Waste Management an Overview
Prof (Dr) Francis Xavier
Kerala Veterinary & Animal
Sciences University
Mannuthy ,Thrissur,Kerala.India
fx@jananeethi.org. Mob 9447131598
Fragile eco system is a vital concern the world over
and any subtle anthropomorphic intervention can initiate ripples of perishable
change. Today our Government’s
priority is to popularize on-site waste management, especially for the
biodegradable wastes, so that the flow of waste to the common stream is reduced
significantly and it can function with better efficiency. Any person or Institution who honour civil and social rights, naturally think about
organic and inorganic waste management to be contained within the existing
rules and regulations of the country. In India eight lakh deaths and morbidity costs
of up to 3.6% of GDP as per latest
research reports ,can be attributed to
unclean air and water. The three pillars of sustainable development viz:
social justice, environmental integrity and economic development, are entwined
on these factors .In any country where there is lackadaisical attitude in waste
handling depletion of natural resources,
social discontent, and eventual economic breakdown, will happen.
Kerala Scenario: Who wastes the most?
The social waste concept of Kerala state differs with
different districts. The fragmented land holding is the major factor ,More over
the 43 rivers also play a role is washing away the pollutants. Social engineering
and Technology application are to be considered under this
scenario. The
social engineering deals with the ethics and efficiency for maintaining
environment. In the case of waste management, it is, broadly, the practice of
reduce, reuse recover and refuse. The
technology application deals with the improvement of assimilative capacity as
well as supportive capacity of environment. The bioconversion process is
applicable to the organic fraction of wastes, to form compost or to generate
biogas such as methane (waste to energy) and residual sludge (manure). Various technologies
are available for composting such as aerobic, anaerobic and vermicomposting.The
thermal conversion technologies are incineration with or with out heat recovery,
pyrolysis and gasification, plasma pyrolysis and pelletization or production of
Refuse Derived Fuel (RDF).
Eight of the 14 districts in
Kerala are disturbed and the daily waste generation with pertinent details are
appended:
1. Kannur municipality generates 20 tonnes a day and dumps it at 8
hecters in Chelora
village near the city for more than 30
years.
2 Kozhikode
corporation generates 150 tonns a day which went to 6.5 hect land at Njeliyanparamb near the cityThe site was used to discard human excreta
since it was established in 1930.The plant was built later. Last year, people protested
for 65 days, demanding the plant’s upgradation, construction of a leachate
collection unit and a landfill to
dispose non-biodegradable waste. Municipal
corporation now dumps 60-70 tonnes waste in a day. Meat shops sell waste
to agencies in Tamil Nadu. A plastic
recycling unit is under construction, even as
waste is accumulated on the roadsides
3 Thrissur
Corporation has 150 tonnes a day with their Dump
yard at Lalur in
10.1 hectaresPeople live close to the century-old disposal
site. Three youths died in 1992 after breathing toxic air while
cleaning a well. The high court ordered immediate solution. A
plant was set up in 2000, but it does not work. In 2010, the LDF
government ordered to implement Lalur Model Project for solid
waste management. UDF discarded the plan when it came to power
in the municipal corporation.
Now, corporation secretly burns waste at night.
4 Kottayam
Municipality: churns out 30 to 40 tonnes a day with a waste treatment plant at Vadavathoor in Vijayapuram
village in
1.4 hectares After
years of protests, the municipality built a plant in 2007 along
with a private firm. But it converted only a part of the waste
into manure. The rest was dumped in the landfill. In 2010,
the high court’s order favoured the firm. Waste is still being
sent to the plant with police protection
5 Kollam Corporation
produces 100 tonns of waste a day .Dumpyard
in Kureepuzha village
in 4 hectares mainly
handled this waste.The land is near
Ashtamudi Lake, an internationally
important Ramsar
site. After protests, a plant was set up in 2002, but it has not become
functional. High Court has ordered that no more waste can be dumped here
6 Kochi Corporation
has 120 to 140 tonns of waste generated with a waste treatment plant at Brahmapuram in Kunnathunad panchayat.It is 14.9 hectares. Till
2006, waste was dumped at a landfill near Southern Naval Command
in Wellington Island. Naval authorities withdrew permission when
a coastguard aircraft suffered bird hit. Corporation started to
use a wetland at
Brahmapuram it had bought in 1998. A plant was built in 2008, but sank in
marshy land. Now, it is recovered and working
7 Alappuzha
Municipality comes with 65 tonns waste a day with their dumpyard at Sarvodayapuram in Mararikkulam Thekk villagein
4.6 hectares.The
municipality entered into an agreement with private firm Andhra Pradesh Technology
Development Centre to build a plant. It could treat only 30 tonnes of waste.
