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PENGOLAHAN LIMBAH

SECARA KIMIAWI

1. Reaction to produce an insoluble solid

2. Reaction to produce an insoluble gas

3. Reduction of surface charge to produce coagulation of a

colloidal suspension

4. Reaction to produce a biologically degradable substance

from a nonbiodegradable subs.

5. Reaction to destroy or deactivate a chelating agent

6. Oxidation or reduction

Six chemical processes :

• Removing metals alkaline precipitations,

precipitation of the metal as the sulfide,

precipitation as the phosphate, precipitation as

the carbonate, or co-precipitation with another

metal hydroxide, sulfide, phosphate, or

carbonate.

1. Reaction to produce an insoluble solid

Chemical substancesChemical Application

Lime Heavy metals, fluoride, phosporus

Soda Ash Heavy metals

Sodium sulfide Heavy metals

Hydrogen sulfide Heavy metals

Phosporic acid Heavy metals

Fertilizer grade phosphate Heavy metals

Ferric sulfate Arsenic, sulfide

Ferric chloride Arsenic, sulfide

Alum Arsenic, fluoride

Sodium sulfate Barium

1. Reaction to produce an insoluble solid

Raw Waste

pH adjust

Oxidation or

chelating agent

destruct

pH adjust or

Chem addition

Floc Sed Filt

Sludge Dewater, Dry

Conditioning

Steps

Return For Seed

Schematic for Removal by forming

an insoluble substances

• If produce insoluble gas it will remove itself

from solution as it is formed

• Ex :

2 NO2- + Cl2 + 8 H+ N2 + 4H2O + 2 Cl-

• Chlorine added in the form of chlorine gas or

hypochlorite, or another chloride compound that

dissolves in water

2. Reactions to Produce an Insoluble Gas

Chemical substances

CHEMICAL

SUBSTANCE

TREATMENT

TECHNOLOGY

Chlorine gas or other

chlorine compound

(hypochlorite, or chlorine

dioxide)

(1). Breakpoint chlorination to

remove ammonia

(2). Alkaline chlorination of

cyanide

Sulfuric or hydrochloric

acids (technical grade or

waste acids)

Removal of sulfide as

hydrogen sulfide gas

2. Reactions to Produce an Insoluble Gas

• Industrial wastewater consists of colloidal

suspensions

• Destabilized industrial wastewater by

chemical coagulation allow separation

of destabilized colloidal material from

water

3. Reduction of surface charge to produce

coagulation of a colloidal suspension

• Unbiodegradable substances altered to

biodegradable materials

• Hydrolysis (acid or alkaline) break up large

organic molecules into smaller segments

• Ex: Substances from cellulose or derivatives acid

hydrolysis + heat

4. Reaction to produce a biologically degradable

substance from a nonbiodegradable subs.

• Chelating agents : organic materials (EDTA) or inorganic

materials (polyphosphates)

• ORGANIC CHELATING AGENTS :

– Destroy by acid hydrolysis

– Destroy by hydroxyl free radical oxidation :

• Fenton’s reagent (H2O2 + ferrous ions)

• Hydrogen peroxide + UV light

• Ozone + hydrogen peroxide

• Ozone + UV light

– Destroy by adding potassium permanganate + heating

– Pass the wastewater through granular activated carbon

5. Reaction to destroy or deactivate

a chelating agent

• Senyawa yg tidak diijinkan dapat

dioksidasi secara kimia, menjadi CO2 dan

H2O

• Contoh :

– Menghilangkan chromium reducing

hexavalent chrome ions (soluble in water &

highly toxic) menjadi bentuk trivalent

• Reducing agents : SO2, sodium/potasium bisulfit, or

metabisulfit, and sodium or potasium bisulfit plus hydrazine.

• pH acid range

6. Oxidation or reduction to produce a

non objectionable subs.

• Kelebihan pengolahan secara kimia:– Efisiensi tinggi (dapat mencapai angka yang

diinginkan)

– Waktu dentensi relatif singkat sehingga volume reaktor/unit pengolahan relatif lebih kecil

• Kekurangan– Ada penambahan zat aditif sehingga

meningkatkan konsentrasi Total Dissolved Solid (TDS). Penyisihan TDS relatif sulit dan mahal: membran atau destilasi

– Meningkatkan beban pengolahan

– Biaya bahan kimia cukup mahal = biaya untuk energi

Chemical treatment

I. Introduction

A. Reasons to Soften

1. Reduce Soap Consumption

2. Improve Aesthetics of Water

B. Reasons not to Soften

1. Expensive Process

2. May be less healthy

3. Hot Water Heaters last longer

Water Softening

3. Competes with health related costs

II. What is Hardness?

C. Carbonate Hardness as CaCO3 = T. Alkalinity as CaCO3

D. Non-Carbonate Hardness = T. Hardness – T. Alkalinity

Water Softening

a. Removed by Boiling

b. Removed by Lime

a. Unaffected by boiling

b. Removed by Soda Ash

B. T. Hardness, mg/L, as CaCO3 = (Ca X 2.5) + (Mg X 4.12)

(MW=100) (40 X 2.5 = 100) (24.3 X 4.12 = 100)

