Decentralised Sanitation Systems

Our sanitation solutions go where centralised sewer systems don’t—giving people access to basic sanitation (a human right), reducing environmental contamination, recovering valuable resources, and producing reusable by-products for agriculture and energy.

To be sustainable, decentralised systems must be low-cost, require little to no water and electricity to run, use locally available materials and bio-based processes, and be simple to operate and maintain. Sustainability also requires buy-in and ownership from the local community as well as policy support from local governments.

BORDA and its partners design, implement and evaluate decentralised sanitation systems around the world.

The urgent need: developing sanitation systems where the sewer doesn’t go

Dar es Salaam, Tanzania city sanitation planning map

FSM: working along the entire sanitation value chain

60% of the world’s population lacks access to safely managed sanitation and 1/3 lack even basic sanitation. Those who do have access to simple sanitation mostly use pit latrines. Particularly in urban areas, the lack of wastewater management endangers public health and pollutes the environment, as informal collection services often dispose of the faecal sludge in water bodies or fields.

Faecal sludge management (FSM) is a multidisciplinary approach to develop solutions for this problem. It includes technical options for customised sludge collection, transport, treatment, and recycling—while also integrating a business model as an essential part of the concept.

In the field of faecal sludge management (FSM), BORDA and its partner CDD Society are pioneers and leaders with over 10 years of on-the-ground project experience around the world.

Our full-cycle approach enables town-scale FSM infrastructure and services adapted to community needs, with FSM systems that are replicable and adaptable to other locations.

Our process includes:

  • stakeholder surveys to better understand local sanitation needs and challenges
  • data collection and analysis
  • data- and stakeholder-informed designs for end-to-end FSM systems
  • location-tailored faecal sludge treatment plant (FSTP) construction and operation, with technical specifications derived from the baseline study

Our system solutions include:

  • policy frameworks for local authorities with stage-based implementation
  • FSTP operating policies
  • streamlined transportation of faecal sludge from septic tanks and pits
  • support for local authorities and state governments in the bidding and selection process, in preparing bid documents and processes, and evaluating bidders

From start to finish, FSM services are designed to ensure that city partners achieve their sanitation goals

Integrating the entire FSM value chain into city planning, generating sustainable income through sludge collection and treatment services






Supported by the Bill & Melinda Gates Foundation

In Devanahalli, a town of 30,000 people located 40 km northeast of Bangalore, the local municipality joined forces with experts from BORDA and our partner CDD Society to design and build a successful, first-in-India faecal sludge treatment plant (FSTP).

No sewer systems for the next 10 years, rapid growth with no piped water supply

Against this stark reality, the need for faecal sludge management (FSM) in Devanahalli was critical. The town faced an urgent need to deal with:

  • lack of treatment capacity for faecal sludge collected in tanks and pits (10x more toxic than sewage)
  • open defecation
  • faecal sludge dumped into fields and water bodies
  • night soil washed out into open drains and ditches

These challenges are typical of countless municipalities around the world. With its FSTP, Devanahalli has become a proving ground for innovation in FSM. In India alone, where water-borne faecal contamination kills 500,000 people every year, FSM can serve 7,000 small towns and cities that will be home to 300 million people by 2030.

A new approach to technology and management

An intensive collaboration in Devanahalli between locals and experts has produced a holistic, scalable FSM solution that meets local needs and works within local conditions along the entire FSM value chain from initial capture to final reuse. The project demonstrates implementations in two key areas:

  1. treatment of faecal sludge for towns of 20–30k people (FSTP design, construction & operation)
  2. management approaches for sustainable operations and financing

Launched in 2016 and financed by the Bill & Melinda Gates Foundation, the success of the Devanahalli FSTP has led to:

  • receipt of the 2017 Best Innovation in Sanitation Award (FICCI – Federation of Indian Chambers of Commerce and Industry)
  • adoption of the Devanahalli model for 30 new FSM projects currently commissioned in towns across India, with over 100 expected by 2019 as part of the Clean India Mission
  • FSM system designs for Nepal, Bangladesh and Bhutan

In a model project attracting international attention, a new approach to town-scale sanitation services

Devanahalli FSTP: odour-free and attractive

Video: Outside Bangalore, India's first faecal sludge treatment plant

A second act for faecal sludge: reusable by-products

sludge → soil conditioner
biogas → fuel for cooking
leachate → composting of solid waste
treated effluent → irrigation

In providing FSM services for all residents, access to homes can be a challenge. Especially in high-density areas, where narrow irregular streets block the large trucks typically used for faecal sludge collection.

