Prepared by

Lombardo & Associates,  Inc.
       90 Canal  St.
    Boston,. MA  02114

1 Introduction 1
2 J\quaculture Systems 1
2.1 Introduction 1
2.2 Combined Aquatic Plants
2.3 Meadow/Marsh/Pond and Marsh/Pond Systems. 3
2.4 Mixed Aquaculture 4
2.5 Peat Beds .. .
2.6 Fish Aquaculture 5
2.7 Vascular Aquatic Plants 6
2.8 Existing Natural Wetlands 9
3 Summary of Important Design Considerations 10
4 Compost Toilets 10
Questions 14
References 15

I. Introduction
This section will outline novel alternatives for treatment of
small wastewater flows, and will emphasize the use of aquaculture
based systems. This Section is not meant to be a design manual,
but will illuminate processes hich show promise in the wastewater
treatment field. It is hoped that this section will provoke thought
ahnut alternative methods of small wastewater flow treatment.
2. Aguaculture Systems
2.1 Introduction
Aquaculture systems can furnish complete or partial wastewater
treatment. Complete treatment is defined as that which producees
secondary or tert&ary effluent characteristics from raw .sewage
whereas partial treatment requires pre—treatment of raw sewage
prior to removal of organics and nutrients in an aquaculture system.
Utilization of wastewater nutrients via aquaculture rather
than disposal, provides a unique wastewater management approach.
Placing emphasis on wastewater as a valuable resource alters
treatment technology, produces a marketable product, and removes
the stigma associated with wastewater disposal.
Two valualle products formed from wastewater utilization
techniques are clean water and some type of biomass such as water
hyacinths,reeds, algae, duckweed, shrimp, carp, catfish, goldfish,
clams, and/or others. Treated, clean water can be reused for a
number of different purposes including groundwater recharge, agri-
cultural irrigation, and industrial use. The biomass produced also
has a number of different utilization pathways including animal
feed, human food, a compost ingredient, an organic source for en—
ergy production, and fertilizer. The revenue generated ft om both
these products will vary according to market demand and will offset
annual operation and maintenance (O/M) costs. The potential
income from reusable water and salable biomass was included in the
annual O/M costs presented in the Cost Effectiveness Analysis•tlodule.
Because productivity is directly related to temperature and
solar radiation in biosystems, climatic variations affect biomass
production and nutrient intake. Several systems specifically
require a greenhouse cover over the aquaculture lagoons. Additionally
climatic (regional) variations will influence the design and cost
of these systems.
This section covers both complete and partial aquaculture-
systems. A complete system will handle raw sewage and produce
an effluent with secondary or tertiary treatment characteristics,
whereas a partial system requires either primary or secondary pre-
treatment prior to wastewater utilization. Combined aquatic plant,
marsh/r eadow pond, marsh/pond, and mixed aquaculture systems are
included for complete aquaculture treatment systems. Systems which require

some type of pre-treatment are peat beds, fish aquaculture,
vascular aquatic plants, and existing natural wetlands.
2.2 Cambined Aquatic Plants
The Max Plank Institute (tiP !) of West Germany has
developed an efficient, low-cost ystem for raw sewage
treatment.(1) Two distinct parts are involved in a series
layout; a filter system (for treatment of settleable solids)
followed by an elimination system (for reduction of dissolved
constituents). Each part grows a different aquatic -
plant to aid in nutrient uptake and removal from wastewater.
The filter segment of the tiP! system contains sand,
gravel, and aquatic plants ( hragmites or reeds). As sewage
percolates through the sand dnd gravel, suspended solids are
left on the filter bed surface and are dewatered. The
colloidal structure of the deposited layer is broken down
by plants as they utilize water and nutrients from the solids.
The elimination system is a gravel-filled trench planted
with bulrush ( Scirpus lacustris) . The bulrush removes organic
compounds, nitrates, phosphates, and heavy metals and provide
and environment unfavorable to pathogenic organisms. Both
segments require crop harvest once or twice a year. About
40 tons of plant material per acre per year are harvestable
with the MPI system. Both the reed and bulrush will grow to
a height of 6½ - 7 ft. before harvest. Nutrient removal
will continue after plant harvest.
MPI System Flow Dia ram

