating. Consequently, supplemental heat is mandatory to promote composting. The Phoenix, which is insulated, has been designed to be heated easily. Air enters the tank at a single port that can be connected to a heat source, such as a solar collector.

The Phoenix can be used at a reduced rate at ambient temperatures colder than 55 degrees F (13 C). Liquids will still evaporate and drain. Some use is possible even while the tank is frozen, for the compost pile will melt slowly and be treated when temperatures rise. Nevertheless, it should be kept in mind that at very low temperatures, significant composting does not occur and the tank essentially functions as a holding vessel.

Unlike conventional plumbing, which can rupture when frozen, the Phoenix tank is not damaged by freezing.

MaintenanceMaintenance is the other major parameter affecting capacity. Frequent, thorough maintenance — spraying liquid, adding bulking material, and mixing the compost pile — increases the rate of decomposition.

Moisture management. The proper moisture level and porosity of the compost pile (from the addition of bulking agents, such as wood shavings) must be established. The Phoenix includes a liquid spray system to help maintain moisture levels. The addition of bulking material is a simple task when performed frequently. The Phoenix includes built-in rotating tines to mix the bulking material with waste; additional raking often is unnecessary.

Pile aeration management. Because raw fecal matter is too wet and nonporus to compost, it must be mixed with a bulking agent — we recommend white wood shavings — to provide the structural support and the airspaces necessary for aerobic decomposition. The bulking agent must be thoroughly mixed into the pile. The more frequently the bulking agent is added to the pile, the less frequently mixing the pile will be required.

User behavior. At day use facilities, the urine-to-feces ratio is higher than at overnight facilities. This translates into an increase in capacity of 30 percent.

Total sustainable use. The amount of use that the Phoenix can sustain in any month correlates reasonably well with the average ambient temperature for that month. Use at 150 percent of capacity can be sustained for long periods as long as monthly averages are within ratings. Even higher rates of use can be accommodated for short periods, such as a Fourth of July Weekend. The capacity of properly maintained Phoenix systems for different ambient temperatures is shown in Table 1. A sample capacity calculation is presented in Table 2.


PF-199 PF-200 PF-201
Height 53″ 68″ 84″
Width 40″ 40″ 40″
Front-back 62″ 62″ 62″

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Table 1Phoenix capacity in uses per day and (year) 

as a function of ambient temperature

Temperature Model 200 Model 201
=< 32 F (frozen tank) 200 cumulative 300 cumulative
55 F 15 (5,500) 25 (9,000)
65 F 30 (11,000) 50 (18,000)
75 F 60 (22,000) 100 (36,000)
Adjustment. If day use is the predominant use (higher urine to feces ratio), increase the capacities for 65 and 75 degrees by approximately 30 percent.
Table 2. Sample capacity calculation for a Phoenix PF-201 (GIF, opens in new window).

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Facility design & site selection requirements and tipsSelecting a site. Choosing a site for a Phoenix facility will have dramatic effects on system capacity, building design, user accessibility, energy use, maintenance effort, and construction cost. Therefore, thoughtfully consider the needs of the composting toilet (and maintenance personnel) when selecting a site.

Sloped terrain. The Phoenix can be installed on level ground, but taking advantage of sloped terrain will reduce the excavation requirements and allow easier access to the tanks for maintenance. It is more convenient for maintenance persons to enter a daylight basement (Figure 2) through a vertical door than to descend stairs into a full basement. A daylighted basement can also be smaller, since large doors in front of each Phoenix permit the required maintenance area to extend outside the building. We recommend a daylight basement if the terrain slopes 20 degrees or more. Access to the toilet rooms is provided easily by extending a small deck to the hillside.

Flat terrain requires a full basement or an elevated building. In a full basement, an alternating-tread staircase (Figure 1) allows compact, convenient access to the tank area. Providing a 5-foot area in front of the Phoenixes, artificial lighting, and reflective white walls, facilitates maintenance. Avoid a flooded basement by building above maximum high ground water, elevating the building slightly, sloping soil away from the foundation, and adhering to good drainage practices.

