Rural Development Organization (RDO) Gramya Bhavan Aruvankadu-India



In 2016, Mr.Valentin Post of WASTE in the Netherlands who had earlier partnered with the RDO Trust in the construction of household toilets to eliminate open defecation in the Nilgiris, under the FINISH Programme discussed with Mr.Perumal, Founder/Director of RDO Trust to explore the possibility of constructing a Faecal Sludge Treatment Plant (FSTP) for recycling of black water. After due clarification on what this entire process was about, Mr.Perumal using his contacts and good offices, initiated a discussion with Mr.Kandavadivel of High Field Estate to explore the possibility of setting up the FSTP in his estate. This initiative was dropped as Mr.Kandavadivel expressed that there was an objection from the nearby residents for this activity. Mr.Perumal then discussed with the management of Chamraj Estate and was able to not only get their acceptance but also their immediate response in providing 25 cents of land area after up-rooting the tea bushes present in the area for the construction of the FSTP.

Pilot Project at Chamraj Estate

Thus, the first FSTP was established at Chamraj Estate in the Nilgiris. This FSTP was a model of the vertical and horizontal planted drying bed technology and was found to be very effective. Though the Chamaraj group was keen to use the dry sludge compost to their tea garden, they were unable to do so as their entire estate was under the Fair Trade and Rainforest Alliance certification which does not permit the use of human excreta as compost even if it is treated.

Therefore this initiative was seen only as a research and development intervention in the field of efficient and effective Faecal Sludge Treatment which could be replicated as a model for a circular economy initiative at a later stage.

Securing Water for Food (SWFF)

 The United States Agency for International Development (USAID) WASTE, SIDA, and BORDA pooled US 500,000 and implemented the Securing Water for Food(SWFF) program which ran from June 2017 to May 2020. Globally, water scarcity is on the rise, and addressing these shortages is a challenge. The  SWFF program aims to enable the production of more food with less water and/or make more water available for food production, processing, and distribution in developing and emerging countries. The SWFF program is investing in innovations at the water-food nexus that has high potential to be brought to scale to improve water availability and efficiency along the food value chain, thus boosting food security, alleviating poverty, and stimulating inclusive growth. The partner organizations under the SWFF program offer acceleration support and technical assistance to local beneficiaries to alleviate the water scarcity problem and improve water availability for food production.

As providence would have it, WASTE and RDO Trust showcased this as an innovative intervention in the recycling of black water for a Circular Economy in Sanitation for Agriculture under the Securing Water For Food Programme in the year 2017 with the USAID – Round IV Grand Challenge.


 The Resource Recovery Parks of two Town Panchayaths, Ketty and Adigarahatty have been brought under the SWFF Project for the recycling of black water and the production of co-compost. Two faecal sludge treatment plants have been constructed with a capacity to recycle 69,500 litres of black water. By streamlining the entire process of compost production and incorporating the dry faecal sludge from the FSTP, a total quantity of 691.50 Tons of co-compost was produced and distributed to 1,753 vegetable growing farmers in an area of 962.12 hectares of land.

 The co-compost produced in the FSTP was sold at Rs.4,200 per ton during the first year and Rs.5,000 per ton during the second year.

Institutional Arrangements

 As a means to institutionalize the participation and involvement of women farmers, 4 Women Farmers’ Producers’ Companies, 34 Farmers’ Interest Groups, and 104 Women Farmers’ Groups have been established. A total of 1,753 farmers are enrolled as members to benefit from the input and marketing tie-up with Agri-business companies. This results in realizing better prices for the vegetables produced and thereby better income with reduced input cost. Farmers’ Service Centres have also been established to further develop the agri-business through these farmers institutions.


Faecal sludge treatment plants at both KRRP and ARRP consist of:

  1. Constructed wetlands and
  2. Co-composting

Private honey sucker operators collect faecal sludge from households and go to RRPs to safely dispose of the faecal sludge into the constructed wetlands. Since the collected faecal sludge comprises of a mixture of raw sewage, partially digested sewage, and some fully digested sewage, a conventional sludge drying bed may not be effective. While there are several technologies available for the treatment of sludge of this nature, the one found most suitable was the constructed wetlands technology.

The constructed wetland consists of two parts:

The long solids retention period favors further mineralization and pathogen die-offs. The percolate quality considerably improves but may still require a polishing treatment. The filter and drainage system of the constructed wetlands is similar to a drying bed.

1. The first part is a vertically constructed wetland for treatment of sludge. This constructed wetland comprises of gravel and sand and is planted with native marsh plants that are tolerant to a wide range of environmental conditions (varying humidity, salinity). The sludge is loaded on the bed and dewatered by percolation and by evapotranspiration through the plants. The root system of the plants maintains the permeability of the sludge layer and sludge can be added continuously. Sludge has to be removed once every fortnight.


