SEWAGE TREATMENT PROCESSES

FOR WARM AND DEVELOPING

COUNTRIES

Marcos von Sperling

ITB

Webinar

07 July 2020

Federal University of Minas Gerais

Brazil

PRESENTATION OUTLINE

• Open access literature

• Simple methods for sewage treatment in developing

countries (description, few design parameters)

• Comparison of processes (applicability,

performance, capacity)

• Focus on domestic wastewater (sewage)

OPEN ACCESS LITERATURE ON

SIMPLE METHODS FOR

WASTEWATER TREATMENT

OPEN ACCESS LITERATURE (IWA)

Free to download → IWA Publishing

http://www.iwapublishing.com/open-access-ebooks/3567

~ 1500 pages

Free to download → IWA Publishing

http://www.iwapublishing.com/open-access-ebooks/3567

OPEN ACCESS LITERATURE (IWA)

Biological wastewater treatment series

Latest

addition

(2017)

Evaluation of Monitoring Data (2020)

Link for downloading e-book and

Excel spreadsheets:

https://iwaponline.com/ebooks/book/

777

Marcos von Sperling (UFMG)

Matt Verbyla (Univ. San Diego, USA)

Sílvia Oliveira (UFMG)

644 pages, 92 examples, 75 Excel

spreadsheets

OPEN ACCESS LITERATURE (IWA)

MAIN TREATMENT PROCESSES THAT CAN

BE USED IN DEVELOPING COUNTRIES

(WARM-CLIMATE REGIONS)

(with several experiences from Brazil)

~ 1 billion people in the

tropical zone

~1.5 billion people in the

tropical + subtropical

zone

Source: Chernicharo (2016)

TROPICAL AND SUBTROPICAL ZONES IN THE WORLD

(implications for wastewater treatment)

Sewage treatment processes in Latin America

Sample from 2734 WWTPs Adapted from Noyola et al (2012)

Sewage treatment processes in Latin America

Sample from 2734 WWTPs Adapted from Noyola et al (2012)

Source: ANA. Brazilian Atlas on sewage treatment.

All 2657 WWTPs in municipality main cities.

.

Sewage treatment processes in Brazil

STABILIZATION PONDS

Facultative

Largest in Brazil (Maracanau): 1.0 km length, 0.3 km width

STABILIZATION PONDS

Facultative

STABILIZATION PONDS

Regions with warm winter and

high sunshine

Ls = 240 to 350 kgBOD5/ha.d

Regions with moderate winter

and sunshine

Ls = 120 to 240 kgBOD5/ha.d

Regions with cold winter and low

sunshine

Ls = 100 to 180 kgBOD5/ha.d

Simplified design criteria

Calculation of surface area using organic surface loading rate

Anaerobic pond – Facultative pond

STABILIZATION PONDS

Northeast Brazil - 1 Anaer. pond + 1 Facult. pond + 3 Matur. ponds (70 ha)

Anaerobic – facultative - maturation ponds

STABILIZATION PONDS

Maturation ponds

in series

Facultative pond

Anaerobic pond

UASB – POLISHING PONDS

1st – Baffled ponds

UASB

2nd – Elongated ponds

Coarse filters 3rd – Ponds with coarse filters

Lagoa da Prata (Brazil) – 60,000 inhabitants

Ponds in series

STABILIZATION PONDS

Comparison between variants (warm-climate regions)

General item Specific

item

System of ponds

Facultative Anaerobic

–

facultative

Anaerobic -

facultative -

maturation

Removal BOD 75 - 85 75 – 85 80 - 85

Efficiency COD 65 - 80 65 – 80 70 – 83

(%) SS 70 - 80 70 – 80 73 - 83

Ammonia <50 <50 50 – 65

Nitrogen <60 <60 50 – 65

Phosphorus <35 <35 > 50

Coliforms 90 - 99 90 - 99 99.9 – 99.9999

Requirements Area

(m2/inhab)

2.0 – 4.0 1.2 – 3.0 3.0 – 5.0

CONSTRUCTED WETLANDS

MAIN TYPES OF CONSTRUCTED WETLANDS

Surface flow: water level above surface

Constructedwetlands

Floating macrophytes

Emergentmacrophytes

Submergedmacrophytes

Subsurface flow: Water level below support

medium surface

Horizontal Vertical

HORIZONTAL SUBSURFACE-FLOW

CONSTRUCTED WETLANDS

Planted unit

Unplanted unit

After previous

treatment (septic

tanks, anaerobic

baffled reactors,

UASB reactors)