If high ground water or impenetrable rock precludes excavation, an elevated building is necessary. A stairway, or an extended ramp for universal access, is required for user access. We have constructed a bench type toilet (Figure 3) that reduces floor height, and a serpentine ramp around the building, for these situations.

Disposal of liquids. Suitable conditions must exist for disposing of the liquid end product from the Phoenix. If local conditions, such as high ground water, preclude a leach field, then provide a holding tank, a raised bed evapotranspiration system, or a Phoenix liquid evaporation system. A holding tank requires strict attention to prevent overflows.

Preventing unauthorized dumping and vandalism. If the Phoenix is located near a parking area, the design must prevent the emptying of recreational vehicle holding tanks into the toilet. Locate the building far enough away from the parking area that drain hoses cannot reach it, or elevate the building slightly so that the toilet is above an RV’s holding tank. Provide a waste dump near the building that offers a convenient alternative, and post signs advising users against dumping chemical toilets and holding tanks into the Phoenix.

Similarly, locate trash cans and cigarette disposal containers immediately outside the building to reduce misuse of the Phoenix. If trash collection needs to be minimized, a trash container inside the toilet room will intercept those intent upon misuse, while not attracting others to dispose of their trash.

Designing the building. Nearly any building design satisfying the following conditions is compatible with the Phoenix:

  • The Phoenix must be located directly below the toilet or toilets.
  • The tank must rest upon a smooth, level, flat surface
  • Convenient access, good lighting and ventilation, and adequate space in front of the Phoenix, must be provided for maintenance operations.
  • Adequate space for storing the bulking agent and supplies must be provided.
  • The Phoenix 4-inch DWV ventilation pipe should be supported by the building framing, and extend above the roof ridge for proper air flow.
  • A drain, holding tank, or evaporation system for the liquid end product must be provided.
  • Electricity must be available for the Phoenix’s ventilation fan, pump(s), and other systems.
  • The tank area must be maintained at or above the temperature upon which the Phoenix’s capacity rating is based.

Placing the tank. The dimensions of the Phoenix’s components are shown above. Installation clearances are shown in Figure 5.Provide convenient access to the Phoenix so that the composted end product can be removed easily from the basement area. It is very convenient with a daylight basement to locate a 3-foot-wide or larger door directly in front of each Phoenix so that the composted material can be shoveled directly into a wheelbarrow or other container (we provide a bin). For full basements, a good stairway is essential. Ladders and wall-mounted rungs not only are inconvenient, they are dangerous. Lapeyre manufactures a very compact 56-degree alternating tread stair that is quite convenient for basement access.

Placing the toilets & urinals. One or two toilets can connect to a Phoenix tank. The twelve-inch diameter toilet chutes can enter the Phoenix tank top anywhere within the dashed lines in Figure 5, although centering the chutes is preferable. For a two-toilet installation, the toilets must be located back-to-back against a common partition wall. Dimensions of the Phoenix toilets and installation clearances are shown in the following figure.

A trapless porcelain or stainless steel urinal can be connected to the Phoenix with conventional 1-1/2-inch DWV pipe. The pipe must slope continuously toward the Phoenix and enter the tank at least 6 inches away from side walls. The DWV pipe connects to the urinal drain and extends vertically through the floor or horizontally through the wall.

Options for managing Phoenix Leachate. Your selection of a site and building design should accommodate a sensible system for disposing of the liquid end product from the Phoenix, as not all liquid will be evaporated. Three strategies are viable (but some are better than others):

Ground disposal on-site. If soil conditions and pertinent environmental considerations allow, the simplest strategy is piping the liquid to a small leach field. If high ground water and/or a thin soil layer is a problem, an earthen raised bed can be constructed.

Off-site disposal. The excess liquid can be transferred into a holding tank, and subsequently disposed of at an approved site.

Evaporation on-site. A secondary evaporation system is a viable strategy in warm, dry climates. Under favorable conditions, the Phoenix’s companion evaporation system can evaporate all of the liquid end product and limited amounts of graywater. In cold, humid sites, no appreciable evaporation occurs. Please see Appendix A, and/or contact us, for site-specific information on evaporation systems.

