lesson 9 wastewater treatment basic … conceps and treatment steps.preliminary and primary...

INSTALAÇÕES DE TRATAMENTO 1

WASTEWATER TREATMENT

LESSON 9


Basic Conceps and Treatment

Steps.Preliminary and primary

treatment



Typical pollutants to remove at WWTP: BOD5, COD, TSS, N, P and

TC /FC (Total and Fecal coliforms), depending on the receiving

waters and legislation.

BOD5 – Biochemical Oxygen Demand over 5 days and 20ºC (CBO5

in portuguese)

Corresponds to the consumption of oxygen by biological activity in 5

days at 20 ºC. Indicates the amount of oxygen needed to stabilize

biodegradable organic matter

BOD5 (particulate + dissolved) usual range between 200 e 500 mg O2/l.



COD- Chemical Oxigen Demand) (CQO, in portuguese)

Corresponds to consumption of oxygen via chemical oxidation using a

powerful oxidants (i.e potassium dichromate), during 2h.

The BOD5/CQO of raw urban wastewater varies usually between 0,3

and 0,8. In final treated effluent, the relation varies usually between 0,1

and 0,3.



Aerobic oxidation (or anaerobic oxidation)

Dissolved Oxygem (blue) and BOD5 evolution (orange)



TSS interferes with turbitity, light penetration, reaeration, oxygen bentic

demand,

TS (Total Solids) (100%) (example: distribution for domestic wastewater (100ºC) SS (Suspended Solids) (35%) Settleable Solids (60%) (20% in total) Non Settleable solids (40%) (15-20 %) NFS (Non filterable Solids) (65%) Colloidal matter (10%) Dissolved matter (90%) (60% in total ) Volatile (organic (at 600º C)) and fixed Solids



Removal of TSS and particulate BOD5

in sedimentation tanks

Removal also of dissolved BOD5

in aeration tanks


Nutrients (N and P)

Eutrophication


Nutrient removal at WWTP

(oxidation ditch)


Costa do Estoril System

Control of Bacteriological Contamination

(Total Coliforms ; Fecal Coliforms; E ccoli; Enterococci )

By desinfection (Ex.by ultra-violet radiation,….) or location of

final disposal (long sea outfall)

UV desinfection

Costa do Estoril WWTP


Control of Bacteriological Contamination



PRELIMINARY

TREATMENT

PRIMARY

TREATMENT

TERTIARY

TREATMENT

SECONDARY

TREATMENT

Liquid phase and solid phase (sludge)



Preliminary treatment

Primary sedimentation

Secondary treatment (biological treatment + secondary sedimentation)

Sludge thickening

Sludge digestion

Biogas


Removal of coarse solids by interception - racks

and coarse screens (hand-cleaned or

mechanically cleaned);

Removal of grit, sand and gravel - grit chambers;

Equalization (equalization of flow and mass

loading of BOD and TSS) -equalization tanks;

Removal of oil and grease – oil and grease

tanks.

Pre-aeration (control of odors, improve treatability,

removal of grease and grit)

Flocculation

PRELIMINARY

TREATMENT




OVERFLOW (BY-PASS)



FLOW MEASUREMENT – PARSHALL FLUME (with a sensor)



SCREENS (HAND-CLEANED AND MECHANICALLY CLEANED) (1+1)



OIL AND GREASE REMOVAL TANK


Removal of settleable solids and floating material

(removal of organic and inorganic suspended solids) –

primary sedimentation tanks (rectangular or circular);

Primary sludge (typically 3 to 5% solids concentration).

PRIMARY

TREATMENT


Efficiencies: TSS (»50%) ; BOD5 (»20%) (Decre-law nº 152/97)

Enhanced Primay Treatment (with added chemicals: alum, iron

salts; floculation)-Physico-chemical treatment



CONVENTIONAL PRIMARY SEDIMENTATION TANK (Circular)



Main Design Information for Conventional Sedimention Tanks

Detention time – 1,5 to 2,5 h (average flow)

Surface loading Rate (SLR) – 30 to 120 m/day (average to peak

hourly flow).

Depth - >3m

Typical efficiences: TSS (≥ 60%); BOD5 (≥ 30%)

Enhanced primay treatment (including settlers and chemicals:

alum, iron salts) – Much more higher SLR (» 10 m/h ) and lower

detention times.

Efficiencies of TSS and BOD5 removal of respectively over 80%, and

over 50%.