  • The filtered wastewater continues to flow to the horizontal constructed wetland.
  • The dried sludge is removed from the bed and gets mixed with organic waste for co-composting

2. The second part is a horizontal constructed wetland for the treatment of the filtered wastewater from the vertically constructed wetland. It consists of a sand-gravel matrix (sealed at the bottom) planted with wetland plants like PhragmitesTyphaScirpus,

Horizontal flow soil filters are commonly found, and easier to construct than vertical flow filters, but they are less efficient at eliminating nitrogen. Wastewater is treated through several processes, in which bacteria and fungi play important roles.


  • The treated wastewater can be reused for the composting process or directly for irrigation.


Co-composting is the controlled aerobic degradation of organics, using more than one feedstock (faecal sludge and organic solid waste). Faecal sludge has a high moisture and nitrogen content, while biodegradable solid waste is high in organic carbon and has good bulking properties (i.e. it allows air to flow and circulate). By combining the two, the benefits of each can be used to optimize the process and the product.

At the RRP, municipal solid waste (MSW) is received and the dry and wet waste (biodegradable solid waste) is segregated. The dried faecal sludge from the vertically constructed wetland gets mixed with this wet waste for the co-composting process.


  • The Co-compost is used to add nutrients to the soil which is polluted due to excessive usage of chemical fertilizer.

Grey Water

Innovative water capture and storage technologies approach enables people to improve and manage their water supply, reducing reliance on freshwater and public water supply systems. An innovative approach to managing water supply for food production is the use of non- conventional water sources like treated wastewater.

In the project area villages around Ooty and Coonoor of the Nilgiris District in Tamil Nadu, due to topographical constraints (rock beds), groundwater is not so easily available for irrigation. Freshwater availability from public supplies is decreasing and rainfall is also becoming inconsistent, based on rainfall data of the last ten years1. Farmers, growing vegetables are facing major challenges in keeping up the water supply especially in the dry season. To extend the crop season, this project has focused on recycling the greywater being generated at every household in the villages, with appropriate treatment for irrigation of the vegetable crops.

Greywater from the households that have been collected is treated to a level that it becomes suitable for irrigation. It also meets the safety and quality standards for recycling as set by the Tamil Nadu Pollution Control Board. The treated greywater is stored in farm ponds and then used for vegetable crop irrigation.

Greywater is the wastewater generated in households other than from toilets (therefore without faecal contamination). The source of greywater includes the water used in kitchen sinks, washbasins, showers, baths, and washing clothes. “Combined greywater” is the term used for this composition. The greywater collected is dependent on the quality and type of water supply and user practices at the household level.

The Project beneficiaries are specifically women farmers, Farmers groups, and Self-Help Groups.

2 Design objectives of the Grey Water Treatment System

 The overall objective of the proposed Grey Water Treatment Systems in the villages is to allow for greywater to be regularly channeled from the households to the treatment points before it reaches the farm ponds. This is to allow for maximum capture and treatment so that treated wastewater is available for recycling and use by the farmers while also ensuring that the health of the community is not adversely affected. This would in turn ensure that the natural environment is safeguarded against contamination. The proposed approach to be adopted for the treatment process is cyclic – ensuring that the nutrient cycle and the water cycle do not cross contaminates each other and that nutrients are put back into the soil. The objectives can be summarized as follows:

  1. Capture and treat grey water and allow for nutrients present in it to flow back to the soil by using treated greywater for agriculture.
  2. Capture the treated greywater making it available for recycling especially for use during the dry season extending the crop season for the farmers and decreasing dependence on freshwater/groundwater for irrigation
  • The Treatment System should be aesthetically agreeable so that it can demonstrate the integration of Grey Water Treatment Systems in the farming community
  1. The Grey Water Treatment System should be low cost and robust so that replication is simple and effective
  2. The Grey Water Treatment System should be safe for the farmers as they reuse the treated water for irrigation

Design considerations

Houses in the villages in Nilgiris are usually arranged in rows as shown in Figure 1. Wastewater other than from toilets (black water) is directed in PVC pipes out of the house usually into the backyard. These pipes carry the greywater (from sinks, showers, kitchen, utensil washing, clothes washing) to either cement-lined open channels or open dug channels in the soil (Figure 2 & Figure 3). These channels either end in the vegetable fields directly without any treatment or are directed to farm ponds, where it gets collected and is used by the farmers for irrigation of crops (usually garlic, carrots, potatoes, beans, broccoli, salad crops). At present, there is no treatment provided. Hence this wastewater carries food waste, detergents, soaps, and rainwater.

Grey Water Treatment Concept

 Basis of design

 Treating greywater in the villages has to consider technology options that are suitable for temperatures ranging from around 5 degrees to 25 degrees and an annual rainfall of around 1250 mm. As the community of farmers expects a simple, robust system with minimal operation and maintenance requirements a natural biological treatment system working in tandem with the natural environment around it would be the most effective.

