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MODERN WASTEWATER TREATMENT

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 The
removal and degradation of organic
matter under controlled condition
 Primary
treatment
 Secondary treatment
 Tertiary treatment
A
physical process that involves the
separation of large debries, followed by
sedimentation
 Comprises grit tank and settling tank
 Settling tank also known as sedimentation
tank (sand and gravel)/clarifier
 About half suspended organic solids settle to
the bottom as sludge or biosolids (primary
sludge)
 Consist
of biological degradation
(decomposed and the number of pathogens is
reduced)
 The effluent from primary treatment may be
pumped into a tricklingfilter bed ( an
aeration tank/a sewage lagoon
 Disinfection step is generally included at the
end of treatment
•
•
•
Rocks provide a matrix supporting the growth
of a microbial biofilm that actively degrades
the organic material under aerobic
conditions
Effluen from primary treatment is pumped
into a tank and mixed with bacteria-rich
known as activated sludge
air and pure oxygen pumped through the
mixture promotes bacterial growth and
decomposition of the organic material
 Water
siphon off the top of the tank
 Sludge is removed from the bottom
 Some of the sludge is used as an inoculum for
the incoming activated sludge
 Gram
negative bacteria : Zooglea,
Pseudomonas, Alcaligenes, Achromobacter,
Flavobacterium
 Gram positive : Corynebacterium, etc
 Fungi : Fusarium, Trisporon, Ascoidea
 It
contains a high level of the organic
nutrients phosphate and nitrate
 Nitrosomonas : oxidize ammonia to nitrite
 Nitrobacter : oxidize nitrite to nitrate
 Aerobic
digestion tank
 Anaerobic digestion tank
 The
degradatif and fermentative process
divided into 2 stages : acid forming and
methane forming
 Genera of Methane forming stage :
Methanobacterium, Methanosarcina,
Methanococcus (convert acetate, hydrogen
and CO2 to methane)
 Complex
organic compounds
(polysaccharides, fats, protein)
Hydrolisis
 Hydrolysis by extracellular bacterial enzymes
 Monomeric compounds (sugar, fatty acids,
amino acids)
 Higher organic acids
Acidogenesis
 Acetic acid, H2, CO2
Acetogenesis
 CH4
methanogenesis
 In
situ bioremediation:
biostimulasi,bioaugmentasi, biosparging
 Ex situ biremediation
 Composting
 Landfarming
 Above-ground bioreactors
 Biopiles
Note filamentous bacteria
Note Vorticella and
other protozoa
L
L0
L
L
L
L
Composition of sludge
• Predominantly water
• Micro-organisms
• Viruses, pathogens, germs in general
• Organic particles, heavily bio-degradable
• Organic compounds, inert, adsorpted to sludge flocs
• Heavy metals
• Micro-pollutants, pharmaceuticals, endocrine disrupters
 All non-degraded compounds extracted from wastewater are found in the
sludge
12 Sludge treatment
Urban Water Systems
© PK, 2006
- page 21
Hyperion, Playa del Rey, CA)
 Involve
some type of physicochemical
treatment such as coagulation, filtration,
activated carbon adsorbtion of organics and
additional disinfectan
Goals of sludge treatment
Volume reduction
• Thickening
• Dewatering
Elimination of pathogenic
germs
• If used in agriculture as fertiliser or compost
Stabilisation of organic
substances
•
•
•
•
Recycling of substances
• Nutrients, fertiliser
• Humus
• Biogas
Gas production
Reduction of dry content
Improvement of dewatering
Reduction of odour
12 Sludge treatment
Urban Water Systems
© PK,
2006 page 25
Overview
Wastewater treatment
Process water
Primary, secondary, tertiary sludge
Thickening
Hygienisation
Stabilisation
Biogas
Thickening
Agriculture
Dewatering
Disposal site
Drying
Gujer (1999)
Energy
Construction industry
Incineration
12 Sludge treatment
Urban Water Systems
© PK,
2006 page 26
Atmosphere
Cryogenic air separation facility, Hyperion, Playa del Rey, CA)
Flotation unit
12 Sludge treatment
Urban Water Systems
© PK,
2006 page 29
Primary
substrate
Plasmid
Size
(kb)
Host
Toluene
pWW0 (TOL)
115
Pseudomonas putida
mt-2
Alkylbenzene
sulfonate
ASL
91.5
Pseudomonas testosroni
octane
OCT
~500
P.oleovorans
Naphthalene
Nah7
83
P. Putida PpG7
 Chromosomal
gene encode ortho pathway :
acetyl CoA and succinate
 TOL plasmid encodes meta pathway :
acetaldehide and pyruvic acid
 The
genes encoding catabolic enzymes : xyl
genes
 The xyl genes : xylCAB (upper) and xyl
XYZLEGFJKIH (lower/meta).....operon
 the host : capacity to degrade not only
toluena but also m- and p- xylene, other
benzena derivates
 Encode
degradation toluene and xylene to
benzoate and metylbenzoates
 Encodes
degradation of benzoate and
methylbenzoate to acetaldehyde and pyruvat
 Xyl
R, xylS
 When a substrat enters the cell, it binds to
the XylR protein to form a XylR-toluene
complex (ex= toluen)
 The complex binds to promoter of the xylR
operon to activating transcription of
xylR...............activation the upper
pathway genes
Gene
Enzyme
xylA
Xylene oxygenase
xylB
Benzyl alcohol
dehydrogenase
xylC
Benzaldehyde
dehydrogenase
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