The ventilation system. The Phoenix is equipped with a rugged, efficient, ventilation system. The fan housing mounts directly over a precut hole on either side of the tank top, or at any other accessible location in the tank top. This allows the fan to be cleaned easily without removing it from the housing, or to be replaced easily.

Four-inch flexible hose connects the fan housing to 4-inch DWV pipe. The hose and pipe are easily contained within a 2×6 framed wall. The pipe and hose should slope continuously towards the fan housing so that liquid from rain or condensation will run back to the fan drain.

The 4-inch DWV pipe should exit through the roof near the ridge to avoid potential snow loads and downdrafts. Several shroud arrangements can conceal one or several juxtaposed Phoenix and evaporator vent pipes as long as the exhaust air exits several feet above the roof in an upward direction. Do not enclose any vents in a louvered cupola.

If the Phoenix is used in subfreezing temperatures, insulating the exterior vent pipe and the interior sections passing through cold areas helps prevent condensation and freezing. The room in which the Phoenix is located should be provided with a 25-square-inch (150-square-cm) opening for ventilation makeup air.

The electrical system. All electrical devices and accessories supplied with the Phoenix operate on direct current: exhaust fans, pumps, light fixtures, and the system monitor and controller. Twelve-volt systems are the default, but 24-volt systems are available (we install both, and can help you determine which is best for your situation). If power from a utility’s electrical grid is not available, electrical requirements can be met from an independent generating system, such as our photovoltaic system. We provide an a.c. power supply for use where 120-volt a.c. is available.

Photovoltaics. If a photovoltaic system is required, provisions must be made for mounting the photovoltaic array in an unshaded area, routing the array output conductors into the building, and locating the batteries and controller in the maintenance area. If utility supplied 120-volt a.c. electricity is available, locate an electrical outlet close to the Phoenix for the power supply and controller.

Strategies for managing the tank temperature. As explained above, the Phoenix must be in a warm environment to compost effectively. The composting process itself generates energy that increases the temperature of the compost pile, but first the compost pile must be warm enough for sufficient activity to take place. As the temperature of the Phoenix is increased, the rate of composting and heat generation increases.

In a below-ground basement, the predominant influence on the temperature of the tank room is the temperature of the ground, which can be much cooler than the outside air temperature during the season of use. Moreover, in some climates the outside air temperature varies greatly throughout a 24-hour period. If the ambient temperature in the Phoenix room drops below 65 degrees F(19 degrees C), the tank cools and the rate of decomposition declines sharply, reducing capacity. At ambient temperatures of 55 degrees F (13 degrees C) and lower, composting slows to a virtual standstill.

Preventing a cold tank room. Basically, there are two strategies:

Insulation. The first step is insulating the entire tank room, including the floor and foundation walls to reduce heat loss to the ground.

Supplemental heat for the tank room and/or tank. In a well insulated room, a relatively modest input of energy results in a significant rise in temperature. We have constructed many buildings incorporating an active solar collector in the roof framing. Hot air from this collector is ducted into the tank room, or to the Phoenix’s air inlet. Conventional electric or gas space heaters also can be used to heat the room.

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Maintenance requirementsThe Phoenix operates much like a garden compost pile, requiring adequate food, air, moisture, and heat to support the organisms that transform wastes into a stable end product. The key to successfully operating a composting toilet is maintenance and the easier it is to perform, the more reliably it will be done. The Phoenix’s design invites proper maintenance with its convenient access doors, rotating tines, separation of liquid from solid waste, and liquid spray system.

  • Rotating tines stir the compost pile from outside the tank and control the movement of compost downward to the access area.
  • Internal baffles separate the liquid and solid end products before the liquid receives secondary aerobic treatment beneath the lower baffles.
  • Fresh water and/or treated liquid is automatically sprayed periodically onto the compost pile to inoculate the pile with bacteria, and to maintain the compost pile’s moisture so that the solid end product is merely moist, not dripping wet, and can be removed easily from the entire tank bottom below the lower tines.