LESSON 10


Secondary Biological – Trickling

filters, activated sludge and ponds.


Attached-growth treatment processes (also known

as fixed-film processes): biological treatment

processes in which the microorganisms

responsible for the conversion of the organic

matter or other constituents in the wastewater to

gases and cell tissues are attached to some inert

medium, such rocks or specially designed ceramic

or plastic materials;

Suspended-growth treatment processes: biological

treatment processes in which the microorganisms

responsible for the conversion of the organic

matter or other constituents in the wastewater are

maintained in suspension within the liquid.

Pond processes: Biological treatment by natural

processes, involving the use of bacteria and/or

algae) (anaerobic, facultative, aerobic, maturation

ponds) .


MAIN SECONDARY

TREATMENT

(BIOLOGICAL)


Trickling filters (low-rate- without recirculation,

high rate and super high rate flow-with

recirculation);

Rotating biological contactors;

Packed-bed reactors.

SECONDARY

TREATMENT

(BIOLOGICAL)

MAJOR ATTACHED

GROWTH


The Trickling filters was developed firstly in Salford, England, in

1893, by Joseph Corbett, passing the wastewater through a

rocky media.



Biofilm

Sprinkler (Euler theoriem)

Trinkling filters



Trinkling filters



Rotating Biological Contactors



Design Information for Trickling Filters

ITEM Low rate High rate Super high

rate

Filter Medium Rock, slag Rock, plastic Plastic

Hydraulic loading (m/dia) 1-4 9-37 14-84

BOD5 loading (kg/m3.d) 0,08-0,40 0,5-1,0 0,5-1,6

Depth (m) 1,5-2,4 0,9-1,5 3,0-12,0

Recirculation ratio (-) 0 1-2 1-2

Sloughing (-) Intermittent Continuous Continuos

BOD5 removal efficiency (%) 80-90 68-85 65-80


Activated-sludge process:

Conventional (plug-flow);

Continuous-flow stirred-tank;

Pure oxygen;

Extended aeration.

Oxidation ditch

Aerated lagoons.

SECONDARY

TREATMENT

(BIOLOGICAL) MAJOR

SUSPENDED

GROWTH




Reactor

X, V, S

Q , S0 8 Settling tank

(Q – Qw ), S, Xe

Qr , Xr , S

Qw , Xr

The activated sludge was developed in England in 1914 by Arden and Lockett

and was so named because it involved the production of an activate mass of

microorganisms capable of aerobically stabilizing a waste. Many versions of the

original process are in use today, but fundamentally they are all similar. The

system shown in figure is a continuous-flow stirred-tank activated sludge

system.

Q-Flow ; S-Substrate; -Volume;

X-Biomass

Qw, Xr – Excess sludge

Qr, Xr – recirculating sludge

e - effluent

Q



Operationally, in the activated sludge process organic waste is

introduced into a reactor where an aerobic bacterial culture is

maintained in suspension. The reactor contents are referred to as the

mixed liquor (ML). In the reactor, the bacterial culture carries out the

conversion of organic matter. MLSS is the suspended solids in the

mixed liquor.

The aerobic environment in the reactor is achieved by the use of

diffused air or mechanical aeration, which also serves to maintain the

mixed liquor in a completely mixed regime.



After a specified period of time, the mixture of new cells and the old

cells (X) is passed into a settling tank where the cells are separated

from the treated wastewater. A portion of settled cells (sludge) (Xr) Is

recycled to maintain the desired concentration of organisms in the

reactor, and a portion is waste (excess sludge). The level at which the

biological mass in the reactor should be kept depends on the desired

treatment efficiency and considerations related to growth kinetics.



CONTINUOUS-FLOW STIRRED-TANK REACTOR

(MECHANICAL AERATION)


(MECHANICAL AERATION)




(DIFUSED AERATION)



DIFUSED AERATION



COMPRESSED AIR PIPING



Typical design information for suspended growth treatment processes)

Process

modification

Qc, (d) F/M

Kg CBO/(kg

MLVSS.d)

Volumetric

loading kg

CBO/(m3.d)

MLVSS (mg/l)