A. Hardness Classifications

a. Soft Water = 0 to 70 mg/L

b. Moderate Hardness = 71 to 150 mg/L

c. Hard Water = > 150 mg/L

Water Softening

III. Methods of Softening

A. Lime-Soda Ash Chemistry

1. 1st Stage Treatment (Lime only)

* CO2 + Ca(OH)2 CaCO3 + H2O

* Ca + 2HCO3 + Ca(OH)2 2CaCO3 + 2H2O(pH 8.3-9.4)

* Mg + 2HCO3 + Ca(OH)2 CaCO3 + Mg + CO3 + 2H2O(pH >10.8)

a. Carbon Dioxide Removal (< 8.3 pH)

b. Carbonate Hardness Removal

c. Magnesium Hardness Removal (>pH 10.8)

* Mg + CO3 + Ca(OH)2 CaCO3 + Mg(OH)2

* Mg + SO4 + Ca(OH)2 Ca + SO4 + Mg(OH)2

* Ca + SO4 + Na2CO3 Na2SO4 + CaCO3

2. 2nd Stage Treatment (Soda Ash)

* Ca + Cl2 + Na2CO3 CaCO3 + 2NaCl

PENGOLAHAN LIMBAH

SECARA BIOLOGI

• Proses yang menggunakan bahan organik sebagai

makanan bagi bakteri atau m.o lain

bakteri, fungi, rotifera

• O2 dibutuhkan baik dalam bentuk yg larut ataupun anion

spt sulfat dan nitrat (aerobik)

• Produk akhir : penurunan jumlah polutan organik,

meningkatnya jumlah m.o, CO2, H2O, by-products

• Sebagai pengolahan sekunder, pengolahan secara

biologi dipandang sebagai pengolahan yang paling

murah dan efisien.

• Proses secara biologi berlangsung selama 1-7 hari

Pengolahan limbah secara biologi

Pengolahan limbah secara biologi

• Membutuhkan O2

• Perlu energi besar

• u/ BOD < 400 mg/l

• u/ COD < 2000 ppm

Aerobik

• Tidak membutuhkan O2

• Perlu energi kecil

• u/ BOD > 4000 mg/l

• u/ COD < 2000 ppm

Anaerobik

• Jika bakteri berasal dari limbah maka yang tumbuh

bermacam-macam jenis bakteri dari mulai yang bersifat

patogen maupun probiotik.

• Dalam kondisi semacam ini maka proses hanya dapat

berlangsung secara aerobik.

AEROBIK

Organic Matter

M.O O2CO2M.O H2O

Oxidized Organic Material

Mikroorganisme

Microbial Metabolism

• General nutritional requirements -:

• Carbon Substrate (Org. Or Inorg.)

• Electron Donor

• Energy Source

• Need for molecular oxygen.

• Basic elements required-C,O ,N,H, P,S

• Inorganic elements: K,Mg,Ca,Fe,Na,Cl

-

SINGLE

BACTERIUM

2.0m

ORGANIC

POLLUTANT

AND NUTRIENTS

(C,P,N,O,Fe,S…)

GROWTH - CELL DIVISION

INCREASE IN BIOMASS

(assimilation)

CO2 evolved

(dissimilation)

O2

consumption

Controlled release of energy

Slow Burning!

Mikroorganisme

Mikroorganisme

obligate aerobes:

need oxygen, use it as terminal electron acceptor

obligate anaerobes:

cannot grow in the presence of oxygen

facultative anaerobes:

under certain conditions can grow in the absence of oxygen

• Bakteri • Fungi

• Nemotodes

• Algae

• Protozoa • Rotifera

Mikroorganisme

Pengaruh kondisi lingkungan

Mikroba pH

Temp

NutrientsSubs conc

D.O.

mixing

Bioreaktor (untuk pengolahan limbah)

1. Reaktorpertumbuhan

tersuspensi (suspended growth reactor)

2. Reaktorpertumbuhan lekat(attached growth

reactor)

• Terdiri dari berbagai jenis mikroba

• Mikroba tersuspensi dalam limbah

• Jumlah mikroba dapat terkontrol dengan baik

mudah diuji di lab

• Contoh: Activated sludge : proses aerobik

termasuk oksidasi karbon dan nitrifikasi

• Disertai flokulasi mikroba diikuti filtrasi dan

sedimentasi

Suspended Growth

screens Grit

chamber

Primary

Settling

tank

aeration chlorination

Raw water

Secondary

Settling

tank

Effluent

to disposal

Reareation

Activated Sludge

Pump

Activated

Sludge return

Sludge

ThickenerSludge

Digestion To Sludge Drying

Flow Diagram of ASP

• Screening and Grit Units : to remove large objects and to

reduce particle size

• Primary Settling Tanks : to remove particles from water

sedimentation

– Particulates suspended size : 10-1 to 10-7 mm

– ( > 10-4 : turbidity ; < 10-4 : color & taste)

– 70% of the solids and 30% of the BOD can be removed

• Aeration Tanks : provides 6 to 24 hours retention

– The contents mixed liquor, and the solids are called mixed

liquor suspended solids (MLSS), living and dead microbial

cells

– microorganisms kept in suspension 4 to 8 hr (by

mechanical mixers and/or diffused air),

– M.o concentration maintained by the continuous return of

the settled biological floc from a secondary settling tank to the

aeration tank.

