Acknowledgement:
I take this opportunity to thank Caledonian College of Engineering to give the students
chance to improve their knowledge in advanced solid waste course by allowing the
`students to go for a field trip. Moreover, I would also like to acknowledge with much
appreciation the crucial role of Dr. Basim AL khateeb, for not only making prior
arrangement for the trip but also for accompanying, encouragement and guidance to
finish this assignment and also for teaching us this course. I am extremely thankful to
Be'ah Company and AL Multaqa Landfill for the opportunity of visiting them. Specially,
Mr. Khalid and Reyadh for a very informative and impressive tour.
Nomenclature:
Word
shortcut
Membrane Bio-Reactor
MBR
Reverse Osmosis
RO
Ultrafiltration
UF
Municipal Solid Waste
MSW
Healthcare waste
HCW
Geosynthetics Clay Liner
GCL
1V: 2H
1 vertical : 2 horizontal
Environmental Impact Assessment
EIA
American Standard
US
Chapter 1: Introduction:
As part of a university education Caledonian College of Engineering decided to
organize an exploratory trip to AL Multaqa Landfill and Be'ah Company, in 19th of April
2018.
1.1 Introduction of Solid Waste in Oman and be'ah:
With a population of more than 3 million inhabitants, Oman produce about 1.9 million
tons of solid waste each year and 1.2 kg per capita per day. That consider as one of
the highest worldwide. The solid waste are sent to authorized and unauthorized
dumpsites that may be located in the midst of residential areas for disposal. As a result,
it creating environment and health issues. From this scenario, be'ah was established.
Be'ah is the common name of Oman Environmental Service Holding Company
S.A.O.C. it was established in 2007 and by 2009 the Royal Decree No. 46/2009
granted Be'ah the mandate and the legal status as the entity responsible for solid waste
management in Sultanate of Oman. Be'ahs vision is to conserve the environment of
our beautiful Oman for future generations. In light of this, it works on establishing the
required infrastructure, restructure the municipal waste collection services, and finally
develop the public awareness of waste management. In order, minimize the solid
waste and its effect on the environment and public health. As well as, develop and
support the economy of Oman. The bedrock of the be'ah company is to close the 317
dumpsites and replace it with more than 12 engineered landfills. Beside, construct 25
waste transfer stations around Sultanate of Oman. (Be'ah, 2017)
Figure 1: the open dumping site in Izki
Figure 2: Izki dumping site after be'ah establishing
1.2 AL Multaqa Landfill:
The landfills allow for the sanitary disposal of solid waste and minimize the risk of it to
people as well as, the environment. One of those landfills are located in AL-Amerat in
AL Multaqa area. AL Multaqa landfill located over a slightly inclined area and contains
gravel and sand plain. The area is between major wadi in the East, Northeast and
West, and hills and
small mountains in the
North and South.
the
first
It is
engineered
sanitary landfill in Oman
and gulf region. It is the
third one in the Middle
East region. The landfill
has been implemented
and designed to be
served for 30-40 years
as
per
the
local
and
Figure 3: AL- Multaqa landfill overview
international environmental and technical requirements. Where the location was
selected in 1989 by government and the operations began in early 2011. AL- Multaqa
landfill consist of 5 cells with a total capacity of 10 million m3 of solid waste. Where, the
first cell was completed in May 2005 and the second cell was completed in July 2016..
The landfill is receiving municipal solid waste including commercial and industrial nonhazardous waste from Mutrah, Bawsher, Al-Amerat, Quraiat and the others. Where in
2014, the landfill received 5171 shipments that carry daily waste from various areas.
In other hand, the landfill is expected to be motivated example for the future solid waste
management projects in Oman. (Khalid, 2018)
Figure 4: The first picture taken during our exploratory trip at AL- Multaqa landfill
Chapter 2: Design Aspect
2.1 Engineering Design and Details Specification:
AL Multaqa landfill accept the municipal solid waste (MSW) and green waste only.
