Ecological Wastewater Management:
Opportunities for Decentralized
Non-Polluting On-Site Solutions

Jacky Foo

Carol Steinfeld
Center for Ecological Pollution Prevention (CEPP)
P.O. Box 1330, Concord, MA 01742 USA
Email: info@
Web: www.

David Del Porto
Sustainable Strategies
50 Beharrell Street, Concord, MA 01742 USA


Nearly every island nation has identified critical environmental and public health problems resulting from the disposal of human (and animal) excrement:

• contaminated drinking water wells (nitrates, bacteria)

• outbreaks of gastrointestinal disease, leptospirosis and cholera,

• dying reefs, algae blooms and eutrophication in lagoons


The causes of this pollution include:

• overflowing latrines and privies

• water-sealed toilets

• septic systems

• piggeries

• some sewage treatment plants

• complete lack of sanitation facilities in some places

Girls next to pour-flush latrine outside of Suva, Fiji


The easiest way to divert potential pollutants
from the environment
is to use them up.


Ecological systems utilize the nutrients in water for productive reuse.

Two Process Aspects:

1. Create aerobic conditions:
Aerobic bacteria--oxygen-using bacteria--can work 10 times faster than anaerobic bacteria to destroy pathogens and convert nutrients to a plant-available form.

2. Use plants to eat, drink and evapotranspire the effluent.
Plants both take up nutrients, evapotranspire moisture and provide root zones for biological transformation

The approach:

  • Conserve: Use water-efficient appliances and fixtures, so that less wastewater is created. Examples: dry or microflush toilets and low-flow faucets and showerheads.
  • Pretreat: Filter at the source to remove larger particles so it can be used by plants. In kitchens, use grease and food interceptors. Disinfect with ozone or UV if to be used for potable water.
  • Divert/Separate wastewater components: By keeping flows separate, they can be better and more cost-effectively treated and utilized.
  • Reuse or reclaim effluents for use



Lalati Resort, Beqa Island, Fiji
Upmarket resort with seven guest houses attracts divers and surfers. Owners wanted a site-built
non-polluting zero-waste discharge wastewater system that the staff could easily maintain.

All buildings, including the kitchen, at Lalati Resort (Fiji) are served by

• Aerobic blackwater biofilter/Composting toilet (made of locally purchased plastic container, with fittings; cost: $50USD)

• Microflush toilets (1/2-litre flush/1 pint flush)

• Wastewater Gardens that uses up all washwater (sinks, showers) and leachate from the composter/biofilter

• Rooftop rainwater collection (to 2400-litre cistern) provides much of the resort's water

The staff adds coconut coir every few days. When a composting reactor fills--anywhere from 3 months to 1 year--it is taken to a covered central area to further process. In six months, the material should be fully processed and ready to be added to a composting pile to further process or to be applied to soil.




The Ecological Approach
It is less costly to prevent pollution than to treat it later.


  • Prevents bacterial and chemical pollution (health risks)
  • Prevents nutrient pollution (unwanted water weeds, dying aquatic life and groundwater contamination)
  • Conserves water (less water used, less water needs to be cleaned)
  • Captures and reuses nutrients and water (saves money, no discharge)
  • Can save money over the cost of conventional systems
  • The results: cost savings, natural resources preserved, disease transmission avoided, nutrient and water cycle preserved on site



Simple On-Site Graywater and Blackwater Recycling

Greenpeace Composting Toilet System
(a.k.a. CEPP Twin-Bin Net System)
Yap (& Kosrae and Pohnpei, Micronesia)

• Early 1990s, three different composting toilet systems were designed and demonstrated through local construction workshops on the islands of Yap, Kosrae, Pohnpei, and Palau. (Sponsor: Greenpeace; contractor: Sustainable Strategies)

• When one chamber fills up, it is capped and the other side is made active. When this one has filled, the other side can be emptied. At this point, what is removed is a stable soil-like humus, which can be used as a soil conditioner. It is usually five years before the first chamber is emptied.

• The most succesful installations were in Pohnpei, whereby several were built by the property owners with plans and a small subsidy provided by a local agency.