The plant worked for a few months, then the firm asked for more money. The
municipality decided to run the plant on local expertise. But it cannot treat more
than 6 tonnes of waste. The rest is dumped unsegregated in landfills
8 Thalasserry
Municipality with 15 to 20 tonnes a day and the handling unit at a dump yard at Punnol Pettippalem near
Thalassery cityin 3.2 hectares The century-old dump yard is in a thickly
populated area near sea coast. Wells are contaminated, people have skin and
respiratory diseases, and fisher folk complain there is less fish to
catch. A government primary schoolis close by. Protests intensified two years
back, culminating in police action on March 20 this year. Protesters were
brutally beaten up.
‘Emerging’ waste maker Trivandrum Corporation
(150 tonns a day!)faces a stiff struggle with their dumping yard residents of
Vilappil sala .
Waste management:
Identifying appropriate technology feasible
for the locality is the main point in waste handling. The usual waste handling
methods in our state are :
Burial (labour intensive,
carelessness attract carnivores)
Incineration (need an
incinerator ,costly, labour intensive)
Pit disposal
(carnivores dig it out, pollute water bodies )
Sanitary land
fill (seepage, attract public protest ,carnivores)
Traditional
Composting (Existing methods not user friendly)
Monitoring,Collection,Transporation,Processing,disposal
and recycle /reuse are all the points in appropriate technology. “At source
treatment” is basically for Biodegradable waste. Bio-methination and STP are
all examples. Collection involves a lot of logistic planning .We have to have a
culture where we care for the society. But the segregation at source is an
ideal workable plan. Monitoring is identifying the waste management needs and
recycling opportunities. But minimizing waste output and a supervision of how
that is progressing is a must in an uncivil society. Unsorted non biodegradable
waste treatment techniques are also there. Bio-methanation and
thermal treatment cannot be compared. Bio-methantion technologies should be
evaluated with respect to (a) Pre-sorting methodology, (b) Digester unit utilised , (c) Dewatering of digestate and
reuse of water and (d) Methods proposed for the waste water treatment .Thermal
waste to energy should be subjected to a
preliminary evaluation based on (a)
Technical soundness, (b) material and energy balances, and (c) financial feasibility. The thermal
waste to energy technologies that do not produce liquid water are prima-facie
uneconomical, on a build-own-operate basis without operational subsidy either
as tipping fee or assured inflated energy sale prices.
How to plan
Composting:
Biodegradation is a natural,
ongoing biological process that is a common occurrence in both human-made and
natural environments.
1. Identify goals of the composting project.
2. Identify the scope of the project and socio cultural impact
3. Get political support for changing the
community’s waste management approach.
4. Identify potential sites and
environmental factors.
5. Identify potential compost uses and
markets.
6. Initiate public information programs.
7. Inventory materials available for
composting.
8. Visit successful compost programs.
9. Evaluate alternative composting and
associated collection techniques.
10. Finalize arrangements for compost use.
11. Obtain necessary governmental approvals.
12. Prepare final budget and arrange
financing.
13. Construct composting facilities and
purchase collection equipment.
14. Initiate composting operation and
monitor results.
The composting option chosen must be
compatible with existing processing systems.
Communities should consider these factors:
• preferences of the community
• collection and processing costs
• residual waste disposal costs
• markets for the quality of compost
produced
• markets for recyclables
• existing collection, processing and
disposal systems.
The four composting technologies are windrow,
aerated static pile, aerobic , and anaerobic composting. Supporting technologies include sorting,
screening, and curing. The technologies vary in the method of air supply,
temperature control, mixing/turning of the material, and the time required for
composting. Their capital and operating costs also vary considerably.
Moniter the following:
• compost mass temperatures
• oxygen concentrations in the compost mass
• moisture content
• particle size
• maturity of the compost
• pH
• soluble salts
• ammonia
• organic
and volatile materials content.
Microbes:
Microorganisms are the key in the composting process. Peak
performance by microorganisms requires that their biological, chemical, and
physical needs be maintained at ideal levels throughout all stages of
composting. Microorganisms such as bacteria, fungi, and actinomycetes play an active
role in decomposing the organic materials. As microorganisms begin to decompose
the organic material, the carbon in it is converted to by-products like carbon
dioxide and water, and a humus end
product—compost. Some of the carbon is consumed by the microorganisms to form
new microbial cells as they increase their population. Heat is released during
the decomposition process. If all conditions are ideal for a given microbial
population to perform at its maximum potential, composting will occur rapidly.
The composting process, therefore, should cater to the needs of the
microorganisms and promote conditions that will lead to rapid stabilization of
the organic materials.