The tires are stored but does not degrade. There are around 26000 tons of tires in
AL-Multaqa landfill. While batteries, chemicals, medical waste, any type of paints,
make up, perfumes, and lotions are not acceptable. The accepted waste are placed
in is the first sanitary landfill in Oman. The landfill follow the American standard
(US) and consist of several facilities include:
o
Administrative offices
o
Surrounding fence and gate
o
Workshop
o
Electricity and lighting network
o
Leachate evaporation pond connected to a leachate collection system
o
Leachate transfer system
o
HDPE manholes for leachate collection
o
Surface water runoff collection
o
Internal circular roads with 6 m and wide of 500mm
o
Groundwater monitoring wall
o
the first landfill cell and second landfill cell
o
Unacceptable waste area
o
Flare system of 1000 m3/h
o
Leachate treatment plant
o
Shaft and substation
Cell One:
This cell was designed using asphalt. The asphalt was placed in two layers with a
thickness of 6mm and 8mm respectively so that the above layer protect the
groundwater if any cracks happened in the bottom layer. The cell was constructed
by STRABAG LLC based on the design and tender documents prepared by
FICHTNER consultants. The cell finished in May 2005 but the operation started in
February 2011. A capacity of one million cubic meters is spread over a total area
of 9.5 hectare and a total height of 30 meter in cell one. This cell is not covered by
the final cover till now because the municipality did not approved yet. (Khalid, 2018)
Cell Two:
In other hand, cell two designed with lining system. The lining is used to protect
the groundwater from the leaking of leachate. It is with a slop of 1V: 2H and the
materials as following from the
bottom to the top:
o
Clay
soil
Multaqa
replaced
but
this
in
AL
layer
is
with
another
type of soil that does not
contains any gravel. This
soil is mixed with water
and then compacted. The
compaction
rate
equal
0.94.
o
Geotextiles layer placed
directly on the top of the
Figure 5: Details of cell lining system as per USEPA
landfill floor with puncture resistance
3.5 KN.
o
High Shear strength Geosynthetics clay liner (GCL). The GCL looks like
sponge and contains a material, this material will become hard if the water
touch it.
o
2 mm thick of structured HDPE liner along the slope and smooth along the floor.
o
HDPE Geonet.
o
High strength geotextiles protection layer with puncture resistance of 10.5 N.
o
300 mm gravel used as protection layer and filtration at the same time.
The construction process was completed in July 2016 by SUZE Environment and
the cell was divided into 5 zones but the opening was in July 19, 2015. The area
of cell two equal to 14.2 hectare with a capacity of 2.4 million cubic meters. The
height of this cell about 30 meter and can be exceed to 38 mete due to the
compaction rate = 1.05. (Khalid, 2018)
Shaft:
The landfill provide 16 shafts
around each cell, in cell one,
8 of them are in the left of the
cell and the other 8 are in the
right of it. This shafts are
responsible for the leachate
(contaminated
wastewater)
outlet. It contains pipes that
have many small holes on it to
allow the leachate to pass
Figure 6: One of the shafts provided in cell 1
through it, where the leachate flows through the pipes due to the gravity. All the
shafts are interconnected and linked to leachate pump. (Khalid, 2018)
Substation:
It designed for the future,
when the approval is provided
the cell will be covered by final
cover. Then, the gas wells
collection
will
be
drilling.
Those well will be connected
to the white rooms which
called
substation
and
then
Figure 7: Future substation
transport it to flaring system. (Khalid, 2018)
Inspection Wells:
There are five of inspection wells that are with a depth of 80 meters. Those wells
are used for ground water inspection. Where 13 samples have been collected until
know. The collection of samples are taken each 6 months. They compare all the
13 samples with the first specimen of groundwater before putting any waste, as a
result, all samples are performed well comparing with the original one. (Khalid,
2018)
Evaporation pond:
As per Khalid in 2018, the same lining that provided under cell 2 is provided her
but with a small differences. The lining are presented as following from top and
moving downward:
o
400mm mixture of sand
and compost material.
o
400mm sand
o
Geotextile with puncture
resistance of 10.5kn
o
HDPE Geonet
o
1.5mm LDPE liner
o
Geosynthetics clay liner
Figure 8: Details of evaporation pond lining system
GCL
o
Geotextile with puncture resistance of 3.5kn
o
Grading layer to be placed directly on the waste
Leachate Treatment Facility:
Is the first treatment plant that treats the leachate resulting from waste. It was
operated in 7th July 2016 with volume of 100 meter cubic. The treated leachate
are used within the landfill area for irrigation and road cleaning.
Figure 9: AL-Multaqa leachate treatment facility:
2.2 Flow Diagram of The Facility:
the landfill is run by different facilities, which are working all together in order to
achieve the required result for the waste, leachate and gas The following flow
diagram is describing the landfill facilities:
Figure
Description
Google map location
of AL-Multaqa landfill
Cell 1
Cell 2
2.3 Existing Problems:
There are many few problem that the landfill is faced such as:
Al Multaqa
Landfill site Layout
i.