Conventional

Complete-mix

Extended aeration

High purity oxygen

Oxidation ditch

5-15

5-15

20-30

3-10

10-30

0,2-0,4

0,2-0,6

0,05-0,15

0,25-1,0

0,05-0,30

0,3-0,6

0,8-1,9

0,16-0,4

1,6-3,2

0,08-0,5

1500-3000

2500-4000

3000-6000

2000-5000

3000-6000

4-8

3-5

18-36

1-3

8-36

0,25-0,75

0,25-1,00

0,50-1,50

0,25-0,50

0,75-1,50



Secondary sedimentation tanks (circular)

Extended aeration

SIMARSUL, S.A. / LAGOINHA WWTP (PALMELA)



SECONDARY SEDIMENTATION TANK (Beirolas,

Lisboa)



SECONDARY SEDIMENTATION TANK - Details



POND SYSTEMS (4 different types)

Anaerobic ponds, which are designed to cater for high organic

loading, and are typically absent of DO and contain no significant algal

population. They typically involve long detention times and are deeper

than other types of ponds;

Facultative ponds, which incorporate two different operating modes,

aerobic at the surface and , with the settlement of sludge, anaerobic at

the base of the pond. These ponds are typically shallower than

anaerobic ponds.



POND SYSTEMS

Aerobic ponds, which are shallow to allow algal development and

receive lower solids and BOD loadings.

Maturation / Oxidation ponds, which essentially are used for polishing

of effluent, and are shallow to allow for ultraviolet light penetration and

subsequent disinfection.

There are also mechanically aerated ponds, which can be deeper

than naturally aerobic ponds, since the aeration will reach the lower

layers. which helps in DO as well as mixing ability to prevent short

circuiting

.


Pond systems typically comprise a treatment train, which may involve

a series of ponds:

Anaerobic;

Facultative, aerobic;

Maturation

To achieve BOD reduction (sometimes also nutrient reduction)

(anaerobic and facultative pond) and pathogen reduction (maturation

pond) prior to transfer to the environment (for irrigation reuse or

disposal to receiving waters).

The appropriate treatment train series is dependent on WWTP loading

and requirements of discharges, according to legislation.



Typical Design Information for Pond Systems


Parameter Aerobic

Low rate

Aerobic

Maturation

Aerobic-

anaerobic

facultative

Anaerobic

pond

Aerated

lagoon

Flow regime Intermittently mixed Intermittently mixed Mixed surface

layer

- Completely

mixed

Pond size (há) < 4

multiples

0,8-4,0

multiples

0,8-4,0

multiples

0,2-0,5

multiples

0,1-4,0

multiples

Operation Series or parallel Series or parallel Series or parallel Series Series or

parallel

Detention time (d) 10-40 5-20 5-30 20-50 3-10

Depth (m) 0,9-1,2 0,9-1,5 1,2-2,4 2,4-4,8 1,8-6,0

pH 6,5-10,5 6,5-10,5 6,5-8,5 6,5-7,2 6,5-8,0

Temperature range (ºC) 0-30 0-30 0-50 6-50 0-30

Optimum temperature (ºC) 20 20 20 30 20

BOD5 loading (kg/ha.d) 67-135 ≤ 17 56-202 224-560 20

BOD5 conversion (%) 80-95 60-80 80-95 50-85 80-95

Principal conversion Algae, CO2, bacterial

cell tissue

Algae, CO2, bacterial cell

tissue NO3

Algae, CO2, CH4,

bacterial cell

tissue

CO2, CH4,

bacterial cell

tissue

CO2,

bacterial cell

tissue

Algal concentration (mg/L) 40-100 5-10 5-20 0-5

Effluent suspended solids (mg/L) 80-140 10-30 40-60 80-160 80-250


RA

W W

AS

TE

WA

TE

R

SCREENING

GRIT

OIL AND GREASE

REMOVAL

PRIMARY

SEDIMENTATION

BIOLOCICAL

REACTOR

SECONDARY

SEDIMENTATION

TR

EA

TE

D

WA

ST

WA

TE

R

Grit, sand

and gravel

oils and grease

Primary

sludge Coarse solids Recirculated

sludge

Excess

sludge


TYPICAL FLOWSHEET OF A WWTP LIQUID PHASE


FLOWSHEET OF A WWTP




LESSON 11


Small wastewater treatment

systems.Preliminary design

examples



Septic tank and final land disposal (ex: infiltration trenches,….)

Typically used for small

communities (< 250 p.e.)

p.e. – population equivalent

Typically used for small communities (< 250 p.e.)



IMHOFF Tank : Typically used for small communities (< 2000 p.e.)