2.3 Meadow/Marsh/POnd and Marsh/Pond Systems (2)
Two closed, natural complete sewage treatment systems —
a meadow/marsh/pond (M/M/P) and marsh/pond (M/P) - success-
fully operated at Brookhaven National Laboratory on Long Island.
The basic process involves degritting, aeration, and delivery
of a carnminuted wastewater to the lowland area for nutrient
utilization. Both systems will be discussed together because
of process similarities and production of about the same effluent
quality even though slight differences exist in the basic process.
The M/P system does not have a meadow and, therefore, requires
less land (less land—intensive). However, because no meadow
is utilized, less benefits from crop harvest can be observed.
Both systems utilized a forested area for effluent groundwater
recharge. Local economics will determine which of the two
systems should be chosen.
Both the M/P and M/M/P serve as a total sewage and septage
wastewater mana ement process. Local land prices will determine
if a meadow is economical for crop harvest. Both systems do
provide a grass biomass in the marsh/pond segment which must be
harvested periodically. The pond can be stocked with fish (carp,
golden shinners, and fresh water clams) to reduce (or eliminate)
pond grass harvest. Marsh grasses grown include cattails, duck-
week, and reed canary grass. Other volunteer grasses often
become established.
Four meadow cuttings per year of reed canary grass yield
8 tons dry hay/acre/year. The marsh must be harvested at least
once a year to avoid filling. If duckweed ( Leniria ) is grown in
the pond, water renovation will be uninterrupted throughout
the winter as duckweed continues to vegetate in any season.
Systems utilizing duckweed will produce 240 lb/acre of dry plants
per week when fish are not present in the pond to eat the weed as
Raw sewage
and septage
Raw sewage
and septage*
g ri t
* minimum 5:1 raw sewage to septage ratio

2.4 Mixed Aguaculture
Solar Aquasystenis, Inc. has developed a mixed aquaculture
technique for primary effluent nutrient utilization. The system
involves utilization of bacteria, fish, shrimp, and water hya-
cinths in an enclosed greenhouse to produce clean water and salable
biornass. A system description follows.
The aquacell provides the majority of nutrient removal in this
water reclamation system. Bacterfa and water hyacinths absorb
nutrients present in incoming water and fish and shrimp feed on
bacteria and detritus deposited in the cell, forming a food chain.
Hyacinths are removed by harvesting. Because this system is enclosed
in a greenhouse, its .application is not limited to warmer climate
areas, although cooler climates will have larger land requirements.
Wastewater treatment will be effective year—round.
Over 500 tons of hyacinths/acre/yr are produced in the aquacell
requiring periodic harvesting (usually at least weekly). An operational
example of this type of system is the Hercules Municipal Wastewater
Treatment Facility in Hercules, California.
Raw reuse
2.5 Peat Beds
Peatlands have been characterized as areas: 1) Which have
periodic or permanently waterlogged soils with significant denitr—
ification potential, 2) Where characteristic submerged organic
soils have high cation exchange and sorption capacity, 3) Which
support nutrient deficient or low nutrient tolerant plants, 4)
Which have slow decomposition rates, 5) Which may function
as biotic nutrient filters, sediment traps, and control sun ner
water fluctuations from watershed runoff. These characteristics
describe a medium which is excellent as a natural biological
filter for nutrient utilization via aquaculture from primary or
secondary effluent. One such system has been demonstrated at the
North Star Campground, Chippewa National Forest. (4)
Following primary or secondary treatment, a peat bed planted
with a water tolerant grass (Ruff Stalk Blue Grass or Quackgrass)
series as a biological filter to polish applied effluent by util—
izing nutrients in the wastewater. This type of system is excellent
for seasonal operations such as sun ner camps and resorts for two
reasons; first, nitrogen removal occurs mainly by plant uptake
during the growing season and second, the system has minimal
operation and maintenance requirements.
back flush line

Biomass management requires that the grass be cut when
it reaches a 4” height for minimum matting problems. Quack-
grass and bluegrass yields were 1.7 and 0.6 tons/acre year,
respectively, for a six month growing season.
2.6 Fish Aguaculture (5)
A water stream typical of secondary effluent can be produced
by utilization of a waste stabilization lagoon and a fish aquaculture
lagoon. Fish will feed on bacteria, algae, and detritus which have
utilized nutrients present in the wastewater. Type;of fish grown
include carp, buffalo, channel catfish, goldfish, fathead minnow,
and golden shinners. The sale of fish produced in the lagoons will
partially offset operational costs. Caution in use of fish for
human consumption should be exercised.
The fish aquaculture system relies on bacteria and algae to
remove nutrients from the water which in .turn serve as food for the
fish. The process is dependent upon temperature and, therefore,
would require either storage capacity during colder months so that
treatment could be resumed in the sununer, an alternative treatment
method during winter to preserve high effluent characteristics or
a greenhouse.
.Sewa ge
sludge sludge crop
ha rvest

