19

II REVIEW OF LITERATURE

India is richly endowed with alternate energy resources – solar, wind

biomass and small hydros that are widely distributed across the country.

These sources can be utilized through commercially viable technologies to

generate energy to provide fuel security, without endangering the

environment. The Government has been making efforts to popularize

alternate energy technologies – improved chulahs, biogas plants, biomass

gasifiers, solar photovoltaic systems, energy recovery from urban, municipal

and industrial waste etc. The management of wastes treats all materials as a

single class, whether solid, liquid gaseous and tries to reduce the harmful

environmental impacts of each through different methods (Krishnan, 2012).

Waste management is a challenging problem in all countries more so in

developed countries.

Organic waste are produced wherever there is human habitation such

as household food waste, agricultural waste, human and animal waste and

they can be decomposed under aerobic or anaerobic condition. But some

unscientific methods are followed in disposing of organic wastes leads to loss

of organic matter and also cause environmental pollution.

The present chapter attempts to comprehend the issues related to

“Resource Recovery from Organic Waste through Insti tutional and

Community Biogas Plants” under the following five headings:

A. Alternate energy sources for sustainable development

B. Waste – concept, generation, problems and waste management

C. Waste to Energy – Biogas technology

D. Institutional and Community Biogas Plant – A boon for waste

management

E. Challenges ahead for future perspectives.

20

A. Alternate Energy Sources for Sustainable Develop ment

Sustainable and equitable development is the most important

challenge before humankind in the coming century and is likely to be the

critical issue in the rural areas of developing countries (Chopra, 2004).

Preventing resource degradation resulting from increasing demands, and

preserving valuable natural forests, wetlands, and other fragile ecosystems

from relatively low value uses have been identified as the urgent requirement

for sustainable world (Kausik, 2002). After food, the most pressing concern in

the foreseeable future will be to provide energy for both, subsistence and

economically productive activities in the rural as well as urban areas of the

developing countries. The challenges that India will be called upon to face are

typical. The population is expected to cross one billion by 2000 AD from the

1991 figure of over 843 million. Substantially higher energy would be required

for both, subsistence as well as economic development.

Loulou et al. (2007) points out that the sustainable economic

development implies an improvement in the quality of life and guarantees

fulfillment of subsistence requirement in addition to enhance economically

productive activities. Singh (2008) documents that the sustainability is now

regarded as a major consideration for both urban and rural development world

wide. Although the definition of sustainability has been articulated in many

ways and in different contents, the main challenge lies in its realistic

application in practical situations. Many criteria can be and have been

proposed as a means of judging sustainability. The current debate over

sustainable development is especially poignant in relation to energy supply.

The provision of energy has a significant influence on the pattern of

development and on the particular shape of human settlements (Lal, 2008).

Bhowmik (2010) expresses that the supply of energy is no exception to

this situation. Traditionally, there is need to import fuels and electricity into

towns and cities from other, often distant locations has not been regarded as

a problem. The creation and growth of means of supply, such as roads,

railways, waterways, and associated facilities for transporting coal and

petroleum products, pipelines for carrying oil and natural gas, and networks

for transmitting electricity, have ensured that energy self-sufficiency in an

21

irrelevant issue for towns and cities. However, concern over sustainable

development in urban areas is beginning to raise important questions about

the wisdom and desirability of continuing current arrangements for energy

supply to urban areas (Carazan and Siddayas, 2008).

Rao (2004) states that in the past, standard statistics describe

the pattern of global energy supply have tended, for obvious reasons, to

concentrate on sources of commercially – tradeable fuels and electricity.

Hence, the importance of firewood and dried dung has generally been under

estimated or totally overlooked. In addition to firewood and dried dung,

electricity from hydro power is a renewable source of energy which makes a

significant contribution to global energy supplies. The energy sector has

become a matter of more concern over the years due to the fast rising petrol

and diesel prices over the globe. Heavy reliance upon the conventional fossil

fuels has given birth indefinite headaches for the economies over the globe.

So the need of the hour is to rely more upon the alternate energy sources like

Sun, Wind, Biomass and Organic wastes which are available plenty in our

country. Unlike fossil fuels and uranium for nuclear power, these and other

alternate energy sources, such as solar, wind and tidal, and wave power,

other forms of biomass energy, and to a given extent, geothermal energy,

which cannot be depleted or exhausted (Khattar, 2011).

Provision of adequate energy is a key element in the development

process and one of the main infrastructure requirements for agriculture and

industrial development, employment generation and improvement in the

quality of life of people, especially in the rural and remote areas. It was

expressed by Agarwal (2003) that the present energy portfolio in India is

based on a complex energy mix. The primary energy requirement is more

than 380 millions tons of oil equivalents (mtoe) per year, coming mainly from

indigenous coal, and imported petroleum. Nearly, thirty percent the total

primary energy consumption constitutes biomass in the form of firewood,

agricultural residues, and dung cakes. These traditional energy sources are

used for cooking and village industries in the rural areas. Dayanandan (2003)

pointed out that the use of biomass in traditional store results in par levels

of efficiency and high emissions, causing enormous health damages.

22

Alternate energy devices such as biogas plants, biomass gasifier system and

turbo stores can provide clean energy to the rural masses in an affordable

manner.

The potential of alternate energy sources, in general, and their

individual characteristics and features in particular, are adequately described.

Ahlavat (2008) identified that the alternate energy sources have other

characteristics which have resulted in being regarded as an essential

component for sustainable development. In particular, their frequently quoted,

main attraction is their apparently low environmental impact in comparison

with the use of fossil fuels and nuclear power. This is usually expressed in

terms of comparative carbon dioxide emissions which are specifically relevant

to current concerns about global warming and climate change. The potential

benefits of alternate energy sources can be summarized by comparing

estimates of direct and indirect CO2 emissions, resulting from combustion and

use of fossil fuels in the manufacture, construction and installation of the given

energy technologies under consideration (Goldembatee, 2000).

The production of biomass energy, especially in the form of energy

crops, is particularly appropriate for rural areas, chiefly because of extensive

land requirements and the need for established agricultural skills

(Qasim, 2003). Economics are, of course a primary consideration for biomass

energy production, but nor only in relation to the competitiveness of these

fuels with conventional fuels. Extra capital investment in specialized

agricultural machinery for cultivating and harvesting energy crops and in

facilities for processing, storing and transporting such biomass energy to final

consumers is a major consideration for farmers. Apart from difficulties in

obtaining necessary finance, farmers must also have confidence that, as

suppliers, a realistic and profitable market in biomass energy will emerge and

be sustained. This problem is compounded by lack of confidence of

consumers who are unwilling to invest in new biomass energy-consuming

equipment unless a vibrant and secure market exists to supply these new

fuels. Such concerns need to be addressed realistically and a number of

possible solutions have been proposed (Thakur, 2008).

23

Pachauri (2005) articulates that the energy consumption is bound to

increase over the years with the development of the country. As developing

countries seek to revitalize their economic, their demand for energy will

increase whatever the move towards the dimensions of their development.

There we have to move towards higher generation of energy as a corollary of

development. Agarwal (2005) utters that the science and technology over the

long term must adapt to forms of energy whose use does not harm the

environment.

Sukhatme (2003) views that the word “energy crisis” continues to

dominate the world. With the fluctuating high cost of petroleum, minimizing

dependence on importing conventional energy resources stewardship to

protect the planet and providing affordable energy to all countries including

India have stepped up their energy path for harnessing indigenous alternate

energy sources (Lal, 2008).

Today India is one of the few leading countries in the development and

utilization of alternate sources of energy. The country is blessed with various

sources of alternate energy. In order to understand how alternative energy

sources can help in preserving the earth’s delicate ecological balance, also to

help in conserving its renewable sources of fuel, we need to know that what

kind of alternative energy resources are available, which can be incorporated

in our daily lives.

1. Alternate Energy Sources in India

In India, energy is a mixed combination of commercial and traditional

sources. In present times, some of the major and extensively used alternate

sources of energy include wind, tides, solar, geothermal heat, biogas

including animal waste and organic waste as well as human excreta

(Khan and Rahaman, 2012). This energy of future is capable in solving

the twine problems of energy supply in decentralized manner and helping in

sustaining cleaner environment.

a. Wind energy: India ranks fourth in the world in wind power installed

capacity. Areas with constant and high speed winds are suitable for the

purpose of wind generated energy. Wind power accounts for 6 per cent of

24

India’s total installed power capacity (Sathyasundaram, 2011). One problem

with wind energy is its high initial cost. While development of a coal-based

power plant required around 4 crore per MW, the investment required for wind

and solar power based plant with capacity utilization of 25 per cent requires

an investment of 6 crore per MW. Hence for wider application the cost should

be affordable.

b. Solar energy: India receives abundant energy from the sun because of its

location in the equatorial Sun Belt of the earth. It is a universal, most copious

and inexhaustible source of energy. Harnessing of solar energy can be done

through both the thermal and photovoltaic routes for a variety of application

like cooking, water heating, drying of farm produce, water pumping and so on

(Sukhatme, 2007). At present solar projects contribute less than one per cent

to the total power generated in the country. For instance, wherever the arrays

are installed, nothing can grow on the ground below it because it cuts off

sunlight. If agricultural land were to be used, it would no longer be fit for

cultivation. Except for desert areas and roof tops of building, solar cells cannot

be installed on a large scale (Rao, 2006).

c. Biomass energy: India a tropical country blessed with abundant sunshine

and rains is offering an ideal environment for biomass production. Biomass is

resources which are agriculture related like wood, cow dung, human excreta

and other organic wastes. Among other biomass sources, Waste is all the

more attractive since its valorization enables to produce energy and

disposal of waste streams. Methanisation is a fast growing process that

transforms organic wastes into biogas through a biological fermentation

(http://ec.europa.eu/ environment/etap).

d. Small hydro power: India has been a pioneer in Small Hydro Power

(SHP) and some of the old and languishing plants are being renovated.

