Waste management and treatment

1. INDUSTRIAL WASTE
Management and Treatment

2. Classification of Industries
Industries can be classified into the following four
groups,
• (i) Primary Industry
• (ii) Secondary Industry
• (iii) Tertiary Industry
• (iv) Quaternary Industry

5. What is industrial waste?

6. TYPES OF INDUSTRIAL
WASTE
 Toxic substances are
primarily associated with
industrial wastes
 Range of toxic substances
present in industrial
wastes is too broad to
catalogue

7. Source of Industrial Waste

8. Hazardous waste sources

9. INDUSTRY HAZARDOUS WASTE
Valley of Drums

10. HAZARDOUS WASTE
Classification
 Definition:
 Listed in EPA
regulations
 Ignitable,
corrosive,
reactive, or toxic
 Declared by the
generator
EPA: U.S. Environmental Protection Agency

11. HAZARDOUS WASTE
CHARACTERISTIC

12. HAZARDOUS WASTE ASSESSMENT
CRITERIA
Bioconcentration
 Ability of material to be retained in
animal tissue
 Many pesticides will reside in fatty
tissue of animals
 Most concern – aquatic animals (seals
& penguins) & birds ( pelicans, eagles,
falcons, condors) that feed on fish
LD50
 amount of chemical that is needed to
kill half of a group of test specimens
e.g mice
 Animals in a toxicity study are fed
progressively higher doses of chemical
until half of them die, & this dose is
known as median lethal dose (50%)
 The lower amount of toxin used to kill
50% of specimens, higher toxic value
of chemical

13. HAZARDOUS WASTE
LC50
 Concentration at which some
chemical is toxic
 used where the amount
ingested cannot be measured,
such as in aquatic environment
or in evaluating quality of air
 Specimens such as goldfish, are
placed in a series of aquariums,
& increasingly higher
concentrations of toxin are
administered
 Fraction of fish dying within a
given time is recorded
Phytotoxicity
 Chemical is considered toxic if
it exhibits toxicity to plants
 All herbicides are toxic
materials & when they must be
disposed of, they must be
treated as hazardous waste
ROUGH GUIDELINE : A WASTE IS CONSIDERED TOXIC IF IT IS FOUND TO
HAVE LD50 OF < 50 mg/kg body weight OR IF THE LC50 < 2mg/kg

14. Toxicity assessment

CDI  C
(CR)(EDF)
BW






1
AT






 CDI = chronic daily intake (mg/kg body weight. day)
 C = chemical concentration (mg/L)
 CR = contact rate (L/day)
 EDF = exposure duration (yr) & frequency (day/yr)
 BW = body weight (kg)
 AT = average time (d)

15. CDI equation for different
exposure pathway

CDI 
(CW )(IR)(EF)(ED)
(BW )(AT)
CDI 
(CR)(IR)(FI)(EF)(ED)
(BW )(AT)

CDI 
(CW )(CR)(ET)(EF)(ED)
(BW )(AT)
AD 
(CW )(SA)(PC)(ET)(EF)(ED)(CF)
(BW )(AT)
AD 
(CS)(CF)(SA)(AF)(ABS)(EF)(ED)
(BW )(AT)

CDI 
(CA)(IR)(ET)(EF)(ED)
(BW )(AT)
INGESTION IN DRINKING WATER INGESTION WHILE SWIMMING
INGESTION OF CONTAMINATED FOOD INHALE AIRBORN
DERMAL CONTACT WITH SOIL DERMAL CONTACT WITH WATER

