SUSTAINABLE WASTEWATER TREATMENT

ADAM WONG | CHLOE SIM | KOK KA SHING | PUI CHUN SHIAN | YEONG POH LING | ZACHARY OOI

WHAT IS WASTEWATER?• Liquid waste/sewage discharged into

water bodies

• Used water/liquid that contains impurities or pollutants in different forms

• Produced from different activities (Industrial, Commercial, Household etc)

• Waste from kitchen, toilet, laundry, swimming pools etc.

SOURCES OF WASTEWATER?

1 – Domestic Wastewater

Ø Wastewater from normal living areaØ Sanitary wastewaterØ Generated by home dwellings, public restrooms, hotels, hospitals

& other health centersØ Mostly residential and commercial areaØ 99.9% of water containing only 0.1% of organic & inorganic

solids & also microorganisms

2 – Industrial Wastewater

Ø Generated by large scales from industry areas Ø Contains conventional pollutantsØ Contains toxic pollutants

SUSTAINABLE WASTEWATER TREATMENT• Effective, simple to

operate & low cost

• Environmental-friendly

• Combination of physical, chemical & biological processes

• To remove solids, organic matter from

wastewater

• Partial reduction or complete removal

of excessive impurities in wastewater

Objectives of wastewater treatment :

• Protect the health of humans & environment

• Preserve & protect environmental

quality

• Need to be able to recover nutrients and energy from

wastewater

WASTEWATER TREATMENT METHODS

• Application of physical forces to treat sewage

• No changes chemically or biologically

• Eg. Screening, mixing, sedimentation, filtration etc

• Involves using chemical reaction to improve water quality

• Removal or conversion of pollutants are done by addition of chemicals

• Eg. Precipitation, disinfection, chlorination etc.

• Removes pollutants by biological activity

• Microorganisms such as bacteria are used in biochemical decomposition

• Can be divided into aerobic/anaerobic methods based on availability of oxygen

TYPES OF WASTEWATER TREATMENT SYSTEM

INDIVIDUAL SEPTIC TANK

CONNECTED SEWAGE SYSTEM

INDIVIDUAL SEPTIC TANK - Commonly used in Msia

- Multi chamber storage tank thatseparates the liquid between thesolid waste

- Liquid is allowed to flow out of thestorage tank & be disposedseparately

- Can partially treat sewage

- Of low quality & bad smell

- Works by allowing raw sewage toflow into tank whereby the solidwaste/ sludge settles at the bottomof the tank

CONNECTED SEWAGE SYSTEM- have sewage outlets that are

directly linked to a sewagetreatment plant

- Is a combined plant that convertsraw sewage into effluent and solidwaste

- Treats water by combining oxygenand organic waste to speed up anatural biological breakdown

- Comprises a network ofunderground sewer pipes, pumpstations, sewage treatment plants& sludge treatment facilities

- Generally operate by gravity

WASTEWATER TREATMENT PROCESSES

Wastewater undergoes several stages in its treatment process which can be classified into 3 different stages.

PRELIMINARY TREATMENT

What is the purpose?

to protect the operation of the wastewater treatment

plant.

-Preliminary Treatment operations typically includes

screening, grit removal.

-.Remove or to reduce in size the large, entrained, suspended

or floating solids. Example: pieces of wood,

cloth, paper, plastics, garbage

-Remove heavy inorganic solids , called grit. Example:

sand and gravel, metal or glass.

-Remove excessive amounts of oils or

greases.

Primary

Secondary

Tertiary

• Mainly involves removing solids & some organic

materials• Solids are removed or

separated from wastewater by sedimentation

• Purpose : reduce the velocity of wastewater sufficiently to permit solids to settle and

floatable materials to surface

• Biological treatment is used to remove organic & suspended solid waste

• Uses biological activity to catch dissolved organic matter

• Purpose : reduce BOD (biochemical oxygen demand). Wastewater is cleaned by microorganisms

• Water is thoroughly cleaned by using advance treatment systems

• Chemicals such as disinfection are poured to reduce nitrogen & phosphates

• Bacteria is used to denitrify nitrates in water to produce N02 which is then released into atmosphere

