Post on 06-Mar-2019
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
• 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
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
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
• 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
• 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 ?