_____________________ 1
primary secondary fish
Raw stabilization stabilization ) aquaculture ) Reuse
Sewage lagoon i lagoon lagoon
2.7 Vascular Aquatic Plants* (6)
Lagoons filled with growing vascular aquatic plants (water
hyacinths and/or alligator weeds) can provide secondary treatment
of settled sewage. Nutrients in the primary effluent are utilized
by plants, thus removed from the wastewater. Unless these lagoons
are heated during colder months (as by solar greenhouses), the
use of these two aquatic plants is restricted to warm climates.
Duckweek, bulirush, cattails and others, however, will continue
to ve etate and remove nutrients during cold winter months.
The presence of aquatic macrophytes in place of suspended
algae is the n jor physical difference between aquatic treatment
systems and stabilization ponds. The role of the aquatic macro-
phytes in aquatic treatment in often misunderstood, in that the
plants themselves bring about very little treatment. The function
of the plants is to provide an aquatic support medium suitable for
enhancing the growth of other species, such as bacteria and aquatic
animals, which are responsible for the treatment of applied waste-
water (see Table 1).
* The details of this section have been adapted from “Aquatic
Systems for Secondary and Advanced Treatment of Wastewater”
by A. Scott Weber, G. Tchobanoglous, J.E. Colt, R.W. Ludwig,
and R.E. Stowell presented at 1981 National Conference on
Environmental Engineering, ASCE Environmental Engineering
Division, July 8—10, 1981, Atlanta, Georgia.

Table 1.-Functions of Aquatic Plants Growing in Aquatic Treatment Systems G
Plant Parts Fuf)ction
Roots and/or stems 1. Surfaces on which bacteria grow
in the water column
2. Media for filtration and adsorption
of solids
Stems and/or leaves 1. Attenuate sunlight and thus can prevent
at or above the water the growth of suspended algae
2. Reduce the effects of wind on the water
(e.g., roiling of settled matter)
Reduce the transfer of gases and heat
between the atmosphere and water
The principal wastewater contaminant removal mechanisms operative
in aquatic treatment systems are bacterial metabolic activity and
physical sedimentation. These are the same mechanisms utilized in
the activated sludge and trickling filter processes. The important
difference between conventional and aquatic treatment systems is
that treatment in conventional systems is brought about relatively
rapid in highly managed environments, whereas treatment in aquatic
systems is accomplished more slowly under conditions of less control.
These differences lead to lower construction and equipment costs for
aquatic treatment systems as compared to conventional treatment.
If aquatic systems can be designed to meet secondary requirements
or better, then they should be more cost-effective and less energy
intensive than conventional secondary treatment processes in many
wastewater treatment situations.
Aquatic treatment systems have the potential to remove a number of
wastewater contaminants such as suspended and colloidal solids, blo—
chemical oxygen demand (BaD), nitrogen, phosphorus, heavy metals, refrac-
tory organics, and bacteria and viruses. The principal removal
mechanisms for suspended solids, BUD, and nitrogen in aquatic systems
are described below.