Typical Information for Design of Septic tanks

Single , two or three compartment tanks

Detention time – 1 to 2 days

Depht -1 to 1,5 m

Lenght to with ratio - 2:1 to 5:1

Sludge should be removed at least once per two years.

.



Natural treatment systems (typically for small agglomerations,and at least after primary treatment)

Slow rate (Irrigation) (i.e irrigation of crops)

Rapid Infiltration (sandy soil with high hydraulic condutivity)

Overland flow (over impermeable soils)

Wetlands

(watewater treatment system common in parts of Portugal for

rural small agglomerations: subsurface horizontal flow constructed

wetlands after septic tanks)



Information for design of subsurface flow constructed wetlands

.

Hydraulic detention time (tr) ≤ 2 days

Height (media) (h) – 0,6 to 0,9 m

Porosity of the media (n) – 0,32

Material characteristics (k) - 0,98 (for sand)

Design expression:

A ≥ Q tr ln (BODinf/BODefl)/(k.h.n.)

A (area); BODinf (influent BOD); BODefl (efluent BODe)



1st Example: Preliminary Design of a Primary settling tank

Population (P ) – 2000 pe, C = 150 l/(e.p.day) and Inf.Coef. = 0,8

Fav (average flow) = (2000 x150 x 0,8)/86,400 = 2,77 l/s = 240 m3/day

fp (Peak factor) = 1,5 + 60/ 𝑃 =3,4

Finf. (infiltration flow) = 0

Fp (Peak flow)= fp x Fav + Finf = 2,77 x 3,4 x 0 = 9,4 l/s = 813 m3/day

CRITERIA

SLR (surface loading rate) > 30 m/day (for Fav) and < 120 m/day (for Fp) (criteria)

1,5 h < Tr (Detention time) < 2,5 h

𝐴1 ≥240

30 ≥ 8 𝑚2 → 𝐷 ≥

4𝐴

𝜋 ≥ 3,19 𝑚 → 3,2 𝑚

A = 𝜋 x 3,22/4 = 8,04 → SLR (Fp) = 813/8,04 = 101 < 120 m/day

→ ∀ = 8,04 x 2,8 = 22,51 m3

H = 2,8 m; Detention time (tr) = 22,51

240 x24 = 2,25 h



2nd Example: Preliminary design of a low rate trickling filter

BOD5 load = 2000 x 60 g BOD5/day = 120 kg BOD5/day

CRITERIA

BOD5 loading rate (BL) = 0,08 to 0,40 kg BOD /(m3.day) (criteria)

Hyd. Loading (HL) = 1 to 4 m/day (criteria)

Fav = 240 m3/day 𝐻𝐿 = 1 𝑚/𝑑𝑎𝑦 → 𝐴 = 240 𝑚2

D = 17,5 m

Depth = 2 m → ∀= 240 x 2 = 480 m3

Considering BOD5 Efficiency of settling tank = 30%

BL = 120 x (1-0,3)/480 = 0,35 BOD5/(m3.day) < 0,40



3rd Example: Preliminary design of a constructed wetland after septic tank

Population – 500 ep; C = 100 l/(ep.day); Inf.Coef. = 0,8

Fav = (500 x 100 x 0,8)/1000 = 40 m3/day = 0,46 l/s

Fp (peak flow) = 2 l/s

BOD5 load = 500 x 60 g BOD5/day = 30 kg BOD5/day; BOD5 BOD5 inf.= 30/40 = 0,750 g/l

Considering BOD5 Efficiency of septic tank – 50%

BOD5 inf = (30 x 0,5)/40 = 0,375 g/l

Data: 𝜂 porosity = 0,32 and Tr = 3 days Tr = detention time; ∀ = volume of the wetland

∀ = 40 x 3

0,32= 375 𝑚3



3rd Example: Preliminary design of a constructed wetland after

septic tanks (Cont.)

h = 0,7 m → A = 535 m2 (16,37 x 32,73)

A ≥ Q tr ln (BOD5 in /BOD5 efl)/(k h n)

Efficiency of BOD5 removal

BOD5 efl = BOD5 inf exp- (A K h n/(Q tr)

= 0,375 exp - 535 x 0,98 x 0,7 x 0,32)/(40 x2

= 0,088 g/l

BOD5 efficiency of the total system = 0,750−0,088

0,750= 88%



LESSON 12


Technical visit

(Rio da Mula WTP and Valdeão WWTP)


