2019 يونيو 01

(Co-) composting (Small-scale)

المؤلف*
Bhushan Tuladhar (Environment and Public Health Organization (ENPHO))
Dorothee Spuhler (seecon international gmbh)

المُلخص التنفيذي

Composting at the household level is an important method for managing organic waste, which is normally the largest portion of household waste. Composting reduces the environmental impacts of waste and the produced compost is essential for improving soil fertility and structure. Besides the organic waste, composting can also be applied as secondary treatment for faeces and excreta collected in urine diversion and composting toilets. Degradation of organic material is a natural process, but composting allows us to control and accelerate this process by optimising the environment for microbial activity in the waste. Composting involves three stages: preparation of the waste by adjusting its size, moisture content and carbon-nitrogen ratio; degradation of waste in pits, piles, vessels or vermi-composting; and finally preparing finished compost by curing and screening.

المزايا
As organic waste creates problems such as smell, leachate, flies and rodents, and emission of methane – a greenhouse gas – in landfill sites, composting of organic waste reduces these problems at the landfill site
Production of compost at home will encourage the use of organic farming and reduce the need for chemical fertilisers
Household composting reduces the amount of waste that needs to be collected and managed, thus reducing the cost of solid waste management
In areas where waste collection and management systems are not effective, household composting will reduce haphazard waste disposal and its related environmental impacts
As private scrap dealers generally do not collect organic waste, household composting will help increase the recycling rates
Separation of organic waste and composting at the household level ensures that the remaining waste is clean and easier to recycle
Household composting is a simple practice that anyone can do at home with minimum resources
Household composting can be an educational tool for young children at home
العيوب
If not done properly, household composting can cause problems such as smell, leachate, flies and rodents
Composting requires a little space, especially compost pits or piles
In houses without gardens or flower pots, the compost may not be of much use
المُدخلات المُخرَجات

Faeces, Excreta, Organic Solid Waste

Compost/Biosolids

Introduction

Factsheet Block Body

Municipal solid waste management starts at the household level as households are the main source of waste in most urban areas. Waste minimisation and managing of waste as close to the source as possible are the two most important tools for reducing cost and improving efficiency of waste management systems. Thus, waste recycling at the household level is very important.

Organic matter such as food waste and yard waste are the main components of household waste. Other types of waste generated by households include inorganic components plastics, metals, glass, and inert materials such as soil. The portion of organic waste in household waste is generally higher in developing countries. In Nepal, for example, over 65 % of the total waste is organic waste.

Compost bin in Kathmandu (left) and Compost barrel in Bangladesh (right). Source: ENPHO (n.y.) (left) and WASTE CONCERN (n.y) (right)
Compost bin in Kathmandu (left) and Compost barrel in Bangladesh (right). Source: ENPHO (n.y.) (left) and WASTE CONCERN (n.y) (right)

 

Organic waste can be recycled at the household level to produce animal feed, biogas (i.e. anaerobic digestion small-scale; anaerobic digestion of organic waste) or compost. Among these options, composting is probably the most simple and common method for recycling household organic waste. Composting is the process of optimising the environment in the waste for microbial activity to decompose organic matter into valuable nutrients for the soil. Household composting involves the following three stages: waste preparation, degradation of waste and finishing of waste.

 Waste preparation

Factsheet Block Body

Waste needs to be sorted and prepared for rapid degradation. This includes the following steps:

  • Mix the waste to ensure that the carbon to nitrogen ratio (C:N) is close to 25 – If the waste has too much carbon (normally brown waste such as dried leaves) it should be mixed with waste that has high nitrogen content (also known as green waste such as green grass clippings). Kitchen waste only normally has a suitable C:N ratio for composting.
  • Chop the waste into small pieces. Large pieces of organic waste should be cut to small pieces to accelerate the composting process.
  • Adjust the moisture content to about 50 per cent. A compost pile with 50% moisture should feel moist but water should not be dripping from it.
  • Add a starter such as mature compost or effective microorganisms (EM) to speed up the composting process.