Solids Removal
Solids removal mechanisms found in aquatic treatment
systems are the same as those found in conventional treatment
processes. Hydraulic detention times of several days and
longer are typical in aquatic systems and, as a result, most
if not all settleable and floatable solids are removed by sed-
imentation. Colloidal solids are removed by either entrapment
in the biological slime associated with the submerged portion
of aquatic macrophytes or collision (inertial or brownian) and
subsequent adsorption to other solias (plants, pond bottom,
settleable solids, etc.).
Removal of Biochemical Oxygen Demand
In aquatic treatment systems, BOO associated with settleable
solids is removed by sedimentation. Colloidal and soluble BUD are
removed metabolically by the bacteria attached on the submerged
portions of aquatic plants and in the benthic zone and by bacteria
suspended in the water column. Bacteria attached to submerged
plant’ parts are believed to be the dominant group in colloidal
and soluble BUD removal. Mechanistically, BUD removal in aquatic
systems is similar to that found in a slow rate trickling filter.
The principal difference being that in aquatic systems, biologically
active material (aquatic plants) is used as a substrate for bacterial
attachement rather than an inert material (rock), as is the case
in conventional trickling filters. As noted before, aquatic macro-
phytes do not directly remove significant amounts of BOO and, in
fact may contribute a positive net flux of BOO under certain loading
and climatic conditions.
Nitrogen Removal
The principal mechanism for nitrogen removal in aquatic treatment
systems is nitrificatiori-denitrification, although under certain
conditions, ammonia volatization (high pH) and plant assimilation
(harvesting conducted) may contribute to the total removal. Microbial
assimilation also contributes to the removal of nitrogen, but is
usually small in relation to the total nitrogen loading.
Nitrifying bacteria are most likely to colonize on submerged
portions of aquatic plants. Aquatic plants provide 1) a stationary
substrate for attached growth, which prevents wash out of slow growing
nitrifying bacteria and 2) a source of oxygen, a requirement for
nitrification, which is released through the root hairs to the water
column by the photosynthetic activity.

2.8 Existing Natural Wetland (
Several methods of secondary-or tertiarY-level treatment
are available through the use of existing wetlands. Nutrients
are utilized by variouS bacteria, algae, plants and animals
producing a polished effluent and usable biornaSSs. Algae or
plants grown in this fashion can be reused in the same fashion
as other aquatic biornaSS produced by wastewater treatment.
Existing wetlands currently being treated for nutrient uptake
from secondary effluent include: 1) peatlandS , 2) freshwater -
tidal marsh, 3) wetlandS, 4) cypress domes, and 5) saltwater
marshes. General commentS about these systems are discussed
Peatlands . Increased yields of biomasS (cattails, aspen,
alder, willó T were observed when simulated secondary effluent
was applied to test plots of peat. Nutrients percolating through
the soil were .negligible.
Freshwater Tidal Marsh . Chlorinated secondary effluent was
applied at various modes to a freshwater tidal marsh. A decrease
in total biomaSs was observed when compared to tap water sprayed
vegetation. Chlorinated effluent appears to be slightly inhibitory
to plant growth. Nitrate concentration was highest during high
slack water and averaged about 0.1 rng/1 N0 -M in the marsh effluent.
%4etlaflc!!. . The overland flow irrigation technique was applied
to SU IY a wetland with secondary effluent from a fish processing
plant. Nitrogen, phosphOrOUS and coliforms were reduced 51, 53,
and 99.99%, respeCti velY while an increase in biomass production
was observed.
ç preSS Domes . Cypress domes have been shown to reduce both
nitrogen and phos hOrOuS by 60% each in the natural setting. The
most dramatic change in the ecosystem was the production of a
thick cover of floating plants(w ter fern and duckweed).
ColifOrTfl organisms were reduced by 99.98%. -
Saltwater Marshes . ProductivitY is greatly increased (2-3
time Fwith the add fOn of nutrients to saltwater marshes. The
nutrient source can beseCofldarY se iage effluent. Increased algal
biomasS can be fed to oysters, clams, or fish.

