r / MODELS ,kW METHODS Y

COMPOST TOILETS RECONSIDERED From smaller self-contained units to centralized systems, cornposting toilets are finding a market in cottages, of-the- grid homes and public facilities.

Carol Steinfeld

The Vera Carousel features Q composting canister underneath the floor. Divided into four chambers, it is designed to accept and compost new material in batches.

BIOCYCLE

‘HEN Ernest Schneider bought a composting toilet in 1983 for the house he was building south of San Francisco, his family was apprehensive. “They had been to campgrounds and

weren’t sure what to expect,” he says. Even though there was a septic system on the property, he decided to install a composting toilet because water in his area is expensiye and occasionally unavailable. He also liked the idea of conserving resources and not cre- ating pollution.

Schneider says he and his family have been “very satisfied” with the Carousel sys- tem he purchased. He empties it once every four or five years and spreads the composted “humus“ on his yard. Apart from that, the unit is checked every two weeks for mois- ture, and sawdust or leaves are sometimes added to the compost- ing waste. “It takes some maintenance. but it just makes sense to me,” he says.

One could argue that composting toi- lets are the oldest toi- let system there is . “It’s nature’s way.” says David Del Porto. who has distributed several lines of com- posting toilets since 1973. His company, Ecos, is based in Con- cord, Massachusetts. ”You can compost in a teacup: it’s not rocket science,” he notes. “What is science is managing the process for a minimum of odors, cost, safety and pathogen destruction.” To some, composting toilets are akin to bringing the outhouse in- side. However, unlike outhouses, compost- ing toilets are designed to aerobically de- compose human excrement, urine and toilet paper. ..The emphasis is on controlled pro- cesses,’‘ Del Porto says. “As long as the tem- perature, aeration and moisture are con-

Trolled, the material shguid be composting. Technologies differ and some toilets simply dlow contents to sit at : o w temperatures and slowly decompose, This is known as Doddering, and it takes xuch longer.”

Today. commercially :\-ailable compost- ing toilets can be divided :nto two broad cat- qories: self-contained ULE and centralized systems, both ofwhich c>3ically use either a hatch or continuous prosssing methodolo- 3. Central composters z e remote from the Toilet bowl. usually locatci in the basement (Jr in its own enclosure 10 the side of the

building. Self-contained units. as the name 2 suggests. are single uni: zomposters where- $ by the toilet seat and :he compost reactor are both part of the sarze appliance. These $ can sit in the bathroom. LTd because they re- quire no plumbing, basements or crawl spaces t o a reactor belox7 are not needed.

ing” as it applies to today’s toilets, is done in more than one compost 3amber . These are switched or rotated as :key fill up. The ad- vantage. ,some say. is tk-1 older or advanced compost IS not contamir-3red and is allowed

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In terms of processiq. “batch compost- a

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- Processing fresh crop residues by composting eliminates the need for storage space, a premium in closed environmental systems.

process solids that must be oven or freeze- dried and ground before feeding into the re- actor tanks.

COMPOSTING ADVANTAGES Composting is another biological process

under investigation and offers several ad- vantages over continuously stirred tank re- actors. Crop residues can be processed fresh, eliminating manpower and equipment re- quired for freeze or oven-drying and grind- ing. Processing fresh crop residues also eliminates the need for storage space which is at a premium in closed environmental sys- tems. Composters do not require automated daily feeding of solids (but may be adapted

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to accept daily feedings) and, therefore. may require less time and manpower to operate. Because composting requirei significantly less water than continuously stirred tank reactors, mass and volume are lower. Xddi- tionally, if human solid wastes are pro- cessed, fecal borne pathogens can be re- duced t o safe levels during normal batch operation. Pathogen sun-ival in continuous- ly stirred tank reactors is likely (due to low- er operating temperatures) which suggests that filtration of the reactor effluent might be required before it could be safely handled by the crew.

