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Abstract

Food waste is made up of materials intended for human consumption that are subsequently discharged, lost, degraded or contaminated. The problem of food waste is currently on an increase, involving all sectors of waste management from collection to disposal; the identifying of sustainable solutions extends to all contributors to the food supply chains, agricultural and industrial sectors, as well as retailers and final consumers. A series of solutions may be implemented in the appropriate management of food waste, and prioritised in a similar way to waste management hierarchy. The most sought-after solutions are represented by avoidance and donation of edible fractions to social services. Food waste is also employed in industrial processes for the production of biofuels or biopolymers. Further steps foresee the recovery of nutrients and fixation of carbon by composting. Final and less desirable options are incineration and landfilling. A considerable amount of research has been carried out on food waste with a view to the recovery of energy or related products. The present review aims to provide an overview of current debate on food waste definitions, generation and reduction strategies, and conversion technologies emerging from the biorefinery concept. Copyright © 2015 Elsevier Ltd. All rights reserved.
Food waste generation and industrial uses: A review
Francesca Girotto
, Luca Alibardi, Raffaello Cossu
Department of Industrial Engineering, University of Padova, Via Marzolo 9, 35131 Padova, Italy
article info
Article history:
Received 22 February 2015
Revised 26 May 2015
Accepted 4 June 2015
Available online 27 June 2015
Keywords:
Food waste
Generation
Prevention
Biorefinery
Biofuels
Bioproducts
abstract
Food waste is made up of materials intended for human consumption that are subsequently discharged,
lost, degraded or contaminated. The problem of food waste is currently on an increase, involving all sec-
tors of waste management from collection to disposal; the identifying of sustainable solutions extends to
all contributors to the food supply chains, agricultural and industrial sectors, as well as retailers and final
consumers. A series of solutions may be implemented in the appropriate management of food waste, and
prioritised in a similar way to waste management hierarchy. The most sought-after solutions are repre-
sented by avoidance and donation of edible fractions to social services. Food waste is also employed in
industrial processes for the production of biofuels or biopolymers. Further steps foresee the recovery
of nutrients and fixation of carbon by composting. Final and less desirable options are incineration and
landfilling. A considerable amount of research has been carried out on food waste with a view to the
recovery of energy or related products. The present review aims to provide an overview of current debate
on food waste definitions, generation and reduction strategies, and conversion technologies emerging
from the biorefinery concept.
Ó2015 Elsevier Ltd. All rights reserved.
1. Introduction
Food loss and food waste are often used in scientific literature
to identify materials intended for human consumption that are
subsequently discharged, lost, degraded or contaminated. The
Food and Agriculture Organisation of the United Nations (FAO)
defined food loss (FL) as any change in the availability, edibility,
wholesomeness or quality of edible material that prevents it from
being consumed by people. This definition was provided for the
post-harvest period of food ending when it comes into the posses-
sion of the final consumer (FAO, 1981). Gustavsson et al. (2011)
reported a similar definition of FL but included also the production
stage of a food supply chain (FSC) and not only postharvest and
processing stages. Parfitt et al. (2010) defined food waste (FW) as
the food loss occurring at the retail and final consumption stages
and its generation is related to retailers’ and consumers’ behaviour.
Recently the European Project FUSIONS (Östergren et al., 2014)
defined FW by using the resource flows of the agri-food system.
FW was defined as ‘‘any food, and inedible parts of food, removed
from (lost to or diverted from) the food supply chain to be recovered
or disposed (including composted, crops ploughed in/not harvested,
anaerobic digestion, bio-energy production, co-generation, incinera-
tion, disposal to sewer, landfill or discarded to sea).’’ Any food being
produced for human consumption, but which leaves the food sup-
ply chain, is considered FW while organic materials produced for
the non-food production chain are not considered FW (Östergren
et al., 2014). The definitions of FL and FW therefore overlap.
These terms are used in literature for material discharged at both
the manufacturing and retail stages and the consumption or
household levels, highlighting the need for commonly-agreed
and improved definitions (Williams et al., 2015).
Discharge of food material occurs along the entire Food Supply
Chain (FSC) and it involves all sectors of waste management from
collection to disposal. Detailed analysis of a FSC system will high-
light how the generation of waste material (food losses, organic
waste or food waste) affects all sectors involved in the production,
distribution and consumption of food (Parfitt et al., 2010;
Pfaltzgraff et al., 2013). A FSC starts with the production of food
from the agricultural sector where both farming and husbandry
produce waste or sub-products that may be either organic waste
(i.e. cornstalk, manure), food waste or food loss (i.e. low quality
fruits or vegetable, damaged productions left in the field, good
products or co-products with a low or absent commercial value).
The food processing and manufacturing industry produces food
losses and food waste throughout the entire production phase
due to reasons such as: damage during transport or
non-appropriate transport systems, problems during storage,
losses during processing or contamination, inappropriate packag-
ing. The retail system and markets also generate FL and FW, largely
http://dx.doi.org/10.1016/j.wasman.2015.06.008
0956-053X/Ó2015 Elsevier Ltd. All rights reserved.
Corresponding author.
E-mail addresses: francesca.girotto.3@studenti.unipd.it (F. Girotto), luca.
alibardi@unipd.it (L. Alibardi), raffaello.cossu@unipd.it (R. Cossu).
Waste Management 45 (2015) 32–41
Contents lists available at ScienceDirect
Waste Management
journal homepage: www.elsevier.com/locate/wasman
due to problems in conservation or handling, and lack of cooling/
cold storage (Parfitt et al., 2010).
The generation of FW by the end consumer is caused by over- or
non-appropriate purchasing, bad storage conditions,
over-preparation, portioning and cooking as well as confusion
between the terms ‘‘best before’’ or ‘‘use by’’ dates
(Papargyropoulou et al., 2014). The generation of FW at household
level is influenced by a series of interconnected factors, mainly
socio-demographic characters of the household, consumption
behaviour and food patterns (Glanz and Schneider, 2009).
FL and FW generation produces an impact at an environmental,
social and economical level. From an environmental point of view,
FL and FW contributes to Green House Gas (GHG) emissions during
final disposal in landfills (uncontrolled methane release) and dur-
ing activities associated with food production, processing, manu-
facturing, transportation, storage and distribution. Other
environmental impacts associated with FL and FW are natural
resource depletion in terms of soil, nutrients, water and energy,
disruption of biogenic cycles due to intensive agricultural activities
and all other characteristic impacts at any step of the FSC. Social
impacts of FL and FW may be ascribed to ethical and moral dimen-
sion within the general concept of global food security. Economical
impacts are due to the costs related to food wastage and their
effects on farmers and consumer incomes (Lipinski et al., 2013;
Papargyropoulou et al., 2014).
