1. CHAPTER 2 INDUSTRIAL WASTE
ENVIRONMENTAL HEALTH ENGINEERING ECH 4102
by:
Dr. N Abdullah

2. LEARNING OBJECTIVES
Identify different sources and the major types industrial toxic & hazardous waste
Distinguish treatment technologies for different type of industrial waste
Describe Hazardous waste management and control

3. Waste

4. The Universe of Waste
Sources & composition of solid wastes

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
Q: How to classify and assess the hazard?

10. HAZARDOUS WASTE Classification
Definition:
Listed in EPA regulations
Ignitable, corrosive, reactive, or toxic
Declared by the generator

11. HAZARDOUS WASTE CHARACTERISTIC
Ignitable waste (EPA HW No. D001)
Liquids: flash point < 60°C
Solids: cause fire under standard temp. & pressure
Corrosive waste (EPA HW No. D002)
Liquids: pH < 2 or > 12.5; corrode steel at > 0.25 in/yr rate
Reactive waste (EPA HW No. D003)
Unstable, react violently w/ air or water
For potentially explosive mixtures w/ water
Emit toxic fumes
Toxicity
Leach toxic constituents for solid wastes
Toxicity Characteristic Leaching Procedure (TCLP)
Crush to < 9.5 mm particle size
Agitate in a weak acetic acid in liquid: solid = 20:1 by weight
18 hrs after, filter through 0.6~0.8 µm glass fiber filter
Analyze sample for constituents

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
& will not break down quickly; as smaller creatures are eaten by larger ones, concentration in fatty tissue of larger organisms can reach toxic levels for them

13. HAZARDOUS WASTE LC50 Phytotoxicity
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 = 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
INGESTION IN DRINKING WATER
INGESTION WHILE SWIMMING
INGESTION OF CONTAMINATED FOOD
INHALE AIRBORN
AD= ABSORBED DOSE
ABS = ABSORPTION FACTO R FOR SOIL CONTAMINANT
AF= SOIL TO SKIN ADHERE FACTOR
AT= AVERAGE TIME
BW= BODY WEIGHT
CA=CONTAMINANT CONCENTRATION
CDI=CHRONIC DAILY INTAKE
CF= CONVERSION FACTOR (FOR SOIL & WATER)
CR= CONTACT RATE
CS= CHEMICAL CONCENTRATION IN SOIL
CW=CHEMICAL CONCENTRATION IN WATER
ED= EXPOSURE DURATION
EF=EXPOSURE FREQUENCY
ET=EXPOSURE TIME
FI=FRACTION INGESTED
IR=INGESTION RATE
PC=CHEMICAL-SPECIFIC DERMAL PERMEABILITY CONSTANT
SA=SKIN SURFACE AREA AVAILABLE FOR CONTACT
INGESTION OF CONTAMINATED SOIL
DERMAL CONTACT WITH SOIL
DERMAL CONTACT WITH WATER

16. Types of Industrial Waste

17. 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

18. EXAMPLES OF HAZARDOUS WASTE GENERATED BY INDUSTRIES
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

20. INDUSTRY HAZARDOUS WASTE
From 1956 until 1972, the 17-acre site was operated as a hazardous waste disposal facility.
Over 34 million gallons of industrial waste,
primarily from metal
finishing, electroplating,
and pesticide
production were
deposited in
evaporation ponds.

23. 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:
Concentrated solutions
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

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

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

26. 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:
Bath
formula
Metallic +
cyanide (ppm)
Rinse Conc,
ppm
0.5gph drag-out
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

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

28. LAUNDRY WASTES 4 gallons of waste per pound of clothes.
Waste originates from dye, grease, starch, scouring, dirt
Most installations contain machines and use 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.

29. 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
Asparagus 70
110 30
Carrots 23
1830
Spinach 3
6300
630
Apricots
57-80
260
Tomatoes, whole
3-15

30. MEDICAL WASTE
: 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

31. 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)

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

33. Livestock & Animal Waste

34. EXAMPLE: Hog industry

36. 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

37. TOXICITY FROM THE COLLECTION SYSTEM
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

38. 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
ZINC
10 mg/L
COPPER
ZINC EQUIVALENT (Zn + Cd + 2Cu + 8Ni)
35 mg/L
TOTAL NON-FERROUS METAL
TOTAL SOLUBLE NON-FERROUS METAL

39. Industrial Waste Treatment

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

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

44. 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)
problem in treatment due to inhibition of bacterial growth, so easier & cheaper to develop the necessary bacterial flora in an on-site treatment plant

45. 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
1- the site may be too restricted or land may be too valuable to be used for a treatment plant
2 the company may not wish to get involved in effluent treatment 3

46. 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

47. 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
COD – CHEMICAL OXYGEN DEMAD – WHICH ALWAYS EXCEEDS BOD, IS THE OXYGEN CONSUMED BY A SAMPLE WHEN TREATED WITH ACIDIC DICHROMATE SOLUTION. IT RESULTS FROM OXIDATION OF BOTH ORGANIC & INORGANIC CONSTITUTENTS.