New and emerging technologies, like hydrogen, fuel cells, bio-fuel, battery-

operated vehicles, geothermal and tidal energy, hold promise for meeting the

growing energy needs (Abbasi and Abbasi, 2005).

e. Energy from Organic Waste: It has been estimated that there is about

30 million tonnes by solid waste and 4400 million cubic meters of liquid waste

25

generated every year in urban areas through domestic as well as commercial

establishments. The manufacturing sector also contributes high quantity of

waste. It has been estimated that through recycling garbage there is a

potential to generate 1700 MW of electricity (Vanitha, 2009; Hartmann, 2009).

B. Waste – Concept, Generation, Problems and Waste Management

This heading can be reviewed under the following sub headings:

1. Concept of waste

2. Waste scenario in India

3. Problems of waste

4. Organic wastes as an alternate source of energy

5. Waste management

1. Concept of waste

Waste (also known as rubbish , trash , refuse , garbage , junk , and

litter ) is unwanted or useless materials. Waste is directly linked to human

development, both technological and social. The compositions of different

wastes have varied over time and location, with industrial development and

innovation being directly linked to waste materials. Waste is sometimes a

subjective concept, because items that some people discard may have value

to others. It is widely recognized that waste materials can be a valuable

resource, whilst there is debate as to how this value is best realized.

Such concepts are colloquially expressed in western culture by such idioms

as "One man's trash is another man's treasure ."

In 1997 Hodges defined waste in simpler terms as, “Resources out of

place”. “Solid waste consists of goods and products which society finds that it

cannot be used productively”. Solid waste is a very general term which

includes all kinds of unwanted solid and semisolid wastes other than excreta

produced in urban and rural environment.

According to the Basel Convention, Waste is defined as "Substances

or objects which are disposed off or are intended to be disposed off or are

required to be disposed off by the provisions of international law".

26

United Nations Statistics Division defines "Wastes are materials that

are not prime products (that is products produced for the market) for which

the generator has no further use in terms of his/her own purposes of

production, transformation or consumption, and of which he/she wants to

dispose. Wastes may be generated during the extraction of raw materials, the

processing of raw materials into intermediate and final products,

the consumption of final products, and other human activities. Residuals

recycled or reused at the place of generation are excluded."

Under the Waste Framework Directive (European Directive 75/442/EC

as amended), the European Union defines Waste as an object the holder

discards, intends to discard or is required to discard. Once a substance or

object has become waste, it will remain waste until it has been fully recovered

and no longer poses a potential threat to the environment or to human health.

The UK's Environmental Protection Act 1990 indicated Waste includes

any substance which constitutes a scrap material, an effluent or other

unwanted surplus arising from the application of any process or any

substance or article which requires to be disposed of which has been broken,

worn out, contaminated or otherwise spoiled; this is supplemented with

anything which is discarded otherwise dealt with as if it were waste shall be

presumed to be waste unless the contrary is proved. This definition was

amended by the Waste Management Licensing Regulations 1994 defining

waste as: any substance or object which the producer or the person in

possession of it, discards or intends or is required to discard but with

exception of anything excluded from the scope of the Waste Directive.

Classification of waste

Venkateswaran (1994) classifies solid wastes as:

• Household / commercial refuse

• Street sweeping

• Construction and demolition debris

• Hospital waste and industrial waste

27

Based on the sources Park (1995) classifies waste as

• Refuse that is collected from the street is called street refuse.

It consists of leaves, straw, paper, animal droppings and litter of all

kinds.

• Refuse that is collected from markets is called market refuse.

It contains a large proportion of putrescible vegetable and animal

matter.

• Refuse collected from stables is called stable litter. It contains mainly of

animals droppings and left over animal feeds.

• Industrial refuse comprises a wide variety of wastes ranging from

completely inert compounds such as calcium carbonate to highly toxic

and explosive compounds.

• The Domestic Refuse consists of ash, rubbish and garbage.

Tchobanglous et al. (1997) classified solid waste as

• Food wastes: They are animal, fruit or vegetable residues resulting

from the handling, preparation cooking and eating of foods. It is also

called garbage.

• Rubbish: Consists of combustible and non combustible solid waste of

house holds and institutions excluding food wastes and other putrifiable

material.

• Ashes and Residues: Material from burning of wood, coal, coke and

other combustible wastes in homes, institutions etc., for purposes of

heating, cooking and disposing combustible waste.

• Demolition and construction wastes: From razed buildings and other

structures, waste from constructions, remodeling and repairing of

buildings.

• Special wastes: Such as street sweepings, road side litter, dead

animals and abandoned automobile.

a. Garbage: These wastes have a moisture content of about 70 per

cent and heating value of around 6x10 j/kg

b. Rubbish: These waste contain a moisture content of 25 percent

and heating value of the waste is 15 x 106 j/kg

28

In addition to this classification Umadevi (1994) also includes – Large

waste termed as Bulky wastes which includes auto parts, tree branches etc.,

and special wastes consisting of hazardous wastes eg., radioactive materials

and security wastes namely documents negotiable papers etc.

According to Anubhav (1996) garbage is divided into organic and

inorganic. Household solid waste can also be classified into Biodegradable –

Vegetable peels, left over food etc. Non Biodegradable – Plastic bags, metal

containers and glass bottles etc.

‘Waste wise’ a non governmental agency in Bangalore (1997)

categories waste generated from household as

Biodegradable / Compostable (Wet)

Non Biodegradable / Non Compostable (Dry)

Insanitary waste Non Compostable (Infectious)

Vegetable and fruit peeling, left over food, leaves, flowers, soft shells, animal dung, human excreta etc.,

Plastic, rubber, glass, metal, cans, hardshells wooden blocks, cloth, blades, staple pins etc.

Solid diapers, sanitary pads, used bandages, syringes, expired medicine, pesticide and other toxic matter.

There are many Waste types defined by Modern Systems of Waste

Management, notably including:

• Municipal Waste includes household waste, commercial waste,

demolition waste

• Hazardous Waste includes Industrial waste

• Bio-medical Waste includes clinical waste

• Special Hazardous Waste includes radioactive waste, explosives

waste, E-waste

Waste can be broadly classified into

• Urban Waste

• Industrial Waste

• Biomass Waste

• Biomedical Waste

29

Urban waste includes Municipal Solid Waste, Sewage and Fecal

Sludge, whereas Industrial waste could be classified as Hazardous industrial

waste and Non-hazardous industrial waste.

2. Waste scenario in India

Solid waste generation in India was 229 million tons in 2001 and solid

waste generation per capita per day in India ranged from 100 to 500 grams

(Arrifa and Jayalakshmi, 2005). It is further projected that an additional 1400

acres of land is needed to dispose waste, most of it in urban areas. Modern

urban living brings the problem of waste, increase in quantity, and changes in

composition with each passing day (Singh and Shekhawat, 2002). It has been

estimated that overall municipal waste generated in urban centers anywhere

constituted organic matter. It is also important to note that waste consumption

varied significantly across areas of different economic levels of residents.

Manimozhi et al. (2006) points out that the per capita solid waste reaching

disposal sites in Bombay, Chennai, Calcutta and New Delhi ranges from

0.45 to 0.6 kilo gram per person per day, while in other Indian Cities it is from

0.15 to 0.53 kilogram per person per day. It is established that about

500 grams of biodegradable kitchen waste is generated per day in a family

consisting of four members (Gupta, 2002). Proper waste management helps

to protect human health and the environment and preserve natural resources.

Selvaraj (2012) views that many do not realize the solid waste impact

on climate changes. When organic waste decomposes in land fills and

uncontrolled dumps, it produces methane, one of the major green house

gases contributing to climate change methane emissions from land fills are

projected to reach 39 million tonnes in 2047 from seven million tonnes

in 2007. Proper solid waste management can reduce green house gas

emissions (warming). As most of our urban areas are already congested,

waste disposal sites have to be located far from source, with considerable

cost implications in terms of transport and infrastructure (Murphy and

Mckay, 2007).