Microorganisms in the compost process are like microscopic
plants: they have more or less the same nutritional needs (nitrogen,
phosphorus, potassium, and other trace elements) as the larger plants. There is
one important exception, however: compost microorganisms rely on the carbon in
organic material as their carbon/energy source instead of carbon dioxide and
sunlight, which is used by higher plants. As the more easily degradable forms
of carbon are decomposed, a small portion of the carbon is converted to
microbial cells, and a significant portion of this carbon is converted to
carbon dioxide and lost to the atmosphere. As the composting process
progresses, the loss of carbon results in a decrease in weight and volume of
the feedstock. The less-easily decomposed forms of carbon will form the matrix
for the physical structure of the final product—compost.
Chemical environment:
Several factors determine the chemical environment for
composting, especially: (a) the presence of an adequate carbon (food)/energy
source, (b) a balanced amount of nutrients, (c) the correct amount of water,
(d) adequate oxygen, (e) appropriate pH, and (f) the absence of toxic
constituents that could inhibit microbial activity.
Carbon Nitrogen ratio:
The ratio of carbon to nitrogen is considered critical in
determining the rate of decomposition. Carbon to nitrogen ratios, however, can
often be misleading. The ratio must be established on the basis of available
carbon rather than total carbon. In general, an initial ratio of
30:1 carbon:nitrogen is considered ideal. Higher ratios tend to retard the
process of decomposition, while ratios below 25:1 may result in odor problems. Typically, carbon to nitrogen ratios
for green plant waste range from 20 to 80:1, wood chips 400 to 700:1, manure 15
to 20:1, and municipal solid wastes 40 to 100:1. As the composting process
proceeds and carbon is lost to the atmosphere, this ratio narrows. Finished
compost should have ratios of 15 to 20:1. To lower the carbon:nitrogen ratios,
nitrogen-rich materials such as yard trimmings, animal manures, or biosolids
are often added. Adding partially decomposed or composted materials (with a
lower carbon:nitrogen ratio) as inoculums may also lower the ratio. Attempts to
supplement the nitrogen by using commercial fertilizers often create additional
problems by modifying salt concentrations in the compost pile, which in turn
impedes microbial activity. As temperatures in the compost pile rise and the
carbon:nitrogen ratio falls below 25:1, the nitrogen in the fertilizer is lost
in a gas form (ammonia) to the atmosphere. This ammonia is also a source of
odors.In Kerala the Municipal solid waste (MSW)should have a Carbon Nitrogen
ratio between 25 – 50 initially.
Release of ammonia and impeding of biological activity at lower ratios.
Nitrogen as a limiting nutrient at higher ratios
Moisture:
A moisture content of 50 to 60 percent of total weight is
considered ideal.55% is optimum for MSW in Kerala. The moisture content should
not be great enough, however, to create excessive free flow of water and
movement caused by gravity. Excessive moisture and flowing water form leachate,
which creates a potential liquid management problem and potential water
pollution and odor problems. Excess moisture also impedes oxygen transfer to
the microbial cells. Excessive moisture can increase the possibility of
anaerobic conditions developing and may lead to rotting and obnoxious odors. A
moisture content of 50 to 60 percent of total weight is considered ideal. The
moisture content should not be great enough, however, to create excessive free
flow of water and movement caused by gravity. Excessive moisture and flowing
water form leachate, which creates a potential liquid management problem and
potential water pollution and odor problems. Excess moisture also impedes
oxygen transfer to the microbial cells. Excessive moisture can increase the
possibility of anaerobic conditions developing and may lead to rotting and
obnoxious odors. Composting is considered an aerobic process, that is,
one requiring oxygen. Anaerobic conditions, those lacking oxygen, can
produce offensive odors. While decomposition will occur under both aerobic and
anaerobic conditions, aerobic decomposition occurs at a much faster rate. The
compost pile should have enough void space to allow free air movement so that
oxygen from the atmosphere can enter the pile and the carbon dioxide and other
gases emitted can be exhausted to the atmosphere. In some composting
operations, air may be mechanically forced into or pulled from the piles to
maintain adequate oxygen levels. In other situations, the pile is turned
frequently to expose the microbes to the atmosphere and also to create more air
spaces by fluffing up the pile. A 10 to 15 percent oxygen concentration is
considered adequate, although a concentration as low as 5 percent may be
sufficient for leaves. A pH between 6 and 8 is considered optimum. pH affects
the amount of nutrients available to the microorganisms, the solubility of
heavy metals, and the overall metabolic activity of the microorganisms. While
the pH can be adjusted upward by addition of lime or downward with sulfur, such
additions are normally not necessary. The composting process itself produces
carbon dioxide, which, when combined with water, produces carbonic acid. The
carbonic acid could lower the pH of the compost. As the composting process progresses,
the final pH varies depending on the specific type of feed stocks used and
operating conditions.
