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NNNE4033 TOXIC WASTE MANAGEMENT
DISCUSSION ON ADVANTAGES AND DISADVANTAGES OF HAZARDOUS WASTE TREATMENT AND DISPOSAL METHODS
MUSLIHAH MOHD RAZALI A139018 ENVIRONMENTAL HEALTH AND INDUSTRIAL SAFETY
A. PHYSICO-CHEMICAL TREATMENT
Advantages of physicochemical treatment
Disadvantages of physicochemical treatment
Air- stripping
Soil-vapour extraction
Carbon adsorption
Steam-stripping
Chemical oxidation reduction
1) Treat aqueous organic waste with relatively high volatility, low water solubility and aromatics.
1) Contaminants can be extracted without the need for excavation or the injection of compounds required for in-situ chemical oxidation or bioremediation.
1) Capture volatile organic in gaseous mixtures.
1) Less volatile, more water soluble, constituents such as acetone or pentachlorophenol are more readily remove from water by steam stripping than by air stripping.
1) Capable of destroying a wide range of organic molecules and inorganic wastes.
Steam-stripping
Chemical oxidation reduction
1) The steam stripping process requires some type of air pollution control (APC) mechanism to eliminate toxic emission.
1) Contaminants and/or poor process control can lead to very high reagent consumption.
2) Manpower requirements are low.
Air- stripping
Soil-vapour extraction
1) This process is temperature dependent so that stripping efficiency can be impacted by changes in ambient temperature and the presence of suspended solids may reduce efficiency.
1) High treatment cost.
2) Treat single-phase aqueous organic wastes with high molecular weight and boiling point and low polarity and solubility, chlorinated hydrocarbons and aromatics. Carbon adsorption 1) Limitations are usually economic and relate to the rapidity with which the carbon becomes spent.
2) Have the potential to generate more toxic waste than the original waste.
2) Only effective for volatile organics. references: U.S EPA
B. BIOLOGICAL TREATMENT
Advantages of biological treatment
Disadvantages of biological treatment
1) Complete mineralization vs. physical-chemical treatment 2) Capability for in-situ treatment without having to excavate contaminated soil 3) Generally lower costs for similar wastes
1) More difficult to control as bacterial growth is influenced by a great number of factors 2) Requires more time, and some particularly toxic compounds may degrade so slowly as to be considered persistent if not recalcitrant 3) Requires extensive testing before treatment and monitori ng throughout treatment
C. THERMAL METHOD
B. BIOLOGICAL TREATMENT
Advantages of biological treatment
Disadvantages of biological treatment
1) Complete mineralization vs. physical-chemical treatment 2) Capability for in-situ treatment without having to excavate contaminated soil 3) Generally lower costs for similar wastes
1) More difficult to control as bacterial growth is influenced by a great number of factors 2) Requires more time, and some particularly toxic compounds may degrade so slowly as to be considered persistent if not recalcitrant 3) Requires extensive testing before treatment and monitori ng throughout treatment
C. THERMAL METHOD
Advantages of thermal method
Disadvantages thermal method
1) The basic process technology is available and reasonably well developed. 2) Can be scaled to handle large volumes of liquid waste. 3) An excellent disposal method for biologically hazardous wastes. 4) Large areas of land are not required. 5) Reduction of leachability of the wastes after it is incinerated, thus making landfilling an acceptable method of final disposal, with significant reduction in potential for release of contaminants for groundwater contamination. 1) The equipment is costly. 2) The ash may or may not be toxic, but must be disposed of properly. 3) The gaseous and particulate products of combustion may be hazardous and should be controlled by air pollution control technology. 4) Requires highly trained operators.
D. STABILIZATION AND SOLIDIFICATION
Advantages of stabilization and solidification
Disadvantages of stabilization and solidification
1) Ability to handle oversized material, debris and underground obstructions; 2) Good overall mixing that can be easily verified; 3) Accurate proportioning of reagents with waste; and, 4) Ability to visually verify that all of the waste has been stabilized and take confirmatory samples of the bottom of the excavation. 1) Increased worker exposure; 2) Larger support area is typically required to stockpile material and set-up process equipment; 3) Generally more labor intensive; 4) Potential need to handle and treat contaminated groundwater during excavation and backfilling operations; and, 5) Potential need for excavation support systems.