Preliminary research in lab scale com- posters at Kennedy Space Center has been encouraging. The volume of solid wastes has been reduced between 65 to 75 percent during composting. Volatile solids levels have been reduced between 25 to 60 per- cent (varying with crop type. moisture con- trol, and air flow rates). Also. levels of min- e ra l s de tec ted in aqueous ex t rac t of composted solids (compost tea) have been sufficient for incorporation into plant growth systems.

The cornposters being tested have ap- proximately one liter working volumes and are constructed of PVC pipe. They are sub- merged vertically in an insulating water bath maintained at 30 degrees C. Each end is capped with a rubber stopper through which air lines pass. +lir flow rates are mon- itored and controlled using variable air flowmeters with a range between 10 and 500 mumin-1. After leaving the flowmeters, the air stream passes through gas wash bot- tles containing preheated water (40 to 5 2 degrees C) to humidify the air before enter- ing the composters. Their air stream enters the bottom of the units, providing oxygen and moisture and removing excess heat generated through metabolic activities of microorganisms. The CO? enriched exit air stream flows toward a condenser for re- moval of excess moisture. then enters into a portable low flow infrared gas analyzer for CO? measurement. Carbon dioxide produc- tion is measured in real time and recorded a t five minute intervals using a SUN Sparc Station and OPTO-22 digital and analog in- putloutput boards. Moisture content is based on evaluation of composted sample dry weights.

The next step at Kennedy Space Center is t o construct intermediate scale (15-L) con- tinuous composters. These composters will be part of a series of experiments, which will begin in June, 1997 using an aqueous ex- tract from composted crop residues to grow wheat in closed environmental chambers. Results from these experiments will provide basic data to develop the technologies nec- essary to provide resource recovery compo- nents for ground based humans at Johnson Space Center and. ultimately enable long term human exploration of space. rn Cheryl F. Atkinson is a NRC Research Associ- a t e w i t h NASA at Kennedy Space Center, Florida.

LARCH 1997

Foam flush toilets like this to mature without being disrupted by the Nepon model (inset) are being new nutrients and pathogens in fresh waste. connected ‘0 In some systems, the chambers can be re- composters. The Centrex plus moved from the toilet to take outside. .’Con- unit from Sun-Mar (cutaway) composts in contained, tinuous” composting, on the other hand. rotatable canister. takes place in a single chamber in which the

fresh and older materials are commingled. Finished compost is removed from one end of the unit.

These days, systems also are available with microflush toilets - a factor that has helped to change the public‘s perception of them for the better. ”Many people don‘t like the ‘black hole’ concept,” says Bill Wall, the New England distributor for Clivus Mul- trum, referring to what many compost toilet

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users see when they lift the lid of the toilet. “Now you can have a flush toilet connected

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to your composter. It‘s more traditional. - h d you don’t have to hare a straight chute.“

Another factor in increasing public accep- tance is making them easier to maintain. - Wall says nearly all ofhis customers nos opt for a sen-ice contract he offers. Sen-Ice is available on an annual basis (once per year) for about S200 and on a quarterly basis I four times per year) for about $600 (prices de- pend on location). It usually includes check- ing all parts. leveling the compost and re- moving it if necessary. “This makes the operation and maintenance easy now. so it’s a viable solution for more people.“ he says.

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REGULATIONS AND STANDARDS Composting toilets usually require special

conventional system. Many states allow E counties to make their own decisions. Ap- 2 proval tgically involves local and regional authorities. but due to lack of knowledge of 2 these systems, officials are often vary of 5 granting permits. 4

tems recently were approved in response to ; increasing evidence that conventional sys- 5 tems are a threat to public health. Many homeowners are unable to install nelv sep- tic systems or continue using their current ones, due t o poor soil drainage (see “Proper- ty Owners Turn to Least-Cost Solutions,” April, 1996). Massachusetts’ plumbing code now recognizes these toilets as plumbing fix- tures that must be installed by licensed plumbers. Other states are expected to fol- low this state’s lead.

Property owners also are reconsidering composting toilets as an alternative t o pay- ing skyrocketing sewer rates and holding tank pumping costs. In addition. a zero dis- charge system allows some property owners to use more of their land. Bill Wall notes that some customers have opted for com- posting toilets to save trees that would have come down to make way for septic system leaching beds.

