1) Small and medium scale industries in India face challenges in complying with pollution control regulations due to lack of finances to invest in proper pollution control equipment. 2) Industries are classified as red, orange or green based on pollution levels, with some small industries unfortunately falling into the higher pollution red and orange categories. 3) Proper planning of industrial development needs to take pollution levels into account, considering factors like local meteorological conditions and the pollution handling capacity of local water systems.

1. POLLUTION CONTROL IN SMALL AND MEDIUM SCALE INDUSTRIES
P.S. PANESAR
As per the new policy document the industrial development in
future in all sectors has to be planned in such a way that it is
environmentally sustainable. The existing industry has to comply
with the requirement of the pollution control regulation with in
a time bound programme.
Industries have been classified into red orange or green
depending upon the pollution created by them. Unfortunately, some
of the small scale industries have fallen into red and orange
catagories where control of pollutants to the desired level is a
must. Small scale-industry have peculiar problems of their own.
Individually they hardly have sufficient finances to provide for
MINAS. The actual value of the pollutant may be high on ppm
basis but the total load is at times hardly enough to warrant for
a serious consideration. • The ecology minded citizen today is
very prompt in sending a letter to member secretary about the
inconvinience caused to him. He has every right to do so. But
unfortunately no pollution/~board has man power to deal with allc
such industries. Therefore, some sort of planning strategy has
to be adopted right at the planning state itself so that the
pollutants are kept well with in limits.
POLLUTANTS EMITTED:
Despite the diversified processes that are employed for the
manufacture of chemicals and allied products, the pollutants fall
broadly in a narrow range of selected chemicals species. These
are sulfur dioxide, carbon monoxides, hydrogen sulfide, oxides of
nitrogen, halides, mercaptant and particulate matter. However,
the emission of these pollutants varies considerably with the
process technology and the control equipments used by the
industry.
Most of the state pollution control boards have laid down the
limits of pollutants in water and air. These values can be
obtained on request from the respective pollution control
boards. These limits have to be complied by all sectors of
industries. Unfortunately the punishment for violation by
marginal amount or by heavy amount is
(Contd... 2/-)

2. 2
the same (closure of industry/non bailable warrents of
management). The small and medium scale industry contribute
substantially to the national development and hence they have to
be quided to incorporate pollution control measures within their
available means. The small scale enterpreneurs have to be
exposed to the various parameters required for pollution control.
METEOROLOGICAL DATA:
How the local wind velocity varies with time each season decides
the dispersion of pollutants in the air. Knowledge of
meteorological data is therefore essential before planning an
industry at a given site. According 'to the meteorological
analysis of the weather data for 1965-69 it is found the
pollutability on the eastern coast and southern part of India is
one of the lowest. It is only during the winter months when
'inversion' takes place,the acute problem due to stagnation
occurs.
It is reported by researchers in the India Meteorological
Department at Poona, that the frequency of ground inversion over
India, south of latitude 18° N is very low as compared to nothern
stations. The most frequent thickness of ground inversion is the
range of 201-500 metres. The result of acute inversion with high
lapse rates, is the formation of stable layers.
The purpose of presenting the above data is to provide a
scientific basis to assess the effect of meteorological factors
in retaining pollutants at ground level in the different parts of
India. With the help of other meteorological factors one can
arrive at the pollutability of various areas and assign the type
of industries that can be located in such areas. As a general
rule, the gases leaving the plant stack should be with such
velocity that stack height plus plume rise exceeds 200 to 500
metres based on local conditions.
It is important to note here the above observations are of
general nature only and for each sit6 there must be a study of
micrometeorological conditions in order to determine the effect
of emissions from the proposed plants to be located in that area.
So far there are no data available on national basis for the
levels of the pollutants at the probable sites for industrial
units. However, sufficient meteorological data are available for
most of the industrial cities in India to enable a prima facie,
analysis of suitability from the environmental view point
Pollutability zones of the country based on inversion and stable
layer data are given in Fig 1. It is desired that the appropriate
(Contd.... 10/-)

