Industrial Wastewater Characteristics
Industrial wastewater is a type of wastewater produced by
industrial activity, such as that of factories, mills and mines.
It is characterized by its large volume, high temperature, high
concentration of biodegradable organic matter and suspended
solids, high alkalinity or acidity, and by variations of flow.
The degree of treatment varies according to the means of
disposal, which may be to a municipal sewer system, a receiving
body of water, such as a stream, an estuary, or a large body of
fresh water, or recovery for reuse.
Used to develop method for the treatment of
Improving the design and operation of
biomechanical treatment system used for
degradation of toxic compounds.
Improvement of public health, sanitation, soil
integrity and the conservation of fresh water
How to accomplish waste
used to destroy
3 stages of treatment.
This is only a physical separation to remove solid matter.
Effluent is allowed to settle for a few hours.
The organic and nutrient load is decreased by microbial
Up to 95% so that the effluent is of a quality
to be able to go into rivers.
This is a complete treatment, but it is very expensive
and not used much.
Can be divided into
2. Aerobic treatment processes
Complex series of digestive and fermentative reactions by a
mixture of bacteria. It can remove 95% BOD.
This is the choice if there is a lot of insoluble matter
cellulose, industrial waste.
Degradation is carriead out in large tanks – sludge digestors or bioreactors.
Molecular components are digested and fermented to FA, H 2, CO2.
FA then to acetate, CO2 and H2.
These are substrates for methanogenic bacteria to make methane.
Major products are methane and CO2. Used or burnt off.
There are several kinds of aerobic decomposition processes.
Trickling filter and activated sludge are the most common.
Trickling filter is a bed of crushed rock, ~2m thick.
Wastewater is sprayed on the top (UWI plant).
Liquid slowly passes through the rock, organic matter absorbs to
the rock and microbial growth takes place.
Complete mineralization of organic matter takes place.
Most common is activated sludge.
Wastewater is mixed and aerated in a large tank
Bioremediation is the use of micro-organism metabolism to
remove pollutants. Technologies can be generally classified
as in situ or ex situ. In situ bioremediation involves treating
the contaminated material at the site, while ex situ involves
the removal of the contaminated material to be treated
Bioreactors technologically are the most sophisticated category of
Bioreactors offer a much faster means of waste biodegradation than
land treatment and more control over reaction conditions and effluent
quality than simple biofilters.
Biological Treatment Process
1. The microorganisms are used to convert the organic matter (colloidal and
dissolved) into various gases and into cell tissue.
2. The contaminant of organic substances is ingested and
digested as food along with other energy source by the cell.
GOAL: Degrade organic substances that are hazardous to living organisms and
convert the organic contaminants into inert products.
Microorganisms eat organic contaminant
Microorganisms digest and convert
waste to CO2 and H2O
Microorganisms give off CO2 and H2O
Factors Influencing Bioremediation
For bioremediation of harmful chemicals following factors
are required to be monitored in the effluent:
Dissolved oxygen concentration
These conditions allow microbes to grow and multiply—and eat more
chemicals. When conditions are not right, microbes grow too slowly or die or
they can create more harmful chemicals.
Microbial activity in activated sludge.
Slime forming bacteria like Zoogloea grow and form flocs.
Small animals and protozoa attach to these.
Process of oxidation is similar to the trickling bed.
Effluent containing flocs goes to settling tanks. Flocs settle.
Some floc material is recirculated.
Water spends 5-10 hours in sludge tank, too short for complete oxidation.
Main process is absorption of organic matter to the floc.
BOD of liq waste is reduced by ~95%.
Most BOD is in the flocs. BOD reduction then takes place
by digestion of the flocs in the sludge digestor.
Oxidation ponds or lagoons.
This is very simple treatment used in rural areas, particularly suited for tropical
areas (Portmore sewage treatment Plant).
Take up a large area, are less than 3m deep (allow light to penetrate).
There are odour problems and the process can take over a week.
Three components are essential for the functioning of the oxidation pond. They
Oxidation ponds or lagoons.
The bacteria in the pond oxidise the various organic material producing
carbondioxide, ammonia and water.
The algae grow by utilizing the inorganic material and carbon
dioxide in the presence of sunlight.
The oxygen requirement for oxidation of the organic matter by
bacteria is satisfied mainly by oxygen released by the algae. Also some
oxygen is provided by the contact with the atmosphere. Sunlight is an
important factor in the functioning of the oxidation pond
Anaerobic treatment has advantages over aerobic.
Reduction of excess sludge production up to 90%
Production of energy in the form of methane gas
No or very little use of chemicals
Lower treatment costs
High flexibility, since it can be applied to very different types of
effluents (higher and lower loading rates, mesophilic or thermophilic
conditions, more or less complex wastewaters, etc.)
Anaerobic organisms can be preserved unfed for a long time, which
makes it possible to treat wastewaters that are generated with longer
(seasonal production) or shorter (holidays and weekends) pauses in
Bioremediation continues to be the favored approach for processing
Bioremediation utilizes microbes such as bacteria, fungi, yeast, algae, and
Three categories of bioremediation techniques have been identified: in
situ land treatment (treatment of contaminated material on site),
biofiltration, and bioreactors.
Bioremediation is highly efficient system, if proper conditions are
maintained example pH, temperature, nutrients.
Bioremediation is cost-efficient and helps chemical and physical methods
of managing wastes and environmental pollutants.