CDI 
(CS)(IR)(CF)(FI)(EF)(ED)
(BW )(AT)
INGESTION OF CONTAMINATED SOIL

16. TOXIC WASTE SOURCES
TOXIN SOURCES
ACIDS – mainly inorganic but some organic
causing; pH < 6
ACID MANUFACTURE, BATTERY MANUFACTURE,
CHEMICAL INDUSTRY, STEEL INDUSTRY
ALKALIS – causing pH > 9 BREWERY WASTES, FOOD INDUSTRY, CHEMICAL
INDUSTRY, TEXTILE MANUFACTURE
ANTIBIOTICS PHARMACEUTICAL INDUSTRY
AMMONIACAL NITROGEN COKE PRODUCTION, FERTILIZER MANUFACTURE,
RUBBER INDUSTRY
CHROMIUM – mainly hexavalent but also less
toxic trivalent form
METAL PROCESSING, TANNERIES
CYANIDE COKE PRODUCTION, METAL PLATING
DETERGENTS – mainly anionic but some
cationic
DETERGENT MANUFACTURE, TEXTILE
MANUFACTURE, LAUNDRIES, FOOD INDUSTRY
HERBICIDES & PESTICIDES – mostly
chlorinated hydrocarbons
CHEMICAL INDUSTRY
METALS – mainly Cu, Cd, Co, Pb, Ni, & Zn METAL PROCESSING & PLATING, CHEMICAL
INDUSTRY
PHENOLS COKE PRODUCTION, OIL, REFINING, WOOD
PRESERVING
SOLVENTS – mostly benzene, acetone, carbon
tetrachloride & alcohols
CHEMICAL INDUSTRY, PHARMACEUTICALS

17. WASTE GENERATOR WASTE TYPES
Chemical Manufacturers Acids and Bases, Spent Solvents, Reactive
Waste, Wastewater Containing Organic
Constituents
Printing Industry Heavy Metal Solutions, Waste Inks Solvents,
Ink Sludges Containing Heavy Metals
Petroleum Refining Industry Wastewater Containing Benzene & other
Hydrocarbons Sludge from Refining Process
Leather Products Manufacturing Toluene and Benzene
Paper Industry Paint Waste Containing Heavy Metals,
Ignitable Solvents
Construction Industry Ignitable Paint Waste, Spent Solvents, Strong
Acids and Bases
Metal Manufacturing Sludges containing Heavy Metals, Cyanide
waste, paint waste
EXAMPLES OF HAZARDOUS WASTE
GENERATED BY INDUSTRIES

19. INDUSTRY HAZARDOUS
WASTE

22. METAL PROCESSING
WASTES
 Metal Finishing: involves stripping, removal of undesirable oxides, cleaning and
plating.
 The most ubiquitous contaminants are chromium, zinc, copper, nickel, tin and
cyanides. Alkaline cleaners, grease and oils are universally present.
 Two major sources of waste:
1. Concentrated solutions
2. Rinse waters
 Sources of wastes –numerous & extremely variable in quantity & quality
 Metals forms:
 large particles of pure metal in suspension
 metallic ions & complexes in solution

23. Wastes can be classified as follows:
a) MINING – ore production & washing (also contains inert SS)
b) ORE PROCESSING – smelting, refining, quenching, gas, scrubbing
(also contains sulfides, ammonia & organics)
c) MACHINING – metal particles usually mixed with lubricants
d) DEGREASING – metals mostly in solution with cyanides, alkalis &
solvents
e) PICKLING – acids with metals & metallic oxides in solution
f) DIPPING – alkalis with sodium carbonate, dichromate, plus metals
METAL PROCESSING WASTES

24. g) POLISHING – particles of metals & abrasives together
h) ELECTROCHEMICAL OR CHEMICAL BRIGHTENING &
SMOOTHING – acids, mainly sulfuric, phosphoric, chromic & nitric with
metals in solution
i) CLEANING – hot alkalis with detergents, cyanides & dilute acids plus metals in
solution
j) PLATING – acids, cyanides, chromium salts, pyrophosphates, sulfamates &
fluoroborates plus metals in solution
k) ANODIZING – chromium, cobalt, nickel & manganese in solution
METAL PROCESSING WASTES

25. Bath
formula
Metallic +
cyanide (ppm)
Rinse Conc,
ppm
0.5gph drag-out
Rinse Conc,
ppm
2.5gph drag-out
Nickel,
40oz/gal nickel sulfate
8oz/gal nickel chloride
6oz/gal boric acid
82,000 Ni 171 Ni 855 Ni
Chromium,
53 oz/gal chromic acid
.53 oz/gal sulfuric acid
207,000 Cr 431 Cr 2155 Cr
Cadmium
3.5 oz/gal cadmium oxide
14.5 oz/gal sodium cyanide
23,000 Cd
57,700 CN
48 Cd
120 CN
240 Cd
600 CN
Characteristics of Metal-Plating Wastes
 Most stripping baths - acidic contain H2SO4, HNO3 and HCl
 Alkaline baths - sodium sulfide cyanide and hydroxide are also used.
 [chemicals] are usually less than 10%, 100,000 mg/l.
 Common plating baths are as follows:

26. Metal Processing Waste
 method of treatment – depends on form of metal, Conc., pH,
other constituents, & desired effluent standard
 Treatment are :
1. Modifications in design and/or operation- to minimize or
eliminate the waste.
2. installation a P-Chemical treatment plant
3. Modifications include:
- eliminating breakable containers
- drip pans, rinses
- reducing spillage
- fog rinses
- reclaiming metals

27. LAUNDRY WASTES
 4 gallons of waste per pound of clothes.
 Waste originates from dye, grease, starch, scouring, dirt
 Most installations contain 25-35 machines and use 25-30 gal. of water per
washing cycle.
22 gal. are cold and 8 hot
resulting in an average discharge
water at 100F.
50,000 gal/wk installation
can be expected.
 100 lbs of detergent are used
per week
Analysis Commercial Domestic
pH 10.3 8.1
Alkalinity, ppm 511 678
TDS, ppm 2114 3314
BOD5,ppm 1860 3813
Grease, ppm 554 1406
Treatment of Laundry Wastes
 Acidification with H2SO4, CO2 or SO2 followed by coagulation with alum or
ferric sulfate.
 After chemical coagulation, trickling filtration and activated sludge processes are
effective.

28. CANNED FOOD WASTE
 Require great deal of water as wash water from cleaning vegetable,
sorting, peeling and coring, spillage from filling and sealing machines,
wash water from cleaning floors, tables, belts.
Product Volume,
per case,
gal
BOD5
ppm
SS
ppm
Asparagus 70 110 30
Carrots 23 520-3030 1830
Spinach 3 6300 630
Apricots 57-80 200-1020 260
Tomatoes, whole 3-15 570-4000 190-2000

29. MEDICAL WASTE
 1987-88: New York and New Jersey beach closures due to washed-up
medical wastes
 November 1988 – Medical Waste Tracking Act (MWTA) added medical
waste to RCRA
 Types of medical waste:
 Cultures and stocks
 Pathological wastes
 Human blood and blood products
 Used sharps
 Animal waste
 Isolation waste
 Unused sharps

30. MEDICAL WASTE
Method of Disposal:
 Favored treatment option is
incineration
 Required for “Red Bag” (or Yellow
bag in some countries )(potentially
infectious) waste
 Used for most waste for extra safety
and “aesthetics” (incinerated waste is
not recognizable as medical waste)

31. RADIOACTIVE WASTE
 High-level waste :
1. spent nuclear fuel
2. Transuranic waste – defense-
related waste
3. Uranium mill tailings
 Low-level waste
1. Natural occurring radioactive
materials (NORM)
2. accelerator-produced radioactive
waste
 Mixed waste – radioactive and
hazardous

32. Livestock & Animal Waste

33. EXAMPLE: Hog industry

35. TOXICITY FROM THE COLLECTION
SYSTEM
Uncontrolled discharge – lead to poisonous gases
Health of sewer workers – damage
Levels of HCN & H2S of 0.03% in atmosphere are toxic
H2S –problem of anesthesia – difficult detection
Some organic solvents may cause similar difficulties

36. High cost of constructing a waste collection system
70% of the total cost for treatment & disposal
Strict control on discharge of toxic substances eg. HCN, H2S
Some organic solvents may cause similar difficulties
Tend to be immiscible with water, volatile & intoxicating
Also may form explosive mixtures
TOXICITY FROM THE COLLECTION
SYSTEM