 

A volunteer explains composting options in Siddhipur. Source: ENPHO (n.y.), Sapc. Pradhan
A volunteer explains composting options in Siddhipur. Source: ENPHO (n.y.), Sapc. Pradhan

 

Degradation of Waste

Factsheet Block Body

Once the waste is converted into raw material for composting, the waste can be degraded using one of the methods mentioned below. The degradation process should be controlled by maintaining adequate temperature, moisture and aeration. There are different types of vessels for composting at this stage: composting in pits, composting in piles, in-vessel composting and vermi-composting.

Compost pits

One simple method for composting organic waste is to put it in pits and let it turn into compost over a period of six months or more. This process requires some space and time but the main benefit is that the waste is not visible as it is buried in the pit.

 

Compost piles

In this method, the waste is put in piles on the ground and regularly turned to allow aeration. The size of the pile may vary depending on the amount of waste and available space, but generally, it should be 1 to 2 m on each side and not more than 1.5 m in height. Chicken wire or wooden planks can be used to keep the pile together.

 

In-vessel composting

Compost can also be made in made in bags or bins. Normally holes are made in the bin or bags to allow aeration. Compost bins can be made from 100 to 200 litre plastic bins or barrels. In order to allow proper aeration, the bin is normally divided into two sections with a grill separating the two sections. Organic waste is put into the top section and allowed to degrade and once the compost is prepared it is removed from the bottom section. Because of the natural draught created in the bin by the grill and the holes, frequent turning of the waste is not required in this method. Municipalities and NGOs in countries such as Nepal, Bangladesh and Sri Lanka have been distributing compost bins to residents at subsidised rates to promote household composting (TULADHAR 2004; ALI 2004; LEKAMMUDIYANSE et al. 2009).

 

Vermi-composting

This involves the use of special types of earthworms to convert organic waste into worm casting, which is better than ordinary compost in improving soil’s structure and fertility. Vermi-composting is a simple and effective process that can be done indoors in the kitchen itself as it requires very little space and does not cause problems such as odour. Most common worm species for vermi-composting are Eisenia foetida, Lumbricus rubellus, and Eisenia hortensis (KOFF et al. 2007). The worms are placed in bedding made of loose materials such as coconut husk or shredded paper in a shallow box or tub and fed with soft organic matter such as kitchen waste. After about two months the compost can be harvested by putting the compost in the shape of a cone and scrapping off the top layers. The worms go to the bottom of the cone as they run away from light.

Vermi-composting in Kathmandu (left) and worms used for vermi-composting (right). Source: ENPHO (n.y.), S. Pradhan
Vermi-composting in Kathmandu (left) and worms used for vermi-composting (right). Source: ENPHO (n.y.), S. Pradhan

 

Vermi-compost, ready to use. Source: ENPHO (n.y.)
Vermi-compost, ready to use. Source: ENPHO (n.y.)

 

Finishing

Factsheet Block Body

Once the compost is prepared, it needs to be cured and screened before it is applied in the soil. The composting process is complete when (KOFF et al. 2007):

  • The compost pile’s internal temperature has decreased to within 5 degrees of outside temperature.
  • There is little or no discernible plant material left in the compost
  • The compost has a dark brown, crumbly and rich look (similar to chocolate cake)

 

Once the compost is ready, it should be left for about a month for curing and then screened using a fine screen. The end product can now be used as soil amendment (use of compost). Any material that has not yet decomposed can go back into the compost pile or bin.

Plan of bin composting. Source: ENPHO (n.y.)
Plan of bin composting. Source: ENPHO (n.y.)

 

Composting of faeces and excreta and co-composting

Factsheet Block Body

Besides organic waste, composting can also be applied as a secondary treatment for faeces and excreta collected in UDDTs (urine diversion dehydration toilets) or vault composting toilets. The process is the same as the one that takes place in any pit-composting toilet (e.g. fossa alterna, arboloo). Composting can also be applied for the secondary treatment of sludge from twin-pits for pour-flush toilets or digest from anaerobic digesters or any other pre-treated sludge. Even better results can be achieved when organic wastes are composted together with faeces in order to optimise the C/N ratio. Co-composting can be done either in the toilet or off-site similar to pure household waste (in compost, compost piles, In-vessel composting Vermi-composting). See also VALLEY VIEW UNIVERSITY (2008) for more information.