Similar to the Waste Management Hierarchy introduced in
Europe, based on a hierarchy of solutionsof distinct steps (waste pre-
vention, reuse, recovery and recycling of materials, energy recovery
and safe landfilling of residues) and often graphically representedby
a reverse triangle (Cossu, 2009), the Environmental Protection
Agency (EPA, 2014) defined the following hierarchy concept in rela-
tion to FW management: source reduction, feed hungry people, feed
animals, industrial uses, composting, incineration or landfilling.
The first steps to be taken in reducing FW generation should com-
mence by tackling the undesirable food surplus, and preventing
over-production and over-supply of food (Papargyropoulou et al.,
2014; Smil, 2004). The subsequent steps in the hierarchy foresee
the utilisation of FW as animal feed or in the industrial sector.
Several options are available for an industrial-scale use, ranging
from the use of food waste for energy production by means of anaer-
obic digestion (e.g. bio-hydrogen or bio-methane productions) to
the production of specific chemical compounds as precursors for
plastic material production, chemical or pharmaceutical applica-
tions. Composting can be applied to recover nutrients or as a carbon
sequestration process, through the formation of humic substances.
Composting can be used to treat FW or residues from industrial pro-
cesses (e.g. digestate). Landfilling or incineration represents the last
and least desirable option. It is an acknowledged fact that biodegrad-
able organic material is the main source of adverse environmental
impacts and risks in traditional landfilling (odours, fires, VOC’s,
groundwater contamination by leachate, global climate changes,
etc.) (see also Manfredi et al., 2010; Thomsen et al., 2012; Beylot
et al., 2013) while thermal treatment, although providing for energy
recovery, is limited by the low heating values of organic waste
(Nelles et al., 2010). Accordingly, these options are not highly sought
after (Papargyropoulou et al., 2014; Vandermeersch et al., 2014).
This paper reviews the data available on the magnitude of food
waste generation, the strategies for food waste reduction and the
possibilities reported and discussed in scientific literature for
industrial uses of food waste.
2. Generation of food waste
The Food and Agriculture Organisation of the United Nations
estimated that 32% of all food produced in the world was lost or
wasted in 2009 (Gustavsson et al., 2011; Buzby and Hyman,
2012). While 870 million people are reported as being chronically
undernourished, approximately 1.3 billion tons/year, i.e. one third
of the food produced for human consumption, is wasted globally
(Kojima and Ishikawa, 2013). In United States nearly 61 million tons
of food waste are generated every year (GMA, 2012). Dee (2013)
reported a food waste generation rate of 4 million tons per year
in Australia. Other food waste generation data regards South
Korea with 6.24 million tons per year (Hou, 2013), China with
92.4 million tons per year (Lin et al., 2011) and Japan where about
21 million tons of food waste were generated in 2010 (Kojima and
Ishikawa, 2013). In Europe, food waste generation is estimated at 90
million tons annually (EC, 2013). Studies indicate the United
Kingdom (UK) as the Country with the highest FW generation rate
in Europe, reaching more than 14 million tons in 2013 (WRAP,
2013; Thi et al., 2015; Youngs et al., 1983). Quested et al. (2013)
reported a generation of food waste at household level of 160 kg
per year in UK, representing 12% of the food and drink entering a
home and 30% of the general waste stream from UK household.
Nellman et al. (2009) reported that a percentage ranging between
25% and 50% of food produced is wasted through the supply chain.
The order of magnitude of food waste generation is consistent
and is not limited to developed Countries. Gustavsson et al.
(2011) reported data on FW generation from different parts of
the world, indicating that FW generation displays a similar order
of magnitude in both industrialised Countries and developing
Countries (DCs). Nevertheless, industrialised and developing
Countries differ substantially. In the latter, more than 40% of food
losses occur at the postharvest and processing stages, while in the
former, about 40% of losses occur at the retail and consumer levels
and, on a per-capita basis, much more food is wasted in the indus-
trialised World than in DCs (Gustavsson et al., 2011).
The causes of food losses and waste in low-income Countries
are mainly linked to financial, managerial and technical limitations
in harvesting techniques, storage and cooling facilities in difficult
climatic conditions, infrastructure, packaging and marketing sys-
tems. Many smallholder farmers in DCs live on the margins of food
insecurity, and a reduction in food losses could have an immediate
and significant impact on their livelihoods. Food supply chains in
DCs should be strengthened, encouraging small farmers to orga-
nize, diversify and upscale their production and marketing.
Investments in infrastructure, transportation, food industries and
packaging industries should also be boosted, with both the public
and private sectors playing an important role in achieving this.
The causes of food losses and waste in medium/high-income
Countries relate mainly to consumer behaviour as well as to a lack
of coordination between the various actors in the supply chain.
Farmer-buyer sales agreements may contribute towards the
wastage of farm crops. Food may also be wasted due to quality
standards, with food items that do not fit with the required shape
or appearance being rejected. On a consumer level, inadequate
planning and expiry of ‘‘best before dates’’ likewise lead to large
amounts of waste, combined with the at-times careless attitude
of consumers. Food waste in industrialised Countries can be
reduced by raising awareness amongst the food industries, retail-
ers and consumers. This inevitably implies the unnecessary use
of huge amounts of resources used in food production, and conse-
quent increase in GHG emissions (Gustavsson et al., 2011).
In terms of the wasted investments, Nahman and de Lange
(2013) estimated costs of edible food waste throughout the value
chain in South Africa at approximately 7.3 billion per annum,
equivalent to 2.1% of annual gross domestic product. In the
Unites States 85 billion worth of food was estimated to be thrown
away every year (Parfitt et al., 2010), 28 billion in China (Zhou,
2013), 27.8 billion in Australia (Dee, 2013), 40 billion in
Europe and nearly 17 billion in the UK (WRAP, 2015).
F. Girotto et al. / Waste Management 45 (2015) 32–41 33
Two aspects are in connection with the FW generation problem:
prevention upstream and source segregation downstream. The pri-
mary action to be implemented in a successful FW management
strategy is prevention of generation. The unavoidable generated
FW amount needs, then, to be properly source segregated.
Prevention can be achieved either attempting to reduce losses
and, therefore, decreasing the demand for food production, or
diverting food losses, exceeds, and still safe and edible FW to other
end-consumers. FW prevention campaigns have been promoted by
advisory and environmental groups, and by media focus. Several
papers have analysed the behaviour of companies and the popula-
tion in developed Countries at different levels (household, restau-
rant, retail) to assess the governing factors influencing wastage of
food products (Glanz and Schneider, 2009; Schneider and
Lebersorger, 2009; Silvennoinen et al., 2012; Quested et al., 2013;
Katajajuuri et al., 2014; Garrone et al., 2014; Graham-Rowe et al.,
2014; Mena et al., 2014).