37. TYPICAL CONSENT CONDITIONS FOR
DISCHARGE TO SEWERS
PARAMETER CONSENT CONDITION
MAXIMUM TEMPERATURE 40-50OC
pH 6-10
SUBSTANCES PRODUCING INFLAMMABLE VAPOURS NIL
CYANIDE CONCENTRATION 5-10 mg/L
SULFIDE CONCENTRATION 1 mg/L
SOLUBLE SULFATES 1250 mg/L
SYNTHETIC DETERGENTS 30 mg/L
FREE CHLORINE 100 mg/L
MERCURY 0.1 mg/L
CADMIUM 2 mg/L
CHROMIUM 5 mg/L
LEAD 5 mg/L
ZINC 10 mg/L
COPPER 5 mg/L
ZINC EQUIVALENT (Zn + Cd + 2Cu + 8Ni) 35 mg/L
TOTAL NON-FERROUS METAL 30 mg/L
TOTAL SOLUBLE NON-FERROUS METAL 10 mg/L

38. Industrial Waste
Treatment

41. SUMMARY OF ALTERNATIVE
TREATMENT TECHNOLOGIES (1992)
Solidification/stabilization (28%)
Soil vapor
extraction
(18%)
On-site
incineration
(11%)
Off-site
incineration
(15%)
Ex situ
bioremediation
(6%)
In situ
bioremediation
(4%)
In situ
flushing
(3%)
Soil
washing
(3%)
Thermal
desorption
(5%)
Soil aeration,
in situ flaming &
chemical neutralization
(2%)
In situ vitrification
(<1%)
Dechlorination
(<1%)
Solvent extraction
(<1%)
Other innovative
(<1%)

42. Application of Innovative
Treatment Technologies
Soil vapor
extraction
Thermal
desorption
Bioreme-
diation
In situ flushing Solvent
extraction
Soil washing
0
10
20
30
40
50
60
70
80
90
100
VOCs
SVOCs
Metals
Number
of
applications

43. PRE-TREATMENT
Pretreatment is on-site, advantages:
recovering specific substances in an uncontaminated
condition
avoidance of contamination of a much larger wastewater
stream
In some cases, dilution of the wastes by admixture with sewage
reduces the toxic inhibition
many industrial wastes are deficient in some nutrient (N or P)

44. PRE-TREATMENT
Key factors in deciding for or against pre-treatment:
Availability of space
Availability of expertise
Sludge and/or odor production may create a nuisance
Possibility for the introduction of clean technologies

45. PHYSICAL METHODS
PROCESS AIM EXAMPLES
SCREENING REMOVAL OF COARSE SOLIDS Vegetable canneries, paper mills
CENTRIFUGING CONCENTRATION OF SOLIDS Sludge dewatering in chemical industry
FILTRATION CONCENTRATION OF FINE
SOLIDS
Final polishing & sludge dewatering in
chemical & metal processing
SEDIMENTATION REMOVAL OF SETTEABLE SOLIDS Separation of inorganic solids in ore
extraction, coal & clay production
FLOTATION REMOVAL OF LOW SPECIFIC
GRAVITY SOLIDS & LIQUIDS
Separation of oil, grease & solids in
chemical & food industry
FREEZING CONCENTRATION OF LIQUIDS &
SLUDGES
Recovery of pickle liquor & non-
ferrous metals
SOLVENT
EXTRACTION
RECOVERY OF VALUABLE
MATERIALS
Coal carbonizing, plastics manufacture
ION EXCHANGE SEPARATION & CONCENTRATION Metal processing
REVERSE
OSMOSIS
SEPARATION OF DISSOLVED
SOLIDS
Desalination of process & wash water
ADSORPTION CONCENTRATION & REMOVAL Pesticide manufacture, dyestuffs
removal

46. PHYSICAL PRE-TREATMENT
METHODS
Devices to improve effluent
quality
eg. screening, filtration, coarse or
fine, to reduce solids, grease trap,
grit arrestors, sedimentation etc.
The effluent from high-rate filters
often has a BOD & COD similar
to settled sewage & is suitable
either for discharge to a sewer or
for further biological treatment on
site

47. CHEMICAL METHODS
may be used in addition to biological treatment
Aims- to convert waste into a settleable form
For oxidizing particular compounds (eg. Cyanide) since it is
expensive & liable to lead to the production of undesirable
chlorinated organics
 For pH correction & improving solid removal

