Lecture 18 (Hazardous Waste) Flashcards
Transportation and Storage
The CRADLE TO GRAVE concept
HW generated at source requires movement by trucks to further
Requires serious care & attention while moving
HW to be properly packed & labelled for transport to
ensure safe handling
Storage facilities are used to store waste temporarily before treatment & disposal
Characteristics
D001 – Ignitability (flammability)
D002 – Corrosively
D003 – Reactivity (oxidizer)
D004 – Toxicity (poison)
Ignitables
Examples include: Acetone, Methanol, Ethanol
Corrosives
pH less than 2.0 or greater than 12.5
eg. Hydrochloric acid, Sodium Hydroxide
Reactives
Normally unstable and reacts violently without detonating
Reacts violently with water
Generates toxic gases, vapors, or fumes when mixed with water
Forms an explosive mixture with water
Toxics
Includes metals, such as mercury, lead and compounds
Includes acutely toxic chemicals, which are very dangerous (i.e. Sodium Azide
Treatment Methods
Physical
Chemical
Biological
Physical Treatments
Primarily isolate or concentrate particular materials, reduce their volume, solidify, detoxify
Involves variety of separation techniques
Chemical Treatment
Methods Include: Neutralization Chemical oxidation Reduction Anodic electrolysis
Neutralization
carried out when the waste contains excessive amount of acid or alkali
Chemical Oxidation
used to destroy toxic cyanide molecule with oxidising agents
Reduction
used in the conversion of hexa valent chromium into trivalent chromium
Anodic electrolysis
used for the destruction of cyanide
Biological Treatment
Biological treatments typically involve organic wastes.
Microorganisms of various types, break down substances into alternate, more desirable forms
