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