Graywater and Blackwater Recycling: Success Factors

The success of introducing composting toilets (and other alternative wastewater systems) depends on

• Installation

• Education: technical support and operator education

• Design: some are better than others

• Cultural factors: perceptions about system height, exreta handling, etc.

• Cost: affordability (costs range from USD$60 to $3,000)

• Awareness: perceived need for better sanitation


(Further systems have been built and demonstrated in Fiji and Tonga)


Manufactured Composting Toilet Systems

Manufactured systems offer ready-made hardware and uniformity, although they can be expensive to import and still require considered installation and user education.


• Rock Islands, Palau (15)

  • Installed due to high fecal coliform levels around islands due to tourist latrines
  • EcoTech Carousel Composting Toilet Systems installed; four rotatable containers in bioreactor, based on Norwegian design
  • Sponsored by Palauan and U.S. agencies
  • High acceptance
  • Extra liquid is drained to Wastewater Gardensbetween the two toilet rooms.

• Yap Institute of Natural Sciences (YINS)

• W. Samoa and Tokelau Atoll

(1. Manono island, Samoa 2. Opening of system at YINS)




To optimize these systems further, CEPP has:

• reduced the size

• optimized biological processing (faster!)

• lowered the cost


(simple urine-diverting toilet composting system in Mexico)


Urine Diversion

In the United States, Europe, Australia and Asia, urine is diverted to prevent eutrophication and nitrate pollution and to recover nutrients.


• urine is usually sterile

• urine contains 90% of the nitrogen in wastewater


This can be done with urine-diverting toilets. The urine is

• combined with graywater and used to fertigate crops


• composted with high-carbon materials (wood chips, sawdust, cardboard, etc.)

(urine-diverting toilet from Sweden)


Graywater/Washwater and Shallow Aerobic Leachfield Systems

These aerobic planted (root zone) systems are increasingly installed as they provide faster aerobic processing of effluent.

• Constructed Wetlands: Saturated systems that provide aerobic transformation.

• Wastewater and Washwater Gardens: are like wetlands but unsaturated, allowing for more aerobic activity, faster processing.

• Shallow, planted, aerobic leachfields: provide more aerobic treatment than standard ones. The challenge is to prevent them saturation with rain


These systems can be scaled up to serve clusters of homes and even whole communities.

Managing Decentralized Solutions

Globally, more communities are moving toward managed decentralized solutions, as they can be less expensive and more effective.

The goal is to provide centralized management of decentralized systems. For many areas, it is more cost-effective to fund and train a team of people to manage many onsite systems than it is to construct, operate and train personnel for a central WWTP.

Organizations to manage decentralized systems, include municipal utilities, water boards, and management contracts.

Water supply and wastewater are linked, as enhancing piped water supply historically has the concurrent issue of more wastewater to manage. Also, wastewater choices affect water quality.



Cluster (Village) and Central Systems


Sludge can be dewatered and composted or land applied (where appropriate) where nutrients can be used by plants, such as timber crops.

Resulting effluent can be tertiary treated with wetlands and other aerobic root zones systems

Or it can be land applied for use by timber crops and other crops (coconut plantations)



Solar Aquatics: This is tank-based system, which serves a community of 300 homes, acts as a super-optimized artificial wetland. Water is reclaimed for flushing toilets.

Water Hyacinth Large Central System: This water hyacinth system is a polishing pond at a large wastewater treatment plant in California. Water hyacinth (a high-protein pig food) takes up the nutrients and further treats the effluent before it is discharged to the ocean. Eutrophication possibilities are thus reduced.


Systems for Commercial Organic Effluents:
Creating Resources


Vailima Brewery


Montfort Boys Town: Biogas



Growing fish or duckweed; best if product is not for human consumption, unless it is tested first.

Montfort Boys Town



Jacky Foo




CEPP is looking for a site at which to establish a demonstration of two systems
and educate a local resource person or agency.


Center for Ecological Pollution Prevention (CEPP)
P.O. Box 1330, Concord, MA 01742 USA
Web: www.

The CEPP EcoSan Center promotes ecological sanitation (EcoSan) systems, practices
and programs--we link people, programs, information, and resources.