Valdeão WWTP, Almada

(Technical visit of 3012-11-26)

Pop – 6 000 e.p. BOD5 inf = 375 mg/l

Fav – 1271 m3/day SST inf = 563 mg/l

Fp – 47,7 l/s CQO inf = 844 mg/l

Effluent requirements (future) (The municipality is considering the up-grading

of the WWTP with disinfection in order to fulfill those requirements)

BOD5 efl = 25 mg/l

CQ efl = 125 mg/l

SST efl = 35 mg/l

FC (MPN/100ml= 2 000 (for discharge in the Tagus estuary)

FC (MPN/100ml= 100 (for irrigation and cleaning)



Valdeão WWTP - Location

Valdeão WWTP – photo



Fase Líquida

EE Lamas

Desidratação

Mecânica

(filtro banda)

Espessamento

Gravítico

( V= 6.7 m3)

Meio de disposição final

(aterro sanitário)

Descarga

de Lamas

Desarenador

Gradagem

Águas Residuais

Afluentes

Tanque

Arejamento

Meio receptor

Fase Sólida

EE

Decantador

Secundário

Tanque

Arejamento

Decantador

Secundário

Circuito Principal

Obra de Entrada

Circuito de lamas

Legenda

GradadosMeio de

disposição

final

Areias

Câmara de

distribuição

Parshall

Tanque de

Lamas

(V= 1 m3)

Valdeão WWTP – Treatment scheme



Valdeão WWTP – Future layout



Valdeão WWTP – Screening Valdeão WWTP – Grit removal and flow

measurement

Valdeão WWTP – Headworks

Valdeão WWTP – Parshal Fume



Valdeão WWTP – Pumping installation

Valdeão WWTP – Pumping installation



Valdeão WWTP – Aeration tanks

Valdeão WWTP – Aeration tanks



Valdeão WWTP – Settling tank

Valdeão WWTP – Settling tank



Valdeão WWTP – sludge thickening tank

Valdeão WWTP – sludge thickening tank

Valdeão WWTP – sludge filter press equipment Valdeão WWTP – sludge storage tank




LESSON 13


Terciary Treatment. Solids Processing

Methods.Legislation.


Removal Treatment method

Total suspended solids (TSS) Filtration and microscreening

Microorganisms

Sand filtration

UV disinfection

Maturation ponds

Disinfection with chlorine or ozone

Membrane technologies (microfiltration)

Nitrogen Nitrification /denitrification

Phosphorus Chemical precipitation

Biological processes

MAIN TERTIARY TREATMENT PROCESSES




TERTIARY TREATMENT / SAND FILTRATION

BEIROLAS (LISBON) WWTP


TERTIARY TREATMENT / SAND FILTRATION




TERTIARY TREATMENT / UV Disinfection (MPN FC«2000; TSS«40 mg/l)

GUIA (CASCAIS) WWTP



TERTIARY TREATMENT / UV DISINFECTION





.

Sludge Wastewater Treatment

The main purpose of sludge stabilization is control of patogenic

microorganisms and odor.

The main purpose of dewatering is to reduce the water content in

the sludge.


Unit operation / unit process

or treatment method Function

Preliminary operations:

Grinding

Screening

Degritting

Blending

Storage

Particle size reduction

Removal of fibrous materials

Grit removal

Homogenization of solids streams

Flow equalization

Thickening:

Gravity thickening

Flotation thickening

Centrifugation

Gravity-belt thickening

Rotary-drum thickening

Volume reduction

Volume reduction

Volume reduction

Volume reduction

Volume reduction

Stabilization:

Chemical stabilization

Anaerobic digestion

Aerobic digestion

Composting

Sludge wetlands

Stabilization

Stabilization, mass reduction

Stabilization, mass reduction

Stabilization, product recovery

Stabilization, value indution

Conditioning:

Chemical conditioning

Other conditioning methods

Improve dewaterability

Improve dewaterability


SOLIDS PROCESSING METHODS

CHARACTERISTICS OF SOLIDS AND SLUDGE PRODUCED


Unit operation / unit process

or treatment method Function

Dewatering:

Centrifuge

Belt-filter press

Filter press

Sludge drying beds

Reed beds (constructed wetland)

Lagoons

Volume reduction

Volume reduction

Volume reduction

Volume reduction

Storage and volume reduction

Storage and volume reduction

Heat drying:

Direct dryers

Indirect dryers

Weight and volume reduction

Weight and volume reduction

Incineration:

Multiple-hearth incineration

Fluidized-bed incineration

Co-incineration with solid waste

Volume reduction, resource recovery

Volume reduction

Volume reduction

Application of biosolids to land:

Land application

Dedicated land disposal

Landfilling

Beneficial use, disposal

Disposal, land reclamation

Disposal

Conveyance and storage Solids transport and storage


CHARACTERISTICS OF SOLIDS AND SLUDGE PRODUCED



SOLIDS PROCESSING METHODS / SLUDGE PUMPING

GUIA (CASCAIS) WWTP



Sludge

Sand

Gravel

Drains


SLUDGE DRYING BEDS (Small WWTP)



Sludge thickening

Sludge digesters

Biogas storage Heat exchangers


LAYOUT EXAMPLE



Conventional standard-rate single stage process

High-rate, continuous-flow stirred tank, single stage process


ANAEROBIC DIGESTION



Two-stage process


ANAEROBIC DIGESTION



SOLIDS PROCESSING METHODS/ANAEROBIC DIGESTION





Costa do Estoril (CASCAIS/Outeiro da Lota) WWTP-4 km far from

WWTP Liquid phase.





BIOGAS STORAGE


SOLIDS PROCESSING METHODS/CENTRIFUGE SLUDGE

DEWATERING




SLUDGE TRANSPORT BY TRUCK




SOLIDS PROCESSING METHODS/CO-GENERATOR


SOLIDS PROCESSING METHODS / ODOR CONTROL (Scrubbers)



PR

IMA

RY

SL

UD

GE

SE

CO

ND

AR

Y S

LU

DG

E

SLUDGE

THICKENING

DIGESTION

(ANAEROBIC)

DEWATERING

(CENTRIFUGATION)

DE

WA

TE

RE

D

SL

UD

GE


TYPICAL FLOWSHEET OF A WWTP

SLUDGE TREATMENT



MAIN LEGISLATION (WASTEWATER)

Decree-law nº 152/97 ,of 19 June (Diretive nº91/271 CEE, of 21 May) (“urban wastewater treatment Diretive”);

Decree-law nº 345/98, of 9 November (1st modification of the DL nº

152/97, concerning requirements for discharging to sensitive zones”)

Decree-law nº 194/2004, of 22 June (2 nd modification of the DL nº 152/97, identification of “ 25 sensitive zones and 9 no sensitive zones) ;

Decree-law nº 188/2008 of 8 October June (3 rd modification of the DL nº 152/97, identification of “18 sensitive and no 3 sensitive zones) ; MAIN LEGISLATION (WASTEWATER TREATMENT SLUDGE)

Decree-law nº 275/2009 of 25 June (use of wastewater treatment sludge for farming pruposes );


Decree-law nº 152/97 (Article 2…)

.e. (population equivalent) means the organic biodegradable load having a

five-day biochemical oxygen demand (BOD5) of 60 g of oxygen per day;

primary treatment means treatment of urban waste water by a physical

and/or chemical process involving settlement of suspended solids, or other

processes in which the BOD5 of the incoming waste water is reduced by at least

20 % before discharge and the total suspended solids of the incoming waste

water are reduced by at least 50 %;

secondary treatment” means treatment of urban waste water by a process

generally involving biological treatment with a secondary settlement or other

process in which the requirements established in Table I are respected;

appropriate treatment means treatment of urban waste water by any

process and/or disposal system which after discharge allows the receiving

waters to meet the relevant quality objectives ....



Decree-law nº 152/97, of 19 June

Pop ≤2000 in fresh waters sensitive zones (or Pop ≤ 10000 in coastal zones):

Appropriate treatment is applicable.

Pop >2000 (or >10000 in coastal zones): Secondary treatment, at least

TABLE 1 Parameter BOD5 CQO TSS*

Concentration (mg/l) and/or

% of reduction

25

70-90

125

75

35

90

*facultativ parameter

For Sensitive zones (risks of eutrophication or bacteriological comtamination)

(Pop >10000 p.e) further treatment ( reduction of NCOD , P ou CF/CT) –

TABLE 2

Parameter P N

Concentration (mg/l)

% reduction

2 (<100 000)

1 (≥100 000) 80

15 (<100 000)

10 (≥100 000)

70-80



Decree-law nº 152/97 (Cont.) (Artº 4)

Member States shall ensure that urban waste water entering collecting

systems shall before discharge be subject to secondary treatment or

an equivalent treatment as follows:

- at the latest by 31 December 2000 for all discharges from

agglomerations of more than 15 000 p.e.,

- at the latest by 31 December 2005 for all discharges from

agglomerations of between 10 000 and 15 000 p.e.,

-at the latest by 31 December 2005 for discharges to fresh-water and

estuaries from agglomerations of between 2 000 and 10 000 p.e.