The focus of measures implemented will vary from Country to
Country as highlighted by the work of Gustavsson et al. (2011).
In developed Countries, food waste prevention should focus on
the consumer’s behaviours at household level, while in developing
Countries it should focus increasingly on the retail and distribution
system. The issues of food security and utilisation of food surplus
to satisfy the nutritional needs of the poor represent indirect mea-
sures of FW prevention.
BIO Intelligence Service carried out a survey about FW genera-
tion across EU27 (EC, 2010) which resulted in a technical report
where three priority options are highlighted: data reporting
requirements, date labelling coherence, and targeted awareness
campaigns.
The retail system may result in the generation of FW through-
out various stages of food distribution and purchase: damage dur-
ing transport or non-appropriate transport systems, problems
during intermediate storage, losses during processing or contami-
nation, inappropriate packaging, problems in conservation or han-
dling, lack of cooling/cold storage. The food supply chain is also
affected by loss of products nearing their expiry date (Aiello
et al., 2014).
Other potential influences discussed in the literature can be
divided into production and distribution level, and consumer level.
Prevention strategies related to the first point are: development of
markets for ‘sub-standard’ products, development of contract
farming linkages between processors and farmer, marketing coop-
eratives and improved market facilities (Gustavsson et al., 2011)
together with studies targeted in finding the optimal turnover fre-
quency and wholesale pack size (Eriksson et al., 2014). Wasted
investments should provide an incentive to push the food industry
to reduce food waste generation in order to gain benefits on both
the financial and environmental fronts. More specifically, interven-
tions should first and foremost be targeted at the processing and
packaging stages of the fruit and vegetable value chain, which
alone accounts for the 13% of the total, as well as the distribution
stage of the fruit and vegetable value chain, and the agricultural
production and distribution stages of the meat value chain
(Nahman and de Lange, 2013).
Betz et al. (2015) reported several actions geared at FW preven-
tion and reduction, and indicated award schemes including incen-
tives for food industries reducing FW generation. Future preventive
measures should focus on the return of fresh products (shifting
responsibilities from local shops to retail companies), internal opti-
misation (benchmarking amongst retail outlets within a company
and application of best practices), training, information and educa-
tion of employees, and amending the display at the end of the day
when stocks are decreasing (Lebersorger and Schneider, 2014;
Scherhaufer and Schneider, 2011). If food losses have to be dis-
carded at the retailer’s expense, this will act as an incentive for
the outlet to minimise losses by optimising planning and ordering
according to demand. Lebersorger and Schneider (2014) reported
how, in the bread & pastry market, shifting the responsibility for
unsold products from bakeries to the retail company would pro-
vide an incentive for retail outlets to reduce high quantities of
wasted bread, for example by optimising demand planning and
ordering and providing specific information to the supermarket
customers.
On a household level, consumer behaviour may produce a huge
impact on FW generation. Since the past Century, a wide range of
factors influencing FW generation has been identified (Youngs
et al., 1983) such as poor selection of food items, overbuying, poor
food storage, excessive preparation losses, inability to use
by-products, poor cooking/holding techniques, shortage of labour
and equipment, excessive portion sizes, inability of the eater to
remove all edible material, service method. Nowadays, over-
or inappropriate purchasing, bad storage conditions,
over-preparation, portioning and cooking as well as confusion
between the terms ‘‘best before’’ or ‘‘use by’’ dates are still some
of the main factors affecting food loss. This behaviour is influenced
by a series of interconnected factors, mainly socio-demographic
characteristics of the household, consumption behaviour and food
patterns. Moreover, the barriers to surpass in achieving food loss
minimisation at household level may also involve emotional or
psychological aspects. The householder may wish to be a ‘‘good
provider’’ in terms of supplying an abundance of healthy food for
the family. A lack of food may produce a sense of inability to take
care of the needs of the family, in this way driving the purchase of
additional goods unnecessarily. Another example is avoidance of
frequent trips to shops, resulting in the purchase of more food
products to avoid running out. A general lack of awareness of the
amount of FW generated at household level may exert a strong
impact on food waste generation, due to the fact that small quan-
tities thrown away a bit at a time with other waste does not pro-
vide the proper order of magnitude of the problem to consumers
(Graham-Rowe et al., 2014). At consumer level a wide range of
optimal behaviours can be listed: planning meals in advance,
checking levels of food in cupboards and fridge prior to shopping,
making a shopping list, storing meat and cheese in appropriate
packaging or wrapping, storing vegetables and fruit in the fridge,
using the freezer to extend the shelf-life of food, portioning rice
and pasta, using up leftovers, using date-labels on food (Quested
et al., 2013; Eriksson et al., 2014).
Additional measures should be considered, including the raising
of customer awareness and information (Scherhaufer and
Schneider, 2011). Whitehair et al. (2013), for example, found out
how to simply reach a 15% reduction in FW generation from
Universities’ canteens by using written messages such as ‘Eat what
you take. Don’t waste food’ or ‘All taste, no waste’.
With regard to the set of activities aimed at addressing lost,
exceeding and safe wasted food to alternative end-consumers,
donation of food constitutes a specific application of urban mining
in view of the fact that food is recovered for its original purpose –
human intake (Schneider, 2013a) and it is a valid alternative to
minimise FW generation. Donation is a well-established food
waste prevention measure implemented worldwide. The largest
domestic hunger-relief organisation in the United States of
America is Feeding America, a national network of more than
200 food banks operating within all 50 states, as well as the
District of Columbia and Puerto Rico. It coordinates the distribution
of edible food and grocery products with the help of 61,000 agen-
cies, which supply 37 million people in the US. Three billion
pounds of food were collected and distributed to people in need
in 2009 (Echevarria et al., 2011).
The European Federation of Food Banks was established in 1984
and more than 30 years later there are 247 food banks operating in
34 F. Girotto et al./ Waste Management 45 (2015) 32–41
21 European Countries. According to the reports published on their
website, a total of 401,000 tons of food were collected and dis-
tributed to 31,000 social welfare organisations in 2011. It is esti-
mated that these products are worth several hundred million
and approximately 5.2 million people are supported by these
goods (FEBA, n.a.).
The largest contribution to the amount donated, with a share of
36% in 2006, was made by dairy products; the next largest product
group was biscuits, cereals and starchy food with a share of 31%,
and the third largest group was fruits and vegetables at 15%
(European Food Banks, 2007; Schneider, 2013a). The majority of
the products (55%) distributed by the European Food Banks are
donated by the European Union or by member states (4%). Part
of these products has been subject to a withdrawal or intervention
approach used to stabilise market prices.
