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P2 PRESENTATION
N Dip in Chemical Engineering
Program : Work integrated learning
Company : SI Group
07 January 2015 to 07 January 2016

INTRODUCTION
 Most industries discard water that is harmful to the
environment into municipal storm drainage. Chemical
industry is one of the most industry which produces
contaminated water into the drainage, more
especially manufacturing and mineral processing
company.
 Most petroleum refineries, chemical and
petrochemical plants have onsite facilities to treat
their wastewaters so that the pollutant concentrations
in the treated wastewater comply with the local and/
or national regulations regarding disposal of
wastewaters into community treatment plants or into
rivers, lakes or oceans.

INTRODUCTION CONTINUES….
 Effluent treatment is a process of converting water
that is no longer needed or suitable for its most
recent use into an effluent that can be either returned
to the water cycle with minimal environmental issues
or reused.
 Treatment means removing impurities from water
being treated. Although disposal or reuse which
occurs after treatment must be considered first by the
laboratory.
 Acceptable impurities concentrations may vary with
the type of use or location of disposal. The local and
/or national regulation regarding wastewater disposal
have their own standards / specification (impurity
concentration tolerance).

INTRODUCTION CONTINUES….
 The effluent sample is the one after
treatment which does not necessarily means
it is pure still water ready to drink but it
simply means it is on spec. It can either be
reused or disposed to the lake , oceans or
community treatment plant for further
treatment.
 The influent sample is the one before
treatment which is rich in impurities.

DISCUSSION
o Impurities varies with industries. Petroleum
refineries has its own impurities so is
chemical plants and resin plants.
o As a result, a treatment done in each
industry will also vary since they are not
removing the same impurities.
o There are common impurities like COD
(chemical oxygen demand) ,pH (how acidic
or basic is your liquid) and few others.

DISCUSSION CONTINUES….
o The focus in this presentation will be on the following:-
1. COD
2. Phenol content
3. Ph
Chemical oxygen demand
• The COD test is commonly used to indirectly measure the
amount of organic compounds in water. It expresses the amount
of oxygen originating from potassium dichromate that reacts with
the oxidizable substances contained in 1𝑙 of water under the
conditions of the specified procedure.
• I mol K2Cr2O7 is equivalent to 1.5 mol O2

CHEMICAL OXYGEN DEMAND
 The measuring range for COD which comply with the local and /
or national regulations regarding disposal of wastewater is
between 500 -10 000mg/𝑙 of COD.
 There are number of substances which affect the COD results.
The table above shows the influence of foreign substance to the
COD.
Concentrations of foreign substances in mg/l or %
Cl- 5000 SO3
2- 10 H2O2 650
Cr3+ 25 NaNO3 10%
CrO4
2- 50 Na2SO4 10%
NO2
- 25 Na3PO4 10%

CHEMICAL OXYGEN DEMAND CONTINUE…
 This was checked in a solution with a COD of 5000mg/l, it was found that some
of the factors affecting COD was this foreign substances.
 Should your sample have a concentration of this foreign substances higher than
the given ones on the table above, your COD will be higher than 5000mg/l and
the opposite is always true.
 The table above shows the tolerance of concentration of foreign substances in
your water.
 Oxidation reduces the biochemical oxygen demand of wastewater, and may
reduce the toxicity of some impurities.
 Secondary treatment converts some of the impurities to carbon dioxide, water,
and bio-solids, which is why chemical oxidation is widely used for disinfection.
 COD reduction is one of the most common challenges faced by most industry
that needs to comply with local and/ or national regulation of the country. If it is
not properly addressed, it may result in non-compliance fine.

PHENOL CONTENT
 Phenol content is the amount of phenol in the effluent. The
acceptable amount of phenol in water that can be disposed
to the municipal drainage is on a range of 0.10 -2.50mg/l
phenol.
 Since SI Group (Schenectady International Group) is the
world’s leading developer and manufacturer of chemical
intermediates, phenolic resins, alkyl phenolic resins, and
alkylated phenols, most if its products are made out of
phenol.
 Therefore it is expected that the amount of phenol in
wastewater to be high. There are also some factors affecting
phenol content like foreign substances just like with the
COD.
 The table below display the influence of foreign substances,
which was checked in solutions containing 2 and 0 mg/l
phenol.

PHENOL CONTENT
 Any of the above substance’s concentration plays a part in phenol
content in wastewater. Just like with the COD, should the
concentration be slightly higher your phenol content will be off
spec.
 The reduction of phenol is not an easy thing to do, especially with
all this foreign substances involve. One would recommend a
vacuum distil but that might require a large amount of energy
since the boiling point of the mixture/ solutions a bit high.
Concentrations of foreign substances in mg/l or %
Al3+ 50 Fe3+ 25 PO4
3- 500 Free chlorine 1.5
Ca2+ 500 Hg2+ 500 S2- 0.5 EDTA 1%
Cd2+ 500 Mg2+ 500 SiO3
2- 500 Surfactants 0.1%
CN- 500 Mn2+ 500 S2O3
2- 0.5 NaCl 20%
Cr3+ 500 NH4
+ 500 ZN2+ 500 NaNO3 20%
Cr2O7
2- 50 Ni2+ 500 Na2B4O7 2%
Cu2+ 5 NO2
- 5 Na2SO4 15%

PH
 PH is basically a test of how acidic or basic your
liquid is.
 Nothing complex about it, all you do is to have
your sample cooled to room temperature and
put an electrode into your sample and get your
results.
 The acceptable PH by the national regulation of
the country ranges between 6 -10.
 Any Ph between these ranges is acceptable, but
it is preferred to discharge wastewater that is at
least neutral of 7.

