21 Feb 2000
Institute of Advanced
     Studies, UN Univ., Japan
AEON Foundation, Japan
Internet Conference on 
Material Flow Analysis 
of Integrated Bio-Systems
(March-October 2000)
Organized by
Integrated Bio-Systems Network
UNU/IAS Alumni Association, UN Univ.,Tokyo
with the assistance of :
MFA Conference Planning Group
UNESCO Microbial Resources Centre, Stockholm


Amrit B. Karki and Upendra Gautam
Consolidated Management Services Nepal (P) Ltd.
Min Bhawan, New Baneshwor, Kathmandu, Nepal.

Photos  overview of all images and pictures

Consolidated Management Services Nepal (CMS) P. Ltd. with the financial assistance of United Nations High Commissioner for Refugees (UNHCR), constructed a latrine-attached biodigester in 1998 at Jantemod of Ward No. 1 of Pathari Village Development Committee (VDC). Users of this public pay-latrine  are the residents of Jantemod, passengers of  bus services and the people who come there twice a week during "Hatiya" (local marketing day). The ten latrines (four for females and six for males) together with three urinals for males provide a daily input needed for the 15 m3 fixed dome Chinese model biodigester. Users of the latrines pay a reasonable fee for the services used.

The community latrine was put for common use with effect from 15 March 1998. It is visited by 250 regular and 35 occasional users per day. With about daily available 115 kg of human excreta as raw material for feeding the biodigester, about 5.75 m3 of gas production is expected per day. Currently, the gas is being used to provide illumination inside the latrines. Thus, two lamps consuming each 0.07 m3 gas per hour are lit for about 10 hours during night. Although it was envisioned to provide the excess gas to the interested household (s) located close to the project site for cooking purposes as a substitude  to firewood, this plan has yet to materialize as conservative belief system considered thus cooked as "impure". 

Two compost pits were constructed beside the biodigester for storage, treatment and utilization of digested effluent from biodigester. A part of slurry is being used by the watchman to fertilize his kitchen garden. Effluents (called "slurry") from biogas are safe for handling compared to raw excreta as pathogens are killed in course of anaerobic digestion process Such slurry has been proved to be a high quality organic fertilizer for plant nutrition. But still there seems to be a need for practical and demonstrative type of training to local people to acquaint them in managing the biodigester for proper utilization of the slurry. However, due to cultural or religious belief, people are reluctant to use the sludge  produced from human excreta. This belief can be overcome by educating the people. 

Environment and sanitation training programme was simultaneously implemented with the participation of the selected leaders/community workers and personnel of institutions of the refugee affected areas of Ward No. 1. This programmer has helped the local mass, community and institutions to understand and appreciate the appropriate and multiple uses of human excreta for environment-friendly local sustainable rural development. Such a situation indicates a clean need of an intensive programme for the biogas users. 

Keywords: Latrine-cum-biodigester, human faeces, effluent, stabilized manure, Management Committee


Sanitation and community health of the camps inhabited by about one hundred thousand Bhutanese refugees in Nepal in the eastern Jhapa and Morang districts of Nepal as well as in areas affected by these refugees is one of the main concerns of United Nations High Commissioner for Refugees (UNHCR). It is essential to treat human waste properly to prevent infestation of various water-borne diseases that spread through faecal contamination such as worms (hook worms, round worms), bacterial (typhoid, paratyphoid, dysentery, cholera) and viral infections (gastro-enteritis resulting in diarrhea and hepatitis), especially in crowded areas like refugee camps and refugee affected areas. 

Anaerobic digestion technology is one of the appropriate methods for treating human waste wherein more than 95 percent of the pathogens found in human faeces get killed in the process. Furthermore, biogas and stabilized compost (which are almost pathogens free are obtained as byproducts of the anaerobic digestion process. The slurry has been proved to be high quality organic materials for plant nutrition. The technology is economically viable, technically feasible, environmentally sound and socially being increasingly more acceptable [1, 2, 4, 6].

With above backdrop, Consolidated Management Services Nepal P. Ltd (CMS) with financial assistance of UNHCR have implemented an integrated project namely (i) Installation of Community Latrine-cum-Biogas plant and (ii) Conduction of Training in Environment and Sanitation. This inter-related project was implemented between October 1997 and February 1998.


The principal objectives of the project were as follows:

  •  To improve sanitary conditions of the community members residing near Ward No.1 of Pathari VDC;
  •  To educate the local community on health, hygiene and sanitation aspects so that they can improve their quality of life;
  •  To produce and utilize pathogen-free stabilized manure (bio-fertilizer) from faecal sludge to improve soil fertility, and
  •  To use biogas as an alternate energy for domestic cooking and lighting to reduce/replace kerosene and firewood.