Maintenance requirements and frequency depend upon the amount of use the system receives. The bulking agent must be mixed into the waste pile thoroughly, and trash removed, at least every few hundred uses. A heavily used system requires frequent attention and considerable bulking agent (about 1 gallon/100 uses). Locate a storage bin for bulking agent, and a container for liberated trash, conveniently near the Phoenix.Waste pile moisture must be checked and either more bulking agent or liquid added as needed. Systems in hot, dry climates, or systems that are used very lightly, require more attention to moisture control. Keeping the waste pile moist also prevents fires from vandalism or misuse. All Phoenixes include a programmable automatic spray system that uses liquid end product and/or fresh water to moisten the compost pile periodically.

Under many circumstances users can add bulking material through the toilet after each use, a “wood shavings flush.” This reduces mixing requirements so that periodically rotating the tines is sufficient to maintain a homogeneous mixture.

We strongly recommend keeping a log of conditions and actions (e.g. door counter readings, amount of bulking agent added, compost pile height) for a historical record and continuity among maintenance persons. We provide a suggested format and a get-started set of log pages along with our operating manual.

The finished end product must be handled carefully since it can contain some parasites and pathogens. However, it also contains valuable nutrients. Burying it near some plants will allow these nutrients to be reused. If it is pasteurized first, the small quantity of Phoenix solid end product can be used for revegetation (the pasteurizer’s heat source can be a solar collector).

Our complete manual, Phoenix Operation and Maintenance Instructions, is available on our Literature Rack.

Solid end product (compost). The amount of end product, and the frequency of its removal from the Phoenix, depends upon the amount of use, the rate of decomposition, and the quality of maintenance the system receives. The volume of finished end product is reduced by evaporation, draining (which also carries away dissolved and suspended solids), and decomposition. Coarse wood shavings, recommended for a bulking agent, do not decompose completely. However, they do compact and smaller particles fill some of the air voids.

Finished material should be removed from the Phoenix at least every two years. Approximately 12 bins of material (90 U.S. gallons, 350 liters, or 12 cubic feet) should be removed from beneath the tines. The amount of solid end product which must be removed from the Phoenix so use is sustainable will be about 30 liters (8 gallons) for every 1,000 uses, less if the tank is used at a lower rate or receives mostly urine. If this is too much, some material can be reintroduced at the top of the tank to maintain the compost level or some loosened material can be left in the clean out area below the tines.

Under the EPA’s sludge rule, 40 CFR part 503, Phoenix compost is a class B material suitable for land disposal in an area with restricted public access, e.g., burying on site. Finished compost must be handled carefully since it can contain some parasites and pathogens. However, it also contains valuable nutrients which can be reused by plants. If the compost is pasteurized, (a solar pasteurizer is easy to construct and very effective in sunny areas) it can satisfy EPA Class A requirements and may be applied on site with no restrictions.

Liquid end product. After filtering through the compost pile, the liquid receives secondary treatment in the well-aerated, stable, peat moss medium beneath the bottom baffle. The stability and tremendous surface area of peat provides an excellent filtering medium for treating liquid.

The amount of liquid discharged from the Phoenix depends upon the amount of use it receives, and the temperature and relative humidity of the ventilation air. Approximately 20 liters (5 gallons ) of liquid is added to the Phoenix for every 100 uses.

Incoming ventilation air circulating above the secondary liquid treatment medium can evaporate some of this liquid. The remaining liquid draining from the tank should be directed to a leaching field, holding tank, or a secondary evaporator. The liquid end product contains considerable bacteria and dissolved salts, but generally has a low coliform indicator concentration (<200 org/100 ml), low BOD, (<50mg/liter) and low TSS (<100 mg/1itre) compared to septic tank effluent, so a short (10-foot) leach line is all that is necessary.

Zero discharge on-site. If the Phoenix is located in an area where zero discharge is desired or mandatory, the liquid can be stored in a holding tank for periodic removal, or it can be eliminated with a secondary evaporation system. Either a small evapotranspiration bed or a compact active evaporator system can be employed. We can assist with design of the former and can supply the latter. Our liquid evaporation system includes a storage tank for peak loading, and a vent system and controls to optimize evaporation while using energy efficiently. Please get in touch with us for additional information.

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