48. COMMON PRE-TREATMENT
METHODS
COMMON CHEMICALS USED:
CHEMICAL PURPOSE
CALCIUM HYDROXIDE pH adjustment, precipitation of metals & assisting
sedimentation
SODIUM HYDROXIDE Used mainly for pH adjustment in place of lime
SODIUM CARBONATE pH adjustment & precipitation of metals with soluble
hydroxide
CARBON DIOXIDE pH adjustment
ALUMINIUM SULFATE Solids separation
FERROUS SULFATE Solids separation
CHLORINE Oxidation
ANIONIC
POLYELECTROLYTES
Enhance coagulation & flocculation

49. PRIMARY SEDIMENTATION
TREATMENT
Wastewater treatment :
preliminary, primary & secondary (+tertiary if necessary)
Preliminary – usually screening & grit removal;
- have little effect on toxic materials
- (But Effect primary sedimentation to toxic wastes –
important)
- Toxic materials in suspension (e.g., Particulate metals) –
effectively removed
Good flocculant - has great capacity for adsorption & removes
majority of dissolved metals, pesticides & other toxic organics

50. PRIMARY SEDIMENTATION
TREATMENT
Chemicals addition – enhance the effectiveness of primary
sedimentation; also, assist the precipitation process
ADVANTAGES:
enables industry to avoid secondary biological treatment
Enables waste to be discharged to a sewer, estuary or sea
DISADVANTAGES:
can be expensive, often requires pH correction, & may
produce large quantities of sludge with a disposal problem

51. PRIMARY SEDIMENTATION
TREATMENT
Chemically enhanced sedimentation
 main aim: increase removal of solids
But since many toxins (metals & chlorinated organics) adsorb
strongly, their removal also increase to levels similar to combined
primary & secondary treatment

52. PRIMARY & SECONDARY
TREATMENT
TYPICAL FOR ENHANCEMENT: LIME
METAL
CONC. IN
WASTEWATER
(mg/L)
% REMOVAL BY
SEDIMENTATION
% REMOVAL (WITH
LIME) BY
SEDIMENTATION
IRON 6.3 48 80
COPPER 0.6 28 60
CHROMIUM 0.34 40 58
LEAD 0.12 33 55
MERCURY 0.028 15 50
NICKEL 0.08 15 15
ZINC 0.7 38 70

53.  Technique most commonly employed to precipitate metal
 Optimum pH – varies depend on metal
 Typical value – 8.0 – 9.0
 Zinc – avoid high pH to prevent formation of zincates
 Other constituents of waste (e.g., Ammonia) – can affect
solubility of metal hydroxide; thus, impossible to predict
accurately level of residual metal in treated effluent
PROCESSING WASTES
-Precipitation by pH Adjustment-

54.  not all hydroxide precipitation – satisfied with pH adjustment
 Example : Cr6+
 present in wastes from metal plating
 Must reduce to Cr3+ form before treatment with lime or caustic
soda
 Reducing agents – sodium bisulfate, sulfur dioxide & ferrous
sulfate
 Reduction process – carried out under acid conditions &
subsequent addition of alkali precipitates trivalent chromium
hydroxide
PROCESSING WASTES
-Precipitation by Reducing Agent-

55.  Particular type of precipitation system used in metal plating
industry
 Principal feature – rinsing stage immediately after metal plating
stage – chemical rinse which precipitates metal from liquid
around the article being plated
 Further water rinse is required to wash off treatment chemical
PROCESSING WASTES
-Precipitation by Integrated treatment-

56.  Advantages :
 Water can practically reused
 Metals are not precipitated in a mixture – can be recovered
 However, sometimes difficult to adapt system to existing plating
lines – require extra tank in line
PROCESSING WASTES
-Precipitation by Integrated treatment-

57.  Once metals precipitated from solution – liquid & solid phases must be
separated
 2 Methods of settlement:
1. Small installation
 circulate or rectangular tank installation
 effluent flow <25 m3/day
 convenient to carry on batch basis
 settlement can take place in same tanks as that used for reaction (e.g.,
SBR)
PROCESSING WASTES
-Settlement for Solid Liquid separation-