Ponniah (2005) conveys that traditionally, disposal of solid wastes

were disposed to a ground. In the past, with low population densities

30

biodegradable solid waste products disposal presented few ecological

problems. With high population densities and each household producing

significant quantity of both biodegradable and non-biodegradable solid waste

materials are accumulating on both the limited areas of land and the marine

water at ecologically damaging levels. The issue of urban poverty is

inextricably linked with waste. In India a million people find livelihood

opportunities in the areas of waste, engaged in waste collection and recycling

through well organized systems and also substantial population of urban poor

in other developing countries earn their livelihood through waste.

In domestic activities 30 to 40 per cent of the domestic waste is organic

in nature, which needs to be disposed on day to day basis. The bins overflow

and the entire street becomes dirty and attracts the street dogs and rag

pickers (Kumar and Singh, 1999). The average collection efficiency for MSW

(Municipal Solid Waste) in Indian cities is about 72.5 per cent as a result of

which, a substantial part of the waste generated remains unattended,

affecting the quality of life of millions of people. Solid waste should be

managed through a number of activities such as waste prevention, recycling,

composting, controlled burning or land filling. Using a combination of these

activities that protects the community and the local environment is referred to

as Integrated Solid Waste Management (ISWM). The ISWM programme can

help green house gas emissions and slow down the effects of climate change

(www.epa.gov/globalwarming).

Urban planners, municipal agencies, environmental regulators, labour

groups, citizens groups response which are rooted in local dynamics,

rather than borrow non-contextual solutions from else where. Expensive

technologies are being pushed to deal with our urban waste problem, ignoring

their environmental and social implication. The improved technologies are

now available for collection, treatment and processing standards with, which

enables to improve the quality of the garbage to meet the pollution advantage

of power generation world over (Kumar, 2002). Many innovative approaches

are being adopted for sustainable solid waste management Viz. reduces

waste technological interventions, and institutional reforms. India could learn

31

from these experiences and devise strategies and approaches that best suit

its own MSW management requirements (Rampal, 2000)

Mapuskar, (2007) articulates that a significant large portion of the

municipal solid waste is organic in nature and a single large of such purely

organic waste is the vegetable market. All cities and towns have one or more

vegetable markets where everyday fresh vegetables and fruits arrive and, are

sold either on wholesale or on retail basis. The quantity of waste generated in

such markets varies from one to a few hundred depending upon the size of

market. As per an estimate, around 50,000 tonnes of vegetable market waste

is generated in India.

In the contemporary Indian situation, there is need for large amount of

energy from all possible sources. Human waste and household organic

wastes have large energy content and their potential can be tapped for

realization of energy in two ways. By drying and burning we can release

the energy and secondly by allowing it to decompose we get biogas by

anaerobic fermentation. Handling human excreta in open environment is

delicate and impractical, biogas is free from the above drawbacks and also

the nutrient value of biomass is retained in the form of manure which is

odourless and stable. This increases soil fertility and provides humus for solid

conditioning (Chauhan and Srivastava, 2006).

Every year, about 55 million tonnes of municipal solid waste (MSW)

and 38 billion litres of sewage are generated in the urban areas of India. In

addition, large quantities of solid and liquid wastes are generated by

industries. Waste generation in India is expected to increase rapidly in

the future. As more people migrate to urban areas and as incomes increase,

consumption levels are likely to rise, as are rates of waste generation

(Rao, 2004). It is estimated that the amount of waste generated in India will

increase at a per capita rate of approximately 1-1.33% annually. This has

significant impacts on the amount of land that is and will be needed for

disposal, economic costs of collecting and transporting waste, and the

environmental consequences of increased MSW generation levels

(Dhanuja, 2006).

32

According to the Ministry of New and Renewable Energy (MNRE),

there exists a potential of about 1700 MW from urban waste (1500 from MSW

and 225 MW from sewage) and about 1300 MW from industrial waste.

The Ministry is also actively promoting the generation of energy from waste,

by providing subsidies and incentives for the projects. Indian Renewable

Energy Development Agency (IREDA) estimates indicate that India has so far

realized only about 2 per cent of its waste-to-energy potential. A market

analysis predicts that the Indian municipal solid waste to energy market could

be growing at a compound annual growth rate of 9.7 per cent by 2013.

3. Problems of waste

Waste management is a challenging problem in all countries, more so

in developed countries. Lakshmanan (2009) says that domestic waste from

urban areas, without proper planning, is turning to be a problem unconquered.

Waste which are produced in large quantities all over the world; create major

environmental and disposal problems. Nath (2003) views that the towns and

cities are characterized by over crowding, congestion, inadequate water

supply and inadequate facilities of disposal of human excreta, waste water

and solid waste. The waste accumulation has increased simultaneously with

the rapid increase in residential colonies, fast food outlets, vegetable vendors,

fruit shops and other customer outlets in the respective areas.

Viswanathan (2005) informs that the amount of large solid refuse has

been gradually increasing and its treatment and disposal has become a major

social and environmental problem as well as a challenge. The insanitary

methods adopted for disposal of solid wastes is a serious health concern

with significant environmental, social and health costs associated with it.

Open dumping of garbage facilities are the breeding of disease vectors such

as flies, mosquitoes, cockroaches, rats and other pests (Maheswari, 2005).

The recent estimates indicate that nearly two billion people (about one

third world’s population) are without any basic facilities and by 2021 the

number may increase to three billion. Waste generation increases with

population expansion and economic development. Solid waste generation is

one of the serious environmental issues in urban areas needing special

33

attention (Rao, 2004). Today, solid wastes are considered as one of the major

sources for pollution in the human environment. The solid waste generated

causes enormous environmental damages to the soil and water sources

(Setua and Setua, 2008).

Mani (2006) views that in fact, waste is a misplaced resource and it is

not possible to destroy it. Materials may come to only two possible discharges

into the environment and the other is reuse or reclamation or recycling.

Conditioning of organic wastes can help in pollution abatement.

Problems of waste are reviewed under the following headings:

a. Environmental costs: Diaz et al. (2006) communicates that waste attracts

rodents and insects which harbour gastrointestinal parasites, yellow fever,

worms, the plague and other conditions for humans. Exposure to hazardous

wastes, particularly when they are burnt can cause various other diseases

including cancers. Waste can contaminate surface water, groundwater, soil,

and air which cause more problems for humans, other species, and

ecosystems. Waste treatment and disposal produces significant green house

gas (GHG) emissions, notably methane, which are contributing significantly to

global climate, change (Mani, 1996).

b.Social costs: Sivashankaraiah, et al. (2008) states that waste management

is a significant environmental justice issue. Many of the environmental

burdens cited above are more often borne by marginalized groups, such as

racial minorities, women and residents of developing nations. However, the

need for expansion and siting of waste treatment and disposal facilities is

increasing worldwide.

Ray (2008) express that there is now a growing market in the

transboundary movement of waste, and although most waste that flows

between countries goes between developed nations, a significant amount of

waste is moved from developed to developing nations.

c. Economic costs: Muck and Brash (2009) exhort that the economic costs

of managing waste are high, and are often paid for by municipal governments.

Money can often be saved with more efficiently designed collection routes,

modifying vehicles, and with public education. Environmental policies such as

34

pay as you throw can reduce the cost of management and reduce waste

quantities. Wilson et al. (2006) opines that the informal waste sector consists

mostly of waste pickers who scavenge for metals, glass, plastic, textiles, and

other materials and then trade them for a profit. This sector can significantly

alter or reduce waste in a particular system, but other negative economic

effects come with the disease, poverty, exploitation, and abuse of its workers.

d. Education and awareness: Education and awareness in the area of waste

and waste management is increasingly important from a global perspective of

resource management. The Talloires Declaration is a declaration for

sustainability concerned about the unprecedented scale and speed of

environmental pollution and degradation, and the depletion of natural

resources. Local, regional, and global air pollution; accumulation and

distribution of toxic wastes; destruction and depletion of forests, soil, and

water; depletion of the ozone layer and emission of "green house" gases

threaten the survival of humans and thousands of other living species,

the integrity of the earth and its biodiversity, the security of nations, and

the heritage of future generations.

4. Organic wastes as an alternate source of energy

India being a large country, spread over in different agro climatic

zones, have variety of solid wastes in different regions which also vary in

season to season to regular production of biogas from this solid waste

materials. Biomethanation with concomitant production of biogas and a safer

end product for disposal of land (compost) has been the direction in which

many countries have put in a great deal of effort (Kausik, 2002).

Methane gas is the main ingredient of gas which is produced from

wastes. Smelly stiff, like rotting garbage, agricultural and human waste

releases methane gas-also called “Land fill gas” or biogas” (Amrit et al.,

2005). The energy produced from organic wastes has been one of the main

energy sources for the mankind ever since the dawn of civilization,

every year million tons of agriculture and forest residues are generated.

These are either wasted or burnt inefficiently in their loose causing air

pollution (Gunasegarana, 2002).

35

Tester et al. (2006) point out that the energy crisis demands effective

planning and use of the limited energy sources. Since exhaustible energy

sources in the country are limited; there is an urgent need to focus attention

on development of alternate energy sources and use of energy efficient

technologies. Hence energy recovery from organic wastes could be one of the

best alternatives to overcome energy problem.