التطيبق

Household composting is applicable in all households and most institutions that generate organic waste. Certain methods such as compost pits and compost piles require some outdoor space but compost bins can be placed on balconies and vermi-composting can be done indoors as well in an area less than 1m2. Household composting is especially beneficial for households with home gardens or indoor plants that can use the compost. Economic benefits of household composting include reduced cost of waste disposal and reduced cost of fertilisers.

Faeces and excreta form urine diversion dehydration toilets and composting toilets as well as sludge from twin-pits for pour-flush toilets or digestate from anaerobic digesters  or any other pre-treated sludge can also be composted together with organic waste in order to sanitise these products and to increase composting yields. However, when composting such products, special care should be taken since the associated health risk is higher than for kitchen waste.

المراجع

Sustainable Composting Case Studies and Guidelines for Developing Countries

This publication presents the findings of a research on “Promoting Composting as a Business for the Urban Poor” in the form of guidelines based on case studies from India, Bangladesh, Sri Lanka, Pakistan and Ethiopia.

ALI, M. (2004): Sustainable Composting Case Studies and Guidelines for Developing Countries. Leicestershire: Water Engineering and Development Centre, Loughborough University URL [Accessed: 01.06.2019]

Efficiency of the Household Compost bin as a Waste Management Technique in Sri Lanka

The paper presents the findings of a survey of 70 households using compost bins in Gampaha Municipality. During the study two compost samples from each of the bins were also tested.

LEKAMMUDIYANSE, L.M.M.U. ; GUNATILAKE, S.K. (2009): Efficiency of the Household Compost bin as a Waste Management Technique in Sri Lanka . المُدخلات: International Journal of Basic & Applied Sciences IJBAS-IJENS: Volume 10 , 89-94. URL [Accessed: 05.08.2010]

User Survey Indicates the Success of “Saaga” Home Compost Bins

This article presents the findings of a survey of 76 home compost bin users in Kathmandu, which was done about one year after the compost bins were sold at a subsidized rate to residents by Kathmandu Metropolitan City by the municipality.

TULADHAR, B. (2004): User Survey Indicates the Success of “Saaga” Home Compost Bins. المُدخلات: ENPHO Magazine 2004: URL [Accessed: 01.06.2019]

Compost Barrel

This brochure describes the compost barrels, promoted in Bangladesh and explains how to use them. 4

WASTE CONCERN (n.y): Compost Barrel. Dhaka (Bangladesh): WASTE CONCERN URL [Accessed: 01.06.2019]
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This book is the first in a series on Urban Solid Waste Recovery, and represents an attempt to document the experiences of recycling activities in cities around the world. It covers the whole waste chain from municipal or agricultural generation of organic waste to different treatment methods, such as composting, co-composting, anaerobic digestion with production of biogas, and briquetting.

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The thesis consists of three papers, the first of which investigates incineration of faecal matter as a treatment and sanitation method using a locally fabricated incinerator made of steel sheets. The second and third papers investigate composting of faeces and food waste at two size scales, using 78-litre and 216-litre wooden reactors.

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Efficiency of the Household Compost bin as a Waste Management Technique in Sri Lanka

The paper presents the findings of a survey of 70 households using compost bins in Gampaha Municipality. During the study two compost samples from each of the bins were also tested.

LEKAMMUDIYANSE, L.M.M.U. ; GUNATILAKE, S.K. (2009): Efficiency of the Household Compost bin as a Waste Management Technique in Sri Lanka . المُدخلات: International Journal of Basic & Applied Sciences IJBAS-IJENS: Volume 10 , 89-94. URL [Accessed: 05.08.2010]

Sustainable Composting Case Studies and Guidelines for Developing Countries

This publication presents the findings of a research on “Promoting Composting as a Business for the Urban Poor” in the form of guidelines based on case studies from India, Bangladesh, Sri Lanka, Pakistan and Ethiopia.

ALI, M. (2004): Sustainable Composting Case Studies and Guidelines for Developing Countries. Leicestershire: Water Engineering and Development Centre, Loughborough University URL [Accessed: 01.06.2019]

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Factsheet on the operation and maintenance of vermi-composts.

