Waste Management for Food &
Agriculture IndustryCleaner Production for Food industries
Thilina Gunawardhana
Dept. of Chemical & Process Engineering
University of Moratuwa
Cleaner Production
In simple terms, it is management of the
process effectively so that you minimize
the waste generated, and manage the
waste efficiently, by recycling, reusing or
converting it to more useable option such
as energy or value added products.
Waste management in food industries is
massively important to sustain the growth
and economize the production.
Environmental Challenges Faced by
the Food Industry Water availability
Wastewater discharge
Air emissions
By-product disposal
Utilization
Chemical residues
Solid waste disposal
Food packaging materials
Life Cycle Analysis (LCA)
The first step of waste management is to
analysis the process and critically observe
what happens to the material flow and
waste generation.
Life Cycle Analysis (LCA) can be used in
this scenario.
LCA on Beer Production Facility -
Example Raw material acquisition
Beer production
Bottle production
Packaging and bottling
Transportation/storage/distribution
Waste Management Strategies
Different waste management strategies have
been proposed by different environmental
legislations and policies.
The EU approach to waste management as
follows,
◦ Waste prevention by improving product design
◦ Recycling and re-use including packaging waste,
end-of-life vehicles, batteries, electrical and
electronic waste
◦ Improving final disposal and monitoring.
Waste Management Strategies
The other policies also adhere to a very
similar methodology.
They all can be summarized as below.
◦ Prevention
◦ Recycle
◦ Reuse
◦ Efficient Discharge
Food & Agricultural Waste
Management Dairy industry
Fermentation industry
◦ Brewery waste
◦ Winery waste
◦ Distillery waste
Beverage industry
Fruit and vegetable industry
Meat and poultry
Agricultural waste
Food Waste Treatment Methods
Unlike other wastes, food industry wastes are very much difficult to handle and treat.
It contains a lot of nutrients and favorable conditions especially for microorganisms, making it much susceptible for spoilage which could generate foul odor.
Some of the treatment methods which are used in food waste handling are listed in the next slides.
Food Waste Treatment Methods
Bioremediation,
Anaerobic digestion,
Aerobic digestion,
Thermophilic anaerobic digestion,
Sequencing batch reactor,
Electrodialysis, wet oxidation,
Pyrolysis,
Incineration,
Solid state fermentation
Ozonation
Bioremediation
Bioremediation technologies can be
classified as in-situ or ex-situ.
In-situ bioremediation treats the
contaminated water or soil where it was
found, whereas ex-situ bioremediation
processes involve removing the
contaminated soil or water to another
location prior to treatment
Ex-situ bioremediation
Slurry-phase bioremediation
◦ Contaminated soil is blended with water and other additives in a large tank to keep the microorganisms – which are already present in the soil – in contact with the soil contaminants.
◦ Nutrients and oxygen are added and conditions in the bioreactor are controlled to create the optimum environment for the microorganisms to degrade the contaminants.
◦ Bioreactors are used for this purpose.
Ex-situ bioremediation (Solid-phase
bioremediation) Landfarming
◦ Contaminated sludge, soils or sediments are
spread on fields and cultivated in the same
way as a farmer might plough and fertilize
agricultural land.
◦ The soil is periodically turned over to mix air
into the waste
Ex-situ bioremediation (Solid-phase
bioremediation) Composting
◦ Aerated static pile composting
Compost is formed into piles and aerated with blowers or vacuum pumps
◦ Mechanically agitated in-vessel composting
Compost is placed in a reactor vessel where it is mixed and aerated
◦ Windrow composting
Compost is placed in long piles known as windrows and periodically mixed with means of mobile equipment
Ex-situ bioremediation (Solid-phase
bioremediation) Biopiles
◦ Biopiles are a hybrid of landfarming and composting.
◦ Biopiles are similar to landfarms because they are both above-ground engineered systems consuming oxygen, generally from air, to stimulate the growth and reproduction of aerobic bacteria which, in turn, degrade the pollutants adsorbed to soil.
◦ While landfarms are aerated by tilling or plowing, biopiles are aerated most often by forcing air to move by injection or extraction through slotted or perforated piping placed throughout the pile
In-situ bioremediation
Bioaugmentation
◦ The addition of organisms or enzymes to a
material in order to remove any undesirable
chemicals.
Bioventing
◦ In the ‘in-situ’ process, air is injected into
contaminated soil at an optimal rate,
increasing soil O2concentration and thereby
stimulating the growth of indigenous aerobic
bacteria.
In-situ bioremediation
Biosparging
◦ Biosparging is used for treatment of
groundwater contaminations.
◦ It involves the injection of air under pressure
below the water table to increase
groundwater oxygen concentrations and
enhance the rate of biological degradation of
contaminants by naturally occurring bacteria.