While, the energy needs of our country is increasing at a rapid rate,

and the energy resources that are indigenously available are limited and may

not be sufficient in the long run to sustain the process of economic

development (Dayanadan, 2003). The need for of alternate energy increases

tremendously as they are available in zero or negligible cost. Vandana (2002)

brings forth that conventional sources of energy available to use are in the

form of coal, oil, electricity and nuclear energy, which are fast depleting.

Hence energy crisis can be reduced to large extent by combating energy

crisis through alternate sources of energy.

To meet the energy requirement, the effective use of organic wastes

has now emerged as potential alternative energy source (Ramasamy, 2011).

The energy produced from organic waste, as a source of energy is

environment friendly, renewable relatively cheap and locally available.

There is an urgent need to make available technologies for increasing the

producing of energy from organic waste and ensure its efficient utilization.

This would so a long way in promoting the sustainable use of wastes for

meeting energy requirements and would also result in additional benefits to

the society.

5. Waste management

Jha (2005) explains that the waste management is the collection,

transport, processing or disposal, managing and monitoring of waste

materials. The term usually relates to materials produced by human activity,

and the process is generally undertaken to reduce their effect on health,

the environment or aesthetics. Waste management is a distinct practice from

resource recovery which focuses on delaying the rate of consumption of

natural resources. Waste management practices differ for developed and

36

developing nations, for urban and rural areas, and for residential and

industrial producers. Management for non-hazardous waste residential and

institutional waste in metropolitan areas is usually the responsibility of local

government authorities, while management for non-hazardous commercial

and industrial waste is usually the responsibility of the generator.

Waste is actually a misplaced resources and this concept is slowly

gaining recognition. There are various forms of resources recovery from

waste that are currently practiced to varying degrees.

According to Beukering (1994), the term “recycling” has evolved into a

concept encompassing any productive use of what would otherwise be a

residual requiring disposal. This generalizations, however, includes many

more activities than recycling alone.

Recycling can be defined as a method to reprocess waste in order to

recover an original raw material. Two categories of recycling can be

distinguished. Closed loop recycling is the processing of residuals in order to

recover and reuse the material in the same production activity. Open loop

recycling in this process, reclaiming residuals is preceded by marketing of the

waste. Since many producers or consumers are unable to recycle waste

themselves, it is either disposed off or marketed. This type of recycling occurs

most widely (Zafar, 2009).

Reuse is a process by which materials in its end-use form is reclaimed

and again used in the same form. No significant transformation of the residual

occurs. An example is the returnable bottle or the use of newspapers for

packaging purposes.

37

Diagram of the waste hierarchy

There are a number of concepts about waste management which vary

in their usage between countries or regions. Some of the most general, widely

used concepts include:

• Waste hierarchy - The waste hierarchy refers to the "3 Rs" reduce,

reuse and recycle, which classify waste management strategies

according to their desirability in terms of waste minimization. The waste

hierarchy remains the cornerstone of most waste minimization

strategies. The aim of the waste hierarchy is to extract the maximum

practical benefits from products and to generate the minimum amount

of waste i.e. resource recovery.

• Polluter pays principle - the Polluter Pays Principle is a principle where

the polluting party pays for the impact caused to the environment. With

respect to waste management, this generally refers to the requirement

for a waste generator to pay for appropriate disposal of the waste

(www.recoveredenergy.com).

Disposing of waste in a landfill involves burying the waste, and this

remains a common practice in most countries. Landfills were often

established in abandoned or unused quarries, mining voids or borrow pits.

A properly designed and well-managed landfill can be a hygienic and

relatively inexpensive method of disposing of waste materials. Older, poorly

designed or poorly managed landfills can create a number of adverse

environmental impacts such as wind-blown litter, attraction of vermin, and

38

generation of liquid leachate. Another common byproduct of landfills is gas

(mostly composed of methane and carbon dioxide), which is produced as

organic waste breaks down anaerobically. This gas can create odour

problems, kill surface vegetation, and is a greenhouse gas (Rasure, 2011).

Design characteristics of a modern landfill include methods to contain

leachate such as clay or plastic lining material. Deposited waste is normally

compacted to increase its density and stability, and covered to prevent

attracting vermin (such as mice or rats). Many landfills also have landfill gas

extraction systems installed to extract the landfill gas. Gas is pumped out of

the landfill using perforated pipes and flared off or burnt in a gas engine to

generate electricity (Baker et al., 2004).

Incineration is a disposal method in which solid organic wastes are

subjected to combustion so as to convert them into residue and gaseous

products. This method is useful for disposal of residue of both solid waste

management and solid residue from waste water management. This process

reduces the volumes of solid waste to 20 to 30 percent of the original volume.

Incineration and other high temperature waste treatment systems are

sometimes described as "thermal treatment". Incinerators convert waste

materials into heat, gas, steam and ash (Ahlavat, 2008).

Incineration is carried out both on a small scale by individuals and on a

large scale by industry. It is used to dispose of solid, liquid and gaseous

waste. It is recognized as a practical method of disposing of certain

hazardous waste materials (such as biological medical waste). Incineration is

a controversial method of waste disposal, due to issues such as emission of

gaseous pollutants.

Incineration is common in countries such as Japan where land is

scarcer, as these facilities generally do not require as much area as landfills.

Waste-to-Energy (WtE) or Energy-from-Waste (EfW) is a broad term for

facilities that burn waste in a furnace or boiler to generate heat, steam or

electricity. Combustion in an incinerator is not always perfect and there have

been concerns about pollutants in gaseous emissions from incinerator stacks.

Particular concern has focused on some very persistent organics such as

39

dioxins, furans, PAHs which may be created which may have serious

environmental consequences (Vinneras et al., 2006).

Hangaragi (2009) exhort that the energy content of waste products can

be harnessed directly by using them as a direct combustion fuel, or indirectly

by processing them into another type of fuel. Thermal treatment ranges from

using waste as a fuel source for cooking or heating and the use of the gas fuel

to fuel for boilers to generate steam and electricity in a turbine. Pyrolysis and

gasification are two related forms of thermal treatment where waste materials

are heated to high temperatures with limited oxygen availability. The process

usually occurs in a sealed vessel under high pressure. Pyrolysis of solid

waste converts the material into solid, liquid and gas products. The liquid and

gas can be burnt to produce energy or refined into other chemical products

(chemical refinery). The solid residue (char) can be further refined into

products such as activated carbon. Gasification and advanced Plasma arc

gasification are used to convert organic materials directly into a synthetic gas

(syngas) composed of carbon monoxide and hydrogen. The gas is then burnt

to produce electricity and steam. An alternative to pyrolisis is high

temperature and pressure supercritical water decomposition (hydrothermal

monophasic oxidation).

Resource recovery (as opposed to waste management) uses LCA

(life cycle analysis) to offer alternatives to waste management. For mixed

MSW (Municipal Solid Waste) a number of broad studies have indicated that

administration, source separation and collection followed by reuse and

recycling of the non-organic fraction and energy and compost/fertilizer

production of the organic waste fraction via anaerobic digestion to be the

favoured path (Dhussa and Varshney, 2000).

An important method of waste management is the prevention of waste

material being created, also known as waste reduction. Methods of avoidance

include reuse of second-hand products, repairing broken items instead of

buying new, designing products to be refillable or reusable (such as cotton

instead of plastic shopping bags), encouraging consumers to avoid using

disposable products (such as disposable cutlery), removing any food/liquid

remains from cans, packaging and designing products that use less material

40

to achieve the same purpose (for example, light weighting of beverage cans)

(Naveen et al., 2011).

C. Waste to Energy – Biogas Technology

Waste generation rates are affected by socio-economic development,

degree of industrialization, and climate. Generally, the greater the economic

prosperity and the higher percentage of urban population, the greater the

amount of solid waste produced. Reduction in the volume and mass of solid

waste is a crucial issue especially in the light of limited availability of final

disposal sites in many parts of the world. Although numerous waste and

byproduct recovery processes have been introduced, anaerobic digestion has

unique and integrative potential, simultaneously acting as a waste treatment

and recovery process (Zafar, 2009).

Studies have shown that communities that employ waste-to-energy

technology have higher recycling rates than communities that do not utilize

Waste-to-Energy (Narasith, 2008). The recovery of ferrous and non-ferrous

metals from these plants for recycling is strong and growing each year.

In addition, numerous studies have determined that WtE plants actually

reduce the amount of greenhouse gases that enter the atmosphere

(Selvaraj, 2012).

Nowadays, these plants based on combustion technologies are highly

efficient power plants that utilize municipal solid waste as their fuel rather than

coal, oil or natural gas. Far better than expending energy to explore, recover,

process and transport the fuel from some distant source, Waste-to-Energy

plants find value in what others consider garbage. These plants recover the

thermal energy contained in the trash in highly efficient boilers that generate

steam that can then be sold directly to industrial customers, or used on-site to

drive turbines for electricity production (Murphy and McKay, 2001). WtE plants

are highly efficient in harnessing the untapped energy potential of organic

waste by converting the biodegradable fraction of the waste into high calorific

value gases like methane. The digested portion of the waste is highly rich in

nutrients and is widely used as biofertilizer in many parts of the world.