-For urban waste water discharging into receiving waters which are

considered sensitive areas..... the Member States shall ensure that

collection systems are provided at the latest by 31 December 1998 for

agglomerations of more than 10 000 p.e.




. Urban waste water discharges from agglomerations of between 10 000 and 150 000 p.e.

to coastal waters ....and between 2 000 and 10 000 p.e. to estuaries situated in “less

senstive” areas may be subjected to treatment less stringent than seconday providing that:

- such discharges receive at least primary treatment; comprehensive studies indicate that

such discharges will not adversely affect the environment.

-..............

Member States shall ensure that urban waste water entering collecting systems shall

before discharge be subject to appropriate treatment in the following cases:

- for discharges to fresh-water and estuaries from agglomerations of less than 2 000 p.e.,

-for discharges to coastal waters from agglomerations of less than 10 000 p.e.

-.............

-In exceptional circumstances, when it can be demonstrated that more advanced treatment

will not produce any environmental benefits, discharges into less sensitive areas of more

than 150 000 p.e. may not be subject to secondary treatment




Member States shall ensure that urban waste water shall before discharge into sensitive

areas be subject to more stringent treatment than secondary treatment, ... from

agglomerations of more than 10 000 p.e.

Discharges from those urban waste water treatment plants shall satisfy the relevant

requirements (tertiary treatment) (Table 2).

Less sensitive areas

A marine water body or area can be identified as a less sensitive area if the discharge of

waste water does not adversely affect the environment as a result of morphology,

hydrology or specific hydraulic conditions which exist in that area




A water body must be identified as a sensitive area if it falls into one of the following

groups:

(a) natural freshwater bodies, estuaries and coastal waters which are found to be eutrophic

or which in the near future may become eutrophic if protective action is not taken.

(b) surface freshwaters intended for the abstraction of drinking water which could contain

more than the concentration of nitrate laid down under ...

(c) areas where further treatment is necessary to fulfil Council Directives (i.e

microorganisms removal...).



Decree-law nº 149/2004, 22 de June (up dated in 2008)


25 sensitive zones (see map)

3 no sensitive zones

(Cabo da Roca, Madeira, Porto Santo)



LESSON 14 and 15


WWTP Photos. Planning of WWTP.

Aspects of detailed projects. Tender

procedures. Hydraulic and

environmental aspects.

Construction and operation.


SIMTEJO - Saneamento Integrado dos Municípios do Tejo e Trancão, S.A. is

AdP Group company responsible for the collection, treatment and disposal of

wastewater from the municipalities of Amadora, Lisbon, Loures, Mafra, Odivelas

and Vila Franca de Xira (Tagus and Trancão watersheds) serving a total

population of about 1.5 million inhabitants. The wastewater is conducted to

several pumping stations and WWTP, where it is treated and returned to the

receiving environment or in some cases reused.

The investment plan, to be completed by 2013, includes 32 WWTP, 93 pumping

stations and 339 km of pipes and interceptors.


SIMTEJO - SANEAMENTO INTEGRADO DOS MUNICÍPIOS DO TEJO

E TRANCÃO, S.A. / THE COMPANY


Municipalities served: Lisbon - Amadora – Oeiras;

Population: 756 000 inhabitants-equivalent;

Dry weather design flow: 3.3 m3/s;

Wet weather design flow: 6.6 m3/s;

Type of treatment: tertiary, comprising:

Pretreatment;

dry weather primary treatment Multiflo;

wet weather primary treatment Actiflo;

secondary treatment Biostyr biofiltration;

UV disinfection;

liming of sludge;

chemical odor control.

Investment: 72 M € (10 M € financed by EU).


ALCÂNTARA (LISBON) WWTP

SIMTEJO, S.A.


