Table 6 Advantages and limitation of physical and chemical methods in water, soil, and air pollution

1

Soil pollution

a)

Physical method

Advantages

Disadvantages

References

Soil washing

• Cost-effective and time-saving

• Remove a range of contaminants, both organic and inorganic at the same time

• Require large area in the setup of system

[121]

• Not work on very silty and clayey sites

• Wastewater from soil washing contains chemical additives, which may need specialized treatment which is generally difficult and expensive

Soil covering

• Cost-effective and time-saving

• Polluting ground water

[122]

Soil replacement

• Enhance load-bearing capacity

• Reduce settlement

• Improve stability of soft soils

• Costly method

[121]

• Require proper compaction and compatibility between the replacement material and the existing soil

Encapsulation

• Minimum water ingress and leachate generation

• Avoid the escape of gases and vapors

• Long-term program of monitoring and maintenance

[123]

• Groundwater pollution

Nano-remediation

• No groundwater is pumped out

• No soil transportation

• Better remediation

• Very small spaces in the subsurface

• Nanoparticles remain suspended in groundwater

[121]

• Nanomaterials used for remediation do not move very far from their injection point

b)

Chemical method

Vitrification

• Significant reduction of waste

• Costly method

[124]

• Maintenance of poisonous gases is difficult

• Significant advantage in terms of storage and disposal

• Treat various waste such as soil with buried waste, dried sludges, tailings, sediments, organic waste, chemical waste, radioactive waste, and mixture of hazardous waste

Chemical leaching

• Heavy metals can be easily recovered

• Significant amount of chelating agent is required

[121]

Chemical fixation

• Conversion of pollutants into less toxic form and reduced their bioavailability, mobility, and ecological risk

• Influenced by environmental conditions

[125]

• Material used are metallic oxides, clays, or biomaterial

• Cost-effective

Electrokinectics

• Protecting natural ecosystem

• Consumption of electric energy

[126]

• Effective in the treatment of saturated and unsaturated soils

• Effects of electricity on soil characteristics

Chemical oxidation

• Effective for the removable of polycyclic aromatic hydrocarbon

• By-products of chemical oxidation are of potential risk to the environment

• Further research is required to achieve maximum pollutant removal efficiency

[127]

• Effective for the removable of various recalcitrant organic compounds

• Used in combination with other remediation methods

• Require less time

• Can be easily modified

2

Water pollution

a)

Physical method

Sewage dumping

• Labor-saving

• Putrid odor

[128]

• Produce energy

• Bacterial imbalance

• Fertilizer production

• High installation costs

• Reduce public health risk

• More use of power

• Maintenance costs

• Environment footprint

• Environment friendly

• Massive land utilization

Mechanical garbage collector

• Remove suspended solids up to 2–3 mg

• Available at low cost

• Easy to operate

• Simple construction

• Potable

• Work long time

• Human resources are not used

[129]

• Cannot withstand higher loads

• It can clear drain width up to its width only

• Sound and vibration during process

Mechanical sewage collector

• High efficiency of removable of suspended solids

• Easy to opeate

• Cost-effective

• Eutrophication

[130]

Active pharmaceutical ingredient

• Removing fats and oils from wastewater

• Treat wastewaters of refineries, petrochemicals and chemical plants, and other industries

• Cannot produced large varieties of products

[131]

Corrugated plate interceptor (CPI)

• High efficiency of oil and fat removal

• Low-energy consumption

• Simple operation

• Using corrosion-resistant plates, acid, alkalinity

• Dense structure raises concerns about deformation

• Large surface area is required

• Expensive oil/bottom scrapers required that are maintenance intensive

• Ineffective with small oil droplets or emulsified oil

• Require long retention time to achieve efficient separation

[132]

Dissolved air flotation

• Small space requirement

• Recovered solids are 3–4 times thicker than gravity sedimentation

• Faster processing time

• Low initial cost but high operational cost

[133]

b)

Chemical method

Iron-enhanced sand filters

• Treat dissolved phosphate

• Decrease eutrophication

• Require better analytical method for detection

[134]

Chlorination

• Cost-effective

• Remove microorganism

• Chlorine can be toxic

• Cause irritation to the eyes, nasal passages, and respiratory system

[135]

Advanced oxidation process

• Remove organic contaminants from water

• Not producing large sludge

• Rapid reaction rate with less retention rate

• Not require large area

• High operating and maintenance cost

• Complex chemistry to specific contaminants

[136]

Photochemical degradation

• Degrade insecticides and pesticides

• Need improvement to achieve complete mineralization

[166]

Ozonation

• Good removable rate for all pesticides

• Ozone has short life span

• It should be generated on-site, which increases the cost of treatment

• Free redicals causing side effects to human

[136]

Fenton

• Remove organic contaminants

• More toxic intermediate products

• Costly

[167]

Adsorption

• Cost-effective

• Fast, flexible, and simple design

• Continuous removal of entrapped sludge

[136]

3

Air pollution

a)

Physical method

Scrubbers

• Small space requirements

• No secondary dust source

• Handles high temperature and humidity gas streams

• Corrosion problems

• High-power requirements

• Water-disposal problems

[123]

Electrostatic precipitators

• Reduce mercury emission

• Home air cleaners

• Incinerators

• Used in coal-burning plants

• Less effective in removing very small particles and gaseous pollutants

• High setup cost

[168]

Baghouse filter

• Gentle cleaning method extends filter bag lifespan

• Low operational cost

• Require more space

• Not efficient as pulse-jet system

[96]

b)

Chemical method

Flue gas desulfurization

• Simple process

• No sewage and acid treatment

• Low-energy consumptions

• Purified flue gas does not need secondary heating

• Low sulfur removal efficiency

• Large investment

• Large equipment

• Large floor area

• High technical requirements for operation

[169]

Carbon sequestration

• Reduces the emission of greenhouse gases

• Costly process

[120]