Land pollution

Introduction Solid waste is classified into five main types by

making reference to the sources of waste andthe institutional arrangements for waste

collection and disposal. These five types of solid waste are municipal solid waste,

construction & demolition (C&D) waste, chemical waste, special waste and other solid

waste. The detailed interpretations of some commonly used terms are described below.

Municipal solid waste

It includes domestic waste, commercial waste and industrial waste.

Domestic waste It refers to household waste, waste generated

from daily activities in institutional premises and refuse collected from public cleansing

services. Public cleansing waste includes dirt and litter collected by the Food and

Environmental Hygiene Department (FEHD), marine refuse collected by the Marine Department and waste from country parks collected by the Agriculture, Fisheries and Conservation Department.

The TWO major domestic wastes are plastic and metal cans.

Plastic

Bacteria can decompose some types of the plastics. These are called biodegradable materials, and will not cause serious pollution problem after decomposition. However, non-biodegradable plastics, which cannot be decomposed, will lead to serious pollution problems.

Metal can

Metal cans are not biodegradable. When they are thrown into the environment, they cause land or water pollution. Besides, these natural resources are wasted.

Commercial waste It is waste arising from commercial activities

taking place in shops, restaurants, hotels, offices, markets in private housing estates, etc. It is collected mainly by private waste

collectors. However, some commercial waste is mixed with domestic waste and

collected by the FEHD. Some not mixed is also collected by the FEHD for historical

reasons.

Industrial waste It is waste arising from industrial activities and does not include C&D

waste and chemical waste. It is usually collected by private waste collectors.

However, some industries may deliver their industrial waste directly to landfills

for disposal

Current situation

Household and other municipal waste loads have risen steadily, in line with the growth in population and wealth of the community. There is no sign of a let-up because another two million people are expected to live in the SAR by 2016.

                                                                                                    

                

 

Effect  The most important of land pollution

is effect on hygiene. Bacteria, and give off bad smells may decay some of the materials in the garbage. The decayed materials will create problem of hygiene. Pathogenic bacteria and other pests may also grow on the decayed materials and diseases may then be spread.

                                                                                        

             

 

What will happen to the landfills?

                                                                                                 

                   The three strategic landfills will run out of space in 10 to 15 years. Without waste reduction measures and sufficient public filling areas, SENT landfill might run out as early as 2005.

Recycling

Hong Kong recycled about 35 percent of its municipal waste (mostly commercial and industrial waste) and the government wants to increase this to about 60 per cent by 2007. A number of initiatives were undertaken in 2000 with significant support from the green groups.

                                                                                   

                                 

Some of the highlights were: newspaper vendors were encouraged to stop

distributing papers in plastic bags the number of housing estates with waste

separation bins doubled to more than 700 the number of items recycled by hotels and

the airport were increased more recycled products were added to the

government's purchasing guidelines four new temporary sites were allocated for

use by the re-cycling industry

Special waste

-Clinical waste-Animal carcasses-Radioactive waste

Clinical waste Source

-being produced in hospitals and government clinics

E.g. contaminated sharps, infectious waste and human tissues

Deal-Segregating from ordinary refuse and being

collected separately for proper disposal. -Most clinical waste will be disinfected as far as

practicable and disposed at designated landfills. -Human tissues and body parts from operating theatres shall be disposed of by incineration as far as practicable

Animal carcasses

Source: Slaughterhouses Street collections Society for Prevention of Cruelty to

Animals Hong Kong Jockey Club Ocean Park

Deal-Land filling of animal carcasses may generate

health hazards. Some animal Carcasses are infectious and spread diseases.

-It is proposed to build animal carcass treatment facilities (ACTF) for proper disposal of animal carcasses to prevent the spread of diseases.

Low-level Radioactive waste

Source-Industry and medical and educational institutions

Americium-241 Smoke detector sourcesPromethium-147 Luminous watch dials & contaminated articles Radium-226 Lightning conductors and luminous watch dials Thorium-232 Rayon mantles for kerosene lanterns

Deal

The wastes are properly packaged in new stainless steel standard containers

Chemical Waste

Definition Chemical wastes are liquid, semi-

solid and solid wastes which are dangerous in nature or cause a risk of pollution to the environment

Problems Indiscriminate disposal of chemical waste Release into coastal waters causes

damage to local marine life and accumulation of toxins in seafood

Uncontrolled disposal of municipal waste facilities and into sewerage systems and sewage treatment facilities resulting in costly repairs and replacement of these facilities

Solutions The chemical Waste Treatment

Center-CWTC Handle with 100,000 tones

chemical waste per year

Main Activities of CWTC Chemical Waste Collecting Waste Profile Analysis Chemical Waste Treatment Physical/Chemical Treatment Incinerator The Ancillary System are designed to

support the treatment processes. They are Waste Container Handling, Storage Tank Farm, Laboratory Computer System