Lumpur aktif

• Final Settling Tanks : provide longer detention (2h) and lower

overflow rates (30 to 50 m3/m2.day)

• the sludge settles to the bottom of the tank still active and able to

remove more BOD from the waste water maintains and

increases the microorganism concentration in the aeration chamber

– key factor to increase BOD removal from the waste water

• << 24 hr in the aerobic process BOD concentration should not

exceed about 2,000 mg/l on the effluent

• Thickener : part of the separation of the activated sludge

from the mixed liquor in the secondary clarifiers

– Type of thickeners Gravity Thickening, Thickening by

Flotation, and Centrifugal Thickening

– reduce sludge volume by 50 - 70%

Lumpur aktif

Advantages

• Diverse; can be used for one household up a huge plant

• Removes organics

• Oxidation and Nitrification achieved

• Biological nitrification without adding chemicals

• Biological Phosphorus removal

• Solids/ Liquids separation

• Stabilization of sludge

• Capable of removing ~ 97% of suspended solids

• The most widely used wastewater treatment process

Suspended Growth

Disadvantages

• Does not remove color from industrial wastes and may

increase the color through formation of highly colored

intermediates through oxidation

• Does not remove nutrients, tertiary treatment is

necessary

• Problem of getting well settled sludge

• Recycle biomass keeps high biomass concentration in

aeration tanks allowing it to be performed in

technologically acceptable detention times

Suspended Growth

Seluruh modifikasi ini dapat menghasilkan efisiensi

penurunan BOD sekitar 80%-90%.

trickling filter

cakram biologi

reaktor fludisasi

RBC (rotating biological contactor)

Attached Growth

• All microbes attached to the medium

batu, plastik, dll

• The microbes able to access the organis

matter in the waste water

• Trickling filter, RBC, Fluidized bed

Attached Growth

• Terdiri dr lapisan batu dan kerikil dgn tinggi

90 cm-3 m

• Air limbah dialirkan secara perlahan melalui

lapisan ini.

• Bakteri akan terkumpul & berkembang biak

pd batu dan kerikil mengkonsumsi

bahan organik yg terdapat dlm air limbah

Penyaring Trikel

Penyaring Trikel

Pretreatment

Primary

TreatmentRotating

Biological

Contactors

Secondary

ClarifiersSolids Handling

INFLUENT

Disinfection

EFFLUENT

RBC Flow Scheme

RBC Secondary Treatment

Plastic Media

1.6 rpm

40 %

Submerged

Microorganisms “Treat” the Wastewater by Using Organics

Provides Large Surface Area

Rotating

CONTACTOR

ShaftIndividual Disc

Discs

RBC COMPONENTS

• Anaerobic digestion is widely used to treat wastewater

sludges and organic wastes because it provides volume

and mass reduction of the input material.

• Anaerobic digestion is a renewable energy source

because the process produces a methane and carbon

dioxide rich biogas suitable for energy production helping

replace fossil fuels. Also, the nutrient-rich solids left after

digestion can be used as fertiliser.

Anaerobic digestion

• The digestion process begins with bacterial hydrolysis of

the input materials in order to break down insoluble

organic polymers such as carbohydrates and make them

available for other bacteria.

• Acidogenic bacteria then convert the sugars and amino

acids into carbon dioxide, hydrogen, ammonia, and

organic acids.

• Acetogenic bacteria then convert these resulting organic

acids into acetic acid, along with additional ammonia,

hydrogen, and carbon dioxide.

• Methanogens, finally are able to convert these products

to methane and carbon dioxide.

Anaerobic digestion

The key process stages of anaerobic digestion

There are four key biological and chemical stages of anaerobic digestion

Hydrolysis

Acidogenesis

Acetogenesis

Methanogenesis

A simplified generic chemical equation for the overall processes outlined

above is as follows:

C6H12O6 → 3CO2 + 3CH4

• Slow rate process required long times

retention

• For waste of high organic strength --?

COD > 2000 ppm

• Capable treating some substances

cellulosic materials, aromatic compounds,

chlorinated solvents

Anaerobic digestion

Aerobic vs Anaerobic

• Pengolahan secara biologi yang tidak tepat akan

menyebabkan timbulnya bau busuk dan penggumpalan

bahan berlemak. Jika tidak diatasi segera maka akan

sangat mengganggu.

• Untuk menghindari proses pengolahan limbah yang tidak

efektif dilakukan terlebih dahulu pre-treatment dengan

tujuan agar tidak terjadi over load COD, diusahakan

agar COD maksimal 2000 ppm.

• Tujuan pre-treatment adalah agar beban COD lebih

rendah dan limbah lebih homogen.

Apa akibat dari proses biologi yang tidak

tepat pada pengolahan limbah cair ?

TERIMA KASIH