identification of odorous compound in pesticide industry &its … · 2001-01-02 ·...

Identification Of Odorous Compound In Pesticide Industry & Its Control Technologies

Gaurang H .Ban (Asst.prof) and Neha SrivastavaEnvironment Engineering Department

L.D Engineering College Ahmedabad, India

[email protected]@ymail.com

Abstract— : Air quality is affected not only due to conventional air pollutants but also due to unpleasant odour. Odour has distinctly different characteristics and is undoubtedly the most complex of all the air pollution problems. Odor or malodor, which refers to unpleasant smells, is nowadays considered an important environmental pollution issue. Till date, not much attention has been paid towards odour problems in India. Odour problem gains significance due to high increase of the industrial activities, particularly, pharmaceuticals, agro-chemicals and fertilizer plants, pesticides which release odorous gases into the ambient air. In addition there are several natural and man made sources which contribute in odours generation. As a result of these activities several pollutants such as hydrogen sulfide (rotten egg odour), ammonia (sharp pungent odour), carbon disulfide, Mercaptan, product of decomposition ofproteins (especially of animal origin), phenols and some petroleum hydrocarbons are emitted into the air environment . This paper is attempt to throw some light on the causes , including its sources , various odours compounds-its physical and chemical properties and odour control technologies related with pesticide industry.

Keywords: odour pollution, chemical compounds control technologies.

I.INTRODUCTION Odour can be defined as the “perception of smell” or in scientific terms as “a sensation resulting from the reception of stimulus by the olfactory sensory system”. Attention to odor as an environmental nuisance has been growing as aresult of increasing industrialization and the awareness of people’s need for a clean environment. As a consequence, efforts to abate odor problems are necessary in order to maintain the quality of the environment. Undesirable odours contribute to air quality concerns and affect human lifestyles. Whether pleasant or unpleasant, odour is induced by inhaling air-borne volatile organics or inorganic. As main responsible odorous components in foul air, hydrogen sulphide and Mercaptan need to be controlled restrictedly for odour reduction

because of their low thresholds. Pesticides are defined as the substance or mixture of substances used to prevent, destroy, repel, attract, sterilize, stupefy or mitigate any insects. The word pest comes from the Latin word “pestis” which includes an animal or plant that occurs in such abundance as to present a distinct threat, economically or medically to man or his interest. A pest may be insect, fungus, weed, rodent, bacteria, virus, nematodes, acarid / mite, parasite and even animal or bird. Pesticides are basically toxics and persistence; it can enter in food chain and causes injury to human health. It also destroys the diversity and food web and causes ecological imbalance. Pest control therefore needs regulation on the interest of human health and environment. Undesirable odour contributes to air quality concerns and affect human lifestyles. Odour is undoubtedly the most complex of all the air pollution problems.

II.OVERVIEW OF ODOUR POLLUTION IN THE ENVIRONMENT

Odor substances emitted from any source will be regarded important in the context of odor pollution if they are dispersed in the surrounding area. Odour sources can be classified as follows. Sources of Odours are:1. Point Sources: Point sources are confined

emissions from vents, stacks and exhausts.2. Area Sources: Area sources may be unconfined like sewage treatment plant, waste water treatment plant, solid waste landfill, composting, household manure spreading, settling lagoons etc.3 .Building Sources: Building sources of odour like pig sheds and hog confinement chicken.4 .Fugitive Sources: In this source of odour, emissions are of fugitive nature like odour emissions from soil bed or bio-filter surface.This description is presented here to point out the relationship between any activity (industrial, agricultural, household, etc.) that can be a sourceof odors and their odor release. Such a relationship is important and critical in the framework of odor abatement in order to understand any activity that results in odorous gases and the kinds of odor compounds that

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might be produced. Table 1 shows the sources of odor in the environment and the released odor compounds.

TABLE1.SOURCES OF ODOUR IN THE ENVIORMENT Sources Odorous compounds A .Chemical and petroleum industries:• Refineries Hydrogen sulfide

ammonia Mercaptan, , Aldehydes

• Inorganic chemicals (fertilizers, phosphatesproduction, soda ash, lime ,sulfuric acids, etc.)