PROCESS DESCRIPTION
 Large amount of water is used during manufacturing of products
but after each process cleaning or rinsing of reactors and other
equipment's is requires, therefore effluent is system is created.
 Most industries has now adopted a zero effluent system where by
all their contaminated water is recycled back to the process for its
recent use.
 In most companies that might be a challenge since the
substances inside is unknown and that might affect the quality of
the product.
 Determining all the substances involve might be costly and very
complex.
 All water used around the chemical plant is directed and
connected to the pipeline linked to the effluent farm.
 The water could be from cleaning the reactors, condensers,
vacuum cooling systems or even scrubbing of floor which could
be containing chemical must all flow to the effluent.

PROCESS DESCRIPTION CONTINUES…
Stage
1
Stage 2 Stage 3 Treatment
Storage
 The effluent is divided into 4 sections.
 Water will flow into the first section where the solids will settle and
liquid will overflow into the second section and some of the solids
that did not settle from the previous settle will settle then.
 Second section will also be full of water and over flow to the third
section and be pumped into the vessel where the treatment will
be taking place.
 The treated water will be transferred to the last section where it is
ready to be discharge or disposed to the municipal wastewater
treatment for further treatment with low impurities and less
harmful.

PROCESS DESCRIPTION CONTINUES…
 There are no operating conditions, the only variable that must be
controlled is the Ph.
 Low ph is preferred for a better settling rate of solids. You must
wear a minimum standard PPE at all time since you are working
with dangerous chemical like hydrogen peroxide and sulphuric
acid.

RECOMMENDATION
 One can recommend that a sample must be
taken to the laboratory twice a week for at least
a year to check the impurities and all this foreign
substances.
 If the plant produces the same products for a
year, the effluent will contain the same
impurities.
 The water can be reused once all substances
inside are determined. E.g, if phenol content in
an effluent is 0.5%, that means on your next
batch you must charge 99.5% of it and 100.5%
of water, the same apply with the rest of
substances.

RECOMMENDATION CONTINUES…
 If not reused on batches, it can be treated to
reduce toxicity and corrosiveness.
 Once the treatment is achieved, it can be used
on the cooling system since it will be less
corrosive.
 If not through cooling towers, it can be used on
vacuum pump cooling system Or the minimum
treatment required to meet the levels of the
government can be done and be discharged.
 This can first be first be tried on a pilot plant and
check how affected is the quality of the product
compared when using fresh clean water.

 One can also recommend decomposition of
phenol.
 Combustion of phenol is another way, however,
for compounds containing benzene rings,
combustion is hardly ever complete, especially if
they are burnt in air.
 The high proportion of carbon in phenol means
that you need a very high proportion of oxygen
to phenol to get complete combustion
 C6H5OH+7O2→6CO2+3H2O

• Sometimes it is necessary to modify the phenol first to make the reaction
faster.
• For example, benzoyl chloride has the formula C6H5COCl. The -COCl
group is attached directly to a benzene ring.
• It is much less reactive than simple acyl chlorides like ethanoyl chloride.
• In order to get a reasonably quick reaction with benzoyl chloride, the
phenol is first converted into sodium phenoxide by dissolving it in
sodium hydroxide solution.
• The phenoxide ion reacts more rapidly with benzoyl chloride than the
original phenol does. Solid phenyl benzoate is formed.

CONCLUSION
 Effluent is an outflow of water from the man made structure which
flow into municipal drainage, lake, ocean or an open land.
 It must meet the standard level of the government before it can
be discharged, that’s were treatment comes in.
 Most petroleum refineries, chemical and petrochemical plants
have onsite facilities to treat their wastewaters so that the
pollutant concentrations in the treated wastewater comply with
the local and/ or national regulations regarding disposal of
wastewaters into community treatment plants or into rivers, lakes,
or oceans.
 The acceptable PH by the national regulation of the country
ranges between 6 -10. Any Ph between these ranges is
acceptable, but it is preferred to discharge wastewater that is at
least neutral of 7.

ACKNOWLEDGEMENT
I would like to acknowledge my supervisors
and my mentor together with my colleagues
from different departments that I have been
through, more especially Mr Nirushann Reddy
for guiding me every step of the way.
I would also like to acknowledge the company
for the opportunity to do my in-service training.

REFERENCES
1. http://www.industrialtreatment.co.za
2. http://www.wastewater.gov.za
3. http://www.cod.co.za
4. http://www.pwm.co.za
5. http://www.effluent.co.za
6. http://www.effluenttreatment.com

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