41

Most wastes that are generated, find their way into land and water

bodies without proper treatment, causing severe water pollution. They also

emit greenhouse gases like methane and carbon dioxide, and add to air

pollution. Any organic waste from urban and rural areas and industries is a

resource due to its ability to get degraded, resulting in energy generation

(Murad, 2007).

The problems caused by solid and liquid wastes can be significantly

mitigated through the adoption of environment-friendly waste-to-energy

technologies that will allow treatment and processing of wastes before their

disposal (Saha et.al 2010). These measures would reduce the quantity of

wastes, generate a substantial quantity of energy from them, and greatly

reduce environmental pollution (Joseph, 2002). India’s growing energy deficit

is making the Central and State governments become keen on alternative and

renewable energy sources. Waste to energy is one of these, and it is

garnering increasing attention from both the Central and State governments

(WHO, 2006).

While the Indian Government’s own figures would suggest that the cost

of waste to energy is somewhat higher than other renewable sources, it is still

an attractive option, as it serves a dual role of waste disposal and energy

production.

The recovery of energy from wastes offers additional benefits as

follows.

• The total quantity of waste gets reduced by nearly 60 percent to over

90 percent, depending upon waste composition and adopted

technology.

• Demand for the land, which is already scarce in cities, for land filling its

reduced.

• The cost of transportation to far-away land fill sites also gets reduced

proportionately., and

• Net reduction in environmental pollution

(http://urban india.nic.in/public infor/swm/chap15.pdf)

42

Technologies for the Generation of Energy from Wast e

Mukherjee and Chakrabarti (2005) puts across that energy can be

recovered from the organic fraction of waste (biodegradable as well as

non-biodegradable) through thermal, thermo-chemical, biochemical and

electrochemical methods.

i. Thermal Conversion : This process involves thermal degradation of waste

under high temperature. In this process complete oxidation of the waste

occurs under high temperature. The major technological option under this

category is incineration. However incineration has been losing attention

these days because of its emission characteristics.

ii. Thermo-chemical conversion : This process entails high temperature

driven decomposition of organic matter to produce either heat energy or fuel

oil or gas. They are useful for wastes containing high percentage of organic

non-biodegradable matter and low moisture content. The main technological

options under this category include Pyrolysis and G asification.

The products of these processes (producer gas, exhaust gases etc) can be

used purely as heat energy or further processed chemically, to produce a

range of end products.

iii. Bio-chemical conversion : This process is based on enzymatic

decomposition of organic matter by microbial action to produce methane gas,

and alcohol etc. This process, on the other hand, is preferred for wastes

having high percentage of organic, bio-degradable (putrescible) matter and

high level of moisture/water content, which aids microbial activity. The major

technological options under this category are anaer obic digestion

(bio-methanation) and fermentation. Of the two, anaerobic digestion is the

most frequently used method for waste to energy, and fermentation is

emerging.

The USEPA defines Anaerobic Digestion as a process where

microorganisms break down organic materials, such as food scraps, manure

and sewage sludge, in the absence of oxygen. In the context of solid waste

management, anaerobic digestion (also called biomethanation) is a method to

treat source separated organic waste to recover energy in the form of biogas,

43

and compost in the form of a liquid residual. Biogas consists of methane and

CO2 and can be used as fuel. The liquid slurry can be used as organic

fertilizer.

iv. Electrochemical Conversion : Electrochemical conversion in the

context of waste to energy refers typically to microbial fuel cells (MFC).

These systems are developed to trap the energy from wastes, where the

reduction-oxidation machinery of immobilized microbial cells is catalytically

exploited, for the accelerated transfer of electrons from organic wastes, to

generate electricity and bio-hydrogen gas. However, this methodology needs

extensive evaluation studies on bulk scale liquid waste treatments and stands

at a nascent level in India as well as worldwide.

A potential for generating about 1000 mw of power from urban and

municipal wastes and about 700mw from industrial wastes has been

estimated for the country. This potential is likely to increase the further

economic development (Singh, 2007).

The main objectives of the National Programme or Energy Recovery

from Urban, Municipal and Industrial wastes are as follows:

• To create conducive conditions and environment with financial and

fiscal to help, promote, develop and demonstrate the utilization of

waste for recovery of energy.

• To improve the waste management practices through adoption of

renewable energy technologies for processing and treatment of

wastes prior to disposal.

• To promote setting up of projects for recovery of energy from

wastes from urban, municipal and industrial sectors.

In today's energy crisis, it is recognized that renewable energy sources

can be the alterable sources of energy to provide the basis for sustainable

energy development on account of their inexhaustible nature and

environment-friendly features (Viswanathan, 2005). The challenge now is to

implement the latest technology at the grass root level effectively. Additionally

the economy of biogas plants can be improved by using high biogas potential

44

substrates in combination with cattle dung. One such substrate being night

soil, rich in nitrogen content was added to the cattle dung digesters to combat

the nitrogen deficiency and also improve the gas production (Schertenleib and

Meyer, 2002).

Another thing is human waste disposal in an innocuous form in highly

populated and developing countries, such as India is an ever growing

problem. Improper disposal of human excreta results in the contamination of

water bodies, soil and food crops. This practice poses a serious health hazard

because human excreta is the principal source of pathogenic organisms,

which may be transmitted by direct contact, contaminated water and food,

insects and other vectors. Human excreta must therefore be treated before its

ultimate disposal into the environment or its use in agriculture in order to

reduce the spread of communicable diseases and prevent the pollution of the

environment, water sources and soil (Jha, 2005). The problem of treatment

and disposal is more aggravated at low temperature and high altitude regions,

such as Himalayan regions of India, where no proper human waste disposal

method is in practice. Although, aerobic degradation of organic waste is

considered to be efficient, anaerobic digestion appears to be more suitable in

view of the generation of biogas which can be used for maintenance of

digester temperature (in addition to better hygiene) with least human

intervention (Lakshminarayanan, 2011).

D. Institutional and Community Biogas Plant - A Boo n for Waste

Management

Biogas refers to a gas made from anaerobic digestion of agricultural

and animal waste, food waste and sometimes municipal solid waste and

biofuel crops. The design is based on the type of organic waste to be used as

raw material, the temperature to be used in digestion, and the material

available for construction. Methane is the combustible component of biogas

and the digestate slurry is a valued fertilizer. Most people are not aware that

as the world turns to using renewable energy, the one huge source that has

barely been used up to now is biogas methane.

45

There are differing definitions for biogas. Itodo and Philips (2011) says

that a methane rich gas that is produced from the anaerobic digestion of

organic materials in a biological-engineering structure called the design.

Bates (2007) describes that “a gas mixture comprises around 60 per cent

methane and 40 per cent carbon dioxide that is formed when organic material,

such as dung or vegetable matter are broken down by microbiological activity

in the absence of air, at a slightly elevated temperature and clean, cooking,

lighting fuel” also know as “swamp gas, marsh gas and gobar gas.

Manure, either from human beings or from animals, is a major pollutant

source in rural areas. Anyone who has visited India, for example will

remember the acrid smell of burning manure. The acrid smoke leads to

endemic eye disease, and the drying manure is a perfect breeding ground for

flies of all types. The manure would also go a long way to improve the quality

of the soil and hence increasing the harvest if these valuable mineral were

returned to it instead of going up in smoke.

Table 2: Gas Production per Kg of Dung

Types of Dung Gas production / Kg dung

cu.m

Cattle

Pig

Poultry

Human

0.023 – 0.04

0.04 – 0.059

0.065 – 0.116

0.02 – 0.028

Source: Energy Resources Development 2002.

Itodo and Philips (2011) opine that to produce the Biogas a feed stock

material must be used such as vegetable matter and dung. However, it is the

general belief that liquid – manure systems work best for anaerobic digestion

in the production of biogas. The yield from human waste is low in comparison

to other manures, but the gas gained should be seen as a bonus; the main

purpose is to find an alternative disposal method, also “reading the amount

that would otherwise be released naturally into the atmosphere and so

reduces the excessive green house effect”. Other benefits of digesting human

wastes are:

46

• Methane being a fuel reduces the amount of wood fuel required and

thus reduces desertification (Xuereb, 1997)

• The waste is reduced to slurry that has a high nutrient content

making an ideal fertilizer

• During the digestion process, dangerous bacteria in the dung are

killed, which reduced the pathogens dangerous to human health

(Bates et al., 2007).

Institutional Biogas Plant and Community Biogas Pla nt

The International Reference Centre for Waste Disposal (IRCWD)

examines a number of areas where it has been used and identifies that

institutional and community biogas plants provide benefits including:

• Economies of scale

• Surplus gas for income generating activities

• More efficient operation as the plant usually has a full-time operator

• Equity consideration, people can work in return for gas

Strieber et al., (2006) identifies that how biogas technology was used

for sanitation in Kigali, Rwanda on a community level and providing gas that

cost the household $0.23 per person per day “significantly less than the

current cost of improved oil”. These are the examples where biogas

technology has also been a success in institution such as prisons in Kaski,

Nepal and Kigali, Rwanda, where the prison holds “5000 people who together

produce 50cu.m toilet waste per day (producing) a whopping 250cu.m of

biogas per day” (Aryal, 2009). Biogas has also been used widely in schools, in

Maphephethini, Kwazulu – Natal (Sibisi and Green, 2005) and Lem, Ethiopia

where of schools with and average population of 5,500 were fitted with

digesters and the technology is still working today (Worku, 2009).