Ammonia, Aldehydes, hydrogen sulfide, sulfurDioxide

•Organic chemicals (paint industry, plastics, rubber, soap, detergents, textiles)

Ammonia,aldehydes ,sulfurdioxide, Mercaptan, organic acid.

B.Pharmaceutical industry

Aldehydes, aromatic, phenol, ammonia,

C. Rubber, plastics, glass industries

Nitro compounds (amines ,oxides), sulfur oxides, solvents,aldehydes, ketones, phenol ,alcohols

D. Pesticides Mercaptan, ammonia , hydrogen sulfide

E. Pulp & Paper Mercaptans,hydrogen sulfide

III.ODOROUS COMPOUNDS

Odorous substances that are emitted from industrial sources include both inorganic and organic gases and particulate. Many odorous compounds result from biological activity or are present in emissions from chemical processes. Most of the odorous substances derived from anaerobic decomposition of organic matter contain sulfur and nitrogen. Most of the odorous substances are gaseous under normal atmospheric conditions or at least have a significant volatility .Usually, lower the molecular weight of a compound, the higher is its vapor pressure & potential for emission to the atmosphere. The reduced sulfur compounds such as the mercaptans and organic sulfides, tend to be the most odorous, based on their relatively low odour threshold concentrations.Table-2 shows the some important compounds and their particular senses or smelling.

TABLE-2 MAJOR ODOUR COMPOUND AND THEIR

SENSES

Compound Formula Odor senseAcetaldehyde CH3CHO Pungent

Ammonia NH3 Pungent

Butyric acid CH3CH2CH2COOH Rancid

Diethyl sulfide C2H5C2H5S Garlic

Dimethyl amine CH3CH3NH Fishy

Dimethyl sulfide CH3CH3S Decayedcabbage

Formaldehyde HCHO Pungent

Hydrogen sulfide H2S Rotten eggs

Methylmercaptan CH3SH Decayedcabbage

Phenol C6H5OH Empyreumatic

propylmercaptan C3H7SH Unpleasant

Sulfur dioxide SO2 Pungent

Trimethyl amine CH3CH3CH3N Fishy

Valeric acid CH3CH2CH2CH2COOH Body odor

IV. OVERVIEW OF PESTICIDE

INDUSTRY

Pesticide Uses:Generally pesticides are used in three sectors viz. agriculture, public health and consumer use. The consumption of pesticide in India is about 600 gms. / hectare, where as that of developed countries is touching 3000 gms. / hectare. There is a wide range of pesticides found used in non-agriculture situations such as industries, public health and for a number of purposes in the home. Domestic use of pesticides is mainly as fly killer, ant killer, moth killer, repellants, rodenticides and fungicides etc. By and large industrial use of pesticide is of vital importance in the industries such as wood and carpet, wood preservation, paint industry, paper and board industry, leather industry, building industry, miscellaneous industrial application e.g. soluble cutting oils, industrial water systems, drilling fluids etc.

Pesticide production inIndiaPesticide is manufactured as technical grade products and consumable pesticides are then formulated The installed capacity of technical grade pesticide was 1,45,800 tonnes during March 2005, and the production in the financial year 2004-05 was 94,000 tonnes. The year wise actual production during year 2001 to 2005 was given at Table 1

.



Table 1: Actual Production of Technical Grade Pesticides

s.no Financial year

Production(Tonnes/year)

Annual Growth(%)

Overall Annual Growth(2004-

05)/(2002-01)

1. 2001-2002

81,800

2. 2002-2003

69,600 - 15 14.9%

3. 2003-2004

84,800 21.8

4. 2004-2005

94,000 10.8

Source: Annual Report 2005-06 of Ministry of Chemicals & fertilizers, Department of Chemicals & Petrochemicals, page no – 54-55