• Includes both biological & chemical treatments

CONVENTIONAL WASTEWATER TREATMENT

PROCESS

SEDIMENTATION TANKS AND CLARIFIERS

Typical Sedimentation Tanks

Rectangular Horizontal Flow Tank

Circular, Radial-flow tank

Hopper bottomed, upward flow tank

APPROACHES TO SECONDARY TREATMENT

Fixed Film Systems

Suspended Film Systems

Lagoon Systems

LAGOON SYSTEM

ACTIVATED SLUDGE SYSTEM

WASTEWATER MANAGEMENT SYSTEM

A PROCESS USED TO CONVERT WASTEWATER

• REUSE AND RECYCLING

• COLLECTION of WASTEWATER1) CENTRALIZED SYSTEMS2) DECENTRALIZED SYSTEMS

• AWARENESS of WASTEWATER

• TREATMENT of WASTEWATER

1. REUSE & RECYCLING WASTEWATER• TREATED WASTEWATER OR IN SOME CASES

URBAN RUNOFF OR STORM WATER ( RAIN WATER HARVESTING ) COULD NE REUSED EFFICIENTLY.

• WATER RECYCLING IS REUSING TREATED WASTEWATER FOR BENEFICIAL PURPOSES - AGRICULTURAL AND LANDSCAPE IRRIGATION- DRINKING WATER- INDUSTRIAL PROCESSES- TOILET FLUSHING - REPLENISHING A GROUND WATER BASIN.

• ENSURE WATER QUALITY APPROPRIATE FOR THE USE

2. COLLECTION OF WASTE WATER

• GATHER THE USED WATER FROM OUR HOMES, BUSINESSES AND INDUSTRIES AND CONVEY IT TO A WASTEWATER TREATMENT PLANT

• TWO WAYS CAN BE USED TO COLLECT WASTEWATER :I) CENTRALIZED SYSTEMS

II) DECENTRALIZED SYSTEMS

I) CENTRALIZED SYSTEMS• PUBLIC SEWER SYSTEMS • SERVE ESTABLISHED TOWNS AND

CITIES

• PROVIDE TREATMENT AND DISPOSAL SERVICES FOR NEIGHBORING SEWER DISTRICTS

• LARGE-SCALE SYSTEM• GATHER WASTEWATER FROM MANY

USERS FOR TREATMENT AT ONE OR FEW SITES

• ECONOMICAL, ALLOW FOR GREATER CONTROL, REQUIRE FEWER PEOPLE

• PRODUCE ONLY ONE DISCHARGE TO MONITOR INSTEAD OF SEVERAL.

II) DECENTRALIZED SYSTEMS • DO NOT CONNECT TO A PUBLIC SEWER SYSTEM

• MAY BE TREATED ON SITE (MOST COMMON) OR DISCHARGED TO A PRIVATE TREATMENT PLANT

• REQUIRE WELL TRAINED STAFFS AND HIGH COST OF MAINTENANCE

q failure cases happenedq lack of improper

maintenanceq overcome by providing

the person in charge of maintaining the system with enough skills and practices

3. TREAMENT OF WASTEWATER• TO REDUCE THE LEVEL OF

POLLUTANTS IN THE WASTEWATER

• ALLOW HUMAN AND INDUSTRIAL EFFLUENTS TO BE DISPOSED OF WITHOUT DANGER TO HUMAN HEALTH

• UNACCEPTABLE DAMAGE TO THE NATURAL ENVIRONMENT

• CAN BE NATURALLY TREATED BY THE SUN, VEGETATION, SOILS AND MICROORGANISMS

ADVANTAGES & DISADVANTAGES OF WASTEWATER TREATMENT

Can provide clean water that is potable

Maintain clean water for reuse

Filter out potential disease-causing microorganisms & destroys harmful organisms

Purifies water

Provides job opportunities for water treatment researches & maintenance

Saves time, energy & resources

Increased cost & financing

Maintenance troubles

Triggered health concerns among public

CASE STUDY 1 : MALAYSIA

- A SOUTHEAST ASIAN COUNTRY WITH APOPULATION OF 30 MILLION PEOPLE.

- HAS 100% ACCESS TO IMPROVEDWATER SOURCE AND 96% ACCESS TOIMPROVED SANITATION.

WATER CATCHMENT AREAS

• ONE OF THE MAINS SOURCE OFWATER FOR MOST OF MALAYSIA.

• TOTAL OF 189 RIVER BASINS IN THEENTIRE MALAYSIA.