In Dar es Salaam, Tanzania’s most populous city, two BORDA-built faecal sludge treatment plants (FSTPs) make use of innovative solutions for reaching homes and transporting sludge.

  • The Kigamboni plant—which serves 40,000 people from 6,000 households—uses Sludge-Go, a small tractor with a tank-trailer and motorised pump.
  • The Mlalakua plant, which treats up to 5 cubic metres of sludge daily for 20,000 people, employs motorised trikes to transport small tanks and hand-pumping equipment, which are then carried the last few metres on foot.

For both FSTPs, all homes in their service areas are now within reach.

Sludge-Go: a small tractor with a tank-trailer & motorised pump

Motorised trikes transport small tanks and hand-pumping equipment

DEWATS: bio-based, low-cost decentralised wastewater treatment

In many countries around the world, wastewater treatment systems are inadequate or non-existent. Conventional sewerage systems are often difficult or not feasible to build due to financial limitations, lack of density, or the rapid growth of unplanned settlements. As a result, more than 80% of the world’s wastewater is discharged untreated into the environment.

DEWATS are able to supply densely populated urban areas, as well as rural areas, with adequate wastewater treatment. Easy maintenance, low construction and operation costs, and independence from urban infrastructure makes DEWATS suitable for poor urban and peri-urban areas, schools, hospitals, and small businesses with organic loads in their wastewater.

The DEWATS technology implemented by the BORDA network has proven itself for many years in Asia and Africa, and has become an integral part of numerous government sanitation programmes.

DEWATS reduces the organic load in wastewater, one of the most significant causes of disease and environmental contamination

Anaerobic baffled reactor: the heart of DEWATS (click to enlarge)

Dar es Salaam, Tanzania, with its extensive non-sewered areas and a population set to double in the next 10 years, is fertile ground for demonstrating the suitability of DEWATS.

A UN-funded BORDA project, conducted at multiple sites in non-sewered areas of the city, aims to use its comprehensively collected baseline data to develop standards and guidelines that will support the scaling up and replication of decentralised treatment systems across Tanzania.

The project Demonstration of decentralised wastewater projects in non-sewered areas of Dar es Salaam, funded by UNEP and UN-HABITAT, intends to showcase the suitability of decentralised wastewater treatment projects for non-sewered areas such as the large housing developments emerging on the outskirts of Dar es Salaam.

New housing development in a non-sewered area

Video: The Urban Sanitation Challenge (Tanzania) provides context for the UN-Habitat project

School should not make children sick. But in many countries, schools have either have no toilets or they have highly inadequate ones. Girls in particular will often miss school when there are no safe toilets. BORDA and its partners work closely with schools to improve the situation for children.

Applying the School Based Sanitation (SBS) approach in more than 50 Cambodian schools in cooperation with UNICEF, BORDA Cambodia and its partner ESC (Environmental Sanitation Cambodia) have improved the health, hygiene & sanitation situation for more than 30,000 students and teachers.

Our solutions for schools focus on providing water, sanitation and hygiene (WASH) facilities supported by education and proper management:

  • A technical component with the construction of child-friendly toilets, biogas plants to generate energy for cooking in the school kitchens, and a decentralised wastewater treatment system (DEWATS).
  • A social component with hygiene education for students and teachers, as regular handwashing with soap can prevent many diseases.
  • A management component to develop internal processes for maintaining the facilities and providing hygiene education.

Video: an overview of school-based sanitation (SBS) projects implemented by ESC-BORDA in Cambodia

The Abdul Rahman Great Mosque, inaugurated on 20 July 2012, serves more than 10,000 Muslim visitors per day. It is one of the largest mosques in Afghanistan and Central Asia.

Its decentralised wastewater treatment system was attached to an already existing but underdesigned settler, in order to enhance the treatment efficiency of the used water coming from the toilet complex.

The treated water irrigates the garden or is discharged into a nearby drain. The treatment plant is operated and maintained by the mosque management, with training provided by BORDA engineers.

The Adbul Rahman Great Mosque, one of the largest in Afghanistan

Aravind Eye Hospitals is a hospital chain in India that plays a major role in the eradication of a cataract-related blindness in India.