Designs of Biogas Plant for Converting Waste to Ene rgy

The digester provides a sealed vessel that allows the input of feeds

tock and removal of gas, ideally being built of locally available materials.

47

The “Floating Drum”/“Indian” Digester

Developed in 1956, the chamber is made

of masonry and a steel drum placed on top to

catch the biogas. The drum moves up as it fills.

It requires high investment and maintenance.

In KVIC design, the digester chamber is made of

brick masonry in cement mortar. A mild steel

drum is placed on top of the digester to collect the biogas produced from the

digester. Thus, there are two separate structures for gas production and

collection. With the introduction of fixed dome Chinese model plant, the

floating drum plants became obsolete because of comparatively high

investment and maintenance cost along with other design weaknesses.

The “Fixed Dome”/”Chinese Digester”

Dating back to 1936, it consists of an

underground masonry compartment also know as

the fermentation chamber and a fixed dome for

gas storage. The single piece structure decreases

the complexity of maintenance whilst still having

two drains to feed waste. The life span is longer at

around 20 to 50 years increasing its economic feasibility. The Gas and

Agricultural Equipment Development Company of Nepal have developed a

cheaper concrete design built form this that has been around since the early

go’s showing the initial shape is tested and proven.

The Deenbandhu Model

It was originally developed by Action for

Food Production to bring down costs. It proved 30

per cent cheaper than a fixed dome design based

on the Chinese Digester and 45 per cent cheaper

than the Nepalese KVIC plant. It is made entirely

out of masonry with hemisphere gas storage at the

top and concave base working under the same principles as a normal fixed

dome digester.

48

ARTI Biogas plants

ARTI Biogas plants are manufactured using molded

plastic. These are floating dome type biogas plants

designed for household application. The primary use

of these biogas plants is waste management,

whereas the secondary use include biogas for partial

substitution of LPG in the kitchen and watery slurry available for irrigation.

Features:

• Available in two sizes, one for up to 500gm feedstock, and one for up

to 1-2kg feedstock.

• Feedstock required is any type of organic biodegradable waste (ideally,

kitchen and food waste).

• Daily addition of dung or faecal matter is not required more.

Water kiosk biogas plant: The water kiosk biogas plant has a

volume of 54cu.m with two expansion chambers.

The underground structure is located about 0.5 m

below surface. The required area for the toilet building

and biogas plant is approximately 10x15 metres. It is

not recommended to build any structures on top of the

biogas plant. The dimensions of the plant were based

on a sufficient settlement of solids which is achieved

with a hydraulic retention time (HRT) of 5 days. The solids settle and remain

in the system for digestion and biogas production. The system works like a

gas tight septic tank. The solids-free effluent is flowing over to the sewer

connection.

BCSIR biogas plant: In BCSIR Design, the present fixed biogas plants have

an underground cylindrical shaped biogas digester constructed with brick

walls and concrete. The digester is also connected to the outlet tank, which

includes a hydraulic chamber, and bio-fertiliser pit. The size of the plant

depends on the availability of raw materials and demand for gas. It works

according to the principles of constant volume and changing pressure.

49

When the rate of gas production is higher than that of gas consumption,

pressure inside the digester rises and expels some digester contents into the

outlet compartment. When the consumption is higher than production,

pressure inside the digester falls and the expelled materials in the outlet

compartment run back to the main digester.

Malaprabha biogas plant: The Malaprabha biogas plant comprises of

3 compartments. The first compartment is designed to provide for a HRT of

30 days and doubles-up as gasholder. In order to collect the biogas that is

generated in the process of anaerobic digestion of black water, the first

compartment is provided a gas tight cover made from reinforced cement

concrete (R.C.C.). The second and third compartments provide for a total

HRT of 15 days. The chambers act as compensation chambers and facilitate

build up of gas pressure. There is an opening at the bottom of the wall

separating the 1st and the 2nd chamber and an aperture in the wall separating

the 2nd and 3rd chamber to facilitate flow of water through the biogas plant.

The opening (1st to 2nd chamber) provides access to the sealed

1st compartment during construction and doubles-up as maintenance opening

afterwards. The biogas plant is provided with pressure release pipe that vents

biogas before excess gas pressure may damage the plant. Depending on site

conditions, the effluent from Malaprabha Biogas Plants may be drained to an

existing drainage system, infiltrated locally or collected for reuse. The digester

volume equals number of users into litres of water used for flushing (and anal

cleansing, if applicable) per person per day into 45 days HRT. For digestion of

night soil (i.e. excreta), optimum requirement of water is 2.17 litre per person

(Martin, 2009).

Fixed dome biogas plant: Fixed dome biogas plant consists of an

underground brick masonry compartment

(fermentation chamber) with a dome on

the top for gas storage. In this design,

the fermentation chamber and gas holder

are combined as one unit. This design

eliminates the use of costlier mild steel

gas holder which is susceptible to corrosion. The life of fixed dome type plant

50

is longer (from 20 to 50 years) compared to KVIC plant. Because of the

advantages the fixed dome biogas plant was adjudged as the best for

institutions and communities.

Institutional Biogas Plants- These types of plants is designed to cater to the

needs of hostels, schools, convents, hospitals,

industrial organizations where people coming in

large numbers and stay regularly. The generated

wastes will be treated by hygienic waste disposal

methods in an eco-friendly manner. The night soil

(human excreta) generated will directly be fed into

the treatment plant automatically in a hygienic way for production of biogas.

All the institutions have hostels for their students. The major problem

which they are facing today is the way to dispose the human excreta, food

and vegetable waste, hand washing water, vessel washing water. Biogas

plant can only solve the whole problem. There are regular waste disposal

problem in almost all institutions like hostels, hospitals, convents, old-age

homes where more peoples are staying together. The overflow and or

leakage of septic tank or drainage systems create severe environmental

problems and public nuisance, opposition and complaints from the neighbors,

(http://nwedc.in/night-soil-Biogas -plant.html).

In the same time, the cooking fuel consumption of these institutions is

also very high. The monthly budgets for firewood or other cooking fuels are

also increasing regularly for these institutions. The treatment of human

excreta through biomethanation is the remedy to overcome these two

problems at a time. Like any other bio waste, human excreta can be treated

with the help of anaerobic microbes (bacteria). These microbes are not

harmful to human beings. When human excreta are treated with the help of

biomethanation process, the biogas is generated from this waste, through

microbial action. This gas can be used for cooking. When a night soil plant is

installed, there is no need of a separate conventional septic tank. Treated

slurry coming out from the plant can be utilized as liquid fertilizer. All other

easily biodegradable waste can be treated together with human excreta in the

same plant.

51

Through this installation of institution based biogas process

the beneficiary can treat all other degradable waste like cooked food. Fish,

meat and vegetable waste can also be treated in the same plant. The size of

the plant may be different depending upon the availability of human excreta

and other degradable waste. The treatment plant can be installed either as a

single unit or more units in different locations. The installation of a night soil

plant is more convenient during the building construction time. The conversion

of existing septic tanks to night soil treatment digester is a little expensive.

In accordance with the fast growing population, the demand for energy

and the discharge of waste are increasing day by day. To overcome

the energy crisis, alternative energy sources are the only remedy. Generation

of energy from waste is beneficial in many ways. It is most suitable for

eco-friendly waste disposal and also for energy generation.

All easily degradable materials including cooked and raw food wastes,

fruits and vegetable wastes, fish and meat wastes, excreta of all domestic and

wild animals and birds and waste water containing bio waste materials can be

treated with this technology. Slow degradable materials like vegetables, green

or wet plant parts can also be treated with this technology, using specially

designed anaerobic pre-digesters.

Socio-Economic Benefits

� Generation of Energy in the form of Biogas � Generation of organic fertlizer � Saving of garbage dumping land � Minimum waste collection expenses � Better utilization of wastes � Employment opportunities

Community biogas plant: In Institutional biogas system, Household biogas

generators have been accepted because the

connection between the latrine and the digester

requires no contact with the waste, bypassing

any taboos. Implementing the technology in a

more community-based situation may have its

limits but there is evidence that Community

Biogas Plants have been implemented.

52

Design Parameters for Sizing of Biogas Plants

Table 3: Design Parameters for Sizing of Biogas Pla nts

Source: Werner, Stohr ami Hccs (1989)

The optimum biogas production is achieved when the pH value of input

mixture in the digester is between 6 and 7. The pH in a biogas digester is also

a function of the retention time. Methanogenic bacteria are very sensitive to

pH and do not thrive below a value of 6.5. Loading rate is the amount of raw

materials fed per unit volume of digester capacity per day. If the plant is

overfed, acids will accumulate and methane production will be inhibited.

Similarly, if the plant is underfed, the gas production will also be low.