• BIGGEST WATER CATCHMENT AREAIN WEST MALAYSIA: BANJARANTITIWANGSA.

HOW DO THEY WORK?

DAMS

• ANOTHER MAIN SOURCE OF WATER FOR MALAYSIANS.

• TOTAL OF 34 DAMS IN MALAYSIA THAT SUPPLIES WATER.

• SG. SELANGOR DAM, BATU AND KLANG GATES DAM AND ETC SUPPLIES 98% OF WATER TO CITIES LIKE KUALA

LUMPUR & SELANGOR.

PROBLEMS WITH DAMS

• CANNOT REPLENISH FAST ENOUGH DURING THE DRY

SEASON.

• CAN ONLY STORE SO MUCH WATER THAT IS ENOUGH FOR

A PERIOD OF TIME.

• DESTROYS SURROUNDING ECOSYSTEM.

INDAH WATER KONSORTIUM

• A WHOLLY OWNED GOVERNMENTCOMPANY TASKED WITHDEVELOPING AND MAINTAININGAN EFFICIENT SEWERAGE SYSTEM INWEST MALAYSIA.

• FOUNDED IN 1994

• OPERATES IN EVERY STATE IN WESTMALAYSIA EXCEPT KELANTAN ANDJOHOR.

BIOEFFLUENT

• A GREEN INITIATIVE PROGRAM.

• REUSES FILTERED WASTEWATERTO BE USED IN OTHER SECTORS.

• USES PREVIOUS TECHNOLOGYLIKE REVERSE OSMOSIS, SANDFILTERING AND ETC.

BENEFIT OF BIOEFFLUENT

• EFFICIENT POLLUTION CONTROL

• ALLOWS FOR A MORE SUSTAINABLE WATER RESOURCE

• REDUCE PRESSURE ON NATURAL WATER RESOURCES

PROCESS OF MAKING BIOEFFLUENT

POSSIBLE PROBLEMS TO THE SYSTEM

BAD ODOUR COMING FROM SEWAGE PLANTS

• ONE OF THE MOST NOTABLE PROBLEM.

• CAUSES AN UNHAPPY WORKING PLACE AND EFFECTS RESIDENCES NEARBY.

• HYDROGEN SULPHIDE IS THE CAUSE OF THE BAD SMELL.

INSUFFICIENT SPACE FOR NEW WATER TREATMENT PLANTS

• MORE NOTICEABLE IN PLACES LIKE SINGAPORE OR WHERE LAND IS

SCARCE.

• HARD TIME FOR OLD PLANTS TO DEAL WITH NEW LARGER VOLUME

OF WASTE.

• RETROFIT OLD PLANTS WITH NEWER TECHNOLOGY TO INCREASE

TREATMENT CAPACITY.

AGING INFRASTRUCTURE

• HAPPENS MORE FREQUENTLY IN STILL DEVELOPING COUNTRIES.

• HIGHER AND HIGHER MAINTENANCE COST THUS CAUSING A WASTAGE OF

TAXPAYERS MONEY.

• RISK OF A TREATMENT PLANT SHUTTING DOWN.

CASE STUDY 2 : SINGAPORE

• Southeast Asian island country, with an estimated population of 5.5 million living on less than 750

square kilometers of land

• Singapore is known for its robust economy but is

insufficient in one of the world’s most important daily

resources, water

• Location of centre: 20 KohSek Lim Road, Singapore

• WATER HAS ALWAYS BEEN SINGAPORE’S FIRST NATIONAL PRIORITY

• LEE KUAN YEW, SINGAPORE’S FIRST PRIME MINISTER, PUSHED TO DEVELOP A SELF-SUFFICIENT WATER SUPPLY OF SINGAPORE IN RESPONSE TO THE SHORTAGE OF WATER IN THE 1960S AND ‘70S

• OVER THE LAST 50 YEARS, SINGAPORE HAS BUILT A ROBUST AND DIVERSIFIED SUPPLY OF WATER KNOWN AS THE “FOUR NATIONAL TAPS”.

1. WATER FROM LOCAL CATCHMENT

• REPRESENTS ONE OF THE PILLARS OF SINGAPORE’S SUSTAINABLE WATER SUPPLY

• SINCE 2011, THE WATER CATCHMENT AREA HAS BEEN INCREASED FROM HALF TO TWO-THIRDS OF SINGAPORE’S LAND SURFACE

- THE MARINA, PUNGGOL AND SERANGOON RESERVOIR.