The lining system bellow the cell two was provided with a slop of 1V:2H where
the slop should be 1V:3H. So it does not match with the cell one and as a result,
it will create problems while the final cover is placed.
ii.
The lining system under the cell one is not provided as the international form.
iii.
The evaporation pond in the cell one is completely designed wrong.
iv.
The diameter of the pipes that used to transfer the leachate is around 30 cm.
Therefore, there will be a blockage caused by the sediment. Thereby, they have
to clean those pipes annually using water with high pressure.
v.
During the summer season, the temperature is increased and this cause bad
odors that employee there can smell it.
vi.
Some equipment need to be maintained regularly due to the high temperature
that may effect on it. (Khalid, 2018)
Chapter 3: Operation Aspect
3.1 Operation Aspect:
3.1.1
Waste Sources:
At the first, the solid waste in general can be classified into biodegradable
waste (food waste) and non-biodegradable waste (plastic). However, be'ah
deals with both types, but the non-biodegradable waste like: cardboard, metals,
plastics, papers, glasses and wood products should be shredded and bagged.
The landfill received 1100 tons/day of mixed non-hazardous waste that consist
of industrial non-hazardous waste, green wastes and municipal solid wastes.
The waste source in the landfill comes from Muttrah, Al Ammarat, Bousher and
Qurayyat. Moreover, the annual growth rate in AL Multaqa landfill is about 7%
for the quantity of waste while the density of compacted waste is around 0.95
ton/m3. Which can provide 15% of the volume for the daily cover and
intermediate cover. (Khalid, 2018)
Figure 10: Type of wastes received in the landfill
3.1.2
Waste collection and transportation system:
The solid waste located inside the stationary bins are collected in a be’ah
collection trucks at early morning within different regions In Muscat. Then, the
solid waste will be send to Al
Misfah transfer station. After
some time, the municipal
solid waste (MSW) is placed
in another huge truck and
transport
to
al
Multaqa
landfill. While the industrial
non-hazardous
waste
and
commercial waste is collected
and
transported
by
Figure 11: The collection of waste by be'ah's employees
private
company's trucks to the landfill directly. When the trucks reach AL Multaqa
landfill, some process will be followed:
o
First, the truck weight will be
taken.
o
Second, the type of loaded
waste will be check, if it is
acceptable in landfill or not.
o
Then, the accepted waste
will be unloaded in the
tipping area and monitored at the
Figure 12: Loading of be'ah's truck
same time to make sure that all waste are accepted. While the rejected
waste will be taken to Sohar.
o
After that, the truck will be cleaned manually or automatically. Manually,
the employees mix the antifoam with the water. Then this mixture will
be used to clean the bottom of the trucks as well as the wheels. While
the automatically method is done by passing the truck in wheel cleaning
stage where the tires will be washed there. This step is provided to
make sure that the trucks will be completely clean while leaving the
landfill.
o
Finally, the weight of empty truck will be taken.
o
The weight of disposing waste can be calculating using the weight of
loaded and unloaded truck ((Weight of truck enter to landfill- weight of
same truck exist to landfill after clean the bottom side)
3.1.3
Operation and Maintenance:
In the beginning, environmental Impact Assessment (EIA) and level and the
quality of groundwater should be provided before the design and operation
stage of the landfill. Then, the construction of landfill was started, where the
land was excavated and the soil there have been leveled and compacted well
to avoid any presence of sharp stones that may damage the liners. The semitrailers are used in disposal of solid waste, where the waste is disposing from
morning until evening (5 pm).
The decomposition of the waste generate
leachate. This leachate is pumped through the collection pipes that provided at
the bottom of the liners, all the pipes are connected with the leachate treatment
system.
