1. Introduction
1.1 Background
Food waste is a problem faced by Singapore and countries all around
the world. Food waste is defined as “the removal of food from the supply chain
which is fit for consumption, or which has spoiled or expired, mainly caused by
economic behavior, poor management or neglect” (FAO, 2014, P.4). As the global
population increases, the global food supply would be strained to meet the
rising demand. Between 2012 to 2014, 805 million people were chronically
undernourished while food was wasted or lost in other areas around the world
(Galanakis, 2015). While food is scarce in developing regions in the world,
food is also being wasted and lost from the food chain in other places such as
Singapore.
According to the National Environment Agency (NEA), in 2017, food
waste accounted for 10% of total waste generated in Singapore, but only 16% of
the food waste was recycled (NEA, 2018). The remainder of food waste which is
not recycled will be sent to incineration plants to be incinerated. This
process of incinerating food waste can be harmful to the environment as it
produces large amounts of carbon emissions. It is beneficial to increase the
amount of food waste recycled in Singapore as it would reduce overall carbon
emissions.
Regarding the issue on food waste, the main stakeholders would be
the government and government agencies as well as businesses related to the
food industry. The government is responsible for formulating and implementing
policies which will greatly affect the actions taken to reduce food wastage. Such
policies can help facilitate the adoption of new technologies for local
businesses. The government can also launch campaigns to raise awareness for the
management of food waste. Businesses that have a stake in this issue include
local food businesses such as hawker centers, food vendors, supermarkets, wet
markets and food recycling plants. These businesses are responsible for the
management of food waste as it is an important factor to ensure that they have
a sustainable business. Food wastage also accounts for the loss in profits
businesses due to overstocking of perishables, resulting in uncooked food being
thrown away.
The issue of food waste affects all Singaporeans as the vast
majority of Singaporeans contribute to food waste in Singapore. According to a
study conducted by Grandhi and Singh (2016), the general public thinks that
food waste was not an issue since it was natural and biodegradable. Half of the
respondents from the study acknowledged that they could have taken steps to
avoid food waste generated from leftovers after a meal, food becoming spoilt,
and throwing away blemished fruits and vegetables. It was also noted through
the study that there was a lack in sorting of food waste in Singapore. This
showed that there was a lack of awareness among Singaporeans about the
consequences of massive amounts of food waste.
Hawker centers and wet markets contribute to a portion of the total
food waste in Singapore; as it is a place where Singaporeans go to have their
meals and thus leaving food waste if they do not finish their food. Hawker
vendors and market stall owners also contribute to food wastage when the amount
of food ingredients prepared exceeds the demand and is thrown away because the
food is spoilt or expired.
To tackle the problem of food waste in Singapore, Singaporeans must
work towards ensuring food waste is handled in a sustainable manner. Food waste
recovery can improve the sustainability of food systems by making full use of
the valuable compounds which can be recovered from food waste.
1.2 Problem Statement
Ideally, food waste generated by local food centers should be
thoroughly sorted in preparation for processing to be fully utilized in other
means, instead of being disposed of. In
2017, Singapore produced 809,800 tonnes of food waste, while recycling only a
mere 16% of it, with the remaining being incinerated (NEA, 2018). This is
mainly due to the lack of an efficient recycling system at locations (hawker
centres) where a significant amount of food waste is being produced.
1.3 Purpose Statement
This report aims to propose to the NEA Hawker Centre Division in
implementing a closed-loop system to maximize the food waste utilization rate
of hawker centres by providing an efficient system to sort and utilize food
waste generated by food vendors and customers.
2. Proposed solution
The proposed
solution to deal with the problem of food waste in hawker centres is to provide
a closed loop system to maximize the food waste utilization rate of hawker
centres. This closed loop system consists of different stages; collection and
sorting, treatment and utilization of end products. In the sorting stage, food
waste is separated according to their valuable compounds to facilitate the
treatment process. The sorted food waste will then be treated using two waste
treatment methods, anaerobic digestion and composting.
2.1 Collection and sorting
Both composting and anaerobic digestion can be implemented
simultaneously to maximize the utilization of food waste in hawker centers.