About 40 states require composting toilets t o be tested and approved by the Kational Sanitation Foundation (NSF 1. essentially the Underwriters Laboratories of the public health industry. NSF’s Standard 41 is a per- formance standard developed in 1982 t o test the operation, maintenance and perfor- mance t o include the destruction of fecal co- liform. It is undergoing its five-year review this spring. Companies that offer some NSF-

“”listed models are Clivus Multrum. CTS Compost Toilet Sytems. BioLet and Sun-

In Massachusetts. composting toilet sys-

Mar. Vera-EcoTech Carousel, the first sys- tem to be NSF listed, is awaiting renewal. The Phoenix Composting Toilet has Canadi-

Standards Association approval, which also is recognized by NSF.

CURRENT CENTRAL SYSTEM MODELS Vault composters like the Clivus Multrum

and the CTS models consist of a large in-

clined box where material is added t o a starter bed of wood chips or sawdust. Waste moves down an incline which slows its pas- sage to the bottom, helping to aerate it. A baffle at the base of the unit keeps new mat- ter on top. Compost is removed through an access hatch at the bottom of the tank. Oc- casional leveling of the pile with a pitchfork is required. Some users also turn the com- post at that time to prevent densifying. The Clivus Multrum is constructed of crosslink polyethylene; the CTS is fiberglass. Costs range from $3,650 for a residential size CTS (about 18 daily uses) to more than $10,000 for an insti tutional unit . A residential Clivus for a family of four will cost $3,000 to $6,000, excluding the toilet stool or a flush toilet (as is the case for most prices given here for the central systems).

The Phoenix is a tall, polyethylene three part system. Waste falls to a high area. where rotable tines act as a mixing device to break it up and aerate it. Next it falls to a grate, then to a collection box. The tines can be used to hold the newer material while re- moving composted material. Urine drains to an evaporator at the bottom. Three residen- tial models and three models for public fa- cilities range in price from $3,500 to $5,500. Clivus Multrum, CTS and Phoenix brands come with fans but no heater.

The Vera-EcoTech Carousel is a cylindri- cal fiberglass container consisting of an out- er case and an inner case which is divided

- Systems are available with microflush toilets - a factor that has helped to change their perception for the better in the public eye.

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The number of Phoenix corirposting tanks per installation can be varied according to need. The facility in Grand Canyon National Park (inset) features one tank, two photovoltaic panels and an active solar hot air collector.

Nearly all toilets are available with optional heaters and fans (electrical or solar-powered),

1 I . if they are not part

of the units.

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into four revolvable con uid drains to the bottc where it evaporates or utilization or disposal. and composting solids are separated. When one chamber fills up, the next is rotated into position. With typical use: the first chamber would be emptied in two years. It’s avail- able in three sizes ranging in price from $2,153 to $3,389. The Vera Toga 2000 is es- sentially two remov- able rollaway 60-gallon compost reactors. Extra containers can be purchased for more capacity. It costs about $1.100.

Sun-Mar’s new Centrex Plus features a “bio-drum,” e.g. a rotatable canister divided into two parts. A built in bar improves turn- ing. When the primary chamber in the drum is full, material spills into the secondary chamber, which automatically empties into a finishing container. When that is full. it can be replaced with an empty container. Twin 250-watt heating elements can be turned off, on or set at 50 percent. The unit’s capacity is six adults year round. and the price is $1,649 ($1.399 for the nonelectric model). Sun-Mar’s Centrex, a smaller unit featuring an undivided bio-drum and just

A COMPOSTER TOO GOOD TO REFUSE

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Backyard composting programs will work - m the cities that offer the BiostackO Composter.

The unique three-tiered deslgn oi the BiostackB makes light of the hardest part of the composting job -turning the pile. Because it makes composting so easy, the Biostack ensures a successful munici- pal composting pro- gram. And it’s fabricated 0f6O% recycled polyethylene.