Maintaining is done through daily monitoring of the landfill facilities. The daily
reports have a huge significant in assessing the performance of existing
process as well as the cost according to the planned objectives. It show also
the efficiency of the completed work. Moreover, it can identify the differences
between the planned and the achieved results and then identify the required
corrections to achieve the planned results as much as possible. One of the
monitoring method that was observed during the site visit is a monitoring
groundwater well system. The wells were implemented at a depth of 80 meter
in order to assess the quality of ground water. The quality was observed by
taking some samples from the ground water and testing them in the laboratory
and make sure that it is free of leachate. (Khalid, 2018)
3.1.4
Leachate and Gas Generation Control:
Leachate is known as the liquid that drains from a landfill. The composition of
the leachate depends on the type of waste that the landfill contains and the age
of it. In general, it contains suspended and dissolved material. The leachate
are collected in a system called shafts. The shafts pipes are installed
throughout the landfill, where the leachate flow due to gravity into the pipes and
from there to designated ponds (leachate evaporating lined ponds) and finally
to the treatment plant where it is treated biologically. There were two leachate
evaporating lined ponds, one is used and the other is kept as standby (in case
of heavy rain and too much leachate generation). The evaporating pond is with
high performance and durability property, where it is durable during very high
or very low temperatures. Bioremediation is done using the Microorganisms
that break the ammonia in the leachate waste, where the ammonia is converts
to less harmful chemicals (nitrate), then leachate will transport safely into the
sewer and the bacteria will convert the nitrate into nitrogen gas. Finally, the
leachate will be converted from a useless black water to usable water that used
for cleaning and irrigation. (Khalid, 2018)
Figure 13: Generated
leachate from the waste
(before treatment)
Figure 14: Leachate after
treatment
Moreover the leachate treatment plant is with a capacity of 100 m3 /d. the
treatment plant was operated in 7th July in 2016. The leachate is treated using
the following facilities:
o
Lagoon
o
An anaerobic pond
o
A Membrane Bio-Reactor (MBR)
o
2 successive aeration basins for maximal COD/BOD5 and NH4-N
reduction with 5000 m3 for each
o
Ultrafiltration for retention of biomass
o
A Reverse Osmosis (RO) plant for removal of non-biodegradable CODfraction
Figure 15: Overview treatment steps
The leachate pass through general process:
i.
Feed pumps that sucks the leachate from the pond into the denitrification tank.
ii.
De-nitrification/Nitrification: it is anaerobic process where the sludge will
be mixed with the leachate and bacteria. The biological materials (COD,
BOD and Ammonia) will be reduced as much as possible. This process
treat the highly loaded leachate using high-performance bioreactor.
Where the bio-activity increased and adapted biogenesis will reach the
optimal point due to the combination system and an external
membrane.
iii.
Foam tank: is used to collect all the foam from the tank automatically,
then the anti-foam is spread. Later on, it will be condensate and keep it
as a leachate. Finally, it will be send back to the de-nitrification tank.
iv.
Ultrafiltration: this stage provide very high quality separation of the
bacteria from filtrated water
v.
Reverse Osmosis: it provide polishing of the effluent after biological
treatment. As well as, it remove the remaining dissolved salts and nonbiodegradable COD maximal reduction of TN/NO3 - N/NH4 - N.
vi.
Dewatering: is used to minimize excess of sludge powder.
vii.
Cooling System: controlling the temperature that caused by exothermic
reactions in the removal of COD and NH4-N.
Figure16: Anaerobic pond
Figure 17: Aeration system
Figure 18: Reverse Osmosis
Figure 19: Ultrafiltration (UF)
Gas generated from waste mainly consist of methane that produce due to the
lack of oxygen in the waste covered with soil. Where it is very risky due the
explosion property. Therefore, be’ah is installing an effective landfill gas
management system. The system is coordinating and integrating gas
monitoring, collection, and extraction. Then, the gas will be supplied to flare or
utilization projects. (Khalid, 2018)
3.2 Existing Problems:
The landfill face some problems related to the operation and some of them have been
already solved:
i.
When the wind speed reach 35 Km/h, the operation process will be stopped.
While the wind blows the unloading process of the waste will be stopped
especially the plastic waste. As a result, they provide a fence around the landfill
with a height of 6 meter, to make the collection easier.
ii.
In Al Amerat the weather is very hot where the temperature can reach 45C.
This high temperature affect negatively on the bacteria. The bacteria should be
maintained under a temperature below 40 C. therefore, they provide heat
exchanger and cooling tower. The cooling tower will cool the heat exchanger,
and the heat exchanger will cool the leachate.
iii.