A central piece of legislation related to food donation is the
General Food Law EC/178/2002. The aim of this Regulation is to pro-
vide a framework to ensure a coherent approach in the develop-
ment of food legislation. It lays down definitions, principles and
obligations covering all stages of food/feed production and distribu-
tion. According to Article 3.8, food donation falls under ‘‘placing on
the market’’ operations, which are holdings of food or feed for the
purpose of sale, including offering for sale or any other form of
transfer, whether free of charge or not, and the sale, distribution,
and other forms of transfer (EESC, 2014). This definition essentially
points out that all food donations have to comply with the EU
General Food Law. In other words, a food business operator has to
comply with the same rules whether he is selling or donating food.
Food banks and charities are considered ‘‘food business operators’’
(EESC, 2014). According to Article 17 ‘‘food and feed business operators
at all stages of production, processing and distribution within the busi-
nesses under their control shall ensure that foods or feeds satisfy the
requirements of food law which are relevant to their activities and shall
verify that such requirements are met’’ (EESC, 2014). The food busi-
ness operator is held responsible for any hygiene problem occurring
only in the part of the food chain under its own control.
Donations to social services are beneficial from a series of differ-
ent points of view. They reduce waste quantities and waste man-
agement costs (Alexander and Smaje, 2008; Schneider, 2013b)
and may contribute towards promoting a positive image for the
company together, and producing social benefits for the clients of
these services. An example of how this can be implemented is rep-
resented by SOMA, a social supermarket set up in Linz, Upper
Austria. This is a private initiative set up by food wholesalers with
the intention of helping people in need by selling them low priced
food products (Schneider, 2013a).
Aiello et al. (2014) developed a model to determine the optimal
time to withdraw the products from the shelves, and to ascertain
the quantities to donate to non-profit organisations and those to
be sent to the livestock market maximising retailer profit. The opti-
mal time is based on the assumption that the residual market
demand will not be satisfied. Products near to their expiry date
or damaged by improper transportation or production defects are
usually scarcely appealing for the consumer in the target market,
although maintaining their nutritional properties. In particular,
after the optimisation of the variable ‘time to withdraw the pro-
duct from the shelves’ the results show that 44.13% of food losses
is suitable for donation to non-profit organisations, 28.69% to be
sold at the livestock market, and 27.18% is disposed through the
usual channel, namely the landfill.
When discussing the considerably large amounts of FW gener-
ated by consumers at a household level, it is necessary to point
out the basic difficulty in achieving its optimal source segregation.
A series of factors that influence an active participation in
source separation of food waste have been reported in literature,
although the studies performed to date have reported varying
results. Wan et al. (2013) conducted a questionnaire survey in
Malaysia indicating education as the main factor affecting positive
behaviour of consumers towards FW separation rather than conve-
nience. The results of another study performed by Parizeau et al.
(2015) indicated multiple relationships between FW segregation
and household shopping practices, food preparation behaviours,
household waste management practices and food-related atti-
tudes, beliefs and lifestyles. The Authors observed that food and
waste awareness, family and convenience lifestyles were related
to FW generation, and concluded that convenience is a major issue
when asking families to implement source segregation of FW at
their house. Rousta et al. (2015) concluded that convenience and
information go together. In fact, they concluded that information
stickers about food waste sorting and property close location of
drop-off point reduced the miss-sorted fraction by more than 70%.
Similarly, several studies showed that convenience in sorting,
storage space at home, availability of sorting facilities, access to a
curbside collection system and distance to collection points are
important influential factors that can increase the recycling rate
(Rousta et al., 2015; Ando and Gosselin, 2005; Barr and Gilg, 2005).
Bernstad (2014) highlighted how the need for a practical solu-
tion to improve FW separation was more important than providing
appropriate information to consumers. Two different strategies
aimed at increasing household source-separation of FW were eval-
uated in a Swedish residential area: the study involved the use of
written information, distributed as leaflets amongst households,
and installation of equipment for source-segregation of waste,
aimed at increasing convenience FW sorting in kitchens. On the
basis of the results obtained, distribution of written information
amongst households failed to result in either an increased
source-separation ratio, or a statistically significant and
long-term increase of the amount of separately collected house-
hold FW. Conversely, following the installation of sorting equip-
ment in all households in the area, both the source separation
ratio and the amount of separately collected FW increased mark-
edly. Changes remained consistent even months after the installa-
tion of the sorting equipment in the area (Bernstad, 2014).
Bernstad and la Cour Jansen (2011) compared composting,
anaerobic digestion and incineration of FW within a life cycle
approach, highlighting the crucial role of household participation
for efficient source-separation of FW. Incorrect sorting reduces
process efficiency and causes limitation in the final use of sta-
bilised materials from biological treatments.
Prior to implementing any FW management strategy, probably
the best would be to test the opinion of the population in the area
of interest, in order to understand if attitude or convenience is the
main predictor towards food waste separation. Thus, local
Authorities will be guided to design the most meaningful interven-
tion campaign.
3. Industrial uses
Increasing efforts are currently being focused on defining effec-
tive and stable means of obtaining biofuel and bio-products from
FW. These options could afford benefits from an environmental
point of view due to the reduction of methane gas emissions from
landfills and the preservation of natural resources such as coal and
fossil fuels, from a social point of view due to the lack of a food vs.
fuel competition, and from an economical point of view thanks to
costs saving linked to surplus food production and specific invest-
ments in establishing non-food crops dedicated to biofuel or bio-
plastic production.
Biorefineries are the concept underlying industrial FW utilisa-
tion. Similarly to the transformation by oil refineries of petroleum
into fuels and ingredients for use in a wide variety of consumer
F. Girotto et al. / Waste Management 45 (2015) 32–41 35
products, biorefineries convert organic waste and biomasses (corn,
sugar cane and other plant-based materials) into a range of ingre-
dients for bio-based fuels or products. FW produced from agricul-
ture and food processing is abundant and concentrated in specific
locations. These materials could be less susceptible to deterioration
if compared to FW produced at household level at the end of the
FSC (Galanakis, 2012). These characteristics highlight the potential
to develop industrial utilisation processes based on symbiosis
where the wastes from one sector are inputs for other sectors.
Availability of FW and location of potential users define the feasi-
bility of industrial symbiosis (Mirabella et al., 2014). Therefore par-
ticular effort will be required from the agricultural and the
industrial sectors to define sustainable and innovative processes
for residues use and conversion, and from governments to stimu-
late and support this new vision with specific legislations.