The 500-bed hospital in Pondicherry discharges more than 300 cubic metres of wastewater per day. BORDA and its local partners designed and installed a decentralised wastewater system that successfully tackles this problem.

During the planning process, efficient use of the available land and the reuse of the treated water were given the highest priority.

The implementation of this treatment plant allows the hospital to save more than 100,000 cubic metres of fresh water annually, by using treated water to irrigate a large garden and orchard.

Video: Aravind Eye Hospital

Biogas: generating renewable energy from treatment processes since the 1970s

Biogas can be produced from domestic wastewater, compost, faeces, industrial wastewater with organic matter, and livestock and slaughterhouse waste. A biogas plant is often installed with DEWATS to produce methane gas, which can be used for cooking or lighting. Using biogas—a renewable energy source—instead of firewood or other energy sources helps to protect the local environment and mitigate climate change.

Especially for poor families and school kitchens, using biogas brings substantial cost savings, reducing or eliminating the need to buy gas cartridges and firewood. It also enables users to operate small side businesses such as catering services or restaurants.

BORDA has pioneered the implementation and dissemination of biogas applications since the 1970s. In addition to biogas for homes, schools and small businesses, BORDA is also focusing on novel uses such as powering Stirling engines for agricultural use.

Biogas units connect treatment to energy generation

DEWATS biogas unit (click to enlarge)

Together with Cubasolar, BORDA is working in Cuba to strengthen the national network of biogas users from small farms. BORDA provides advice on the development of a strategy for institutional growth of the biogas movement and facilitates technical workshops. A key focus is the introduction of closed-cycle concepts, linking waste treatment with the generation of resources and the protection of aquifers.

DESWAM: decentralised solid waste management

In many poor urban areas, neighbourhoods are difficult to reach and do not have any public or private waste management services. Waste piles up between houses, clogs drains and provides a breeding ground for pests. Decentralised solid waste management (DESWAM) offers concrete solutions to these problems.

The aim: bringing together local communities, governments and the private sector to establish sustainable decentralised structures to collect and treat waste in residential areas.

The BORDA network’s DESWAM service offers demand-driven modules that are adjusted to local environmental conditions and users, and provide different options for waste disposal and recycling. The end result: reuse-oriented infrastructures that keep waste out of the environment, recover valuable resources, and generate income for local communities. Optional modules include:

  • materials recovery facilities (MRFs) built in close cooperation with local governments (where adequate space is available);
  • composting plants where aerobic composting of organic waste reduces greenhouse gas emissions and produces nutrient-rich fertiliser;
  • recycling depots that buy up recyclables, like plastic and glass, and resell them to the recycling industry;
  • sorting facilities where mixed waste is separated into different categories, without further processing;
  • proper disposal of residual waste at official landfills;
  • waste reduction and prevention programmes;
  • educational initiatives.

The BORDA network approach includes:

  • module selection and customisation that takes into account the number of available staff, the amount of waste, topographic conditions, environmental capacity, and financial limits;
  • decentralised facilities that are run by private operators or by community-based organisations emerging from user communities;
  • enabling independent small businesses that can be established in areas with limited space;
  • transferring knowledge to support facility operators;
  • ensuring that facilities have sustainable sources of financing, such as from the sale of compost and recyclables, and monthly fees collected from participating households.

This innovative approach to providing decentralised solutions for waste management ensures sustainable functionality, even under difficult conditions. DESWAM not only contributes to a cleaner environment and improved public health, but also provides jobs and strengthens local development.

Reducing the amount of waste by closing the material and nutrient cycles—together with local community members, the municipality and the private sector

The need: sustainable collection & treatment of waste

Our Indonesian solid waste management projects—KIPRAH (Kita Pro Sampah is Indonesian for “We pro Waste”) VER (Voluntary Emission Reduction)—have been registered and verified as the first community-based composting projects worldwide under the Gold Standard scheme. Operated by community-based organisations, KIPRAH VER projects apply an innovative aerobic composting method that contributes to the reduction of greenhouse gas emissions.

Developed with our Indonesian partners BEST and LPTP, KIPRAH VER was certified to the CDM (Clean Development Mechanism) Gold Standard in 2014. The aerobic composting of organic household waste, combined with reducing the amount of waste, aims to reduce climate-harming methane emissions.

Through its 19 recycling centres and a partnership with German NGO atmosfair, KIPRAH VER offsets the emissions of 5,000 tonnes of CO2 equivalents per year.