Selected by the fobwing cities and counties for their backyard cornposting progmns: Ahmedu Co., CA, San Mateo Co., CA, King Co., WA. L o s Angeles, Burknk,

S a n n Cru7, Denver, Olympia and many more.

one collection tray, is typically only used il- cottages. It ranges in price from $999 for : nonelectric to $1,199. In all of these models leachate - urine and other liquid - drain- t o the bottom. where it is evaporated 01 must be drained for disposal or utilization.

Outside of North America, other central- ized systems include the Rota-Loo in Aus- tralia. the Ekolet in Finland and the Aqua tron in Sweden, all of which are similar tl the Vera-EcoTech Carousel. Sature Loo i! Australia and the Dowmus in England ar, round, single chamber composters.

While large. central composting toilet sys- tems allow long-term retention two years o. more) and more capacity, their large sizes - a few are six to 10 feet high - require spe- cial installation considerations. and man: are best suited to new construction or park and recreation areas. The larger singlt chamber units also are more susceptible t , compaction of the composting mass.

CURRENT SELF-CONTAINED MODELS Due to their small size. these units typi

cally are used in cottages and seasona homes with capacity ranges from two to si: adults. varying with the model. Sun-Mar 01 fers four self-contained models. each featu~. ing a revolving canister-like composte mounted horizontally. A hand crank allow users to periodically rotate the drum, mi>. ing and aerating the material. Urine drain to an evaporating chamber. When the bic drum is full, about a third of its contents ar removed to a finishing tray beneath i t where a heating element raises the tempel. ature and evaporates the liquid.

BioLet’s XL features a priman chambe where a mixing arm slices through the COIF posting waste. aerating it and pushing j

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- ~ I A R C H 199. - -1 .

through a grate. Finished compost falls into a removable tray. It features a radiant heater in the floor of the unit and a convec- tion heater that c i rculates heated a i r around the composter to warm the compost and evaporate leachate.

Vera’s Toga series includes several self- contained models of various capacities, all based on batch composting. Inside are two interchangeable composting chambers. (An exception is the Toga 2000 described above.) Some extend below the floor to al- low more capacity. All come with optional fans and heaters. The BioLet NE also uti- lizes this design.

Sancor’s Envirolet is much like the Bio- Let, but features a perforated inner con- tainer that holds waste, and a movable grate called a “mulcherator” that can be manually pulled to break up, mix and aer- ate the material. All of these systems fea- ture ABS or polystyrene plastic outer cases, except the fiberglass Sun-Mar models.

Prices range from about $850 for a Vera Cottager to $1,470 for a BioLet XL. In gen- eral, smaller systems ensure fewer installa- tion difficulties. However, users must con- stantly remove the finished compost while adding new material. Due to their small size, they often are overloaded and process- ing can be incomplete. Excess liquid o r leachate is the bane of the smaller ones. Odors can occur due to faulty ventilation systems or broken fans.

MICROFLUSH, GRAYWATER AND ACCESSORIES Available microflush toilets include the

SeaLand, which uses one pint of water flushed with a foot pedal, and Evac vacuum toilets, such as those used on airplanes and trains. The new Vera Waterless uses the mass of the waste itself plus simple fluidic engineering to move the material while Nepon toilets from Japan use foam.

The extra water from these toilets must be treated by evaporation, disposal or uti- lization. Clivus and EcoTech offer wastewa- ter systems to treat this liquid, as well as the rest of a home’s washwater, or “graywa- ter.” Clivus and EcoTech offer graywater ir- r igat ion systems that t reat the water through garden beds. These systems must be approved by states on a case by case ba- sis. Graywater irrigation is gaining accep- tance in states, such as California and Ari- zona, according t o Del Porto.

Nearly all toilets are available with op- tional heaters and fans (electrical or solar- powered), if they are not part of the units. Some companies also offer solar compo- nents, such as Ecos’ Soltran solar assisted composting system.