Industrial symbiosis within FSC and biorefineries represent possi-
bilities for a complete utilisation of food processing residues, FL
or FW in a vision of circular flow of resources, zero waste and final
sink of stabilised residues (Cossu, 2012; Curran and Williams,
2012). The potential profitability of chemicals and biofuels pro-
duced from FW will stimulate investments on biorefinery chains
rather than treatments of FW in traditional waste management
processes. Finally legislations have to be developed to stimulate,
support, define and control the marketability of chemicals, materi-
als or biofuels obtained from agro-industrial residues or FW
depending by their final applications (nutraceutical/pharma or
non-feed/nonpharma applications) for a effective management of
products traceability, health and safety issues and environmental
protection (Lin et al., 2013; Tuck et al., 2012).
Valorisation routes of FW in biorefinery chains include both
extraction of high-value components already present in the sub-
strates to be used for nutrition or pharmaceutical applications
and conversion into chemicals, materials or biofuels by the use of
chemical or biological processes. Type, origin, seasonal generation
and territorial distribution of FW will affect transport logistic for its
utilisation and its compatibility with the transformation process.
High and concentrated volumes of FW will be generally required
to sustain large production capacities and meet economy of scale.
Cost-effectiveness of conversion processes will then be ensured by
security of supply at regional scale, low heterogeneity of substrates
and large variety of extractable chemicals, biopolymers and biofu-
els. For these reasons, large fluxes of agro-industrial wastes seem
to be more suitable for biorefinery chains where stability of supply
and substrate homogeneity are required for extraction or produc-
tion of specific commodities while source segregated organic waste
from household or restaurants would be more indicated for treat-
ment processes where composition variability, origins and con-
taminations do not represent limits for the selected process
(Pfaltzgraff et al., 2013).
3.1. Biofuel and bioenergy production
Food waste is characterised by a variable chemical composition
depending on its origin of production. FW may therefore comprise
a mixture of carbohydrates, lipids and proteins, or, if generated
from specific agro-industrial sectors, may be rich in one of these
constituents. Different biofuels are therefore produced from FW
using bioprocesses or thermo-chemical processes, depending on
their chemical composition.
The use of FW for energy production was recently reviewed by
Pham et al. (2015) and by Kiran et al. (2014). FW can be converted
into biofuels or energy by means of the following processes:
- transesterification of oils and fats to produce biodiesel;
- fermentation of carbohydrates to produce bioethanol or
biobutanol;
- anaerobic digestion to produce biogas (methane rich gas);
- dark fermentation to produce hydrogen;
- pyrolysis and gasification;
- hydrothermal carbonisation
- incineration;
Not all the listed processes are currently developed at industrial
level for full-scale application. For example, FW is widely studied
as a substrate for the biological production of hydrogen by dark
fermentation, although no full-scale applications have been rea-
lised to date (Alibardi et al., 2014; De Gioannis et al., 2013).
Incineration is a mature technology applied to reduce waste vol-
umes and produce electrical energy and heat; however, the high
moisture contents of FW limit its application together with the
concerns of local communities on air emissions (Pham et al.,
2015). Anaerobic digestion, on the contrary, is a technology facing
growing interests and large applications (Clarke and Alibardi,
2010; Levis et al., 2010). The high biodegradability and moisture
content of FW are ideal characteristics for biogas production and
digestion residues can be used as soil conditioner or amendment
(digestate) or as nutrient source (e.g. ammonia or struvite).
Biodiesel can be defined as fatty acid alkyl esters (methyl/ethyl
esters) of short-chain alcohols and long-chain fatty acids derived
from natural biological lipid sources such as vegetable oils or ani-
mal fats, which have had their viscosity reduced by means of a pro-
cess known as transesterification, and are suited to use in
conventional diesel engines and distributed through existing fuel
infrastructure. Any fatty acid source may be used to prepare bio-
diesel (Refaat, 2012). Thus, any animal or plant lipid should repre-
sent a ready substrate for the production of biodiesel. However the
use of edible vegetable oils and animal fats for biodiesel production
has traditionally been of high concern due to their competing with
food materials. The use of non-edible vegetable oils in biodiesel
production is likewise questionable, as the production of crops
for fuel implies an inappropriate use of land, water, and energy
resources vital for the production of food for human consumption;
the use of waste oil may therefore represent a more realistic and
effective element for use in the production of biodiesel
(Gasparatos et al., 2011; Timilsina and Shrestha, 2011; Pirozzi
et al., 2012; Refaat, 2012).
The new process technologies developed in recent years have
enabled the production of biodiesel from recycled frying oils,
resulting in a final quality comparable to that obtained with virgin
vegetable oil biodiesel. Canakci (2007) reported that the annual
production of oils, greases and animal fats from restaurants in
the United States could replace more than 5 million litres of diesel
fuel if collected and converted to biodiesel. Waste cooking oil
requires a series of pre-treatment steps to eliminate solid impuri-
ties and reduce free fatty acids and water contents. The
pre-treatment process may include washing, centrifugation, flash
evaporation, and acid esterification. Final ester yield could be up
to 80% (Yaakob et al., 2013). These results are expected to encour-
age the public and private sectors to improve the collection and
recycling of used cooking oil to produce biodiesel.
Waste oils can be co-treated with animal fats from slaughter-
houses and fleshing oils from leather industries to gather cheap
biodiesel feedstock (Alptekin et al., 2014). FW can also be used to
grow microorganisms, microalgae or insects rich in lipids from
which biodiesel can be produced (Ghanavati et al., 2015; Kiran
et al., 2014; Li et al., 2011).
First-generation bioethanol can be derived from renewable
sources of virgin feedstock; typically starch and sugar crops such
as corn, wheat, or sugarcane. Indeed, most of the feedstocks used
in first generation biofuel production are food crops. For this rea-
son, biofuel expansion may compete with food production both
directly (food crops diverted for biofuel production) and indirectly
36 F. Girotto et al./ Waste Management 45 (2015) 32–41
(competition for land and agricultural labour) (Gasparatos et al.,
2011). These barriers can be partly overcome by the utilisation of
lignocellulosic materials for the production of the so-called
second-generation bioethanol. One potential advantage of cellu-
losic ethanol technologies is that they avoid direct competition
for crops used in the food supply chain, as the materials used are
not edible; this option however should be limited to cases in which
an overt sustainable surplus of crops occurs or where crop wastes
and wood wastes are available as feedstock. (Timilsina and
Shrestha, 2011; Pirozzi et al., 2012; Refaat, 2012). Cellulosic etha-
nol has a number of potential benefits over corn grain ethanol,
but although the cost of biomass is low, releasing fermentable sug-
ars from these materials remains challenging.
