WASTEWATER

TREATMENT Lili sugiyarto

Lili_sugiyarto@uny.ac.id

The primary goal

The removal and degradation of organic

matter under controlled condition

Three major steps

Primary treatment

Secondary treatment

Tertiary 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 (primary sludge)

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

the end of treatment

Large-scale wastewater

treatment

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

• air and pure oxygen pumped through the mixture promotes bacterial growth and decomposition of the organic material

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

sludge

Trickling filters

Gram negative bacteria : Zooglea,

Pseudomonas, Alcaligenes,

Achromobacter, Flavobacterium

Gram positive : Corynebacterium, etc

Fungi : Fusarium, Trisporon, Ascoidea

In secondary treatment

It contains a high level of the organic

nutrients phosphate and nitrate

Nitrosomonas : oxidize ammonia to nitrite

Nitrobacter : oxidize nitrite to nitrate

Secondary treatment

Aerobic digestion tank

Anaerobic 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)

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

CH4 methanogenesis

Types of Bioremediation

In situ bioremediation

Composting

Landfarming

Above-ground bioreactors

Activated sludge process

Activated sludge flocs

Note filamentous bacteria

Note Vorticella and other protozoa

Activated sludge model

L L0

L

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

• Predominantly water

Activated sludge plants

Hyperion, Playa del Rey, CA)

Primary aeration tank

Tertiary treatment

Involve some type of physicochemical

treatment such as coagulation, filtration,

activated carbon adsorbtion of organics

and additional disinfectan

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

• Biogas

Urban Water Systems

12 Sludge treatment

© PK, 2006 -

page 26 Overview

Thickening

Thickening

Hygienisation

Stabilisation

Dewatering

Drying

Incineration

Pro

cess w

ate

r

Biogas

Energy

Agriculture

Disposal site

Atmosphere

Wastewater treatment

Primary, secondary, tertiary sludge

Construction industry

Gujer (1999)

Oxygenated systems

Cryogenic air separation facility, Hyperion, Playa del Rey, CA)

Typical steps in modern wastewater

treatment

Urban Water Systems

12 Sludge treatment

© PK, 2006 -

page 29 Flotation unit

Examples of naturally

transmissible catabolic

plasmids

Primary

substrate

Plasmid Size

(kb)

Host

Toluene pWW0 (TOL) 117 Pseudomonas

putida mt-2

Alkylbenzene

sulfonate

ASL 91.5 Pseudomonas

testosroni

octane OCT ~500 P.oleovorans

Naphthalene Nah7 83 P. Putida PpG7

Pseudomonas putida mt-2

Chromosomal gene encode ortho

pathway : acetyl CoA and succinate

TOL plasmid encodes meta pathway :

acetaldehide and pyruvic acid

TOL (pWW0) plasmid

The genes encoding catabolic enzymes :

xyl genes

The Xyl genes : xyl ABC (upper) and xyl

XYZLEGFJKIH (lower/meta)

Xyl ABC

Encode degradation toluene and xylene

to benzoate and metylbenzoates

Xyl XYZLEGFJKIH

Encodes degradation of benzoate and

methylbenzoate to acetaldehyde and

pyruvat