• IN THE LONG RUN, THE WATER CATCHMENT AREA WILL INCREASE TO 90% OF SINGAPORE’S LAND AREA

- MADE UP OF UNPROTECTED CATCHMENTS WHICH CONSISTS OF LAND SUCH AS RESIDENTIAL, COMMERCIAL AND NON-POLLUTIVE INDUSTRIAL

2. IMPORTED WATER

• ONLY ABLE TO SUPPLY HALF THE NATION’S WATER SUPPLY.

• 50% MORE IS IMPORTED FROM, JOHOR, MALAYSIA

• THE CONTRACT DUE TO EXPIRE IN 2061

3. NEWATER• THE MAIN PILLAR OF SINGAPORE’S WATER

SUSTAINABILITY

• IS A HIGH-GRADE RECLAIMED WATER TREATMENT PLANT USING DOMESTIC WASTEWATER WHICH IS THEN FURTHER PURIFIED USING ADVANCED MEMBRANE TECHNOLOGY AND ULTRA-VIOLET DISINFECTION

• CURRENTLY, SINGAPORE’S FOUR NEWATER PLANTS ARE ABLE TO CONTRIBUTE 30% OF THE NATION’S CURRENT WATER NEEDS

• IS FORESEEN THAT BY 2060, NEWATER WILL BE ABLE TO MEET UP TO 50% OF SINGAPORE’S FUTURE WATER NEEDS.

4. DESALINATED WATER• TREATING SEAWATER

• IS THE MOST ENERGY-INTENSIVE AND MOST EXPENSIVE SOURCE OF WATER TO PRODUCE

• TWO DESALINATION PLANTS WITH A COMBINED CAPACITY OF 100MGD CAN NOW MEET 25% OF WATER NEEDS IN SINGAPORE

• IS ANTICIPATED THAT DESALINATED WATER CAN MEET UP APPROXIMATELY 30% OF SINGAPORE’S FUTURE WATER NEEDS

NEWATER TECHNOLOGY TREATMENT PROCESS (4 STEPS)

STEP 1: MICROFILTRATION (MF)

• WHERE THE TREATED UTILIZED WATER IS PASSED THROUGH A MEMBRANE. SUSPENDED SOLIDS, COLLOIDAL PARTICLES, DISEASE-CAUSING MICROBES, AND PROTOZOAN CYSTS ARE FILTERED OUT AND RETAINED ON THE MEMBRANE SURFACE

• THE FILTRATE CONTAINS ONLY WATER, DISSOLVED SALTS AND ORGANIC MOLECULES.

Step 2: Reverse Osmosis (RO)• In which a semi-permeable membrane is used• has very small pores, allowing only very small molecules like water molecules

to pass through• undesirable contaminants such as bacteria, viruses, heavy metals, nitrate,

chloride, sulphate, disinfection by-products, aromatic hydrocarbons, pesticides and others cannot pass through

• the processed water is free from viruses, bacteria and contains negligible amount of salts and organic matters.

STEP 3: UV DISINFECTION• THE WATER IS ALREADY OF A HIGH GRADE WATER QUALITY

• ACTS AS A FURTHER SAFETY BACK-UP TO THE RO

• ULTRAVIOLET OR UV DISINFECTION IS USED TO ENSURE THAT ALL MICROORGANISMS AREINACTIVATED AND THE PURITY OF THE PRODUCT WATER GUARANTEED.

Step 4: Before Storing• the pH value of the NEWater is to be are balanced with the addition

of some alkaline chemicals to restore the acid-alkali or pH balance• After the pH balance has been achieved, the NEWater is now ready to

be piped off to its wide range of applications.

WHY IS NEWATER THE MAIN PILLAR OF SINGAPORE’S WATER SUSTAINABILITY?