3.0 Summary of Important Desjyp Considerations
The design of the arorementioned novel alternatives is still very nuch
a developing art and as such it is very difficult to accurately define design
parameters. Table 2 presents a list of the alternatives arid a summary of the
design considerations a designer should be a’. iare of in beginning to explore
these intriguing solutions to an age old problem.
4.0 Compost Toilets
Compost toilets are waterless, sanitary containers designed to receive
and decompose human wastes, including urine, arid other biodegradable organic
matter. The resulting compost can be used as a garden or soil additive, .l—
though it is often recorninended to bury it in the ground for further decomposi-
tion. (Lane County, undated; loinbardo, 1979). There are two types of
composting toilets commercially available: large and small. The large units,
such as Clivus Multrum, handle both toilet and some kitchen wastes, operdte
in the relatively low temperature range (up to 40°C), and generally require
infrequent removal of compost. The receiving chamber requires approximately
20-30 cubic feet beneath the bathroom floor, and uses very little, if any,
electrical energy. Small units, such as Mulbank, operate entirely within
the bathroom. They handle only toilet wastes, are usually heat—assisted (to
help dehydrate the pile), and operate in the higher temperature range
(40-70°C). Some of the small units are provided with devices to periodically
stir or turn the composting wastes.
Composting toilets are most often considered for use in areas where
extremely poor soil conditions inhibit the use of conventional on-site waste-
water disposal systems and sewer systems are economically infeasible. Many
states have specifically recognized the benefits of composting systems and have
incorporated their use into regulatory language. At least three states (Maine,
Massachusetts and Oregon) compensate for the use of composting systems by
allowing a reduction in the required absorption area necessary for wastewater
disposal. This reduction ranges from 30-40%.
Performance of Coinposting Toilets: Successful operation of a composting
toilet depends upon maintenance of proper conditions to foster good microbial
growth. A moisture content of between 40 and 70 percent is recommended. Below
that, the pile becomes too dry; above that, the system becomes water-logged
and starts to smell because of the anaerobic condition caused by water driving
out the essential oxygen. Human feces and urine, combined with toilet paper,
have an initial moisture content of 85-90 percent. The heat generated in the
early stages of the coniposting process will reduce the moisture somewhat. The
use of peat moss as a bedding, and the occasional use of dry organic matter
such as wood shavings, food wastes, etc. will further reduce moisture content.
Microorganisms generally consume 30 parts by weight of carbon for each
part of nitrogen. Thus the optimal carbon-to-nitrogen ratio of 30 is critical
to the composting process. Carbon and nitrogen content in waste material can
be measured quite accurately in the laboratory. Since the average toilet, user
. O.

Com Lned Aquatic Plants
* Strength of Wastewater
* Climate
* Loading Rate
Meadow/Mars h/Pond
* Strength of Wastewater
* Climate
* Economics of Harvesting
Plant Materials
* Loading Rate
Mixed Aquaculture
* Strength of Wastewater
* Climate
* Economics of Plant Harvesting
* Economics of Greenhouse
* Loading Rate
Peat Beds
* Primary or Secondary
Pretreatment Requi red
* Harvesting Required
* Climate
* Application Rate
Fish Aquaculture
* Stabilization Pond Required
(Pretreatment) Requl red
* Climate
* Economics of Fish Harvesting
(non-human consumption)
* Fish Stocking Rate
* Loading Rate
Vascular Aquatic Plants
* Climate
* Wastewater Strength
* Primary Treatment Required
* Economics of Plant Harvesting
and Possible Greenhouse
* Hydraulic Detention
Existing Natural Wetlands
* Primary or Secondary
* Environmental Sensitivity
of Receiving System
* Loading Rate

does not have access to this analytical convenience, some rather simple
monitoring evaluations can be made to maintain the 30:1 C/N ratio. First, if
a waste item remains structurally unchanged for two to four weeks, then the
C/N ratio is probably too high, and a nitrogen source should be added. Secondly,
if the odor of ammonia appears, too much nitrogen is present, and a high-carbon
source should be added. The latter case is frequently encountered after heavy
toilet use (such as parties and weekends) but is always correctable within a
short while.
Although both aerobic and anaerobic activity occurs in the composting wastes,
the former is desirable because it is a faster process and virtually odorless.
Therefore, composting toilets are designed to favor aeration by the use of vents
and small fans. Fresh air is channeled into the composting chamber and out a
vent stack in the roof. Water vapor is carried out of the pile, and odors,
if any, leave by way of the stack (the same way odors are vented in a conventional
flush toilet).
An important con ideration for compost toilet aeration is the structure
of the composting pile. Excess moisture can be removed from the pile only if
the compost ng material is kept from packing down too tightly. For this reason,
bulky, light material, su h as wood shavings, peat moss, shredded bark, etc.
help keep the pile porous. Mechanically mixing the pile also helps promote
good aeration.
Temperature is a fundamental parameter controlling the compost process.
Initially, high temperature organisms thrive in the wastes, then die off giving
way to lo ,er-temperatUre microbes. The high-temperature stage is essential to
destroy pathogens, while the slower, low—temperature stage promotes stabiliza-
tion of the wastes into humus. To maintain adequate temperatures, the units
should be insulated or slightly heated with coils or heat—tapes. Many of the
waste containers themselve are already well insu’ated, to capture the composting
heat. Insulating the vent pipe can further save heat and also prevent the
recondensation of water vapor back into the pile.
The composting process itself has been known and used for ages to recycle
Sand conserve organic wastes. Composting toilets have been developed, in their
present form, over the last fifty years, beginning in Scandanavia. One of
the most extensive investigations of corr nercially available units was conducted
by Guttormsen. His evaluation developed an overall rating of “good”, “satis-
factory”, or “bad”, with some toilets within each category.- He further reported
a compost weight reduction in the large type of 75 percent, and in the small
type of 90 percent. He found complete destruction of irinoculated Salmonella
and Polio-virus within one to four weeks. Results of other investigations are
summarized below:

Results of Evaluation of Performance of
Composting Toilets
Reference Type of Unit Results Problems
Valdmaa, 1974 small compost safe for
Dindal, 1978 use as a garden
anie ndrrient
Eliot, 1973 “Mulibank” absence of odors,
small amount of
enteric (intes-
tinal) bacteria
Nichols, 1976 large.and large systems large units: flies
small operated more associated with
satisfactorily kitchen wastes,
minimal odors,
fluid accumulation
probably due to
insufficient heat
small units: liquids
and odors due to
overloading and
improper rnai ntenance
Oregon, 1978 large and favorable user temporary odor and
small comments liquid build-up

1. What is the common misconception about treatment with vascular aquatic
2. What factors should be taken into consider tion before a mixed aquaculture
system is employed?
3. What pretreatment is required for a Peat Bed System?
4. What types of plants are most appropriate in a Combined Aquatic Plants
Sy stern?

1. Serdel, K., “Macrophytes and Water Purification,” in Biological
Control of Water Pollution , Ed. by Tourbier, J. and Pierson, R.W.,
University of Penn. Press, 1976.
2. Small, M.M. and Wurrn, C., “Data Report: Meadow/Marsh/Pond System,”
Brookhaven National Laboratory, BNL 5O675, April, 1977.
3. Serfling, S.A. and Aisten, C., “An integrated , controlled environ-
ment aquaculture lagoon process for secondary or advanced waste-
water treatment , in Performance and Upgrading of Wastewater Stabi-
lizatiàn Pond , EPA 600/9—79—Oil.
4. Stanlick, H.T. “Treatment of Secondary Effluent Using a Peat Bed”,
•In: Proceedings of the National Symposium on Freshwater Wetlands
and Sewage Effluent Disposal , University of M chigan. Ann Arbor,
May 1976.
5. Bordach, J.E., Ryther, J.H., and McLarney, W.O., Aguaculture: The
Farming and Husbandry of Freshwater and Marine Organisms , with,
Interscience, New York, 1972.
6. Weber, A.S., Tehobanoglous, S., Colt, J.E., Ludwig, R.W., and Stowell,
R.E., “Aquatic Systems for Secondary and Advanced Treatment of Waste-
water”, Paper presented at 1981 National Conference on Environmental
Engineering, ASCE, Environmental Engineering Division, July 8—10, 1981,
Atlanta, Georgia.
7. Spangler, F.L. et. al., “Wastewater Treatment by Natural and Artificial
Marshes”, IJSEPA 600/2—76—207.
8. Dindal, D., 1978, “Comparing Toilet Compost with other Organic Waste
Sources, “ Compost Science , vol. 19, March/April.
9. Eliot, E., 1973, “A Request for the Approval of Aerobic Decomposition
Apparatus known as Mulibank,” translated memorandum, French Ministry
of Public Health.
10. Guttormsen, D., 1977, “21 Biological Toilets,” Microbiological
Institute, Agricultural College of Norway.
11. Guttormsen, D., 1978, “Some Aspects of Composting Toilets with Specific
Reference to Their Function and Practical Applications in Norway,”
in Individual On-Site Wastewater Systems, Proceedings of the Fourth
National Conference , Ann Arbor Press, Ann Arbor.

12. Lane Co., undated, “Composting Toilets, “(J. Theios, editor)
Lane County Office of Appropriate Technology, Lane County, Oregon.
13. Lornbardo, p., 1979, “Alternative Wastewater Management Systems
and Their Applicability to Arkansas,” The Winthrop Rockefeller
Foundation, Little Rock.
14. Nichols, 1976, “Analysis of Ba t rialPoupulations in the Final
Product of the Clivus Multrun,’ Center for the Biology of Natural
System, Washington University, St. Louis.
15. Oregon Department of Environmental Quality, 1978, “Progress Report,
Composting Toilets.”
16. Guttormsen, 0., ‘Alternative Solutions to Toilets for Vacation Homes
and Permanent Residences,” The Project Committee for Purification
of Sewage Water 21, Norway, 1979.