chapter water quality

7/26/2019 chapter water quality

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WASTEWATER

TREATMENT

TECHNOLOGY

BPS4613

Chapter 1


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Outline

Introduction to wastewater treatment

technology

Water Quality and Regulation

-portable water and surface water- EQA 1974


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Learning Outcomes

At the end of this lecture, student should be

able:

Outline the layout of wastewater treatment plant

Discuss the wastewater treatment technology

Prepared by: Afiza Abdullah Suhaimi /01300/ Ftech /042012


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What comes down the

sewer?



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What is wastewater

treatment

Refer to sewage treatment, or domestic

wastewater treatment

process of removing contaminants from

wastewater, both runoff and domestic



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Objectives of wastewatertreatment

To produce waste stream (effluent)

To discharge or reuse them back into theenvironment


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The Wastewater Treatment

Process

Preliminary Treatment

Primary Treatment

Secondary Treatment

Tertiary Treatment

Sludge Handling &

Treatment


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3 stages of water treatment

Primary

solids are separated

Secondary dissolved biological matter is converted into a solid mass by

using water-borne bacteria

95% of the suspended molecules should be removed

Tertiary biological solids are neutralized then disposed, and treated

water may be disinfected chemically or physically



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A little more detail..



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Preliminary treatment

Remove large objects

Ex: sticks, rags, toilet paper

Raked screen

To prevent clogging in equipment in sewage

treatment plant



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Preliminary Treatment

CoarseScreens

(optional)

GritRemoval

(optional)

FineScreens

Sewer Primary

treatment

Screeningstreatment

ScreeningstreatmentGrittreatment


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Treatment stages - Primary

treatment

In primary treatment screening and sedimentationremove some of the suspended solids and organicmatter. The effluent from primary treatment will contain

high amounts or organic matter

typical materials that are removed during primarytreatment include fats, oils, and greases (FOG) sand, gravels and rocks (grit) larger settleable solids including human waste, and floating materials


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Primary Sedimentation

Tank

Remove grease, oil

Fecal solid settle, floating

material rise to the surface

Produce a homologous liquid

for later biological treatment

Fecal sludge are pumped to

sludge treatment plant


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Primary Treatment

PrimarySettlement

SecondaryTreatment

Sludge

Treatment

Preliminary

Treatment


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Secondary Treatment

Secondary sewage treatment is directed at the

removal of biodegradable organic and

suspended solids, mainly using biological unitprocesses. Disinfection may be included in

secondary sewage treatment.


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Secondary Treatment

Soluble organic fraction removed by biological treatment typically by either tricklingfilters or activated sludge plant (ASP) but could be something else.


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Secondary Treatment

SecondaryTreatment

TertiaryTreatment/

Outfall

Sludge

Treatment

Primary

Treatment


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Treatment stagesTertiary

treatment

Tertiary sewage treatment includes the removal ofnutrients, toxic substances including heavy metals andfurther removal of suspended solids and organic.

Effluent from tertiary treatment is of a high standardand suitable for reuse

remove disease-causing organisms from wastewater

3 different disinfection process Chlorination

UV light radiation

Ozonation


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Outline of

Wastewater Treatment


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1 Screening

Three course screens collect

debris such as rags, plastics

and larger solids. Thescreenings got to the

landfill.



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2 Pre-aeration &

grit removal

Air is pumped into

the pre-aeration

tank where grit

falls out of

suspension into acollection hopper.



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3 Sedimentation

Sedimentation tanks allow heavy solids to settle to

the bottom and fats, oils and greases to rise to the

top. About 60% of solid matter is removed at this

point.



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4 Aerated lagoons

Air is pumped into the lagoonsby large paddle aerators to

provide oxygen to help

microbiological organisms grow

and consume the organic

material as a food supply



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4 Aerated lagoons

Air is pumped into the lagoonsby large paddle aerators to

provide oxygen to help

microbiological organisms grow

and consume the organic

material as a food supply



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6 UV

disinfection

Banks of ultra

violet lamps

mounted in the

wastewater

channel emit

light of a

wavelength thatkills 99.9% of

bacteria as the

wastewater

flows past.



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8 Outfall structure

This distributes the

discharge along 50m of

rock embankment

providing better mixingand a more aesthetic

interface with the river.

7 Wetland pond and land passage

This facility allows the flow to pass

through a wetland pond and a rock

land passage before entering the

river. It also provides addition storage

for wastewater at high river levels

and some extra treatment.


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9 Sludge digesters

Sludge is held in digesters for 20

days at 35C. Anaerobic

breakdown occurs producing a

more stable and more easily

dewatered sludge.


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Summary



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Questions



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