Bioethanol can be produced from FW and agricultural waste,
the latter being cost-effective, renewable and abundant substrates
(Kiran et al., 2014; Sarkar et al., 2012). Pre-treatments are fre-
quently applied to improve carbohydrate saccharification of
organic substrates, as yeast cells cannot ferment starch or cellulose
directly into bioethanol. Cekmecelioglu and Uncu (2013) demon-
strated the feasibility of lowering ethanol production costs using
kitchen wastes as substrate, and by excluding the fermentation
nutrients traditionally used in fermentation practice.
Pre-treatment prior to enzymatic hydrolysis was not required to
obtain high glucose levels from the kitchen wastes, and the nutri-
ents present provided sufficient nutritive medium for yeast to pro-
duce high ethanol yields (Cekmecelioglu and Uncu, 2013). Kim
et al. (2011) reported ethanol yields from FW rich in carbohydrates
between 0.3 and 0.4 g ethanol per g total solids. Waste fruits may
also represent a substrate for bioethanol production. For example,
banana waste or rotten banana, peels and sub-quality fruits have
been extensively studied as substrates for bioethanol production
(Graefe et al., 2011; Oberoi et al., 2011; Hossain et al., 2011;
Arumugam and Manikandan, 2011; Gonçalves Filho et al., 2013;
Bello et al., 2014).
Butanol is obtained from food waste by fermentation processes
using Clostridium acetobutylicum bacteria. This organism features a
number of unique properties, including the ability to use a variety
of starchy substances and to produce much better yields of acetone
and butanol than those obtained using Fernbach’s original culture
(Stoeberl et al., 2011). Butanol as fuel or blending component has
several advantages compared to ethanol, for example a lower
vapour pressure, improved combustion efficiency, higher energy
density, and it can be dissolved with vegetable oils in any ratio
reducing their viscosity. Results for butanol production indicated
a potential of 0.3 g of butanol from 1 g carbohydrates from waste
whey, a substrate characterised by high lactose content. Whey pro-
duction worldwide, estimated in approximately 160 10
6
Mg/year,
contains about 8 10
6
Mg of carbohydrates that could be con-
verted into 2.4 10
6
Mg solvents or fuels every year (Stoeberl
et al., 2011). Similarly, industrial starchy food waste such as ined-
ible dough, bread and batter liquid represent feasible alternative
substrates for fermentative production of butanol with butanol
yields of approximately 0.3 g butanol per g of FW (Ujor et al.,
2014).
Studies indicate therefore the feasibility of alcohol production
from specific fractions of FW and these technologies could also
contribute to solve the debate on the use of food crops for energetic
purposes. Anyway the overall economic viability still has to be
evaluated and further studies are required to identify optimal con-
ditions for cost minimisation and market development (Pham
et al., 2015).
Anaerobic digestion for biogas production (methane rich gas) is
a well established technology perfectly suited for FW management.
Interest in anaerobic digestion (AD) has been continuously grow-
ing over the last decades, being more and more frequently pro-
moted by national programmes for energy production from
renewable resources (Clarke and Alibardi, 2010). Possibilities for
biogas production from FW were recently reviewed by Kiran
et al. (2014), with Kondusamy and Kalamdhad (2014), Pham
et al. (2015) and Zhang et al. (2015) highlighting the potentials
for renewable energy production from anaerobic treatment of
FW. Anaerobic digestion is a mature technology that can be applied
to almost all types of biodegradable substrates as source separated
organic fraction of municipal solid waste, agricultural or industrial
food waste and food manufacturing residues. The potential of
anaerobic digestion process has also recently been evaluated for
the biological conversion of hydrogen and carbon dioxide of differ-
ent origins into methane for energy storage purposes (Burkhardt
et al., 2015) and as carbon capture strategy during digestion of
FW or sewage sludge (Bajón Fernández et al., 2014). Anaerobic
digestion therefore represents a flexible process that can be used
as final conversion process in a biorefinery chain for all those sub-
strates and residual flows not further convertible to high value
products. AD processes are also considered to be the best option
for the biological production of hydrogen, one of the most interest-
ing and promising biofuels (Guo et al., 2010; Ozkan et al., 2010; De
Gioannis et al., 2013).
Several substrates have been evaluated as potentially suitable
for biohydrogen generation through dark fermentation. Amongst
these, FW may represent relatively inexpensive and ideal sources
of biodegradable organic matter for H
2
production, mainly due to
the high carbohydrate content and wide availability. Dark fermen-
tation of FW can also be combined with other bioprocesses to max-
imise energy conversion (Alibardi et al., 2014; Kiran et al., 2014; De
Gioannis et al., 2013). Dark fermentation process performances are
affected by several aspects as the type and treatment of inoculum,
type of reactor, organic loading rate and hydraulic retention time,
process temperature and pH conditions (Wang and Wan, 2009;
Guo et al., 2010; Nanqi et al., 2011). Different process conditions
and specific aspects of the dark fermentation process have been
analysed, although the results remain controversial, at times lack-
ing direct comparability and at times being divergent or even anti-
thetic (De Gioannis et al., 2013). Cappai et al. (2014) recently
reported an optimal pH of 6.5 for hydrogen production from FW
while at pH of 5.5, commonly assumed as the optimum, minimum
hydrogen productions were recorded. Alibardi and Cossu (2015)
demonstrated how changes in FW waste composition markedly
affect hydrogen potential productions explaining the high variabil-
ity of data reported in literature on FW. Favaro et al. (2013)
reported good capacity of indigenous microflora of FW to produce
biohydrogen. De Gioannis et al. (2014) measured significant fer-
mentative biohydrogen productions from different types of cheese
whey at pH values between 6.5 and 7.5, with the highest produc-
tions up to 170 mlH
2
/kgTOC.
Pyrolysis and gasification are thermal processes viewed as
alternatives to combustion in waste management (Pham et al.,
2015). Pyrolysis of food waste, using temperatures between 400
and 800 °C, converts the material from the solid state into liquid
products (so-called pyrolysis oil) and/or gas (syngas), which can
be used as fuels or raw materials intended to subsequent chemical
processes. The solid carbon residues can be further refined by pro-
viding products such as activated carbon. The products of pyrolysis
are therefore gaseous, liquid and solid and their proportion
depends upon the pyrolysis method and the reaction parameters.
Gasification partially oxidises food waste to produce a com-
bustible gas mixture. Temperatures typically range between 800°
and 900 °C. The gas produced can be burnt directly or used as a fuel
for gas engines and gas turbines or used as a feedstock in the pro-
duction of chemicals (e.g. methanol) (Pham et al., 2015).
