municipal waste disposal

8/17/2019 Municipal Waste Disposal

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MUNICIPAL WASTE DISPOSAL

MUNICIPAL WASTE DISPOSAL – the depositing, discharge or placing of waste collectedfrom a town, city or community into or on any suitable area.

A.

SOLID MUNICIPAL WASTES

1. Methods of Collection

a. Manual Collection – garbage collectors go to each house to gather solid wastes byhand and deliver them to a roving open garbage truck.

b. Mechanical Collection – solid wastes are collected by specially designed

sanitation trucks that have closed air-tight compartments and equipped withspecial compacting machinery.


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2. Methods of Disposal

a. Incineration – controlled burning of solid wastes which effectively reduces wastevolume by 90-95%. However, environmental laws, such as RA 9003 (Ecological

Solid Waste Act of 2000) and RA 8749 (Clean Air Act of 1999), prohibit thismethod because it causes air pollution.

b.

Sanitary Landfill – method wherein solid wastes are dumped at a pre-planned site,

compacted and covered with a layer of earth. There are two approaches in sanitary

landfill:

•

Trench Method – primarily used in areas with level ground. A tractor/bulldozer digs a trench and trucks dump wastes into the trench. Then the

tractor/bulldozer compacts the wastes and covers them with excavated

earth that was dug from the trench.


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• Area Method – generally used in rolling terrain or low-lying areas. Trucksdump wastes over a selected area and tractors/bulldozers with special

compacting wheels press down on the wastes. The compacted wastes are

then covered with earth hauled from other sites.

B. LIQUID MUNICIPAL WASTES

1.

Methods of Collection

a.

Manual – no longer practiced right now. In the olden times, in some parts of Asia,community collectors went to homes to collect human wastes, carried them in

carts and used as fertilizers for crops.


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b. Sewers – wastewater is carried from buildings through large pipes or conduits and

brought to a sewage treatment plant before being released to natural bodies ofwater.

Two methods of sewer collection are being practiced:

• Old or Combined System – a combined system designed to carry all formsof wastewater.

• New or Separated System – designed to carry BLACK WATER (toiletwater) and GREYWATER (any other forms of wastewater) separately.


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2. Disposal – Before being released to natural bodies of water, wastewater is put through

a series of treatment stages to remove any biological and chemical contaminants thatcan harm human health or ecological systems. The three standard treatments are:

a. Primary – remove large floating or suspended particles, grit (heavy particles such

as sand or gravel) and any excessive amounts of grease or oil from the sewage

through a series of screen grit chamber and sedimentation tanks. If no furthertreatment is performed, the wastewater is disinfected by the addition of chlorine

and discharged into natural bodies of water. If further treatment is needed, the

wastewater goes to secondary treatment.

b. Secondary - employs anaerobic microorganisms to break down organic matter left

in the sewage in a process called BIOLOGICAL OXIDATION or BIOLOGICALAERATION. This process involves the use of a Trickling Filter, wherein sewage

is mixed with air by allowing it to pass through an air spray and cause it to trickle

slowly through a filter or coarsely-crushed rocks, causing the organic material tobreak down into harmless substances. Unless it goes next to the Tertiary

Treatment, the wastewater is disinfected with chlorine and discharged.

c.

Tertiary – also called Advance Wastewater Treatment, it produces drinkingquality water. In this stage, chemical treatment is used to remove undesirable

elements, such as nitrates, nitrogen and phosphorous, that remain after the

Secondary Treatment.

municipal waste disposal

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