3. authorities should find out level of various pollutants in each
zone and each board in these areas should specify their own
limits.
STATUTORY STEPS TAKEN BY THE'INDUSTRY,
QUASI GOVERNMENT AND CENTRAL GOVERNMNTS
It is heartening to note that the industry in India is
progressive in adopting the latest technologies that are
available to combat pollution hazards. The Indian Chemical
Manufacturers Association has created a special cell for this
aspect of industrial growth in the country and has recently taken
steps to enlighten and educate its memebers in order to take
preventive steps.
The B.I.S. has "undertaken the colossal task of setting the
emission limits for chemical, metallurgical and allied industries
for over last few years. Standards have been finalized and
formulated by B.T.S.shall form the basis for the air pollution and
water pollution limits which will be applicable in each state.
At government level, central as well as state, it is encouraging
to note that awareness of controlling air pollution exists at all
levels. It is also important to mention here that a pragmatic
approach by the authorities concerned has been noticed in the
various industrial projects that have been coming up in the
recent past. Nevertheless, in order to avoid any unreasenable
stand taken up by the State or central authorities on this
account, attempt has been made by the industry to furnish
maximum available information on this subject.
LOCATION SELECTION OF INDUSTRY -INDICATING A PROJECTION ON
POLLUTION LEVEL, METEOROLOGICAL FACTORS, REGIONAL NEEDS:
Small scale industry is bound to experience rapid growth in near
future if the government policy continues to encourage.
With the factors in favour of continued rapid growth the planners
must take into cognisance the air and water pollution aspect with
the industrialisation. The zones marked in Fig. 1 clearly
indicate that nothern India especially near Delhi-Mathura has
stable layers persising beyond 24 hours for major part of the
year. Stringent emission control measures for chemical units in
this zone are required.
The zone covering part of Gujarat, M.P. and U.P. is next area
prone to persisting stable layers, especially during winter. The
industries in this zone must be equipped with techniques of air
pollution control.
(Contd... 4/-)

4. 4
Then comes the zone where pollutability is moderate and diurnal
changes of air can disperse the pollutants. Part of this zone
is highly industrialized due to other economic factors and hence
existing levels of pollutants must be taken into consideration
before selecting the site..
The zone south of the latitude 18° N is having lesser frequency
of stable layers.
The regional needs arise out of a site which infrastructure-wise
is best suited but is either a highly fertile area or near
populated city or topographically poor site from pollution point
of view.
Similarly one will have to study the pollutability of the waste
water receiving system. Unfortunately no models are available to
predict the level of pollution acceptable by the Indian rivers.
All hopes are pinned on the success of Ganga Action type plans.
A MR POLLUTION CONTROL
The waste gases are usually emitted continuously from a process,
but there are situations .which require disposal of waste gases
which are produced intermittently. It is normally not practical
to store these gases prior to treatment. Waste gas storage
would often require compression and compression to high pressure
is often expensive and undesirable. Therefore, the equipment must
be able to handle the maximum volume of flow at the discharge of
the system on a continuous basis.
What particular technique is adopted ;in a situation largely
depends upon the quantity and quality of emission with respect to
the requirement of local laws and ambient air quality. The type
and properties of material being handled and the unit operation
and processes involved in the process become guiding factor for
selection of available tools for pollution abatement.
(a) TYPE QF EMISSION:
It is very important to study the type of emission before we take
a decision on the type of.control equipment to be selected. The
type of emission could be classified as:
(i) Uncontrolled emissions : These are the emission due to
faulty operation and maintenance like the leaks from valves
and flanges and glands etc. of
(ii) From essential part of the process. It is essential to have
complete inventories of polluting components and 100%
material balance of uncontrolled emissions accounted for.
fContd 5/-)