58. 2. Larger installation
 –continuous flow system
 Size of tanks – depend on maximum effluent flow rate &
configuration adopted for tank
 Common type – vertical upward flow pattern having a central
feed well, peripheral collection launder, & sludge cone at the
bottom
 Clarification – enhanced by flocculating agents
 Size & mode of operation of precipitation system – affects quality of effluent
- But, typical figures for well-designed, efficiently operated, settlement system
for metal hydroxide precipitates – range 10 – 30 mg/l ss
PROCESSING WASTES
-Settlement for Solid Liquid separation-

59.  alternative to settlement
 Process - consists in the carrying of
metal hydroxides & other particles
in suspension to surface of liquid in
flotation vessel by increasing
particles buoyancy using bubbles
which adhere to the particles
 Scum containing gas – bubbles
 Separated solids – skimmed off
PROCESSING WASTES
-Flotation for Solid Liquid separation-

60.  Variations in process – in method of
producing carrier gas bubbles
 May be done by :
a) Injecting a super-saturated solution of
air in water under pressure into tank
(dissolved air flotation) or
b) By injecting air through diffuser
(dispersed air flotation) or
c) By electrolysis of water to yield fine
bubbles of H2 & O2 (electrolytic
flotation)
 gas bubbles produced – extremely small
(70-150 m)
PROCESSING WASTES
-Flotation for Solid Liquid separation-

61.  Use of direct filtration – for phase separation
 Seldom appropriate – filter media tends to blind (e.g. clog) rapidly –
due to gelatinous nature of metal hydroxide precipitates
 Where more granular precipitate is obtained – direct filtration satisfied
& high quality effluent can be obtained
PROCESSING WASTES
-Filtration for Solid Liquid separation-

62. OTHER SEPARATION TECHNIQUES
1. Ion Exchange
2. Evaporation
3. Molecular filtration
4. Solvent Extraction
5. Electrodialysis
Flash mixing
Flocculation
Sedimentation Filtration
Carbon
treated
water
GAC
adsorbers
Sump
Sludge
Raw
water

63.  to remove dissolved ionic species from contaminated aqueous streams
 Treatment for both anionic & cationic contaminants
 Ion exchangers – insoluble high-molecular weight polyelectrolytes that have
fixed ionic groups attached to a solid matrix
 Types of ion exchangers:
1. Natural
2. Synthetics- widely used due to greater stability, higher exchange capacity &
greater homogeneity
 Resins used: polymeric materials that have chemically treated to render them
insoluble, & to exhibit ion exchange capacity
ION EXCHANGE SEPARATION

64.  Often in form of spherical resin beads; membranes also available
 Most common synthetic ion-exchange materials:
1. copolymers of styrene
2. divinylbenzene (dvb)
ION EXCHANGE SEPARATION
Treated
water
Influent Influent
Influent
Treated
water
Treated
water
Carbon out
Carbon in
Parallel
operation
Series
operation
Moving
(pulsed)
bed
High contaminant removal
Long column runs
Small systems
Moderate removals
Large systems

65.  To concentration of aqueous
solution
 use only where effluent contains
high concentration of valuable
material
 One application – on
concentration of static rinses
(drag out) from electroplating
operations, especially chromium
plating
 Method: rinse liquor is evaporated to
metal concentration which makes
concentrate suitable for direct reuse
in plating bath
EVAPORATION

66. MOLECULAR FILTRATION
 2 categories:
1. ultrafiltration (UF)
2. reverse osmosis (RO)
 Differentiating characteristic
– molecular weight cutoff of
membrane & corresponding
pressure differentials
required to achieve a given
membrane flux

67. MOLECULAR FILTRATION
Differences RO UF
1. Molecular cutoff limit 100-200 Da 2000-1000000 Da
RO membranes will retain most organic materials as well as many of inorganic
solutes
2. Pressure differential
with trans-membranes
up to 500 psi
as high as 50 psi
Significant economic implication

68. MOLECULAR FILTRATION
 Often when RO is used, upstream UF is provided as pre-treatment
 Main operational problem – chemical & biological fouling of membrane
(particularly with RO – membrane deterioration)
 RO process – used on effluents from electroplating in electronic
components industry
 Continuous development of process & improved mechanical strength of membranes
– increase range of applications