Quantity, quality, and output requirements affect the choice of the technology option for treatment. Before reaching the point of greywater collection, a 5% loss can be assumed due to groundwater infiltration and evaporation loss.

During the rainy season, rainwater (as surface run-off) also flows along with the greywater in the open channels that finally lead to the collection/treatment unit for each cluster of households. Therefore, the final wet flow needs to be calculated for estimating the treatment quantities.

Norms and regulations: The selection of treatment technology also depends on the final effluent quality required. This is usually based on the legal standards of a country or state for greywater reuse. In India, currently, there are no specific regulations or norms for greywater reuse as this concept is just developing, though some states have initiated defining standards for sewage reuse after treatment. As per the regulations from the Central Pollution Control Board (CPCB), 1996, the standard for reuse of treated sewage in agriculture requires a BOD of 100mg/l. There are no specific standards for the reuse of treated greywater in agriculture.

From the farmer community’s perspective, they have been using untreated greywater to some extent while depending extensively on freshwater for irrigation water supplies, which is fast depleting. They are in the need of an alternative source of water supply for irrigation purposes and treated greywater would be a safe alternative.

Treatment Concept

Based on the literature review, the characteristics of combined greywater require a full-fledged treatment system that would be able to remove the organic load (mostly present in the dissolved form), surfactants, and the nutrient content. Separation of streams from kitchen and laundry uses would reduce the pollution burden, though in turn it would create more complexities for treatment at the house level and especially in a rural setting. Therefore, preventive measures (like source control – using organic detergents with less sodium and phosphates, separating kitchen waste at source, installing a screening device in the kitchen so that food waste does not enter the grey water stream) to minimize pollution loads would be more useful and beneficial to the community as well as for the treatment objective.

Literature reviews on technologies for greywater treatment suggests that just physical treatment methods would not be adequate for removing the organic, nutrients, and surfactant loads.

Chemical/biological processes would also be required to remove suspended particles and the organic/nutrient load and surfactants. A combination of physical filtration and sedimentation, biological degradation, and absorption can be considered as an economical and feasible solution for greywater treatment.

Farm Pond

Farm ponds are natural water collection systems that are currently in use at the farms in Nilgiris. These are open excavations in the farms to collect rainwater and also allow for groundwater to filter into it. The recycled greywater is collected and stored in these ponds. The treated water from the farm ponds is safely used for irrigation in the crop field by pumping it out as is the current practice by the farmers.

Keeping in mind the need for a robust, simple to operate and maintain treatment system, while minimizing the pollution load as stated in the earlier sections, with the objective of reuse in agriculture under the Securing Water for Food Programme, 13 Grey Water Recycling units were constructed using simple technologies for efficient use and management by the vegetable growing farmers. Three different models have been tried to study the cost and efficacy.

  • Operation and Maintenance Requirements

The operational and maintenance tasks for both the options are simple and few. However, they need to be carried out regularly as they are essential for the appropriate functioning of the system to ensure that the system may operate as per the design conditions

  1. Regular removal of scum (once every week) from the grease trap
  2. Check conveyance system – sewer lines, inspection chamber for smooth flow (once every week)
  3. Regular removal of dead leaf litter from PGF (once every fifteen days)
  4. Removal of excess algal growth from the pond (when more than 2/3rd of the surface area is covered by algae)
  5. Removal of sludge from the settler once every year
  6. Cleaning of filter media in PGF and Anaerobic filter (once in three years)

SWFF-Achievements and Accomplishments at a Glance

  1. No of villages covered:49
  2. No of farmers baseline: 2328
  3. No of greywater recycling Units:13
  4. Quantity of greywater recycled:75.958 cm
  5. No of farmers adopting the use of Greywater:490
  6. No of backwater recycling unit:2
  7. Quantity of co-compost produced:691.650 tons
  8. No of farmers adopting the use of Co-Compost:1753
  9. Area covered in the adoption:962.12 Acers
  10. Women Farmers Producers Companies (WFPC ) formed 4 Total Members 554
  11. Farmers Service Centers Established 3
  12. Farmers Interest Group (FIG) formed 34 Total Members 680
  13. Women Farmers Groups (WFG) formed 104 Total Members 1138
  14. Total Beneficiaries 2372 members and their families
  15. Loan Disbursed INR 203,00000 (US$ 302,000). Impact:

RDO wishes to express its gratitude to USAID, DGIS, WASTE, SIDA, FINISH, BORDA, Ministry of Science and Technology Government of South Africa, District Collector of Nilgiris, Ketti Town Panchayaths and the Green workers for their unstinted cooperation to make the SWFF program a grand success