V. CHEMICAL CLASS OF PESTICIDES INDUSTRY

Oragno

Phosphate PyrethroidsOrgano

Chloride Neonico

tinoids

Carb

amates

Acephate Allethrin Aldrin Acetamiprid

Aldicarb

Phorate Bifenthrin

DDT Clothianidin

Bendiocarb

Profenofos

Cypermethrin

Endosulfan

Imidacloprid

Carbofuran

Azinphos-methyl

Deltamethrin

Endrin Nitenpyram

Carbaryl

Bensulide Permethrin

Hexachloroben

zene

Nithiazine

Dioxacarb

chlorethoxyfos

Prallethrin

Lindane

Thiacloprid

Malathion Tetramethrin

Dieldrin

Chlorpyrifos

Parathion

VI. MANUFACTURING PROCESS

Pesticides are produced by chemical reactions of organic materials, which seldom go to completion. The degree of completion of organic reaction is generally very much less than those involving inorganic reactions. The law of mass actions states that in order to transform one reactant fully, the other reactant must be present far in excess in weight than the stoichometric requirement. This law is applied in practical field. As a result, the final mass of an organic reaction is associated with not only the desired product, but also untreated reactants and undesired products of side reactions or partially completed reactions. The manufactures of pesticide is hardly accomplished in one reaction,

in most cases, it involves various unit processes and unit operations.

UNIT PROCESSES UNIT OPERATIONS

Alkylation Liquid / Liquid extraction

Carboxylation Liquid / Liquid separation

Acetylation Liquid / Solid separation

Condensation Gas / Solid separation

Cyclization Distillation

Dehydration Crystallization

Halogenation Gas absorption

Oxidation Drying

Sulfonation Grinding

Nitration Mixing

Amination

In each reaction, state some raw material remain un-reacted, and some unwanted product are formed which remain in the system. Desired products are carefully recovered in each step from the system. Unwanted products are discarded, but not carefully. These inevitably become pollutants in wastewater and solid waste. Some are vented out in the atmosphere. Although in some cases some recyclable materials are also profitably taken back in to the system. Impurities present in raw materials may also react with one another and in many cases show up as a scum, froth or tar or simply as un-reacted raw material. In order to understand generation of wastewater, solid waste and emission understanding of unit process and operation is required. The typical unit operation of chemical synthesis is depicted.

VII. MAJOR ODOUROUS COMPOUND

FROM PESTICIDE INDUSTRY

Emissions Profile in Pesticide Industries : In general, process emissions can be classified into point source and fugitive emissions. The point source emission is from process operations and the fugitive emission is an uncontrolled emission from storage tanks/drums, spills, leaks, overflows etc. To identify the various sources of odorous compound and their control system a questionnaire survey and in- depth study of pesticide industries were conducted. In pesticide industry, odours is mainly imparted by Phosphorous , Sulphides and Chlorides. Below Table shows some odours compound.S.no Pesticide Odourous

Compound1. Acephate (

pungent smell) HCL

2. Dimethoate H2S3. Cypermethrin Cl2 , HCl and

SO24. Isoproturon NH35. Ethion H2S and

C2H5SH



6. Malathion H2S7. Phorate ( rotten

eggs)H2S and C2H5SH

VIII. ODOUROUS COMPOUND AND ITS HEALTH IMPACT

IX. THE ODOUR UNIT-UNIT OFMEASURMENT

The relative strength of an odor is determined by dilution. The greater number of dilutions with odor-free air necessary to bring an odorous gas sample to the threshold, or barely detectable, level. So, the odour unit has been established and defined as “It is the amount of odour necessary to contaminate 1ft3 of clean (odour-free) air to the threshold, or barely perceptible,

level.’’ For example, a sample of a gaseous emission contains 10 odour units per cubic foot means that when one part of the sample is diluted with nine parts of odour-free air will have a barely detectable odour

X.ODOUR CONTROL TECHNOLOGIES

Before odor control methods are used, it is essential to look at the sources of the generation of odors. Prevention or reduction of odor generation at the source must be explored. Change of processes and use of different raw materials with less odor potential must be investigated before considering odor control methods.Odour control depends on type of sources:

1) Odour Control from Area Sources.2) Odour Control from Point Sources.In case of point sources such as that of industries, the odour-causing gas stream can be collected through piping and ventilation system and made available for treatment.The various technologies used are described here:A. AdsorptionB. IncinerationC. Wet scrubbing1.Adsorption: In this method, offensive odor components are passed through the adsorption tower containing various adsorbent media, such as activated carbon, a filter, and a molecular sieve. The odor control is effective using this method, even when other methods are not effective. Therefore, this method is widely used as an independent technology or a final approach combined with other methods in order to adhere to public odor regulations. The durability of the adsorbents is more important than the efficiency in odor removal. The reuse or regeneration of adsorbent media is achieved by desorption with steam, heat additions, or plasma.1.1 Activated Carbon or Zeolite Method : In the adsorption method using activated carbon or zeolite particles , odor components are adsorbed physically into small holes of the absorbent materials. Then, they are removed or decomposed chemically by the acid or alkali chemicals coated on the adsorption materials.In the adsorption tower, alkalized carbon,

acidized carbon, and neutral activated carbon are fills as layers according to the types and the strength of odorous components. The layer ofalkalized carbon removes hydrogen sulfide (H2S), methyl Mercaptan [(CH3)2SH],and so forth. The layer of acidized carbon removes ammonia (NH3), Trimethyl amine [(CH3) 3N], and so forth. The layer of neutral activated carbon removes dimethyl sulfide [(CH3)2S], dimethyl disulfide [(CH3)2S2],hydrocarbons.

S.no Properties Exposure & odour

Health Impact

1.Ammonia

2.Chlorine

3.HydrogenSulphide

4. EthylMercaptan

5. SulphurDioxie

Colourless, stable at roomtemp,

Greenish yellow gas, extremely reactive .

Colourless gas, stable, highly inflammable.

Colourless gas, stable under normal storage condition.

Colourless gas, stable,incompatiblewith strongreducing or

oxidisingagents,

TWA-50ppm, Ammoniacal strong, high corrosive in presence of Cu and its alloys.

TLV-0.5 ppm, pungent suffocating bleach like odour.

TWA-10 ppm, smell,of rotten eggs

.Odour threshold is 0.001 ppm

TWA 2ppm, irritating pungent odour.

Exposure ca cause coughing, chest pains difficulty in breathing.

Can ause itching and burning ofthe eyes, ose, throat.

High toxic may be fatal if inhaled. Skin contact may ause burns.

Highly toxic, affects thecentral nervous system.

Can cause fatal.



2. Incineration: Incineration is the oxidation of the odour into carbon dioxide and water by the combustion of the odour with fuel and air. Combustion may be employed when malodors gases , have a low concentration of combustible , and have no heat recovery value. The reaction takes place at temperatures ranging from 750oC to 850oC. This method is classified as follows: direct incineration and catalyst incineration.Direct Incineration: Direct incineration is a method in which flammable odor components are burned and decomposed by a combustion furnace or separate afterburners. The important parameters for direct incineration are as follows. The combustion temperature in the resident zone is designed as 650–800 ºC and the residence time is 0.3–1 s.CatalyticIncineration : The catalytic incineration method is classified as an incineration method. In this method, flammable odor components such as hydrocarbons are burned, oxidized, or decomposed into water and carbon dioxide under a lower-temperature condition with an activated catalyst. Oxidization catalysts such as Pt, V2O5, Co, Mn, Fe, Ni ,are used.3.Wet Scrubbing : Wet scrubbing and gas washing oxidation for odor control were employed extensively because more than 90% of odorous compounds are water soluble. Offensive odor substances were decomposed, oxidized, or converted into non odorous substances with chemical reactions using chemical solutions. This method is considered one of the most fundamental and universal deodorization technologies. Sulfuric acid (H2SO4), hydrochloric acid (HCl), sodium hydroxide (NaOH), sodium hypochlorite (NaClO), hydrogen peroxide (H2O2), sodium thiosulfate (Na2S2O3), sodium sulfite (Na2SO3), and so forth are used as chemicals in washing solutions.