Retention time (also known as detention time) is the average period that a

given quantity of input remains in the digester to be acted upon by the

methanogens. For a night soil biogas digester, a longer retention time

(70-80 days) is needed so that the pathogens present in human faeces are

destroyed. The retention time is also dependent on the temperature.

The methanogens are inactive in extreme high and low temperatures.

The optimum temperature is 35 degrees C. Satisfactory gas production takes

place in the mesophilic range, between 25 degrees to 30 degrees C

(http://www.bioenergy.org.n2/biogas.asp).

Quality and Composition of Human Faeces and Urine

Human excreta consist of faeces and urine. The two are waste

products of the bodily metabolism. The appearance, physical and chemical

characteristics of urine or faeces depend largely on the health of the person

excreting the material, as well as on the amount and type of food and liquid

Design Parameters Parameter Value

pH

Digestion temperature

Retention time (HRT)

Biogas energy content

Gas production per kg of human excreta

Gas requirement for cooking

Gas requirement for lighting one lamp

6-7

20-35

40 - 100 days

6 kwh/m3

0.020-0.028 m3

0.2 - 0.3 m3 person

0.1 -0.15 m3/hr

53

consumed. Therefore, the excreta generated by healthy people eating a

similar diet are quite similar in both physical and chemical composition. In a

study on the composition of human excreta, it was reported that age, sex,

occupation or religion did not affect the chemical composition of the different

fractions. However, a significant variation was that older people excreted

larger amounts of total wet matter than younger, which was linked to a larger

water intake intended to reduce the risk of constipation (Daisy, 2011).

Available human excreta as per age group

It is not surprising that the per capital quantities vary widely. Figures for

collected septate, i.e., fecal sludge stored in septic tanks, can be as low as

0.3 liter/persons/day and as high as 1.31/litres/person/day. Most of the

reported values vary between 0.5 and 1liters/person/day. Based on literature

review, the excreta production per day for an adult is 0.4kg, 10 to 15 years is

0.3kg, 6 to10 years is 0.2kg (Schonning and Stenstrom, 2004).

Night soil based Biogas: Potential of biogas from human waste is 0.07cu.m

per kg in Bangladesh. Guidebooks reported that Biogas generated from

Human excreta is 0.020-0.028 cu.m per kg. The composition of night soil

based biogas is Methane 65-66%, Carbondioxide 32-34%, Hydrogen sulphide

1%, Nitrogen oxide and Ammonia in traces.

Retention Time of Biogas Plants

Water Kiosk comes under the low retention time based biogas plant.

The retention time of this plant is 5 days. But the reduction of BOD

performance is very poor as 30- 40%. Sulabh model, Community latrine cum

biodigester, and BCSIR, are coming under medium retention time based

biogas plant. The retention time of BCSIR is 10 to 15 days. The retention time

of Sulabh is 30 days. The BOD reduction of these two plants is 85%.

The retention time of Community latrine cum biodigester is 21 days.

The retention time of Malaprabha biogas plant is 45 days. It is high retention

time based biogas plant. The Hydraulic Retention Time (HRT) of Latrine cum

bio digester constructed in institutions / communities is 70 days. It ensures

that most of the pathogens are destroyed and have very high retention time.

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Programmes for Promoting Biogas Technology: The Government of

India’s Ministry of Non-Conventional Energy Sources started its biogas

development project in 1981 as one of its programs designed to meet rural

energy needs, especially for cooking.

The objectives of these biogas development programs are to provide

fuel to rural households for cooking, organic manure for application on

agricultural fields, mitigating the drudgery of rural women, and reducing the

pressure on forests. As a result, family-size biogas plants and more than three

thousand community and institution-based biogas plants have been set up in

the country so far. Most of the biogas plants constructed to date, however, are

based on cattle dung as the fuel source. Biogas plants based on night soil

have not yet been established in large numbers. This is due to

the unavailability of night soil at a single location in sufficient quantities

and the fact that the focus for development of biogas technologies has largely

been on technologies using cattle dung as the feedstock

(http://www.mnes.nic.in).

National Project on Biogas Development (NPBD): This project was initiated

during 1981-82 to provide clean cooking fuel and organic manure to the

farmers and other users. The concept of biogas plants has achieved a wide

and excellent appreciation both in rural and urban contexts, but the

performance of the project, methodology adopted for implementation,

technical and administrative support, financial assistance in the form of

subsidy and assistance from public financial institutions have collectively

advanced this program and is rated as “Good”;

This NPBD program is presently being implemented by all the State

nodal agencies, Khadi and Village Industries Commission, (KVIC), National

Dairy Development Board (NDDB), All India Women’s Conference (AIWC);

and Non-Governmental agencies. Incidentally, in some states in the country,

implementation of this program is directly by local rural development

departments/Panchayat/Zilla Parizad and the like, by associating local elected

bodies with these programs. Involvement of local bodies and panchayats is to

be encouraged more to improve the people’s participation and to integrate the

concept and gadgets as an integral part of the daily activity of a common man.

55

Under this National Program, a total of +/-30 lakhs family-size biogas plants

are installed covering 25% of the known potential and +/-3100 large size

biogas plants under institutional, community category. It is also estimated that

over 1.8 million tons of organic manure is recovered from these biogas plants

for agricultural purposes.

Indian Government Support for Waste to Energy: The Indian Government

has recognized Waste to Energy (WtE) as a renewable technology and

supports it through various subsidies and incentives. The Ministry of New and

Renewable Energy is actively promoting all the technology options available

for energy recovery from urban and industrial wastes. MNRE is also

promoting the research on waste to energy by providing financial support for

R&D projects on cost sharing basis in accordance with the R&D Policy of the

MNRE. In addition to that, MNRE also provides financial support for projects

involving applied R&D and studies on resource assessment, technology

up-gradation and performance evaluation.

A number of key statistics, such as the value of recyclables, the

amount of environmental pollution from waste sources, and the quantity of

industrial waste generated, need to be computed to gain a better

understanding of this sector. In terms of research related to waste to energy,

detailed analysis of costs and available funding is needed.

E. Challenges ahead for Future Perspectives

The appropriate technology should reach the people for whom it was

developed. But our country is facing several challenges to reach this goal set.

Social and cultural issues: Myles, (2001) identifies that socio-cultural

issues must be addressed before the implementation as there is a “good

chance of failure, as these technologies are new and alien to rural people”.

It is extremely difficulty to achieve change in excreta disposal practices as

they are part of the basic behavioral pattern of a community and are not

readily modified (Feachem and Cairncross,1978). Chaggu et al. (2002) views

that there is a lack of understanding why the disposal system has to be

changed because of the “lack of perceived benefits” (IRCWD, 1982). The low

education level result in “inadequate financial resources” so the priority is a

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not good excreta disposal when there is competition for financial resources.

According to Strauss et al. (2002) this lack of education level leads a low level

of involvement and without involvement, skills cannot be passed on. This lack

of knowledge and awareness can lead to an unwillingness to use the by-

products (Strauss et al., 2002) decreasing the values. Bates et al. (2007) also

identifies the importance of community involvement to develop a sense of

ownership because without it people will not feel obliged to maintain the plant.

A concern is religious issues over human excreta. Night workers carry

a stigma, Eales (2005) explains that in Kibera residents view this job as illegal

and it is therefore “legitimate to assault those who haul stinking buckets and

drums through narrow alleys.” This leads to working at night because there is

less chance they will be robbed or beaten. Moreover, it is not safe to work in

total darkness in such a dangerous environment. Bates et al. (2007) also

identifies that some communities may see the use of the gas as

unacceptable. A less direct use such as heating water may be a better

application in some societies. Education is also need to explain the hazards of

dumping as Vinneras (2006) explains that at present there is no “real demand

for implementing effective systems for wastewater and faecal sludge

management”. Community wide education would have to combat this issue.

There are also the health issues where “government public health authorities

often oppose excreta re-use because of the health risks involved” (Edwards

and Bater, 1992).

Economic issues: The major issue is the high set-up costs of a biogas

system (Bates et al., 2007). There are labour and material costs associated

with the digesters but also the construction of the gas delivery method.

Hasan et.al (2003) identifies that although decentralized systems do reduce

the cost of investment in comparison to large complex centralized treatment

infrastructure. The social activists projects that majority of government

agencies lack the funds to invest, so it is usual to look to the private sector

Bates et al., 2007., higher levels of government Parkinson and Tayler, 2003.,

or overseas agencies Myles, 2001., to help fund the project. Some labour

costs can be decreased by involving the community who will benefit from

the system providing a sense of ownership and improved maintenance.

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Bates (2007) describes how the system should be sold as a ‘win-win’ situation

to government organizations due to the free clean energy provided and

reduction in waste disposal problems.

The frequency of emptying pits will increase to make this technology

feasible. Strauss et al. (2003) brings forth “unaffordable emptying fees” as a

hindrance to good faecal sludge management. A number of case studies

outline that current emptying causes a burden due to high tariffs. Boot (2006)

explains that in Accra, Ghana the emptying systems are privately run and

have no governmental control over tariffs or disposal points. Where there is

little competition, the operating company charge unaffordable tariffs, whilst

also cutting their own costs by not transporting to a treatment facility and just

dumping it with many practicing the principle of “out of site, out of mind”

(Chaggu, et al., 2002). Increasing the frequency of emptying may be met with

hostility by most users, especially those who do not have a secure tenancy

agreement for their homes who will not want to invest in new wastewater

practices (Parkinson and Tayler, 2003).

