This document provides information about biological treatment of waste through composting and anaerobic digestion. It discusses various composting technologies like in-vessel, aerated static pile, and windrow composting. The composting process and two case studies on composting in Dhaka, Bangladesh and Temesi, Bali are summarized. Key aspects of anaerobic digestion like the process, technologies, uses of products, and calculating reactor size are covered. Other biological waste treatment methods like vermicomposting, biodegradable waste, and aerobic/anaerobic fermentation are also briefly discussed.

2. WELCOME
Course Title: Waste Management
Course Code: 3103
By Group-5

3. A presentation on
Chapter-5
Biological Treatment

4. Name Roll No
Saikot Jahan 1831006
Reyajul Hasan 1831015
Eshrat Jahan Eshita 1831027
Akhi Ayub 1831029
Humaira Rashid 1831039
Group Members

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Table of Contents
Composting
Composting technologies
Operating the composting process
Case study composting- Dhaka Bangladesh and Temesi, Bali, Indonesia
The basics of anaerobic digestion of bio-waste
Anaerobic digestion technologies and operation
Using the products of anaerobic digestion
Calculating the size of an anaerobic reactor
Vermicomposting of bio-waste
Biodegradable waste
Aerobic and anaerobic fermentation
Organic manure

6. Compost is a mixture of ingredients used to fertilize and
improve the soil.
Composting is the natural process of recycling organic matter,
such as leaves and food scraps, into a valuable fertilizer that
can enrich soil and plants. Anything that grows decomposes
eventually; composting simply speeds up the process by
providing an ideal environment for bacteria, fungi, and other
decomposing organisms (such as worms, sowbugs, and
nematodes) to do their work. The resulting decomposed
matter, which often ends up looking like fertile garden soil, is
called compost. Fondly referred to by farmers as “black gold,”
compost is rich in nutrients and can be used for gardening,
horticulture, and agriculture.
What is composting?

7. Composting Technologies
1. In vessel composting: In-vessel composting generally describes a group of methods
that confine the composting materials within a building, container, or vessel. In-vessel
composting systems can consist of metal or plastic tanks or concrete bunkers in which air
flow and temperature can be controlled, using the principles of a "bioreactor". Generally
the air circulation is metered in via buried tubes that allow fresh air to be injected under
pressure, with the exhaust being extracted through a biofilter, with temperature and
moisture conditions monitored using probes in the mass to allow maintenance of
optimum aerobic decomposition conditions.
Figure: In-vessel composting
2. Aerated static pile (ASP) composting: It refers to any of a number of systems
used to biodegrade organic material without physical manipulation during primary
composting. The blended admixture is usually placed on perforated piping,
providing air circulation for controlled aeration . It may be in windrows, open or
covered, or in closed containers. With regard to complexity and cost, aerated
systems are most commonly used by larger, professionally managed composting
facilities, although the technique may range from very small, simple systems to
very large, capital intensive, industrial installations.
Air flow down
into pile
Aeration airflow
through compost pile
Aeration piping
Mechanical
Biofilter exhaust (final
scrub of odors)
Figure: Aerated static pile composting

8. 3. Windrow composting: It is the production of compost by piling organic matter or
biodegradable waste, such as animal manure and crop residues, in long rows (windrows).
This method is suited to producing large volumes of compost. These rows are generally
turned to improve porosity and oxygen content, mix in or remove moisture, and redistribute
cooler and hotter portions of the pile. Composting process control parameters include the
initial ratios of carbon and nitrogen rich materials, the amount of bulking agent added to
assure air porosity, the pile size, moisture content, and turning frequency.
Figure: Windrow composting
4. Vermicompost (also called worm castings, worm humus, worm manure, or worm
faeces) is the end-product of the breakdown of organic matter by earthworms. These
castings have been shown to contain reduced levels of contaminants and a higher
saturation of nutrients than the organic materials before vermicomposting.
5. Black soldier fly (Hermetia illucens) larvae are able to rapidly consume large amounts
of organic material and can be used to treat human waste. The resulting compost still
contains nutrients and can be used for biogas production.
Figure: Vermicomposting
Figure: Black soldier fly

9. Step
1
Step
2
Step
3
Step
4
Step
5
Step
6
Composting Process
Select a
dry, shady
spot near
a water
source
Add
brown
and green
material
in
alternate
layers
Keep the
compost
moist but
not too
wet
Occasiona
lly turn
your
compost
mixture
to provide
aeration
As
materials
break
down, the
pile will
get warm
All done!
Compost
is ready.
A general composting process which we can use in our home garden too.