A system without a fan or heater may swing with ambient temperatures, result- ing in less control of the process. Fans are recommended, especially if the ventilation pipe is six inches in diameter o r less. A fan improves ventilation (reducing the risk of odor) and aeration. Supplementary heat speeds up the composting process, al- though too much heat can dry out and halt

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let - usually odors or incomplete compost- ing. Some manufacturers claim it’s the poor design of past models, but most often, they say, it’s improper maintenance or installa- tion. “Many people overload them.” says Del Porto. “Or they take material out too soon. Or they lose the manual, and pretty soon they’re putting dirt in the composter!” Com- posting toilets got a bad rap in the past, he adds, because manufacturers failed to in- form the owners of their extenske mainte- nance requirements for fear this would de- ter people f rom purchasing them. Consequently, people‘s expectations for ease of use far exceeded the actual day-to-- day maintenance.

Only time will tell whether public health concerns, improved performance. flush toi- lets and service contracts will usher compost-

A varkty of designs are available to treat a household‘s graywater in ing toilets into mainstream America’s bath- garda beds.

compsting. Ideally, the composting mate- rial h u l d have the consistency of a wrung out qonge. Using a moisture meter or in- stallimg a humidistat helps users maintain ideal moisture levels of 50 and 70 percent by weight.

Nearly all manufacturers sell bulking agenh to aerate, add carbon and absorb some excess moisture. Another option Del Ports recommends is using stale popped popmn or dime-sized wood chips. “It has the ideal shape to create air spaces, nooks and crannies for bacteria to grow and good nutrients that are totally consumed in the compmting process,” he says. “You want t o aerate and add carbon, and absorb some ex- cess liquid.” He also sells an additive mix consisting of perlite, vermiculite, screened dark peat, wetting agents and starting nu- tTienb. Wall recommends finely mulched wood, composted leaves, planar shavings or gerbil bedding and pine bark mulch. Both discourage using peat moss alone. “It doesn’t really decompose,” Wall says.

To manage any leachate from the sys- tems, Ecos offers a Wastewater Garden sys- tem, which is essentially a mini-evapotran- spiration bed where plants in a specially chosen medium use up the liquid in a five- gallon pail.

Finished humus from a compost toilet has the consistency of co-mposted leaves. It may be pungent but not offensive if it’s been properly processed. Typically, it’s 10 to 20 percent of the original volume (unless a lot of bulking agent was added). Most states re- quire sending the material to a treatment facility or burying it under at least 12 inch- es of soil but within the root zones of plants that can use the nutrients. Any leachate emptied from composters must, by law, be disposed of in a septic tank; removed by a septage hauler or remanded to a treatment plant for further treatment.

POSITIVE FUTURES Talk to a group of compost toilet users,

and you’re bound to find someone who has had a bad experience with a composting toi-

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rooms. “We’ve got a long way to go.” warns Sun-Mar’s Wilkinson. T h e mainstream still prefers ’out of sight. out of mind.“

Carol Steinfeld is a freelance writer based i n Concord, MA. S h e is uriting a book on com- posting toilets and grayrcater systems.

COMPOST TORLET MANUFACTURERS Aquatron International Nature-Loo Bjornasvagen 21 P.O. Box 1213 11 3 47 Stockholm, Sweden Milton Q 4064 +46-a-790 98 95 Australia

+07- 3367-0601

Box 620 S-135 26 Tyreso, Sweden “1-468-745 06 30

Envirolet Composting Toilet SanCor Industries 140-30 Milner Ave. Scarborough, Ontario M l S 3R3 Canada

Phoenix Composting Toilet Advanced Cornposting Systems 195 Meadows Road Whitefish, MT 59937

phoenix@compostingtoiiet.com

Rota-Loo Environment Equipment 2/32 Jarrah Drive Braeside, VIC.3195 Australia

406-862-3854

+03-587-2447

Sun-Mar Corporation 5035 N. Service Road, C9-C10 Burlington, Ontario LTL 5V2 Canada

compostQsun-rnar.com

Vera-EcoTech Carousel Vera-EcoTech 152 Commonwealth Ave., Concord, MA 01 742

watercon@?igc.apc.org

905-332-1 31 4

508-369-3951

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