5. 5
(b) MEASURES TO BE ADOPTED:
We can broadly classify the pollution control methods into the two
types. These are :
(i) Process modification - Source control or specific
measures.
(ii) Provision of additional equipment for removal of a
particular pollutant'. .
(C) PROCESS MODIFICATION:
Technologists and scientists have been working on the
developments of new processejand innovations for manufacture.
The approach has lead to emergence of new techniques and processes
<or
(i) Removal of particulate matter.
(ii) Removal of gaseous product.
These can each be further divided into control by physical or
chemical removal and dillution by addition of air or dispersion.
Various equipments for particulate matter removal are gravity
settler, centrifugal separation, impingement separator,
electrostatic precipitator, filters, wet seperators like cyclone
scrubbers packed bed, mobile bed, moving bed or venturi scrubbers
etc. The wet scrubbers are also mostly used for simultaneous
removal of gaseous and particulate matter.
Chemical unit operation like adsorption, absorption and
solvent extraction etc. are also being increasingly used.
Catalytic or simple incineration is resorted to, when the recovery
of combustibles is not economically viable. Odour control is also
effectively provided in some of the advanced countries. An
efficient design of stack is an essential component of design in
which the pollution levels are controlled by efficient
dispersion. A general sequence of selection of the available
equipment can be followed as under :
The waste gas may be pure or contain solids and liquids. If it
contains solids, especially those which are noncombustible,
separation methods for the removal of solids should be
considered. These methods include mechanical separation,
electrostatic precipitation or wet scrubbing with water or other
liquids.
(Contd.... 10/-)

6. 6
It is possible that the waste gas may contain liquids which can
be removed by condensation or by activated carbon solvent
extratcion methods. In such cases there are two effluents from
the process, one a waste gas and the other a waste solvent or
liquid. The solvent or liquid can then be processed seperately .
The waste gas can proceed to next treatment step or if it meets
air pollution regulation, can be dispersed directly to the
atmosphere.
The waste gas may be combustible in nature, for this direct
incineration is perhaps the most expedient method. If the
calorific value is not high enough, a - waste gas flare may be
necessary. After incineration, it is possible that solids will be
present in the waste gas, 'which may require mechanical separation
or scrubbing to remove the particulate matter. A waste gas which
is combustible and contains solids is usually dangerous to process
through mechanical separation devices prior to incineration.
The ultimate requirement is to discharge into the atmosphere an
effluent free of particulate matter, odourless, colourless and
without toxic elements.Occasionally the odour problem in a waste
gas which is nontoxic, noncombustible and does not contain any
particulate matter can be handled through the unique methods of
odour counteraction developed by several companies in the last
few years.(This is however, not practiced in India).
Often it is not possible to remove completly the toxic elements
from a waste gas, but proper dispersion through a stack into the
atmosphere can maintain ground level toxicity well below
established minimum. This is not the most desirable- method of
treating waste gas but may be economically expedient and entirely
acceptable to local code's and ordinances. It" should be noted,
however, that such local codes and ordinances have the tendency
to become more stingent, so that better handling methods soon
must be devised. Fig. 2, gives a very comprehensive flow sheet
for treatment of waste gases. We may have to choose appropriate
combinations in series and parallel to treat the effluent gases
to the requirement of codes and laws.
It is going to be very difficult choice for small and medium scale
industry. Electrostatic precipitators and vehturi scrubbers are
rather difficult choice. But equipments like gravity separators,
multiclone, mobile bed contractors may prove to be very handy
equipments to reduce the load of particulate matter by 50 to 75%
at only nominal additional cost. A re-thinking has to be
seriously done on provision of a suitably designed chimney for
appropriate dispersion to meet the requirement of ground level
concentration.
(Contd.... 10/-)

