WASTEWATER
TREATMENT
Lili sugiyarto
The primary goal
The removal and degradation of organic
Three major steps
Primary treatment
Secondary treatment
Primary 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
Secondary treatment
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
Trickling filter bed
• 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
Then goes to a secondary
settling tank
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
The sludge that is not return as secondary
Trickling filters
Gram negative bacteria : Zooglea,
Pseudomonas, Alcaligenes,
Achromobacter, Flavobacterium
Gram positive : Corynebacterium, etc
In secondary treatment
It contains a high level of the organic
nutrients phosphate and nitrate
Nitrosomonas : oxidize ammonia to nitrite
Secondary treatment
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 :
The major metabolic stages
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
Types of Bioremediation
In situ bioremediation
Composting
Landfarming
Activated sludge flocs
Note filamentous bacteria
Note Vorticella and
Activated sludge model
L L0
L
L L
Urban Water Systems
12 Sludge treatment
© PK, 2006 - page 21
Composition of sludge
All non-degraded compounds extracted from wastewater are found in the sludge
• 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
Activated sludge plants
Tertiary treatment
Involve some type of physicochemical
Urban Water Systems
12 Sludge treatment
© PK, 2006 - page 25
Goals of sludge treatment
Volume reduction
Elimination of pathogenic germs
Stabilisation of organic substances
Recycling of substances
• Thickening
• Dewatering
• If used in agriculture as fertiliser or compost
• Gas production
• Reduction of dry content
• Improvement of dewatering
• Reduction of odour
• Nutrients, fertiliser
• Humus
Urban Water Systems
12 Sludge treatment
© PK, 2006 - Incineration
P
Disposal site
Atmosphere
Wastewater treatment
Primary, secondary, tertiary sludge
Construction industry
Oxygenated systems
Urban Water Systems
12 Sludge treatment
© PK, 2006 - page 29
Examples of naturally
transmissible catabolic
plasmids
putida mt-2
Pseudomonas putida
mt-2
Chromosomal gene encode ortho
pathway : acetyl CoA and succinate
TOL plasmid encodes meta pathway :
TOL (pWW0) plasmid
The genes encoding catabolic enzymes :
xyl genes
The Xyl genes : xyl ABC (upper) and xyl
Xyl
ABC
Encode degradation toluene and xylene
Xyl XYZLEGFJKIH
Encodes degradation of benzoate and