Two-phase chemical scrubber using a shower nozzle with a Raschig rings layer: (a) chemical scrubber;

Acid and Alkali Scrubbing Method : In the method of acid and alkali scrubbing, odor components are neutralized and absorbed in alkali water solutions. Usually, acid scrubbing is performed in the first stage and alkali scrubbing is done in the second stage. In the acid scrubbing process, dilute HCl or H2SO4 water solution (pH �3–4) is used and the acid solution is

recirculated. Primarily, ammonia and Trimethyl amine can be removed in this process.The chemical reactions are as follows:

Ammonia: 2NH3 +H2SO4 →(NH4)2SO4

NH3 + HCl → NH4ClTrimethylamine:(CH3)3N +HCL →(CH3)3 NHCLIn the alkali scrubbing process, dilute NaOH water solution (pH�10–12) is recirculated.Hydrogen sulfide, methyl Mercaptan, and so forth can be removed in the following process:Hydrogen sulfide:H2S+2NaOH→Na2S+H2O Methylmercaptan:CH3SH+ NaOH → CH3SNa+ H2O

NaClO Scrubbing Oxidation Method: using the hypochlorous acid soda (NaClO) solution in scrubbing method . Odor components are oxidized and decomposed to nontoxic compounds by the gas washing method using a NaClO water solution. The operation is usually performed for controlling pH = 10. The odor components can be removed primarily according to the following chemical reactions: Alkali gas Ammonia :2NH33NaClO→N23NaCl+3H2O Trimethylamine: (CH3)3N + NaClO →( CH3)3NO + NaCl Acid gasHydrogen sulfide: H2S + 2NaOH →Na2S+ H2O Na2S+ 4NaClO → Na2SO4 + 4NaCl Na2S+ NaClO + H2O→S + NaCl + 2NaOH Methyl Mercaptan: CH3SH + 3NaCL →CH3SO3H +NaCl.

NaClO scrubbing system: (a) schematic diagram

XI.CONCLUSION

Odours are one of the top causes for air pollution. As seen from above mentioned control technologies The comparison of it are shown in tabular form. It is concluded that odour problems can be minimized by using suitable technologies.



TABLE-4 CONTROL TECHNOLOGIES ADOPTED IN INDIA

S.no Pollutant Control system

1. HCl(Hydrochloric acid) Water/Caustic scrubber

2. Cl2 ( Chlorine) Water/Caustic Scrubber

3. CH3Cl(methyl chloride) Incinerator4. H2S

(Hydrogensulphide)Scrubber with NaOH media

5. NH3 (ammonia) incinerator6. CH3OH(methyl alcohol Adsorption

Bed (Charcoal or molecular

Sieve)7. HBr Caustic

Scrubber8. Mercaptan Incinerator

AKNOWLEDGMENT

The present paper has been written under the guidance of Professor (Gaurang H. Ban Asst.Prof. Env. Dep. L.D. College ). His guidance in the area of odour has been very useful to the author. Applied research has already under progress by the author for odours under his guidance .It gives me immense pleasure to offer my sincere thanks to L. D. College of Engineering, Ahmedabad, for giving me the opportunity to present a paper.

REFERENCES[1]Advanced Air And Noise Pollution– volume(2)( Handbook of environment engineering ) BY- Lawrence K. Wang.[2]Analysis, Monitoring And Surveying BY-ARTHUR C.STERN (Air Pollution Volume-2)[3]Introduction To Hazardous Waste Incineration (second edition) BY-JOSEPH J.SANTOLERI and LOUIS THEDORE.[4] Air Pollution Control Equipment Calculations(The Academic Chair’s Handbook)BY- LOUIS THEDORE.[5] Journal Of Environment Management (National Environmental Engineering Research Institute-NEERI) BY-Atul Vaidya and Rashmi Dixit.[6] Journal of Indian Association for Environmental management, Vol 29, No. 1,February, 2002[7] CPCB Newsletter on Odour Pollution & its

Control. [8] perry chemical engg .handbook edition- 8,section-17 gas solid operation and equipment.



identification of odorous compound in pesticide industry &its … · 2001-01-02 ·...

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