10. 1. Select a dry, shady spot near a water
source: Ideal size for your compost area is
3 feet wide by 3 feet deep by 3 feet tall.
You can buy a bin, use chicken wire, or just
isolate an area of ground for your compost
heap.
2. Add brown and green material in alternate
layers: Try and keep the ratio roughly 3 parts
browns to 1 part greens. Make sure larger
pieces of material are chopped or shredded.
3. Keep the compost moist but not
too wet: Moisture helps with the
breakdown of organic matters.
4. Occasionally turn your compost mixture
to provide aeration: This helps speed up
the composting process and keeps things
airy, which cuts the risk of things getting
smelly.
5. As materials breakdown, the pile will get
warm: There might even be steam. Don’t be
alarmed. That means it’s working. Now you
just have to wait.
6. All done: When material is dark
with no remnants of food or waste,
your compost is ready. Add it to lawns
and gardens or anywhere that could
benefit from some good soil.

11. Composting in a large scale and it’s uses.

12. Waste management in Dhaka—
Dhaka has envisioned a strategy for zone-wise waste management through a
network of decentralized composting plants and the establishment of successful
partnerships with the government, private sector and residents. Through
facilitating innovative partnership arrangements, a community-based solid waste
management model for Dhaka has been developed, raising the attention of many
other cities in Bangladesh and in developing countries, who sought to replicate it.
With its emphasis on recycling and resource recovery, this model has improved
the urban environment and the quality of lives of poor people living in slums
CDM based compost project(130 tons per day) in Bulta,Dhaka:
Case study composting –Dhaka Bangladesh Temesi, Bali and Indonesia
Figure: Urban solid waste situation in Dhaka

13. Waste treatment process:
1. collect waste from the sources, from the city
2. appointed a private company to collect the waste and It generates about 60 to 70 tons of waste, organic waste, every day
3. put it in a composting box which is especially designed, has a draining system on the base, and can blow air to insure oxygen in the pile.
4. compost piles are aerated by forced air from the bottom with large floors
5. Quality control is very much important for doing this process. Normally it takes 40 days for the composting process in the pile, and
another 30 days for the maturing phase.
6. After the thermophilic composting phase, the compost is transferred to the maturing shed, where it stays for another 20 to 30 days,
depending on the seasons.
7. Thereafter, it is sealed with a rotating device. And then the next step is bagging and marketing.
The Rotary Club of Bali in Ubud started addressing this problem of
waste, and sponsored a waste recovering facility in Temesi, which is
in the regency of Gianyar, where also the city of Ubud is located.
Temesi’s Waste Types: Temesi's focus lies on organic waste. Given
the waste characteristics in Bali, 85% of this waste is organic and
biodegradable.
Figure: Temesi’s waste types

14. Waste Treatment Process:
• Waste
separation
• Organic
weighing
• Shredding
• Aerobic
decomposition
• 3-4 months
turning
• Sieving • Sales or further
curing
Outsourced
Volume-20%
Process
control by lab
9 mm mesh
control by lab

15. Anaerobic Digestion of Bio-waste
Anaerobic digestion is a process through which bacteria break down organic matter—such as animal manure,
wastewater biosolids, and food wastes—in the absence of oxygen.
Figure: Anaerobic digestion of bio-waste