Applicability and feasibility of these processes are strongly
dependent on waste characteristics such as elemental composition,
heating values, ash, moisture and volatile solids content, the
F. Girotto et al. / Waste Management 45 (2015) 32–41 37
presence of contaminants, bulk density. These characteristics are
crucial for process performances and limit the applicability of gasi-
fication and pyrolysis to FW. The majority of gasification technolo-
gies for example use pre-treated waste as feedstocks and no
gasification/pyrolysis processes have been developed using raw
food waste (Arena, 2012; Pham et al., 2015). Only few researches
were published on gasification or pyrolysis of food waste. Liu
et al. (2014) investigated the effectiveness of catalytic pyrolysis
of food waste by using microwave power for heating. These
Authors reported an energy ratio of production to consumption
(ERPC) of 0.91 without the use of catalysts. CuCl
2
or MnO
2
were
added as catalysts, ERPC increased to 2.04 and 1.93, respectively.
Bio-char (solid product) was in all cases the main energetic product
of pyrolysis while bio-oil or gases yields were variable being the
conversions into gaseous or liquid products competing processes
(Liu et al., 2014). Opatokun et al. (2015) evaluated the pyrolysis
of both dry raw FW and digested FW after biological anaerobic
treatment and concluded that both substrates demonstrated
potential for fast degradation due to high volatile matter content.
Energy content was for both cases mainly spread into biochar
and bio-oil fractions while gases provided significantly lower
energy.
The impact of pre-treatments and drying processes on overall
energy production is still not clear thus FW water content seems
to remain the limiting characteristic of these processes. Processes
not requiring a drying step are hydrothermal water gasification
or hydrothermal carbonisation as both utilise water as the main
reaction medium and reactant. Hydrothermal (subcritical and
supercritical water) gasification can generate hydrogen gas from
biodegradable wastes. Muangrat et al. (2012) investigated the
effect of carbohydrate, protein and lipid proportions in several
FW samples for hydrogen production by using subcritical water
gasification and reported that carbohydrate-rich samples were
preferred for the reaction conditions applied as protein and lipid
promoted side reactions of neutralisation and saponification,
respectively.
Hydrothermal carbonisation (HTC) is a thermal treatment tech-
nique used to convert food wastes and associated packaging mate-
rials to a valuable, energy-rich resource. HTC is attracting increased
attention from researchers, especially for waste streams with high
moisture content (80–90%) (Pham et al., 2015; Li et al., 2013). HTC
was applied to several organic wastes, at different operating condi-
tions, temperature ranges (200–350 °C) and process duration (0.2–
120 h) (i.a. Pham et al., 2015). Results demonstrated that food
waste could be beneficially treated by HTC resulting in the produc-
tion of hydrochar with high carbon and energy. Lin et al. (2013)
reported positive energy balances on HTC treatment of food waste
collected from local restaurants. The presence of packaging mate-
rials may influence the energy content of the recovered solids.
The higher the presence of packaging materials, the lower the
energy content of recovered solids due to the low energetic reten-
tion associated with the packaging materials (Lin et al., 2013).
3.2. Biomaterials production
The challenge of finite fossil resources has been addressed by
academic and industrial researchers with the development of valu-
able compounds and polymers based on renewable resources
(besides the previously mentioned biofuels). The use of
agro-industrial residues for the extraction of high-value chemicals
was recently reviewed by Mirabella et al. (2014). Biopolymers pro-
duction is a possibility facing growing interest as it is applicable
both to agro-industrial residues and organic waste from household
level. The corresponding monomers are accessible either through
fermentation of carbohydrate feedstocks by microbes, often genet-
ically modified, or by chemical processing of plant oils (Fuessl et al.,
2012). The production of biological metabolites to be used as
renewable and biodegradable substitutes for petrochemical prod-
ucts is currently the focus of growing interest. These metabolites
are: lactate for the production of polylactate, a plastic constituent;
polyhydroxyalkanotes, particularly polyhydroxybutyrate, which
are natural storage polymer of many bacterial species with proper-
ties similar to polyethylene and polypropylene; succinate, a valu-
able and flexible precursor for pharmaceutical, plastic and
detergent production (Hassan et al., 2013; Sulaiman et al., 2014;
Li et al., 2015). As for the biofuel production from virgin feedstocks,
considerable debate surrounds the manufacture of bioplastics from
natural materials, raising the issue as to whether they produce a
negative impact on human food supply. In this context, the oppor-
tunity of using waste food in the production of bio-plastics seems a
highly feasible option.
Bio-production of optically pure
L
-lactic acid from food waste
has attracted considerable interest due to its ability to treat organic
wastes with simultaneous recovery of valuable by-products (Li
et al., 2015). A new strategy was reported for effective production
of optically pure
L
-lactic acid from food waste at ambient temper-
ature, regulating key enzyme activity by sewage sludge supple-
mentation and intermittent alkaline fermentation. A production
of optically pure
L
-lactic acid was achieved from food waste at
ambient temperature with a yield of 0.52 g/gCOD (Li et al., 2015).
Dairy industries generate high amounts of whey from milk pro-
cessing for various manufactured products. Whey is a by-product
discharged by the cheese production process, and its disposal is
currently a major pollution problem for the dairy industry
(Abdel-Rahman et al., 2013). Whey is a potent and suitable raw
material for lactic acid production, consisting in lactose, proteins,
fats, water-soluble vitamins, mineral salts, and other essential
nutrients for microbial growth (Panesar et al., 2007).
Theoretically, 4 mol of lactic acid can be produced from 1 mol of
lactose through a homofermentative pathway following the cleav-
age of lactose to 1 mol of glucose and 1 mol of galactose
(Abdel-Rahman et al., 2013). The market for yogurt has also grown
rapidly over the past few years. Consequently, damaged or expired
yogurts create huge amounts of waste products. Yogurt is usually
sweetened with additional sugars, such as sucrose and glucose,
which would result in higher lactic acid production than cheese
whey containing fewer sugars.
At present, amongst the various types of starch-based
biodegradable plastics such as polylactic acid (PLA) and polyvinyl
acetate (PVA), the group of polyhydroxyalkanoates (PHAs) is one
of the most promising. Polyhydroxyalkanoates (PHAs) are linear
polyesters of hydroxyacids (hydroxyalkanoate monomers) synthe-
sised by a wide variety of bacteria through bacterial fermentation
(Reis et al., 2011). The strength and toughness of PHAs are good,
and they are completely resistant to moisture and feature a very
low oxygen permeability. Accordingly, PHA is suitable for use in
the production of bottles and water resistant film (Van Wegen
et al., 1998). The simplest type of PHA is polyhydroxybutyrate
(PHB). The majority of bacteria synthesising PHAs can be broadly
subdivided into two groups. One group produces
short-chain-length PHAs (SCL-PHAs) with monomers ranging from
3 to 5 carbons in length, while a distinct group synthesises
medium-chain-length PHAs (MCL-PHAs) with monomers from 6
to 16 carbons. PHAs accumulate in bacteria cytoplasm as a high
molecular weight polymer forming intracellular granules of 0.2–
0.7 mm in diameter. Typically, PHAs accumulate to a significant
proportion of the cell dry weight when bacteria are grown in a
media that is limited in a nutrient essential for growth (typically
nitrogen or phosphorus), but with an abundant supply of carbon
(for example glucose). Under these conditions, bacteria convert
the extracellular carbon into an intracellular storage form, namely
PHA. When the limiting nutrient is resupplied, intracellular PHA is
38 F. Girotto et al./ Waste Management 45 (2015) 32–41
degraded and the resulting carbon is used for growth (Reis et al.,
2011).