• BECAUSE NEWATER HAS MORE QUALITY THAN PUB WATER

1) COLOUR• 20,000 EXAMINATIONS IN THE COURSE OF

THE RECENT TWO YEARS HAVE BEEN DIRECTED

• HAVE DETERMINED THAT NEWATER IS CLEANER THAN (PUBLIC UTILITIES BOARD) PUB WATER

• PHYSICALLY, NEWATER IS CLEAR AND SHINING

• THE RIVER SOURCES AND RESERVOIR WATER HAS MORE COLOR AS THEY CONTAIN MORE MINERALS AND NATURAL SUBSTANCE

2) SUSPENDED PARTICLES

• THE RIVER SOURCES AND RESERVOIR WATER ALSO CONTAIN MORE SUSPENDED PARTICLES

• THESE PARTICLES ARE WASHED INTO RIVERS AND RESERVOIRS BY RAINFALL RUNNING OFF THE GROUND

• NEWATER THEN AGAIN IS CLEARER, MUCH CLEARER THAN PUB WATER.

3) LEVEL OF ORGANIC SUBSTANCES • THE ORGANIC SUBSTANCE OF NEWATER IS

LESS THAN ONE-TENTH OF PUB WATER CAUSING INDUSTRY USERS TO FIND NEWATER TO BE APPEALING

• THE WAFER FABRICATION PLANTS TAKE THE PUB WATER AND PROCESS IT TO REDUCE THE ORGANIC SUBSTANCE TO A LEVEL THAT IS ACCEPTABLE FOR THEIR OPERATIONS.

• STARTING FROM NEXT YEAR, THE WAFER FABRICATION PLANTS IN SINGAPORE WILL UTILIZE NEWATER INSTEAD OF PUB WATER BECAUSE NEWATER IS CLEANER THAN PUB WATER, AND IS MORE APPROPRIATE FOR THEIR OPERATIONS.

4) BACTERIA COUNT• HARMFUL TO HEALTH AND ARE FOUND

IN ANIMAL WASTE AND SOIL

• RAIN THAT FALLS ONTO THE GROUND WILL CARRY THE BACTERIA INTO THE RIVERS AND THE RESERVOIRS

• BACTERIOLOGICAL QUALITY OF NEWATER IS AS GOOD AS PUB WATER DUE TO THE FACT THAT PRESENCE OF BACTERIA AND VIRUS IS NOT DETECTABLE, THEREBY MEETING THE WORLD HEALTH ORGANIZATION'S STANDARDS

RECOMMENDATIONS FOR FUTURE

IMPROVEMENTS

1) MEMBRANE BIOREACTOR (MBR)

• MEMBRANE SYSTEMS HAVE BEEN CRITICAL TO THE DEVELOPMENT OF ADVANCED WATER-RECLAMATION SYSTEMS

• PROVIDE EXCELLENT PRE-TREATMENT FOR REVERSE OSMOSIS (RO), WHICH CAN REMOVE A VARIETY OF DISSOLVED CONSTITUENTS

2) NATURAL TREATMENT SYSTEM (NTSS)

• HAVE THE ADVANTAGE OF BEING ABLE TO REMOVE A WIDE ASSORTMENT OF CONTAMINANTS, INCLUDING NUTRIENTS, PATHOGENS, AND MICRO-CONSTITUENTS SUCH AS PHARMACEUTICALS AND ENDOCRINE-DISRUPTING CHEMICALS

• IS PROVEN EFFECTIVE FOR THE TREATMENT OF POTABLE WATER

3) NANOTECHNOLOGY

• INCLUDE IMPROVED MEMBRANES AND CONFIGURATIONS

• MORE EFFICIENT PUMPING AND ENERGY-RECOVERY SYSTEMS

• THE DEVELOPMENT OF PROCESS TECHNOLOGY, SUCH AS MEMBRANE DISTILLATION.

4) MICROBIAL FUEL CELLS

• ELECTRICAL ENERGY CAN BE EXTRACTED DIRECTLY FROM ORGANIC MATTER PRESENT IN THE WASTE STREAM BY UTILIZING ELECTRON EXCHANGE TO CAPTURE THE ENERGY PRODUCED BY MICROORGANISMS FOR METABOLIC PROCESSES

• HAS THE POTENTIAL TO PRODUCE ELECTRICAL ENERGY DIRECTLY FROM ORGANIC MATTER IN THE WASTE STREAM

5) URINE-SEPARATING TOILET

• 3 DIFFERENT TANKS ARE CONSTRUCTED, WHICH MAKES THE PROCESS OF WASTE TREATMENT MUCH EASIER AND EFFICIENT

• KEY TO MANAGE NUTRIENTS WITH MINIMAL REQUIREMENTS FOR OUTSIDE RESOURCES, SUCH AS ADDITIONAL ENERGY.

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