7. : 7 :
B WASTE LIQUID
The problem of liquid waste treatment is more complex than gas
effluent treatment. The waste may contain dissolved gases mixed
liquid and suspended solids.
The first step is settling, filtration and centrifugation of
solids from the system. These materials can further be treated
by either concentration to separate dissolved solids, distillation
to separate various liquid constituents or solvent extraction to
remove important and expensive solvents from the system. These
methods are only useful when waste is in concentrated form.
Dilute waste should be treated first to bring it to concentrated
form.
(a) PRETREATMENT METHODS
Centrifugation and Filtration : Solids suspended in the waste
should be first removed in large settling ponds, thickners or
through various floatation methods for dilute waste. It is
usually more practical to use some common filteration or,
centrifugation device often the solid concentration is relatively
high and the particle size is suitable for commercially available
equipments. The theory of batch and continuous operations is too
well known.
(b) EVAPORATION AND CONCENTRATION j_
Concentration of any waste liquid effluent, especially an aqueous
effluent is often desirable step in treatment of any waste
liquid. Concentration may take the form of settling pond or
thickners or tube settlers in which gravity seperation is used to
seperate the heavy and light material in the waste for seperate
treatment. It may take the form of a decanter, when two or more
materials which are immiscible will separate into various layers
to be drawn off as concentrated components of the total waste.
It may take the from of an evaporator, which will take heat to
evaporate the more volatile constituent of the waste having the
less volatile in the evaporator for separate treatment or it may
take the form of an evaporator crystallizer combined, by which
dissolved solids may be removed from liquid by concentration above
its solubility point.
In the case of the gravity separation system, all wastes are
liquid and either must be reclaimed as pure liquid or pass on to
a further treatment step, incineration or direct disposal. In
the case of evaporator there may be three products from the
system a gas or vapour, a concentrated liquid and possibily a
concentrated sludge. The vapour phase may be condensed and once
(Contd 8/-)

8. inoincidiea, reclaimed or disposed off and the solids may be
removed from mother liquor by crystallization and subsequent
filtration and centrifugation. All these equipment are also too
well known.
(C) DISTILLATION:
Distillation like wise is standard chemical engineering unit
operation. This is normally used when liquid waste is made up
of variety of components of different boiling point, it may be
fractionally distilled for separation into various components for
ultimate recovery. In most distillation operation, however,
there is a final residue not suitable for reclamation, which will
require ultimate disposal in some other manner. If the material
is combustible, incineration is usually best choice. However, if
it is non-combustible then deep well disposal or other dis-
persion methods may be used. Distillation is seldom used as a
waste disposal tool since it would be more commonly an integral
part of processing system for by product recovery if recovery
were suitable and possible.
(d) LIQUID - LIQUID EXTRATION:
It is used infrequently in waste liquid treatment problems,
however it should be mentioned as a possibility for future use.
(e) TREATMENT OF DILUTE WASTE WATER:
After all effort at recovery and reuse of process waste have been
made at the production unit, the remaining dilute waste water is
routed through the plant sewage system to control treatment
facility. The dilute process waste should be kept segregated
from return cooling water to minimize the required size of
treatment system. Sanitary sewage can be treated most
economically alongwith process waste but some time state
regulation require separate treatment facilities. No. attempt
therefore, be made for a combined treatment system.
The design of the treatment of system depends on the waste
composition, the permissible discharge levels, and the
amenabilities of the pollutants of treatment by the multitude of
available methods. Common treatement process for dilute waste
water include equalization, nutralization, clarification,
biological oxidation and recovery of specific components. Proper
segregation of various type of liquid waste is specially
important. There has bee^i a tendency in the process industry to
dump all the liquid waste into a giant container which may take
the form of a tankage, a lagoon or settling pond. Such a "brute
(Contd 9/-)