16. The technology of anaerobic digestion allows the use of biodegradable waste for energy production by breaking down organic matter
through a series of biochemical reactions. Anaerobic digestion is an economically viable and environmentally friendly process since it
makes possible obtaining clean energy at a low cost and without generating greenhouse gases. It is considered that the simplicity of AD,
when compared against other biological and thermal technologies for the processing of organic wastes, coupled with its adaptability to
a wide spectrum of feedstocks, that has led to its current scale of adoption. Crop and livestock farmers use AD plants for fuel
production, manure management, and fertilizer production, whilst commercial AD plants can operate with a more diverse set of
feedstocks, including municipal solid wastes (MSW) and industrial effluents, and their focus can often be on the reduction of chemical
oxygen demand (COD) and effluent treatment as well as on energy generation.
Anaerobic Digestion Technology and Operation

17. Using The Product of Anaerobic Digestion
Anaerobic digestion (AD) is the process by
which organic materials in an enclosed vessel
are decomposed by micro-organisms. Biogas
is produced during anaerobic digestion and it
comprises mainly of carbon dioxide and
methane. AD systems are most commonly
known as biogas systems Based on the system
design, it is possible to combust biogas to run
a generator producing heat and electricity.
This can be burned as a fuel in a furnace or
boiler, cleaned, and used as a replacement for
natural gas.
The products of anaerobic digestion are:
• Biogas
• Digestate
• Fibre
• Separated liquid

18. Calculating The size of an Anaerobic Reactor
Situation:
• Boarding school with 250 students and 50 stuffs in a tropical climate
• 0.2 kg/day( wet weight) biowaste with
• TS is 20% and VS is estimated 80% of TS
• Gas to be used in canteen
• Fixed dome reactor below ground
• Construction and operation skills available
Feedstock
300p *0.2 kg/ day biowaste = 60 kg/day wet weight
TS= 20%
1.60+2.60=180 L
Feedstock quality
60 kg wet weight *20% TS=12kg dry matter
80% VS * 12kg=9.6kg/day per 180 L= 9.6/180*1000=53.3kgVS/m^3
OLR=flowrate*concentration /reactor volume
0.18*53.3/5.4=1.78kg VS/m^3
Retention time
30 days
180L/day *30 day=5400 L =5.4m^3
Amount of gas
Biogas yield for veg waste=0.67m^3/kg VS
1.78kgVS/m^3*0.67*5.4m^3=6.4m^3/day
Biogas stove 0.4 m^3/h
Total volume of unit
5.4 m^3 slumy+1.8 gasholder=7.2 m^3

19. Vermicomposting is a simple biotechnological process of composting In
which certain species of earthworm are used to enhanced the process of
waste conversion and produce a better product.
Vermicomposting is a method of preparing enriched composed with the
use of earthworm. It is one of the easiest methods of recycle agricultural
waste and to produce quality compost.
Vermicompost is stable, fine granular organic manure, which enrich soil
quality by improving it’s physiochemical and biological properties. Highly
useful in raising seedling and for crop production.
Vermicomposting of Bio-waste

20. Types of Vermicompost
1. Small scale vermicomposting: personal requirement( 5-10 tons yearly)
2. Large scale vermicomposting: commercials requirement (50-100 tons yearly)
Methods of vermicomposting
1. Bed methods
2. Pit methods
Figure: Bed method Figure: Pit method

21. Biodegradable waste is a type of waste, typically originating from plant or animal sources, which may
be degraded by other living organisms. Biodegradable waste can be commonly found in municipal
solid waste as green waste, food waste, paper waste and biodegradable plastics.
Uses of biodegradable waste
• Composting
• Source of heat
• Source of electricity
• As fuel
Advantage of biodegradable waste
• To reduce our dependency to limited fossil resources
• To reduce GHG emission
• To be carbon neutral
• To consume less energy for production
• To close the cycle increase resource efficiency by possible organic recycling
Biodegradable Waste
Figure: Biodegradable waste

22. Fermentation
The word fermentation comes from the Latin
word fervere, which means “ to boil”.
Fermentation is a metabolic process that
produces chemical changes in organic substrates
through the action of enzymes.
Fermentation is a biochemical process that gets
energy from carbohydrates and doesn’t require
oxygen.
Glucose
Fermentation Examples
• Beer
• Wine
• Mead
• Liquor
• Cheese
• Yogurt
• Sour food containing lactic acid, such as kimchi,
sauerkraut, pickles, and pepperoni
• Leavened bread
• Industrial alcohol, as for biofuels
• Sewage treatment involves fermentation.
• Human muscles initially use aerobic respiration,
but switch to fermentation and produce lactic acid
as an anaerobic energy supply.
Ethanol + carbon dioxide + energy