Installation of Community Latrines

The location map of the project is given in Figure 1A and 1B. 

The design of latrine-cum-biodigester is based upon the drawings and the sketches of the public latrine and biogas plant which has been found operating successfully in the seashore of “Cox Bazzar” in Bangladesh. The relevant drawings are presented in Figure 2 and 3. The project has been implemented by the Slum Improvement Project of Local Government Engineering Department, Dhaka for the benefit of Burmese refugees and the areas affected by these refugees.
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Figure 1A : Location Map for Nepal Figure 1B : Location map of the Project Site in Nepal


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Figure 2 : Layout showing 15 m3 Biodigester, 
Inlet, Outlet and Compost Pit
Figure 3 : Engineering Drawing of Community Latrines

Originally, it was envisioned that the waste of the latrine would be collected into a settling tank and the excess of liquid would be drained into soak pit. But realizing the high ground water table of the proposed site, the system was somewhat modified. The settling tank which was conceived as pre-storage tank was substituted by a manhole chamber. Thus, the faecal raw sludge from the latrines is first collected into this humanhole compartment from where it is led into the biodigester (see Photo-1). Considering that excess of urine can create toxicity to the methanogenic bacteria, a provision was made to drain it into a soak pit particularly from the three urinals constructed in the male section of the latrines. The concept of the integrated production and use of biogas and stabilized manure from the community latrine-cum biogas plant has been given in Figure 4. 

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Photo 1 : Completed Version of the Community Latrines
and Biodigester Showing two Holes that Lead Faecal 
Waste from the Latrines to the Biodigester
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Figure 4 : The Concept of the 
Production of Biogas and 
Stabilized Compost from 
Community Latrines of Pathari 
VDC of Morang District

Altogether ten latrines (four for females and six for males) together with three urinals for males were constructed. The male section of the latrine contains four rooms and three urinals and the female section has six rooms. 

Installation of 15 m3 Biodigester

A 15 m3 capacity GGC (Gobar Gas and Agricultural Equipment Development Company) model biodigester of a fixed dome Chinese type as approved by Biogas Support Program (BSP) of the Netherlands Development Organization (SNV/Nepal) was installed to produce stabilized manure and biogas.

High ground water table greatly hampered the construction of community latrine in the beginning. Therefore for achieving quality masonry work in the process of building the biodigester, continuous dewatering was done to remove accumulated water inside the digester with the help of a pumping machine. This process was completed cautiously and methodologically for achieving desired quality work.

Construction of Compost Pits

As planned, two compost pits with dimension of 1.5 m x 1.5 m x 8 m were constructed close to the biodigester for collection, treatment and utilization of slurry as fertilizer. The design and construction of twin compost pits permit to fill and empty each pit by turn. Thus, in case the first pit is filled in completely, it is left for drying for couple of week and the use of the second one is done (Photo-2).

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Photo 2 : Completed Version of Latrine-cum-Biodigester 
Showing two Compost Pits for Collection and Treatment 
of Digested Effluent of Biodigester


As it was planned to feed the biodigester initially with animal excreta  as raw materials, a mixture of cow dung and water was used for loading the digester. To activate and enhance the process of fermentation in order to shorten the time of gas production, the digester was inoculated with 150 litres of the effluents from the operating digester to which 5 kg of molasses were added. Thus, addition of inoculum that furnished methanogenic bacteria and molasses that provided source of energy to multiply these bacteria resulted into the production of first combustible gas (methane) on ninth day after loading the digester. The production of biogas was tested by using a biogas lamp and a burner in presence of the Chairman of Pathari Village Development Committee (VDC), his staff and the local people. The latrine was put for general public use with effect from 15th March 1999. Since then animal manure has not been added to the digester and it is fed only with latrine wastes.

At present, the latrines are being daily visited by 250 regular and 35 occasional users per day. From 285 latrine visitors, about 115 kg of human excreta is available per day as raw materials for feeding the biodigester (0.4 kg of faeces per person). The actual gas production is about 5.75 m3 per day. 

Two biogas lamps consuming each 0.07 m3 gas per hour are equipped inside the community latrine and they are lighted for illumination during night, while two burners are being tested currently. Presently, the watchman of the installation has been demonstrating the gas for cooking (e.g. preparation of tea). After completing the test, the gas produced is planned to be distributed by the Management Committee to the interested household (s) in the area.