Feeding the bacteria or the leachate with dissolved oxygen under high pressure
produce bubbles which will be shown at the top of the tank. In this case the
foam tank will collect all the foams from the tanks automatically and then spread
a chemical of anti-foam on the foam then keep it as a leachate, after that
sending it back to the nitrification tank, from nitrification 1 it goes to nitrification
2 which contains jet pumps, in these jet pumps the leachate will mixed during
24/7 so it doesn’t get condensate, at the end solid will be on bottom and liquid
will be at top and this will be very difficult for the operation, that’s why mixing it
without stopping is very important step, when it reaches to nitrification 2, the
liquid will be ready to treat mechanically, physically and chemically, in this case
the leachate will be ready to send it to the plant.
iv.
the transportation of waste are unregulated (Khalid, 2018)
Chapter 4: Environmental Impacts
Nowadays, the global impact on the environment must be taking in account when any
strategy is developed. In case if this aspect is forgotten, there will be a change in
environmental loads and no reduction will be attained. (Parte, 2004)
The sanitary landfill represents the most commonly used and viable method for solid
waste disposal worldwide. In other hand, this method will effect on the environment
positively and negatively. Landfill gives rise to positive environmental impact due to:
i.
Utilize the energy given out by the wastes. Where the Landfills give out gases
like carbon dioxide and methane when the waste decomposed automatically.
This gas are used to generate energy. Then the energy is used within the
landfill area in moving the turbines, generators and transformers.
ii.
Treat the leachate that generated form the waste and used for irrigation and
read cleaning purpose.
iii.
The landfills can serve the community in a new way, by turned the landfills into
farmland or public parks once they reach a saturation point.
iv.
The amount of waste disposal was monitored when the landfills were
implemented. Thereby, the statistics were created out as well as the studies.
v.
The safety provided by the landfill is very high compared with other waste
management techniques. (Khalid, 2018)
In other hand, the landfills can affect the environment negatively through:
i.
Air pollution due to the methane gas that releases when the waste are
decomposes. the methane consider as one of the greenhouse gas that can
traps up to 20 times more heat in the atmosphere compared with carbon
dioxide. Therefore, the air surrounding landfill sites stink.
ii.
Effect on Wildlife. As well as, the decomposition organic material and the toxic
substances can affect the soil quality in the areas around the landfill site.
thereby, the local trees can cease to grow
iii.
Landfill fires, where the fire can ignite due to the landfill gases and the sheer
amount of landfill waste.
iv.
Landfill may lower the prices of lands around it, due to the smell, insects and
noise that generate it.
v.
The leakage of the leachate to the groundwater. This can result contamination
of the local groundwater and quickly de-oxygenate water. (Khalid, 2018)
Chapter 5: Conclusion
The waste is accumulate in the ecosystem by leaps and bounds. Thereby, the ways to
tackle with this problem should be rapid. Therefore, the waste management has been
always a center of discussion in Oman, especially in the recent years by the local
governing bodies and the municipalities.
5.1 Improving Measure:
The numbers of open dumping sites are goes in decreasing due to the increasing both
of landfills and awareness of the people. Where the people tends to dumping up of the
wastes in unused land and let them get decompose on their own instead of damaging
the environment. Moreover, by increasing the awareness of the people, the number of
the solid waste that will be taken to the landfill will be decreased. Those waste will be
converted and recycled, therefore the diversion rate will be increased. As well as, in
the future the daily generated waste will be decreased.
5.2 Technical:
In general, be'ah implement new facilities to use in management of the waste such as
landfills, transfer station and healthcare waste (HCW). In particular, AL Multaqa landfill
is the first and the biggest landfill in Oman, and the third one in the Middle East after
Turkey and Israeli. The landfill designed using high quality of materials and new
techniques. Where, leachate treatment facility is used to treat leachate and reused in
irrigation purpose and cleaning of the roads.
5.3 Operational:
The operation of the waste management used in Oman is different than the one used
in the global world. However, be'ah try to improve it year by year to meet the level of
the global waste management. The figures below show the waste management
hierarchy used in Oman and in the global world.
5.4 Recommendations:
From my opinion, they should separate the waste before dumping it. In order, to utilize
the waste in many ways. Moreover, to use the Methane gas in power generation which
then used in landfill purposes and for cement factories. I think, they can provide
hazardous waste treatment plant within the landfill area. Which will save the time, effort
and fuel used in transported it to Sohar. Furthermore, to spray water over the soil used
in daily cover to increase the compaction rate and provide more space.
References:
Be'ah, 2017. Be'ah. [Online]. Available from: https://www.beah.om/. [Accessed: 10h
May 2018].
Khalid, A., 2018. Interview with A. Khalid on 19th April 2018. Al Multaqa Landfill
[Recording in possession of author].
Parte, S., 2004. Environmental Performance of a Municipal Wastewater Treatment
plant. The International Journal of Life Cycle Assessment. [e-journal]. 37 (9). p. 78-82.
Available from: https://link.springer.com. [Accessed: 10h May 2018].
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