69. SOLVENT EXTRACTION
 In general, solvents used are too expensive to be used just once, & contaminants
are highly concentrated in the extract
 Thus, spent solvent from liquid-liquid extraction operations needs further
treatment – to reclaim solvent for reuse & to reduce further volume containing
contaminants
 Some solvent re-purification sequences include the use of distillation or
adsorption

70. ELECTRODIALYSIS
 Can remove dissolved inorganics (mineral content of wastewater)
 When inorganic salt dissolved in water solution, it ionizes to produce positive
charge cations & negative charge anions
 When electrical potential passed through solution, cations migrate to negative
electrode & anions to positive electrode
 Commercial semi-permeable membranes – allow passage of ions of only one
charge:
1. Cation-exchange membranes – permeable only to positive ions
2. Anion-exchange membranes – permeable only to negative ions

72. Different Types of Innovative
Remediation Technologies

73. BIOLOGICAL METHODS
 For organic waste
Most popular
Either aerobic or anaerobic
Anaerobic - popular for treating high strength industrial
wastes

74. BIOLOGICAL TREATMENT
Further treatment : biological
Key to successful – adaptation of microbes to the presence of toxin
Bacteria & protozoa – can acclimatize & great adaptability in degrading
new synthetic organic & toxic compounds

75. BIOLOGICAL TREATMENT
BIOLOGICAL PROCESSES FOR TREATING
TOXIC WASTEWATERS
PROCESSES
REACTOR
TYPE
ADVANTAGES & DISADVANTAGES
AEROBIC
DISPERSED
GROWTH
Tend to be completely mixed, therefore dilutes toxin but affects
whole biomass. Liable to cause settling problems as well as
interfere with oxidation
AEROBIC FIXED FILM
Tend to be plug flow so no dilution unless recirculation is used.
Biomass more robust for shock loads but metazoa more sensitive
ANAEROBIC
DISPERSED
GROWTH
Tend to be completely mixed and suffer from washout of
methanogens. The latter are also more sensitive than acidogens to
toxic effects and have a low growth rate
ANAEROBIC FIXED FILM
Tend to be plug flow but level of attachment not as good as
aerobic filters. Need recirculation to dilute toxins

76. BIOLOGICAL TREATMENT
TOXIC LEVELS IN AEROBIC BIOLOGICAL
TREATMENT
TOXIN SIGNIFICANT LEVEL
HYDROGEN IONS pH < 6 or > 9
PHENOLS 50 – 100 mg/L
AMMONICAL-N 500 – 1000 mg/L
ZINC 10 – 50 mg/L
CHROMIUM 5 – 20 mg/L
LEAD 5 – 30 mg/L
ALKYL BENZENE SULFONATES 3 – 20 mg/L
SULFIDES 5 – 50 mg/L

77. BIOLOGICAL TREATMENT
TOXIC EFFECTS IN ANAEROBIC TREATMENT
TOXIN INHIBITORY CONCENTRATION (mg/L)
IN SEWAGE IN SLUDGE
CHROMIUM - 2
CADMIUM 2 2
COPPER 1.5 -
IRON 10 -
LEAD 100 -
NICKEL 80 -
ZINC 50 -
DETERGENT - 2% OF SS
BENZENE - 50 – 200
CARBON TETRACHLORIDE - 10
CHLOROFORM - 0.1
DICHLOROPHEN 1 -
γ-BHC - 48
TOLUENE - 430 - 860

78. Industrial Waste
Disposal

79. DISPOSAL OF TOXIC WASTES
Proper disposal to prevent any
short or long term hazard to
man & environment
Some require treatment prior to
disposal (e.g., hazardous)
Methods:
1. Incineration
2. To land
3. To Sea
4. Solidification (radioactive
waste)

80. Incinerator

81. -Incineration-
 Reduces waste to solid residues, gases, and water vapor
 Process reduces waste volume by 80–90%
 Solid residues need further disposal (landfilling)
 Emissions have to be closely monitored and controlled
 Economic considerations
 Incineration costs about $125,000 per ton (cost is affected by plant capacity)
 Typical plant capacity is about 1,000 tons per day

82. Disadvantages:
Require ‘care’ when deal with halogenated materials – irritant corrosive
gases may produce
Also a danger to treatment plant – become too complex
Serious problem on toxic wastewater – metallic wastes & radioactive wastes
due to characteristics of:
Contain hazardous elements that cannot be broken down
Appear to be less toxic substances that can replace them
DISPOSAL OF TOXIC WASTES
-Incineration-