48. 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

49. 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
CHLORINE
Oxidation
ANIONIC POLYELECTROLYTES
Enhance coagulation & flocculation

50. 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
Effect toxic material to primary sedimentation – insignificant due to purely physical process of sedimentation & flocculation
Beneficial since it renders less inhibitory waste material into biological treatment
But, selectively concentrates toxins in sludge & may give problem in digestion & in sludge disposal

51. 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

52. 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

53. 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
ZINC
0.7 38 70

54. PROCESSING WASTES -Precipitation by pH Adjustment-
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

55. PROCESSING WASTES -Precipitation by Reducing Agent-
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

56. PROCESSING WASTES -Precipitation by Integrated treatment-
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

57. PROCESSING WASTES -Precipitation by Integrated treatment-
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

58. PROCESSING WASTES -Settlement for Solid Liquid separation-
Once metals precipitated from solution – liquid & solid phases must be separated
2 Methods of settlement:
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)

59. PROCESSING WASTES -Settlement for Solid Liquid separation-
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

60. PROCESSING WASTES -Flotation for Solid Liquid separation-
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

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

62. PROCESSING WASTES -Filtration for Solid Liquid separation-
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

63. OTHER SEPARATION TECHNIQUES
Ion Exchange
Evaporation
Molecular filtration
Solvent Extraction
Electrodialysis
Flash mixing
Flocculation
Sedimentation
Filtration
Carbon
treated
water
GAC
adsorbers
Sump
Sludge
Raw

64. ION EXCHANGE SEPARATION
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:
Natural
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

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

66. EVAPORATION 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

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

68. with trans-membranes up to 500 psi Significant economic implication
MOLECULAR FILTRATION
Differences RO UF
1. Molecular cutoff limit Da 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

69. 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

70. 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

71. 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:
Cation-exchange membranes – permeable only to positive ions
Anion-exchange membranes – permeable only to negative ions

73. Different Types of Innovative Remediation Technologies

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

75. 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

76. 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
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
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
Tend to be plug flow but level of attachment not as good as aerobic filters. Need recirculation to dilute toxins

77. 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

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

79. Industrial Waste Disposal

80. 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:
Incineration
To land
To Sea
Solidification (radioactive waste)

81. Incinerator

82. -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
frequently used for decomposition of organic toxins
Examples of successful use of incineration
Treatment of toxic sulfide liquor from Kraft process for making paper pulp
Treatment of steel pickle liquor
Advantage - regenerate useful compounds

83. DISPOSAL OF TOXIC WASTES -Incineration-
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

84. DISPOSAL OF TOXIC WASTES -To Land-
Where wastewaters contain human toxins – require great care to avoid contaminate groundwater
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

85. 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

87. DISPOSAL OF TOXIC WASTES -To Sea-
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

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

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

90. 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)

91. DISPOSAL OF TOXIC WASTES -Solidification-
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

92. Industrial waste Management

93. HAZARDOUS WASTE MANAGEMENT7%
Air quality 7%
Solid waste
50%
Hazardous waste
36%
Water quality (wastewater/water supply)
1998
Share of Environmental Consulting

94. Industrial Waste Management Hierarchy
Waste minimization
Waste audit
Waste reduction
Waste Exchange
Recycling
Waste audit (after step 4.)
Source reduction
Waste exchange
Recycling
Treatment

95. 1. Waste minimization 1st strategy is to perform waste audit
Waste audit steps:
Identify waste stream
Identify sources
Establish priority of waste streams for minimization
Implement
Track
Evaluate progress

96. 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

97. 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

98. Options of Industrial waste Management
Arid region = very dry land, use for disposal of nuclear waste
Salt formation = waste contain 99% NaCL, for safe disposal (deep repository of waste)
Surface impoundment = disposed of waste in indented soil area such as pit, lagoon, pond
Landfill = buried the waste underground
Underground injection =

99. -END-