The Waste Disposal Ordinance on Waste Management Waste Disposal Ordinance 1987Prohibit livestock keeping in urban areasControls of discharge or deposit of

livestock waste in control areas Waste Disposal Ordinance 1991Controls of chemical waste about

packaging, labeling, storage, collection, disposal, import and export activities

Waste Disposal Ordinance 1994Introduce a heavy penalty for illegal damping of waste and make it an offence to breach of the

license conditions of the waste collection and disposal licenses

Waste Disposal Ordinance 1995Control import and export of hazardous and other

waste in accordance with the requirement Waste Disposal Ordinance 1998Expands the regulations making powers for

implementation of the various waste disposal charging schemes

Development of New Waste Legislation Control for the arrangement of clinical

waste and improves control of waste import and export and illegal dumping of waste

Specifies the requirement of clinical waste producers, collectors and disposal facility operatorsAmend the schedules and prescribes fees for clinical waste collection licenses

Gives effect to the new charging scheme for clinical waste through amendment of the regulation

Gives effect to the new charging scheme for clinical waste through amendment of the regulation

Amends the schedules and clarities the definition of chemical waste in light of amendment to the Dangerous Goods Ordinance –DGO

Gives effect to the revised landfill charging scheme

Composition of domestics waste disposed of at waste facilities (% by weight)

Putrescibles

Rattan / Wo o d

Glass

Textiles

Paper

Plastics

Metal

Others

Solutions to pollution problem of plastics

1. By using degradable plastics instead of the non-degradable one

2. Recycling plastics wastes ( remold the plastic)

A. Development of degradable plastics

Plastics normally undergo extremely slow degradation because the enzymes in micro-organism tend to attract only the ends of the polymer chains

Example????????

1.Biopolymers

It is made by living micro-organism such as paracoccus, bacillus and spirullum.

Poly(hydroxybutyrate) PHB, is a natural polyester made by bacteria

Advantage and disadvantage????Advantage: Micro-organisms found in soil and

natural water sources are able to break down the polymer completely within 9 months.

Disadvantage: Very expensive (15 times more

expensive that polyethene)

2.Photodegradable plastics

As polymer consist of long chain Therefore, light sensitive functional

group –c=o are incorporated in the polymer chains.

As a result, the long polymer chains will be broken down into shorter fragment which will facilitate the process of biodegradation under sunlight

3.Synthetic biodegradable process

By incorporating starch or cellulose into the polymer during production.

Advantage

Since micro-organisms digest starch or cellulose the plastic is broken down into tiny pieces.

--larger surface area for the biodegradable--speed up process

Disadvantage

The products of biodegradation may cause water pollution and the rate of biodegradation is still too slow for the large quantity of plastic wastes generated.

B. Recycling of plastics

1. Direct recycling -----This applies only to thermoplastics. The remolded into plastic items.

2. Recycling of energy -----This applies to most plastics. The plastic wastes are burned in the incinerators. The calorific values contained in plastics are quite high.

Advantages: Reduces air pollution due to the

incineration of plastic Less dumping area is required. Reduces the use of petroleum

Disadvantages: The regenerated plastics usually have

deteriorated properties due to repeated thermal and mechanical processing and can only be used for articles which are not subjected to high stress.

It is not very economical to separate the plastic items from the other wastes at present. Moreover, plastic products may contain dyes, politicizes and fillers so that it is very difficult to classify them by observation.

2. Recycling of energy -----This applies to most plastics. The plastic wastes are burnedAdvantages:a.   The energy obtained from burning plastic

waste can be used for heating or generation of electricity

b.   It is not necessary to separate the plastics c.   Less dumping area is required

Disadvantages: Burning plastics produces toxic gases e.g.

PVC will give HCl. Expensive scrubber systems have to be used to remove them.

3. Recycling of chemicals by pyrolysis------for all plastics Similar to cracking, the plastic wastes can

be pyrolyzed (decomposed at high temperature in the absence of air) at 600-900 to give useful small molecules similar to those obtained from the fractional distillation of crude oil. These small molecules (mainly hydrocarbons) are separated by fractional distillation. Some of the small molecules can be used directly as fuels. Other larger molecules may be employed as raw materials in plastic production.

Advantages:

1. The products are useful raw materials for the manufacture of plastics – this reduces the use of petroleum

2. It is not necessary to separate the plastics

3. Less dumping area is required / saves more lands for other uses

Disadvantages : Pyrolysis may produce toxic gases &

expensive scrubber systems have to be used to remove them. The capacity of handling plastic waste by a pyrolysis plant is also small compared to the total amount of plastic waste produced. The running cost of disposal of plastics waste produced. The running cost of disposal of plastics by pyrolysis is much more expensive than land filling.

Measures to Reduce SolidWaste – Reuse & Recycling The key concept in minimizing

waste is “Reduce, Reuse & Recycle (3Rs)”

The practice of reduce, reuse and recycle helps in minimizing waste, reducing the demand for scarce landfill space & saving resources.

Examples:

1. Metal wastes are collected, identified, separated into different metals. The metals are further cleaned & purified.

2. Newspaper & office paper can be collected for recycling for making corrugated card box and paper board.

3. Most of the locally filled glass beverage bottles recovered for reuse through a deposit system.

The end