The main limitation in using bacterial PHAs as a source of
biodegradable polymers is their production cost. In particular the
average cost is by far the most significant contributor to overall
PHB price, approximately two and a quarter times greater than
the capital cost of equipment (Van Wegen et al., 1998). Using
agro-industrial food waste as substrate instead of virgin feedstock
of refined sugar such as glucose, sucrose and corn steep liquor
could represent a turning point. Sugarcane and beet molasses,
cheese whey effluents, plant oils, swine waste liquor, vegetable
and fruit wastes, effluents of palm oil mill, olive oil mill, paper mill,
pull mill and hydrolysates of starch (e.g., corn and tapioca), cellu-
lose and hemicellulose are all excellent alternatives characterised
by a high organic fraction (Reis et al., 2011).
A three-stage biotechnological process proposed by Reis et al.
(2011) demonstrated good potential for PHA production from
waste/surplus-based feedstocks using enriched mixed cultures.
The basic concept was based on an initial acidogenic fermentation
phase of the feedstock, a second phase of selection and production
of PHA-storing bacterial biomass under dynamic feeding, and the
last phase in which PHA was accumulated in batch conditions. It
is important to underline the main role played by the initial acido-
genic fermentation stage needed to overcome the weak point of
the process represented by the fact that most waste and surplus
feedstocks contain several organic compounds that are not equally
suitable for PHA production. Carbohydrates in fact are not stored
by mixed cultures as PHA, but rather as glycogen. Thus, acidogenic
fermentation is an essential stage to increase the potential of pro-
ducing PHA by mixed cultures from surplus-based feedstocks.
Carbohydrates and other compounds are, in this way, transformed
into VFA that are readily convertible into PHA (Reis et al., 2011).
As assessed by Koller et al. (2013), PHAs and their follow-up
products can be processed to create a broad range of marketable
products for a variety of applications. They have potential in
agro-industrial applications (carriers and matrices for controlled
release of nutrients, fertilisers and pesticides), therapeutic applica-
tions (controlled release of active pharmaceutical ingredients), in
buildings blocks, in packaging materials and surgical implants.
Naranjo et al. (2014) investigated the integrated production of
PHB and ethanol from banana residues as agro-industrial waste.
PHB production was carried out using the glucose obtained in
the hydrolysis stage from banana pulp, while peels were exploited
for ethanol production. The theoretical yields of PHB and ethanol
were 31.5 and 238 kg/ton bananas, respectively. Other food waste
used for PHA production were fruit pomace and waste frying oil
(Follonier et al., 2014), spent coffee grounds (Obruca et al., 2014),
distillery spent wash (Amulya et al., 2014), and margarine waste
(Morais et al., 2014). Zhang et al. (2014) evaluated how PHA com-
position is influenced by ratio of even-numbered to odd-numbered
VFAs from co-treatment of food waste and sewage sludge. The con-
sumption of even-numbered VFAs was correlated with the PHB
synthesis, while the consumption of odd-numbered VFAs was cor-
related with the synthesis of polyhydroxyvalerate (PHV). The rela-
tively constant quality and fermentable sugar content characterise
food waste as an ideal substrate for PHAs production.
As already highlighted for dark fermentation, interconnections
of biotechnological processes for the co-production of bio-fuels
and bio-products therefore represent a key strategy in maximising
food waste utilisation and potential income of the entire biopro-
cess chain (Venkateswar Reddy et al., 2014). Lin (2012) demon-
strated for example that microalgae can grow on pure food waste
hydrolysate without any negative effects on growth or biomass
composition. The outcomes open up for an economically feasible
cultivation of heterotrophic microalgae based on mixed food waste
hydrolysate and a use of microalgal biomass for a production of
biofuels and platform chemicals. In this way it would be possible
to weave a complex and elaborate scheme leading at maximising
the yield within the FW biorefinery concept.
4. Conclusions
The development of sustainable solutions for food waste man-
agement represents one of the main challenges for society. These
solutions should be capable of exploiting the precious resources
represented by food waste to achieve social, economical and envi-
ronmental benefits. The development of sustainable solutions for
food waste management represents one of the main challenges
for society. These solutions should be capable of exploiting the pre-
cious resources represented by food waste to achieve social, eco-
nomical and environmental benefits. Clear and generally
accepted definitions of food waste and related terms are anyway
still missing and estimations on generated amounts are not yet
consolidated. Avoidance of food waste generation could be ideally
obtained by a proper equilibrium between food production and
consumption, but such an optimum arranging is still far from being
attained. A feasible management of excess production of edible
food consists in its redistribution to feed poor people. The practice
of food donation needs to find support from governments to facil-
itate the recovery and redistribution by food banks or social ser-
vices. Agro-industrial residues and household food waste no
longer suitable for human consumption can be used as feedstocks
for the production of bio-plastics and bio-fuels together with the
extraction of high-value components. This requires active partici-
pation from the public as well, in order to end up with a properly
segregated FW to be transformed into resource. Practical and con-
venient solutions hand in hand with proper information campaigns
targeted accordingly the area of interest need to be designed.
Similar to the production of biofuel from virgin feedstocks, consid-
erable debate surrounds the manufacture of bioplastics from natu-
ral materials, raising the issue as to whether they produce a
negative impact on human food supply. In this context, the oppor-
tunity of using food waste as a feedstock in the production of
bio-fuels and bio-plastics seems a feasible option. To conclude
therefore, the interconnection of biotechnological processes in
the co-production of bio-fuels and bio-products represents a key
strategy aimed at maximising the utilisation of food waste and
raising the potential income of the entire bioprocess chain.
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... El primer grupo se centra en la "gestión" de los residuos sólidos mediante estrategias de reciclaje, compostaje o digestión anaeróbica (ver. p. ej., Girotto et al., 2015;Morales-Polo et al., 2018), aquí cobra gran importancia la economía circular (ver. p. ej., Do et al., 2021). ...
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