Using both composting and anaerobic digestion draws benefits from each method
while mitigating the drawbacks. These two systems complement each other as it
reduces the cost of recycling food waste as well as ensuring all types of food
waste produced at the hawker center is fully utilized. Composting helps keep
the cost of processing food waste low and produces compost suitable for
gardening. Anaerobic digestion is able to process most forms of food waste not
suitable for composting and produces methane which can be turned to other forms
of energy.
2.2 Treatment
a. Composting
Composting is a process which involves microorganisms breaking down
food waste in the presence of oxygen. “Composting has been used as a method to
dispose food waste (FW) and recycle organic matter to improve soil structure
and fertility.” (Li, Lu, Ren & He, 2013). The product of composting can be
used as fertilizer or soil conditioner. The by-products of composting are heat,
water and carbon dioxide. Composting is a cheap and simple way of processing
food waste. Composting would be ideal for food waste such as vegetables and
fruits classified as “greens”. Other compounds such as meats are not ideal as
they produce a foul odor and may attract stray animals.
b. Anaerobic digestion
Anaerobic digestion (AD) is a process which involves microorganisms
breaking down food waste in the absence of oxygen. (Zero Waste Singapore,
2008). This process produces biogases (mainly methane) and digestate, which can
be utilized to produce energy and as a compost respectively. Anaerobic
digestion of food waste is able to treat a “wide range of substrates of both
agricultural and industrial origin” (Pesta, 2007). This method is applicable
for any liquid or solid organic waste. However, due to the complexity and
additional machineries needed for this process, anaerobic digestion has a
higher capital and operational cost as compared to composting, in treating food
waste.
2.3 Utilization of end products
Through the treatment processes (composting and anaerobic
digestion), food waste are being turned into bioproducts; mainly compost and
methane. These bioproducts produced are usable resources that could be utilized
to supplement the hawker center’s daily operational needs. Utilization of these
end products creates a closed loop system for the center, which in turn
promotes self-sustainability through the reduction in reliance on external
sources for its daily operations. Examples of the utilization of these end
products would be the usage of compost produced at the in-house rooftop garden
and recirculation of methane produced into the center’s gas pipelines.
3. Benefits
The proposed
solution focuses on having a closed-loop system being implemented in the hawker
centre. This closed-loop system taps on food waste generated by turning them
into usable resources through treatment processes. This resources produced
would then be used extensively in the hawker centre to meet its operational
needs. It is beneficial to have such system in place as it reduces dependency
on external resources, maximizes the utilization of food waste and
3.1 Reduced dependency on external resources
Operating cost of a stall in hawker center is high due to the
fluctuating utilities prices. This is a significant impact to the vendors’
income as utilities cost contributes 9% to the daily operating cost (The
Straits Times, 2015). Thus, having a closed-loop system in place in the hawker
center is beneficial to the vendors. This system allows the food waste
generated within the center to be turned into usable resources, such as
biogases. These biogases produced can be recirculated into the center’s gas
pipeline, which in turn reduces the utilities cost as the recirculated biogases
would reduce the need for gases supplied externally (used for stoves etc.).
3.2 Maximized utilization of food waste
As mentioned earlier on, in Singapore, food waste accounted for 10%
of total waste generated and only 16% of it is being recycled (NEA, 2018), with
the remaining being incinerated. The process of incineration does not eradicate
the waste; instead, it reduces the volume of it by reducing them into ashes
which are dumped into landfill subsequently. This is not sustainable as
according to the Ministry of the Environment and Water Resources (MEWR) in
2019, based on the rate of waste currently being disposed, Singapore’s only
landfill would be running out of space by 2035. Therefore, the only solution to
prolong the landfill’s lifespan would be to maximize the utilization of waste
instead of having them disposed of.
3.3 Hawker center localised garden for
growing of small produce
Hawker centers generate up to an average of 1 ton of food waste
daily. This contributes a significant amount to the overall food waste that
Singapore generates. According to Yahya (2011), 1 ton of food waste will return
approximately 1000 litres in reclaimed water.