Role of Latrine-cum-Biodigester Management Committee 

In order to create local capacity to manage the installed toilet and biodigester and to ensure its operation and maintenance, repair and durability, a Latrine-cum-Biodigester Management Committee was formed on October 20, 1997 under the chairmanship of Mohan Tumbapo, the local VDC Chairman. This committee consists of a total of 12 members selected from various local institutions and intellectuals including representation from UNHCR, Refugee Coordination Unit (RCU) and CMS. The Management Committee had assigned a watchman as a care-taker of the latrine and biodigester. For proper care, maintenance and repair of the latrine, reasonable fees are charged to the latrine users. The total income generation from the latrine users amounts to Rs 2,700 per month (i.e. Rs 2,500 from the latrine users and Rs 200 from the sale of kitchen garden; about US $50). The monthly salary of the watchman is around Rs 2,000 per month and the occasional maintenance charge is Rs 400. The users' pay system covers the expenses for maintenance of the utilities.  For the security of the latrine users, the Committee has completed the fencing around the premises of the utilities. For long-term sustainability, the Committee has agreed to carry out necessary repair and maintenance of the toilet and to resolve all the problems that may arise in the future. The VDC  plans to launch an awareness campaign among the local people for more scientific and maximum use of the utilities. 

Environment and Sanitation Training

An environment and sanitation training programme was implemented from 21 to 26 December 1997 with support from UNHCR. Selected leaders/community workers and personnel of local rural institutions of the refugee affected areas of Ward No. 1 of Pathari VDC in this interactive programme (Photo 3).

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Photo 3 : The Training Coordinator Interacting with the 
Participants of the Environment and Sanitation Training 
Course at Pathari


Proper Use of Gas: The future action plan proposed by the CMS focuses on the proper use of gas produced from the utilities. Although about 40 percent of the family size biogas plants so far installed in Nepal are attached with latrines, considerable number of population has still reservation to use the gas generated from human faeces. Therefore, the rural people residing close to the project site need to be educated and motivated so that they could accept the gas for cooking food and burning lamps. 

Proper Use of Effluent: The local people need to be educated about the proper use of effluent. As originally envisioned in this project, the effluent from biogas plants was planned to be mixed with plant wastes such as leaves, rice straw and or other biodegradable materials in order to make the compost to fertilize agricultural crops, horticultural plants and to raise nursery. For doing that, it is an imperative to motivate and convince the farming community to use locally produced manure from the utility.

Practical-cum-Demonstrative Workshop: In view of resisting the above bottlenecks, CMS has put forth suggestions to UNHCR to conduct demonstrative training-cum workshop on operation and maintenance of latrine-cum-biodigester and proper utilization of slurry by involving the local rural community and institutions of Ward No. 1 of  Pathari VDC. 


[1] Anaerobic Night-Soil Treatment Plants in Burundi. Biogas Forum. 1992/IV No.51

[2] Anaerobic Digester for Stabilizing Domestic Sewage. Biogas Forum. 1993/IV No.55

[3] Biogas From Toilet Waste-Some Figures for Calculation. Biogas Forum. 1992/! No.48 

[4] Biogas and Natural resources Management (BNRM) Issue no. 57, May 1998 

[5] CMS (1998) A manual for Environmnet and sanitation Training Programme. Submitted to United Nations High Commissioner for Refugees, Kathmandu, Nepal. 

[6] CMS (1996) Improvement in Environment and Sanitation Through Anaerobic Digestion of Human Waste. Submitted to United Nations High Commissioner for Refugees, Kathmandu, Nepal. 

[7] CMS (1994) Identification of Alternative Sources of Energy for Bhutanese Refugee Camps in Nepal. Submitted to United Nations High Commissioner for Refugees, Kathmandu, Nepal. 

[8] Gunnerson, C.G. and Stuckey, D.U. Integrated Resource Recovery-Anaerobic digestion-Principles and Practices for Biogas Systems. UNPD Project Management Report Number 5.

[9] Karki, A.B., Gautam, K.M. and Gautam, U. (1995) Status and Trends on Biological Waste Treatment in Nepal. Paper presented at IInd International Conference and Exhibition Forum on Biological Waste Treatment, 21-24 May 1995. Aalborg, Denmark 

[10] Karki, A. B. and Dixit K. (1984) Biogas Fieldbook . Sahayogi Press, Tripureshwor, Kathmandu, Nepal. 

[11] Karki, A. B. (1996) Environment and Sanitation in Bhutanese Refugee Camps. Indigenous Knowledge and Developmnet Monitor, Volume 4, Issue 1, April 1993. 

[12] Khandelwal, K.C. and Mahdi, S.S. (1986) Biogas Technology. A practical handbook, Volume 1. Tata McGraw-Hill Publishing Co. Ltd. New Delhi.

[13] Sathianathan, M.A. (1975) Biogas: Achievements and Challenges. AVARD, Association of Voluntary Actions for Rural Developmnet, New Delhi 110 048.