Particle size:
The particle size of the material being composted is
critical. As composting progresses, there is a natural process of size
reduction. Because smaller particles usually have more surface per unit of
weight, they facilitate more microbial activity on their surfaces, which leads
to rapid decomposition. However, if all of the particles are ground up, they
pack closely together and allow few open spaces for air to circulate. This is
especially important when the material being composted has a high moisture
content All microorganisms have an optimum temperature range. For composting this
range is between 32° and 60° C. For each group of organisms, as the temperature
increases above the ideal maximum, thermal destruction of cell proteins kills
the organisms. Likewise, temperatures below the minimum required for a group of
organisms affects the metabolic regulatory machinery of the cells.The Municipal
solid waste of Kerala should have a a
particle size of 25 to 75 mm for optimum aerobic composting.
Detailing aerobic composting for Municipal solid waste (MSW)
in Kerala:
MSW characteristics : Sorted organic fraction of MSW,
preferable with same rate
of decomposition
MSW Particle size :
Between 25 – 75 mm for optimum results
C/N Ratio : Between 25 – 50 initially. Release
of ammonia an impeding
of biological activity at lower ratios. Nitrogen as a limiting
nutrient at higher ratios
Blending & Seeding : Addition of partially decomposed
matter (1-5% by weight)
reduces composting time.
Moisture content : 55% (optimum)
Windrow size : 3m length, 2m width and 1.5m
height (optimum)
Mixing/turning : Every four or five days, until the temperature
drops from
about 66 – 60oC to about 38oC or less.
Alternate days
under typical operating conditions
Temperature : 50-55oC for first few days and 55-60oC for the reminder
composting period. Biological
activity reduces
significantly at higher temperature (>66oC)
Pathogen control : Maintenance of temperature between 60-70oC for
24 hours
Air requirement : At least 50% of initial oxygen concentration
to reach all
parts of composting material
pH control : 7 – 7.5. Not above 8.5 to minimize nitrogen
loss in the
form of ammonia gas
Inoculums : Not desirable, except in special cases
Degree of decomposition :
Determine by COD test or from
Respiratory Quotient .
Area requirement : ~25 m2 for 1 ton of MSW (only for windrow
formation for
21 days composting and maturity
yard for 30 stabilization.
Area for machinery, packing and storage extra
Post treatment care : Facility for effluent (leachate)
recycling and treatment and
sanitary landfill of rejects (inert materials, sludge from ETP)
Nutrient recovery : 2-4 kg N/ton ; 1-2 kg P/ton ; 1-2 kg K/ton
Product recovery : 18-25% of waste input
Residuals for disposal :
2-20% sieving overflow (plastic, metal, glass, stones)
(Ref:
Varma,2007)
Thumburmuzhy Model:
“Thumburmuzhy Model”
aerobic composting technique(TMACT) developed by Dr Francis
Xavier,Professor at Thumburmuzhy Research station of Kerala Veterinary
&Animal Sciences University , is a rural, cost effective and eco friendly “Waste
Management System” imbibed into the Kerala Agro eco-zone. This Rural
technology is a recommended model by the UNDP Climate change community compendium
*(2011) , among the four ideal rural technology for farmers of India. This
method of composting, which emits very little methane and carbon dioxide, has
been adopted by a number of apartment complexes and rural communities in
Kerala. The aerobic composting Technology ,the ideal fero-cement Bin and the
microbial Consortium developed from cow dung, are the major research
achievements .Research in Veterinary University has modified aerobic compost
unit with a different layering system to handle rural organic waste, farm waste
and dead animal parts which are otherwise wasted and pollutes rivers, roads
highways and water bodies. We have designed a cost effective, rural system for
livestock farms and rural Kerala. The composting unit which is becoming the
darling of decentralised waste management includes a box-like structure with
ferro-cement floor, layers of cow dung, carbon source and waste materials are
subjected to composting in presence of oxygen. The temperature rises rapidly in
the waste to almost 70 degree Celsius and this peak temperature kills pathogens
so is a boon to rural health and community health. Waste management is a big
problem in most of the farms of the state and hence the waste can be
effectively converted into valuable manure by TMACT. The NPK value of
“Thumburmuzhy model compost” using home waste is N.1.57%, P-0.049%, K-0.73%.
Thumburmuzhy compost model; since it is cost effective can be replicated in
rural areas to handle organic waste under Kerala agro climatic conditions. In
90 days time the first crop of manure gets ready. Moreover, livestock/food
waste is a rich source of Nitrogen. Research in other places showed that TBC
and coliforn count in aerobic compost is minimal. Hence, under public health
angle this has to be encouraged. This ideal Rural waste handling technology is
not labour intensive.