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Compost Barrel

This brochure describes the compost barrels, promoted in Bangladesh and explains how to use them. 4

WASTE CONCERN (n.y): Compost Barrel. Dhaka (Bangladesh): WASTE CONCERN URL [Accessed: 01.06.2019]
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Compost Bins as an Alternative Solution to the Problem of Household Waste Problem in Urban Areas

This paper describes a household composting project implemented by SEVENATHA in Dehiwala Mt. Levenia Municipal Council near Colombo in Sri Lanka with support from UNDP.

PREMAKUJMARA, D.G.H. (2000): Compost Bins as an Alternative Solution to the Problem of Household Waste Problem in Urban Areas. URL [Accessed: 05.08.2010]

User Survey Indicates the Success of “Saaga” Home Compost Bins

This article presents the findings of a survey of 76 home compost bin users in Kathmandu, which was done about one year after the compost bins were sold at a subsidized rate to residents by Kathmandu Metropolitan City by the municipality.

TULADHAR, B. (2004): User Survey Indicates the Success of “Saaga” Home Compost Bins. المُدخلات: ENPHO Magazine 2004: URL [Accessed: 01.06.2019]

Vermi-Composting brings better yields and returns – A farmer shows the way

This is the case of a small farmer who chose to be different from the typical resource-poor farmers struggling to make a living in the degraded drylands. His deep ‘love for life’ has not only earned him a decent living, but more importantly, it has inspired many other farmers to emulate him.

AME FOUNDATION (2007): Vermi-Composting brings better yields and returns – A farmer shows the way. (= AMEF Case Study Series 6 ). Bangalore: AME Foundation URL [Accessed: 01.06.2019]

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A case study on household-level composition in Kitgum, Uganda. The project aims at using composting to develop practical operation and management strategies for peri-urban areas and to demonstrate the safe reuse of faces by co-composting them.

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This 12-page factsheet reflects the existing management systems practiced in various areas of Nepal in managing solid waste and contains initiatives of Municipalities; national and local NGOs/CBOs; public and private entities. The paper helps to transfer the lessons and existing practices regarding solid waste management and encourages urban, peri-urban and emerging towns for similar initiatives in urban sanitation.

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Delivering Water, Sanitation and Hygiene Services in an Uncertain Environment: Piloting Ecological Sanitation (EcoSan) in the Emergency Context of Port-au-Prince, Haiti, after the 2010 Earthquake

The earthquake that struck Haiti in January 2010 and the cholera epidemic that followed from October 2010, resulted in one of the largest humanitarian relief efforts in history. Many of the internally displaced persons camps were located in urban neighbourhoods with high groundwater, making onsite sanitation extremely difficult. In response to these unique conditions a small local organization, SOIL, partnered with Oxfam Great Britain to pilot urine diversion EcoSan toilets in camps throughout Port-au-Prince. This briefing paper covers this pilot project from March 2010 through March 2012. During that 2-year period, SOIL’s toilets served over 20,000 people and treated more than 400,000 gallons of human waste, converting it to rich compost.

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مواد تدريبية

Solid Waste Management. Lecture notes

This document provides an overview of the present state-of-the-art of solid waste production and management. It contains the characteristics of municipal solid waste and describes current waste treatment systems and technologies, as well as non-technical aspects like private sector involvement and financial arrangements.

EAWAG ; SANDEC (2008): Solid Waste Management. Lecture notes. (= Sandec Training Tool 1.0, Module 6 ). Duebendorf: Swiss Federal Institute of Aquatic Science (EAWAG), Department of Water and Sanitation in Developing Countries (SANDEC) URL [Accessed: 08.04.2010]
مواد لنشر الوعي

How to Make compost - Poster

This poster illustrates step-by-step instructions to make compost by using compost bin at household level (Nepali).

ENPHO ; UN HABITAT (n.y): How to Make compost - Poster. Kathmandu: Environment and Public Health Organization (ENPHO)

Askai Sticker

This sticker provides messages and slogan on Solid Waste Management. “Askai” is the mascot for solid waste management in Nepal.

JICA (n.y): Askai Sticker. Kathmandu: Japanese International Cooperation Agency (JICA) and Kathmandu Metropolitan City

Compost Barrel

This brochure describes the compost barrels, promoted in Bangladesh and explains how to use them. 4

WASTE CONCERN (n.y): Compost Barrel. Dhaka (Bangladesh): WASTE CONCERN URL [Accessed: 01.06.2019]

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