9. 9
force" approach does not always aid the solution of the problem
and often complicates it to the point of making a clear solution
impossible.
While storage vessel for liquid waste provide very little
economic incentive to management, a well designed waste tank farm
may be most economical first step in the waste treatment system
for processing plant. From such a waste storage segregation
facility it is possible to isolate individual problmes so that a
one step solution is possible. Combination of a large variety of
waste into a large settling pond or lagoon may make one step
solution impossible.
Segregarion of liquid wastes is classified roughly into two
areas. The first is predominently aqueous phase with small
quantities of organic and inorganic material whose recovery for
economic reasons appear to be unfeasible. The antithesis is a
highly concentrated organic and inorganic waste which may offer a
feasible recovery of some of the components or where solution may
be sort 4HNUTI of direct disposal such as incineration.
Fig. 3 suggests the solid separation as the first step. While
such solid seperation may be effected through filtration or
centrifugation where the solid content is high, the liquid waste
may have to pass to a concentration step or ultimately settling
pond or lagoon for removal of such material the combination of
concentration and filteration might remove inorganic salts from
waste by evaporating the water to the atmosphere and completely
eliminating liquid disposals problem. A combination of organic
material with or without water might be fractionally distilled
to remove certain desirable components, leaving residue which
could be incinerated or handled by another approach. Liquid-
Liguid extraction might be used to remove valuable components
from a process stream.
Dilute waste water as pointed out earlier may be treated in
variety of ways to produce a desirable final effluent. This
would include digestion, neutralization, ion-exchange or
incineration, depending upon quantity and nature of the
contaminents. Ultimately, incineration of combustible and
partially combustible residue or on land or river disposal of
concentrated wastes which are difficult to handle may be the
answer. As in the case of gaseous waste it is possible to dipose
the effluent to large volume of water in river, lakes and oceans
or waste land areas where such waste will provide safe and
efficient dispersion of any toxic elements reaching in the water
shed. For this water shed has to be carefully modeled and
monitored.
(Contd.... 10/-)

10. 10
C SOLID WASTE DISPOSAL:
The last perhaps the most difficult area of waste disposal in a
processing plant is that of solid materials. Here again we have
the tendency to look at the disposal of most of solids wastes in
one of the time tested ways without much thought of segregation of
the waste. The so called sanitary land fill method has been used
and abused in the country for many years. Many of the materials
collected for land fill are completely unsuitable for land fill
and in many cases can not be considered-"sanitary.
The first step in solid waste diposal should be segregation of
the material into catagories of combustible and non combustible
wastes and those that are suitable for land fill and those that
are not. If incineration is used, the material which go into the
incineration will produce a gaseous effluent which, depending
upon its make up,"may be discharged directly to the atmosphere or
may require further treatment. A well designed incineration may
do an excellent job on boxes, papers and similar wastes. It may,
however, produce an unsatisfactory effluent when handling plastic
materials such as polythene. It may also deliver gaseous
effluent which is a difinite health hazard when handling
materials such as polyvinyl chloride or polyurethane. This does
not mean that incineration can not be used for such materials,
but only that further gas'processing must be incorporated into
the system so that the effluent is safe and acceptable. Fig. 4
gives a systematic flowsheets.
Therefore it can be seen that there are three distinct
problems, they are quite interrelated in the processing plant and
the total system concept must be used in solving them.
REFERENCES:
1. N.G. Ashar, Air Pollution and its Control in Indian Chemical
Industry, Paper presented at Chemical Technology. Seminar at
Bombay (Jan. 1978)
2. R.D. Ross., Industrial Waste Disposal, Van Nostrand Reinhold
Company, 1968.

11. t
AMRITSAR
BOMBAY
VISHAKKAPATM^M
INDEX
COCHIN
TRlVANORUM
[ 1 AREA OF STABLE LAYER PERSISTING BEYOND
24 HRS EXCEPT FOR MONSOON MONTH
VZpi AREA FOR STABLE LAYER PERSISTING BEYOND
24 HRS DURING ALMOST HALF YEAR
AREA OF STABLE LAYER PERSISTING BEYOND
24 HRS, PRIMARILY DURING WINTER
AREA OF CONTINUOUS AIR CHANGE AT LEAST
ONCE A DAY
AREA WHERE FREQUENCY OF STABLE
LAYER IS VERY LOW
AREA OF MODERATE STABILITY1
ADEQUATE DATA NOT AVA1ABLE AND
RAIN IS UNEVEN.
FIG. 1 POLU1TABILITY ZONES BASED ON INVERSION AND STABLE LAYER DATA

12. FIG. 2. GASEOUS WASTE DISPOSAL - PROCESS FLOW SHEET

13. ,
LIQUID WASTE DISPOSAL PROCESS FLOW SHFFT

14. FIG. 4. SOLID WASTE MANAGEMENT FLOW SHEET