1 WWTP head works 6 Pumping station

2 Pumping station 7 Secondary treatment Biostyr biofiltration

3 Grit / oil and grease removal 8 UV disinfection

4 Dry weather primary treatment Multiflo 9 Sludge treatment

5 Wet weather primary treatment Actiflo 10 Odor control


SIMTEJO, S.A.





SIMTEJO, S.A.


Primary sedimentation

Preliminary treatment

Biogas

Sludge digestion

Secondary treatment Tertiary treatment


SIMTEJO, S.A.



WWTP Portinho da Costa, Almada

(preliminary treatment, enhanced primary treatment (DENSADEG) and

biofiltration)

Discharge in the estuary by a long sea outfall



WWTP Quinta da Bomba, Almada

(preliminary treatment-screening and sand removal; primary treatment, trickling filters.

Thickening and mechanical dewatering of sludge)

(currently up-grading the treatment (filtration and UV desinfection) and anaerobic

digestion of sludge)



WWTP Machico, Madeira

(preliminary treatment, enhanced primary

treatment, biofiltration and UV disinfection)

Saneamento [A25.5]



WWTP Meia Serra, Leachate from landfills, Madeira

(Aerated pond, physical-chemical treatment and reverse osmosis)

(treated wastewater reuse for industrial uses)



WWTP S. João da Talha

(preliminary treatment, equalization tank, physical-chemical treatment

(enhanced primary), activated sludge; sludge anaerobic digestion,

mechanical dewatering).

Discharge in the Tagus Estuary

entrada da ETAR jusante do tratamento primário tanque de arejamento efluente final



WWTP, Fataca, Odemira

(septic tank and constructed wetland)



WWTP Sado, Beja

(Stabilization ponds, 32 constructed wetlands (2 ha), and chlorine disinfection.

Treated wastewater reuse for urban park irrigation.



Ponte de Vagos WWTP, SIMRIA

Example of a WWTP Project, based

on low rate activated sludge

(extended aeration)



Pop (2030) – 5000 ep

Fav – 5000 m3/day

Fp – 15 l/s



Casal Novo WWTP, Águas da

Figueira, SA

(Example of a WWTP Project,

based on a constructed wetland)



Pop (2025) – 100 ep

Cap (2025) – 100 l/hab.day)

Fav – 10 m3/day

Fp – 55 m3day

Wastewaters Septic tank wetland Septic tank

Casal Novo WWTP



Septic tank Wetland

3 compartments (17,5 x 10) x 0,7

(4,80 x 2,40) x 1,60



ETAR DE CASAL NOVO


TENDER PROCEDURES (announcement, tender programme, technical and

juridical and legal clauses, technical specifications, project and other technical

documents.)

WITH DETAILED PROJECT (including description and justification, and

drawings)

WITH PRELIMINARY PROGRAM (including established requirements)



HYDRAULIC AND ENVIRONMENTAL ASPECTS


• Gravitic or pumping inflows (continuous or intermittent flows to the WWTP).

• Overflows and “by-pass”.

• Flow measurement: different approaches and flowmeters (critical section;

parshall plume) for WWTP management and invoicing.

• Hydraulic profile (taken into account continuous and local head losses).

• Level of the receiving waters (hydraulic calculations from downstream to up-

stream), effects of climate change-adaptation.


HYDRAULIC AND ENVIRONMENTAL ASPECTS

(cont.)


• Efficient use of water (reuse) and energy (variable special drivers in

pumps, aeration). Production of energy (turbines; co-generation).

• Use and fate of biosolids/sludge (land application farming; landfilling).

• Equipment and electrical installations.

• Instrumentation and control.



• Topography for “available heads” – construction of platforms.

• Ensuring access to water and energy. Access to vehicles (circulation)

• Soil foundations – sand? clay? mud? Strategy of construction and groundwater

control (lowering water table by “well point” or other systems).

• Construction aspects and materials – protective coatings; impervious surfaces;

thermic isolation (anaerobic digestion). Structural calculations – Concrete (walls,

pillars, beans in buildings).

LAYOUT CONCERNS



• Final discharges works.

• Hydraulic circuits: water supply; effluent reuse pipes; irrigation pipes; overflows

and “by-pass” sewers; sludge pipes; storm water and drainage sewers;

recirculation pipes.

• Aesthetic concerns. Green structures.

• Odor and noise control.

• Sampling sections for monitoring.

LAYOUT CONCERNS

lesson 9 wastewater treatment basic … conceps and treatment steps.preliminary and primary...

Documents