Regulation and management: The implementation of decentralized

wastewater treatment system will only be successful if the necessary

knowledge and skills to operate and maintain them are “available at the local

level” (Parkinson and Tayler, 2003). It is necessary to consider the

development of an effective and needs responsive policy towards the issue of

wastewater management. The Household Centered Environment Sanitation

approach provides a framework where the emphasis not on waste as a

burden but as a resource, decisions about implementation start at household

level rising up through community making sure that all users fully understand

what is happening by making the system “Locally organized and people-

driven”. As per the statement Heymans et al. (2004) the community will gain

the necessary skills to operate the technology because they have been

made aware of all benefits that be told to embrace it by government.

Many wastewater systems stop working due to neglect and this kind

implementation will only lead to this situation.

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Critical Issues for Success

Future Perspectives : The literature and the present study demonstrate that it

is possible to use the anaerobic digester to anaerobically treat Night soil when

diluted appropriately. This holds an enormous potential for faecal wastes

treatment in developing countries where majority of sanitation facilities are

on-site systems. However before the system can be adopted on a scale

similar to its acceptance for the treatment of domestic sewage in tropical and

sub-tropical climatic conditions, it will be essential to carry out more

experimental studies. In this regard the following suggestions are made for

further research work:

1. Most of experiments similar undertaken in this research are for lesser

period only. It should be undertaken over a much longer period to establish

steady state conditions that will enable correct assessments of long term

treatment efficiencies, optimal loading rates, optimal hydraulic retention times,

suitable dilution ratio, and gas production potentials among others.

2. During such experiment, efforts should be made to minimise, if not

completely eliminate, the loss of biogas due to leakages and also an analysis

of the biogas produced must be carried out to determine the percentages of

methane and carbon dioxide in the biogas.

3. Production of biogas is significantly affected due to drop in temperature.

Thus, until now, this technology has been of little use in the higher altitude or

cold climate. Therefore, research work needs to be initiated in view of

increasing the efficiency of gas at the cold climate or in higher altitudes.

4. Research efforts should have undertaken to improve the designs of night

soil based biogas plant.

5. Such long term experiments should provide the required information for

optimum design and operation/maintenance guidelines when using the

anaerobic digester for the treatment of night soil. Biogas production is

diminished significantly in cold climate or at higher altitude, while the

methodology for warming the digester to raise the temperature seems

sophisticated, costly and unaffordable to the ordinary people. For example the

59

design propagated in Nepal is costly and no substantial research has been

initiated to lower its cost for wider application of the technology.

6. Several studies carried out in the past have confirmed that there is an

increase in mosquito breeding after the installation of biogas. Therefore,

serious thinking needs to be given to solve this problem because of the fact

that fatal disease like malaria can occur in the community due to unwanted

proliferation of mosquitoes.

7. Still there is less awareness amongst the farming community pertaining to

the utilization of bio-slurry as fertilizer. This aspect appears to be neglected in

the future. Agriculturists and Biogas promoters will be carried out sufficient

demonstrations and experiments to convince the farmers about the added

benefits of slurry as an organic fertilizer compared to Farm Yard Manure.

Public perception and participation: All socially oriented programme

end-up with success once the pulse and perception of public is accounted.

To achieve this, the role of local bodies is so important and to mobilize the

public opinion on the benefits individuals accrue and also collectively

reflecting on the society in larger interest. Educating the public automatically

makes them to participate at every level of technology integration in to the

society. This process can be accelerated by acting on complementary basis

by supporting each other by the local implementing mechanism and program

supporting organization, by identifying the needs and aspiration of local and

accommodating the same by way of extending help in all fronts.

Technology information dissemination: Once, public show and

understands the importance of a scientific program for development, providing

scientific information will be the next priority to stabilize the public perception.

Popular science articles etc play a major role. This can be achieved both by

head quarter of scientific organization and below the hierarchy.

Training local resource personnel: Training local personnel as a human

resource for development is the next step. This helps in calling innovations

from the bottom of the society, to suit local needs and utilization of local

material availability. This aspect of training may be handled by known

60

technical people, institutions, universities or NGO’s and the like. In fact, users

can train prospective users also.

Technical expertise development: For successful implementation, the

technical expertise of the implementing machinery needs to be refurnished at

the level of Panchayat units/Blocks/or the hills. To do so, specially tailored

technical information to suit this level of audience is a must and this can only

be handled by expert institutions or recognized technical back-up units set-up

for this purpose or laboratories associated with respective technologies.

However, lack of proper co-ordination at all levels of the sponsoring scientific

organization and unmindful continuation of useless centers, leads to chaos

and detrimental to the program itself.

Research and Development support: Providing financial support to

institutes associated in popularizing the technologies helps in developing user

oriented, location and raw material specific designs to upgrade the efficiencies

of a given design and penetration of the design in to the society. This

assistance helps in integrating these designs as a part of local social

economic activity by the rural entrepreneurs due to their interaction with R&D

center and this scenario only sustains the best in long run (MNRE, 2004).

Technical and administrative support: The institutional level support

(State level and District level) on the above said subjects and tuning the local

administration to understand the policies of the scientific organization and

providing day to day support in guidance and helping in promoting the

enthusiasm of the upper level staff must be the basic function of the first level

regional centers/offices. These centers must upgrade the technical knowledge

and arrange demonstration, work experience, studies, for the implementing

staff. This can be achieved by conducting workshops, seminars, conferences,

training programs, local meetings and arranging meetings with experts in

respective fields.

Financial assistance: Harnessing of natural energy sources by mankind is

not unknown. However, only in the past hundred years the present civilization

explored all possible methods to convert the energies of various fossil fuels to

suit day-to-day conveniences. The growing insecurity on continuous

61

availability of these fossil fuels made policy makers to harness energy from

natural sources in a systematic way to suit the present life styles. This was the

beginning of developing the designs to tap energy content from Solar and its

other forms. This naturally necessities to grant subsidies or other forms of

financial incentives to popularize these technologies (Linares and

Rosenweig, 1999).

Intervening Factors: For successful implementation of renewable energy

technologies, depending on the scale of operations, various intervening

factors also play their respective roles. These factor needs to be carefully

examined.

Technological Interventions: Technology driven approach to developmental

activities is a serious technological intervention. In fact, location specific, user

friendly and cost effective technologies penetrate the society faster than

complex systems involving complex activities (Lal, 2008). Frequent

introduction of new designs, changing certain parameters in the middle of the

program implementation, to accommodate gadgets not tested earlier and the

like, will have adverse effect on the success of the program.

Policy Changes: Frequent changes in the program implementation

brought-in due to modification in fiscal incentives, and operational parameters

of a program will have adverse effect on the success. Always, it is advisable

to notify and approve scientific program for at least three years to last without

any major changes. This helps and assures various segments of program

implementation to act and plan on a strong footing. Frequent changes also

indicate lack of clarity on the strengths of the program and on its positive

impact on the society (Mahalingam, 2011).

Political Interventions: Interference of politicians, information of program,

awarding subsidies etc., to suit their interest always felt detrimental to the

organisation itself. This kind of political interference forces scientific

organisation to adopt wait and see policy and fear of being victimized.

Also frequent changes of governing bodies also affect the working

atmosphere of the organisation, though the core programs go on without must

changes and become a routine and casual (Majumdar, 2006). At the same

62

time, if the political will is weak and heavily depends on coterie the out come

will be more disastrous. Similarly, though political will is strong, helpful, but not

able to withstand the tactical plan and vicious nature of the techno-

administration also yields no results.

Impediments in transforming and technology to the p ublic

• to get maximum support from the community, involvement of people in

technology development, transfer and monitoring should be made an

integral part of the process.

• a network of appropriate technology agencies should be established for

sharing regional and geographical responses to specific technologies.

• success stories and ‘failures’ need to be documented for further

research on the subject. Inter-regional exchanges on the subject will

help trigger the process.

• the list of proven and available appropriate technologies need to be

enlarged by getting some of the time-tested traditional technologies

(wisdom) into the list.

• there is a need to integrate traditional wisdom into the process of

technology development and dissemination. Traditional artisans and

craftsman should always be taken into account while planning

interventions.

• research and development be given priority for engineering products

that can withstand the changing market scenario and compete with the

products of modern technology.

• information on appropriate technology must be made available to

potential users. If needed, multi-media approach may be followed for

making the products of appropriate technology as popular as other

consumer products.

• use of folk art, folk media should be a good medium for effective

dissemination of technologies.

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• direct marketing of products should be encouraged through ‘village

fairs. Even ‘rural technology shops’ can be opened in selected places

in the country.

• efforts must be directed to get the planners and the government

interested in the products of appropriate technologies. Interventions for

getting policy directives must be attempted.

• periodic meetings on specific themes will help understand the process

better and will strengthen the appropriate technology movement which

is currently in the process of phasing out.