The reclaimed water can be used for irrigation for a hydroponics system
to grow local produce for use within the hawker centre that the farm is located
in.
Furthermore, the compost produced from the recycled food waste
collected from the hawker centre can be used to enrich the growing medium for
the produce grown in the hawker centre garden for use by the vendors for their
own use in their stalls.
As for the biogas produced from anaerobic digestion, it can be used
to fuel the generators the systems that run the hydroponics farm like water
pumps for irrigation and UV lamps to keep the produce in optimum lighting
levels throughout the day.
4. Evaluation
4.1 Site limitations
One possible challenge which the proposed treatment system may face
would be the limited space which most hawker centers have. Installing equipment
to treat the food waste may not be feasible for small hawker centers as there
would be no space for the equipment. The proposed garden would also be limited
to the space around the hawker center.
4.2 Operational cost
Installing an anaerobic digester on site would be costly and could
potentially cost the hawker center more money to maintain its operation. From
the point of view of stakeholders who invest money in installing an anaerobic
digester on site, the benefits of the treatment system must outweigh the cost
of operation. Stakeholders must weigh the benefits of recycling food waste
against the cost of such a system to ensure their business is sustainable and
that the system will eventually cover the capital cost.
4.3 Inertia of hawker centers to adopt new
system
As composting and anaerobic digestion are not familiar terms to
hawker stall owners and managers of hawker centers, it may be difficult to
implement a new system as it will take time for hawker centers to familiarize
and adopt new technology. Hawker vendors may also not be well trained to
operate equipment to treat food waste. The initial stage of implementation
would be difficult as it requires a change of mindset towards handling food
waste as opposed to the traditional method of dumping food waste in a bin.
Basic lesson on using those machinery can be taught free to all
hawker stall owners, at the same time explaining to them the benefits on
adopting these new technology.
5. Methods/Procedure
5.1 Primary research
A survey was conducted to identify the problem with regards to food
waste in hawker centers. Respondents were asked about their contributions to
food waste at hawker centers and their opinion on the rate of recycling food
waste at hawker centers as well as the main factor which limits food waste
recycling. The survey was conducted to justify the need for food waste
recycling at hawker centers as well as identify the current problem which
limits the food waste recycling rate. Interviews with hawker stall owners were
also carried out to gain further insight into how food waste at hawker centers
is being handled.
5.2 Secondary research
Secondary research was conducted by reading research articles
related to food waste treatment methods and utilization of products from
recycling food waste, which will help in developing a closed-loop system for
recycling food waste at hawker centers. Local statistics on the rate of food
waste recycling were taken from the NEA website.
6. Concluding statement
Food waste has
serious social and environmental implication but many of us don’t think twice
about it. Furthermore, with the increase of population, landfills running out
of space and human living longer. There is compelling need to increase the
recycling rate then letting food waste be send for incineration. Our proposed
on closed loop system could be a sustainable approach by the end-product could
be a usable resources that could be utilized to supplement the hawkers center
daily operational needs.
The benefits of
implementing a closed-loop system for food waste in hawker centers would be
limited by the willingness of hawker centers to adopt such a system. The NEA
could play a big role in encouraging hawker centers to recycle food waste. To
ensure this system is well received by hawker centers around Singapore, some
incentives could be given to hawker centers which are willing to adopt the
system. In a survey conducted regarding this issue, 32.5% of respondents said
that lack of awareness among Singaporeans is one of the main factors which
limited the recycling rate of food waste at hawker centers. Furthermore, 22% of
respondents said that inadequate policies being implemented by relevant
authorities is a contributing factor which limits food waste recycling in
Singapore. To ensure successful implementation, it is vital that NEA takes
initiative in campaigning for food waste recycling and educating Singaporeans
on the importance of recycling food waste.
A pilot project
is recommended to test the feasibility of implementing the recycling system in
hawker centers around Singapore. The pilot project will involve upgrading a
hawker center by installing food waste treatment equipment as well as planting
a garden in close proximity to the hawker center. The project should be
monitored and if successful can be adapted and implemented in hawker centers
all around Singapore.
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