23. Aerobic Fermentation
Aerobic fermentation refers to the set of chemical reactions involved in the production of energy by completely oxidizing food.
It releases carbon dioxide and water as by-products. Aerobic respiration mainly occurs in higher animals and plants. It is the most efficient
process among various processes of energy production.
Figure: Aerobic fermentation

24. Electron
Transport
chain
Aerobic
Fermentation
Steps
Glycolysis
Krebs
Cycle

25. Glycolysis
Glycolysis is the first step of aerobic respiration, which occurs in the cytoplasm. This process breaks down glucose into two
pyruvate molecules. The pyruvate molecules undergo oxidative decarboxylation to form acetyl-CoA. 2 ATP and 2 NADH are the
yield of this process.
Figure: Glycolysis process

26. Krebs Cycle
Krebs cycle occurs inside the mitochondrial matrix. A complete breakdown of acetyl-CoA into carbon dioxide occurs in the Krebs
cycle, regenerating the starting compound, oxaloacetate. During Krebs cycle, releasing the energy from acetyl-CoA produces 2 GTPs, 6
NADH, and 2 FADH2.
Electron Transport Chain
The production of ATP during the oxidative phosphorylation uses the reducing power of NADH and FADH2. It occurs in the inner
membrane of mitochondria. The below figure shows the overall chemical reaction of aerobic respiration.
C6H12O6 + 6O2 → 6CO2 + 6H2O + 36ATP
Anaerobic Fermentation
Chemical breakdown of organic substrates by microorganisms into ethanol or lactic acid in the absence of oxygen.
Anaerobic Fermentation occurs in the locality of the cytoplasm in microorganisms such as yeast, parasitic worms, and bacteria.
Steps of Anaerobic Fermentation
• Glycolysis
• Partial oxidation of pyruvate

27. Based on the pathway of pyruvate oxidation, fermentation consists of two types;
1. ethanol fermentation
2. lactic acid fermentation.
Figure: Anaerobic fermentation

28. Ethanol Fermentation
Ethanol fermentation mainly occurs in yeast in the absence of oxygen. In this process,
removing the carbon dioxide results in the decarboxylation of pyruvate into acetaldehyde.
Acetaldehyde is then converted into ethanol by using the hydrogen atoms of the NADH. The
effervescence occurs due to the release of carbon dioxide gas into the medium. The balanced
chemical equation for ethanol fermentation is as follows:
C6H12O6 → 2C2H5OH + 2CO2 + 2ATP
Lactic Acid Fermentation
Lactic acid fermentation mainly occurs in bacteria. During lactic acid fermentation, the
pyruvate converts into lactic acid. The overall chemical reaction for ethanol fermentation and
lactic acid fermentation are as follows:
C6H12O6 → 2C3H6O3 + 2ATP
Difference Between Aerobic and Anaerobic Fermentation

29. Aerobic Fermentation Anaerobic Fermentation
Set a chemical reaction involved in the production of energy by
completely oxidizing food.
Chemical breakdown of organic substrates into ethanol or
lactic acid by micro-organisms in the presence of oxygen.
Occurs in both cytoplasm and mitochondria. Occurs in the cytoplasm.
Occurs in higher animals and plants. Occurs in yeast, parasite, and bacteria.
Uses molecular oxygen as the final electron acceptor in the
electron transport chain.
Does not use oxygen.
Produces six water molecules per glucose molecule. Does not produce water.
Glucose is completely broken down into carbon dioxide and
oxygen.
Glucose is incompletely oxidized either into ethanol and
lactic acid
NAD+ regeneration occurs in the electron transport chain. NAD+ regeneration occurs during the partial oxidation of
pyruvate.
ATP is produced during the NAD+ regeneration. ATP is not produced during the NAD+ regeneration.
36 ATP is produced. Only 2 ATP is produced.
Aerobic Fermentation VS Anaerobic Fermentation

30. Thank You