Thermal processes
Incineration
◦ During the process, the waste is fed into the incinerator’s combustion chamber where conversion of solids and liquids into gases occurs at 870–1200°C.
◦ The following types of incinerations are used in the industry.
Circulating bed combustor
Fluidized bed
Infrared combustion
Rotary kilns
Thermal processes
Pyrolysis
◦ Pyrolysis transforms hazardous organic materials into gaseous components, small quantities of liquid and a solid residue (coke) containing fixed carbon and ash.
◦ Pyrolysis of organic materials produces combustible gases, including carbon monoxide, hydrogen and methane and other hydrocarbons.
◦ The typical types of pyrolysis units are,
Rotary kiln
Fluidized bed furnace
Molten salt destruction
Thermal processes
Gasification
◦ The gasification products are synthetic gas (called syngas, consisting mainly of carbon monoxide and hydrogen 85%, with smaller amounts of carbon dioxide and methane), other by-products including liquids and solid residues – ash, or char
◦ The types of gasifiers in the industry are,
Entrained flow gasifiers
Fluidized bed gasifiers
Fixed bed gasifiers
Other Thermal Processes
Briquetting
Activated carbon
Evaporation
Evaporation is the vaporization of a liquid
from a solution or slurry and is applicable
to liquids, slurries and sludges.
After the liquid portion of the waste is
evaporated, the waste volume is
considerably reduced.
◦ Vaporization
◦ Concentration
◦ Crystallization
Membrane Processes
Membrane processing is a technique allowing for concentration and separation without resorting to thermal processes.
Particles are separated on the basis of their molecular size and shape with the use of pressure and specially designed semi-permeable membranes◦ Reverse osmosis (RO)
◦ Ultrafiltration (UF)
◦ Nanofiltration (NF)
◦ Microfiltration (MF)
◦ Gas separation (GS)
◦ Electrodialysis (ED)
◦ Pervaporation (PV)
Ozonation
Ozone (O3) is one of the strongest
oxidizing agents that is readily available.
It is used to reduce color intensity, to
eliminate organic waste, to reduce odor
and reduce total organic carbon in water
Anaerobic Digestion
Mesophilic digestion
◦ Mesophilic digestion is the most commonly
used process for anaerobic digestion, in
particular waste sludge treatment.
◦ The digester is heated to 30–35°C and the
feedstock usually remains in the digester for
15–30 days.
◦ Gas production is less, larger digestion tanks
are required
Anaerobic Digestion
Thermophilic digestion
◦ Thermophilic digestion is less common and not as ‘mature’ a technology as mesophilic digestion.
◦ The digester is heated to 55°C and residence time is typically 12–14 days.
◦ Thermophilic systems result in higher methane production, faster throughput and better pathogen and virus ‘kill’,
◦ But they require more expensive technology, greater energy input and a higher degree of operation and monitoring
Aerobic Digestion – Advantages
over Anaerobic Digestion Volatile solids reduction is approximately
equal to that obtained anaerobically
Lower BOD concentrations in supernatant liquor
Production of an odorless, humus-like, biologically stable end product
Recovery of more of the basic fertilizer values in the sludge
Operation is relatively easy
Lower capital cost
Aerobic Digestion – Disadvantages
over Anaerobic Digestion A high power cost is associated with
supplying the required oxygen
A digested sludge is produced with poor
mechanical dewatering characteristics
The process is affected significantly by
temperature, location and type of tank
material.
A useful by-product such as methane is
not recovered
Types of Digesters
Covered lagoon
◦ Covered lagoon digesters are the simplest
anaerobic digester system.
◦ These systems typically consist of an
anaerobic combined storage and treatment
lagoon, an anaerobic lagoon cover, an
evaporation pond for the digester effluent and
a gas treatment and/or energy conversion
system.
Types of Digesters
Complete mix digesters
◦ The complete mix digester is a large, vertical
poured concrete or steel circular container
◦ Nowadays, complete mix digester can treat
organic wastes with total solid concentration
of 3 to 10%.
◦ Complete mix digesters can be operated at
either the mesophilic or thermophilic
temperature
Types of Digesters
Plug flow digesters
◦ Plug flow digesters are normally used where wastes are collected as solids (solids greater than 11%). Plug flow digesters are large tanks (often built into the ground) with an impermeable plastic cover.
◦ Although the contents are usually heated, they are not mixed because they move through the digester as a combined mass or a ‘plug’.
◦ Plug flow digesters have been used mostly with scraped dairy wastes, but a few were also applied to swine wastes
Other Methods
Ultrasound irradiation
Solid-state fermentation
By-Products from Food Waste
Bioenergy
◦ Bioethanol
◦ Biogas
◦ Biodiesel
Fertilizer
Animal feed/dietary supplements
Flavanols
Other chemicals
Combustible gases through gasification
Biodegradable polymers