83.  Where wastewaters contain human toxins – require great care to avoid
contaminate groundwater
DISPOSAL OF TOXIC WASTES
-To Land-
 For less hazardous wastes – lagoon; may have connection with watercourse
but also permits infiltration (+ some evaporation & possibly some
degradation)
 Long term – swelling & blinding of soil may reduce infiltration capacity
 More hazardous – land disposal policy : segregation followed by long term
containment of hazardous material in impervious disposal sites

84. TREATMENT OF HAZARDOUS WASTES
 Secure landfill – instead of one impervious liner, require multiple liners &
must be stabilized or in containers
 Similar to sanitary landfill – leachate is collected & a cap is placed on
landfill once completed
 Require continued care; EPA require 30 years monitoring

86. unlimited capacity for dilution & infinite retention time
Capable of diluting acute toxins below toxic threshold but problems may
arise with substances that accumulate due to geochemical or
biochemical mechanisms
Further complication – international aspect; may transport around the
world
DISPOSAL OF TOXIC WASTES
-To Sea-

87. Common practice:
I. Discharge by pipeline to inshore waters
o Dispersion in buoyant jet can give adequate initial dilution
o But, inshore areas sensitive to pollution; being used as
shellfisheries & recreational zones
DISPOSAL OF TOXIC WASTES
-To Sea-

88. II.Deep sea disposal
o Several international agreements - volume of hazardous
disposal has declined & nature of waste has changed
o Organohalogens, carcinogenic substances, Hg & Cd
compounds, & plastics – banned
o Less hazardous material – still takes place but in packaged
form & only in deep sea
DISPOSAL OF TOXIC WASTES
-To Sea-

89. DISPOSAL OF TOXIC WASTES
-Solidification-
make some hazardous wastes suitable for disposal
(e.g., oily wastes, sludges contaminated with pcbs &
fly ash contaminated with heavy metals)
reduce mobility of hazardous constituents by binding
them into solid matrix (low permeability – leach
resistance)

90.  Binding mechanisms – depend on agent employed (typical: cement
based, possolanic or silicate based, thermoplastic based or organic
polymer based
 Cheaper agents widely used – cement, asphalt & pozzolanic-based
 Promising result in short term tests
 Longer term – less certain except for vitrification
 Technique – only financially possible for nuclear waste
 Disadvantages are cost and irreversible
DISPOSAL OF TOXIC WASTES
-Solidification-

91. Industrial waste
Management

92. HAZARDOUS WASTE
MANAGEMENT
50%
Hazardous waste
7%
Solid waste
7%
Air quality
36%
Water quality
(wastewater/water
supply) 1998
Share of Environmental Consulting

93. Industrial Waste Management
Hierarchy
1. Waste minimization
 Waste audit
 Waste reduction
2. Waste Exchange
3. Recycling
Source reduction
Waste audit (after step 4.)
Waste exchange
Recycling
Treatment

94. 1. Waste minimization
 1st strategy is to perform waste audit
 Waste audit steps:
1. Identify waste stream
2. Identify sources
3. Establish priority of waste streams for
minimization
4. Implement
5. Track
6. Evaluate progress

95. 1. WASTE MINIMISATION
Strategies to minimize as far as possible the types, quantities
& concentration of any toxic wastes discharged through good
housekeeping:
extending the life of process solutions by filtration, topping up,
adsorption
Altering the production process to use less toxic compounds,
e.g. Substituting copper pyrophosphate for copper cyanide in
electroplating solutions
Dry cleaning prior to wash-down, which remove a large
proportion of the pollutant in solid form

96. 1. WASTE MINIMISATION
Attempt to minimize (cont.):
Evaporation of strong organic liquors, which can often produce a
burnable product
Minimizing & segregating any flows which contain toxic
material.
separate wastes for safety reasons, e.g. Cyanides or sulfides &
acid wastes, trichloroethylene (TCE) & alkaline wastes
to segregate for treatment reasons, but segregation can be very
expensive

97. Options of Industrial waste
Management

98. -END-