2. Composting and Recycling of Municipal Solid WasteBy
Dr. Seema Jilani
(Associate Professor)
Institute of Environmental Studies
University of Karachi
Karachi, Pakistan

3. Content Description of Composting & Compost Benefits of Composting
End use of Compost
Pilot research study on Assessment of MSW composting & compost quality
Conclusions

4. Controlled biological decomposition process
What is composting?
Controlled biological decomposition process
Grass clippings
Compost
Food scraps
It is an aerobic, biological process which uses naturally occurring microorganisms to convert biodegradable
Leaves
In composting naturally occurring microorganisms help to convert organic wastes into a humus material called compost

5. What is compost?
Compost is a dark brown with crumbly, porous, earthy smelling, soil like material which can be used as fertilizer / soil conditioner.

6. Benefits of composting
Recycling Organic Waste ----It is an environmentally sound means of recycling organic materials
Waste Minimization ---It is one way to reduce the amount of waste we produce.
Cost Reduction---Garbage handling is the most largest expense for many cities. Composting can reduce those costs
Kill Pathogens

7. End use of Compost Improve soil structure, texture & aeration
Prevent erosion
Increases the soil's water-holding capacity.
Compost loosens clay soils and helps sandy soils to retain water.
Green-house gas reduction
may be used to condition heavy clay or mineral soils

8. Assessment of MSW Composting & Compost Quality

9. Facts & Figures Generation rate of MSW = 12000 tons per day
- 80% Solid Waste is recyclable in nature
% is food waste
% comprises of bones, paper, plastic, glass, metal, textile,
leather etc..
About 60% garbage transported to dumping grounds
20-25% garbage picked up by scavengers
Uncollected waste end up in drain either burned or left at the mercy of nature

10. Current Constraints Existing system of SWM  inefficient, inadequate
No scientifically designed landfill site
Poor hygienic condition
Low level awareness regarding SWM.
Large amount of recyclable material and energy are thus discarded.

11. Research Objectives To assess the feasibility of MSW composting
To analyze the quality of finished compost samples
To propose an effective and sustainable SWM for Karachi city

12. Research Methodology
Solid waste samples were collected from different localities of Karachi.
For compositional analysis, manual sorting and weighing of individual component was conducted
The sorted organic matter was then subjected to open windrow composting
Windrow composting is one of the cheapest and easiest methods used for organic wastes management.

13. Windrow Composting A pile of waste was formed
To speed up the natural decay process following factors were managed
Air (oxygen 5-15%)
Moisture – 60%
Food (C:N ratio---30:1), and
Temperature – 75C (thermophile range)
heap is made up to feet above the ground level
By managing these factors you can speed up the process otherwise slow natural decay process

14. Phases of Composting
Phases of Composting
 Initial decomposition is carried out by mesophilic microorganisms, which rapidly break down the soluble, readily degradable compounds.
As the temperature rises above about 40°C, the mesophilic are replaced by thermophilic, At temperatures of 55°C and above, many microorganisms that are human or plant pathogens are destroyed.
During the thermophilic phase, high temperatures accelerate the breakdown of proteins, fats, and complex carboydrates like cellulose and hemicellulose, the major structural molecules in plants.
temperature gradually decreases and mesophilic microorganisms once again take over for the final phase of "curing" or maturation of the remaining organic matter.
Composting goes through three distinct phases that can be characterized by temperatures.
Mesophilic Phase (moderate temperature, 40 oC)
Thermophilc Phase (high temerpature, 55oC–65oC)
Mesophilic Phase (moderate temperature again)

15. The Main players
Bacteria: major decomposers, breakdown simpler forms of organic material
Actinomycetes: degrade complex organics such as cellulose, lignin, chitin, and proteins – earthy” smell, long “spider webs” filaments
Fungi: Break down tough debris, too dry, too acidic or too low in nitrogen for bacteria to eat

16. When is composting finished?
When mature compost is obtained with following characteristics
The color turn dark brown
It is crumbly, loose, &
humus-like
It has an earthy smell
It contains no readily
recognizable feedstock
The pile size shrunk to
about 1/3 of its original volume

17. Material flow for the conventional Composting process

18. Research Methodology Composting duration = 12 weeks
Curing duration = 3 weeks
Finished compost samples screened out and analyzed in the laboratory using Standard method

19. Simple test for finished Compost
Bag test: sealing compost in a plastic bag for several days should not produce foul odor when open

20. Research Methodology Parameters selected: pH Soluble salts
Organic matter
Nutrients (Nitrogen, Phosphorus & Potassium)
C/N ratio
Analytical technique followed:
ASTM
USEPA method

21. Results Table 1. Composition of MSW generated in Karachi
Components High Middle Low
( % by weight)
  Organic wastes
Paper & Cardboard
Plastic & polythene
Textile
Rubber & Leather
Metals & Tin
Glass
Miscellaneous

23. Table 2. Physical and Chemical Characteristics of MSW
6.4
Moisture
(% dry basis) 36
 <50
Organic matter
(% wet basis) 57
>20
Nitrogen
0.81
0.6
Carbon 33
No specs
C/N ratio
(total dry weight)
40:1
25-50:1
Parameters
Average Values
Standards
*Average of 8 samples

24. Table Comparative average values of pH, Soluble Salts & Organic Matter in MSW composts, cowdung and chemical fertilizer samples.
Sample Type pH Soluble salts Organic matter
(m.mhos/cm) (dry basis)
MSW Compost
(High income) ( ) ( ) (56-60)
MSW Compost
(Middle income) ( ) ( ) (54-58)
MSW Compost
(Low income) ( ) ( ) (45-50)
Cowdung
(organic fertilizer) ( ) ( ) (48-52)
Chemical fertilizer
( ) ( ) (37-39)
Proposed Italian
Standard < >20

25. Table 4. Comparative average nutritional values and C/N ratio in the
sample of composts, cowdung and chemical fertilizer
Sample Type Org.Carbon Nitrogen Phosphorus Potassium C/N Ratio
(%) (%)dry basis (%) dry basis (%) dry basis
MSW Compost
(High income) ( ) ( ) ( )
MSW Compost (Middle income) ( ) ( ) ( )
MSW Compost
(Low income) ( ) ( ) ( )
Cowdung
(Organic Fertilizer) ( ) ( ) ( )
Chemical fertilizer
( ) ( ) ( )
MSW Compost
Quality Standard > > > > <25

26. Conclusions Karachi MSW suitable for composting due to
high percentage of biodegradable organic waste (71- 74%)
suitable moisture content ( %) and
C/N ratio ( :1)
Compost Quality were found with in acceptable limits
pH ( )
Soluble Salts ( m.mhos)
Organic Matter ( %)
Nitrogen ( %)
Phosphorus ( %)
Potassium ( %)

27. Conclusions
Application of MSW Compost would be good for Karachi sandy soil
High quality compost could be produced by mixing nitrogen containing compounds (cow manure, poultry manure, yard waste etc).
Further investigation is required to evaluate the economic and technical feasibility of composting
in the context of other waste management options.