CePTS UFMG/Copasa, Brazil (50 p.e. each)

Source: Epur Nature, presented in Dotro et al (2017)

VERTICAL FLOW WETLANDS – FRENCH SYSTEM

Raw or primary-settled sewage

InfluentEffluent

VERTICAL FLOW WETLANDS – FRENCH SYSTEM

CePTS UFMG/Copasa, Brazil (100 p.e.; French system)

TYPICAL REMOVAL EFFICIENCIES IN

CONSTRUCTED WETLANDS

Wetland Type Horizontal

subsurface

flow (HF)

Vertical

flow (VF)

French Vertical

flow (FVF)

Main treatment step Secondary Secondary Combined

primary and

secondary

Total suspended solids (TSS) > 80% > 90% > 90%

Organic matter (BOD5, COD) > 80% > 90% > 90%

Ammonia nitrogen 20 – 30% > 90% > 90%

Total nitrogen 30 – 50% < 20% < 20%

Total phosphorus (long term) 10 – 20% 10 – 20% 10 – 20%

Coliforms 2 log10 2-4 log10 1-3 log10

Source:

Dotro et al (2017). Biological Wastewater Treatment Series. Volume 7: Treatment Wetlands.

UASB REACTORS AND POST-TREATMENT

UASB REACTOR

(Upflow Anaerobic Sludge Blanket)

From small to large installations

Hundreds of inhabitants One million inhabitants

Very important in Brazil!!!

UASB REACTOR

UASB REACTOR

Removal efficiencies and design parameters

(domestic wastewater)

Values for design purposes:

BOD: ~ 65-70%

COD: ~ 60-65%

Hydraulic retention time: 6 to 9 h (for Q average)

Height (H): 4.0 to 5.0 m

Onça WWTP – Brazil (1,000,000 inhab)

UASB – TRICKLING FILTER

UASB

reactors

2ary sedim.

tanks

trickling filters

Trickling filters after UASB reactors

Design criteria for average flow (rock bed)

Parameter Value

Organic loading rate (kgBOD. m-3.d-1) 0.5 – 1.0

Hydraulic loading rate (m³.m-2.d-1) 15 – 30

Filter depth (m) 2.0 – 3.0

Sludge production (kgSS per kgBOD removed 0.8 – 1.0

Source: Chernicharo and Bressani-Ribeiro (2020)

(Betim WWTP, Copasa, Brazil, 370,000 inhab) Source: Copasa

ReatoresUASB

Tanques de aeração

Decantadores secundários

UASB – ACTIVATED SLUDGE

UASB

reactors Aeration

tanks

2ary sedim.

tanks

Activated sludge

Main characteristics

General

item

Specific item Type

Conventional Extended

aeration

UASB –

activated

sludge

Removal

efficiency

BOD (%) 85 - 95 93 – 98 85 – 95

COD (%) 85 - 90 90 - 95 83 – 90

Ammonia (%) 85 - 95 90 - 95 75 – 90

Energy Installed power (W/inhab.) 2.5 – 4.5 3.5 – 5.5 1.8 – 3.5

Energy consumption

(kWh/inhab.year)

18 – 26 20 – 35 14 – 20

Sludge

mass

To be treated

(g TS/inhab.day)

60 – 80 40 – 45 20 – 30

To be disposed of

(g TS/inhab.day)

30 – 45 40 – 45 20 – 30

CAPACITY OF THE PROCESSES

FOR BOD, AMMONIA,

NITROGEN, PHOSPHORUS AND

PATHOGENS REMOVAL

BOD REMOVAL

98%

70%

80%

90%

EFFICIENCY

Activated sludge

Trickling filters

Wetlands

Overland flow

Septic tank –

anaerobic filter

Ponds

UASB

ReatoresUASB

Tanques de aeração

Decantadores secundários

UASB + postMBBR

Membranes

Others

AMMONIA REMOVALActivated sludge and

submerged aerated biofilters

(full nitrification expected)

Trickling filters

(partial nitrification with usual loading rates;

higher efficiencies with plastic media)

Maturation ponds

(various mechanisms)

Vertical flow wetlands

(partial nitrification with 1 stage,

full nitrification with 2 stages)

NITROGEN REMOVAL

Activated sludge with BNR Maturation ponds

BNR: biological nutrient removal

PHOSPHORUS REMOVAL

Activated sludge with BNRP precipitation with

chemical products

N removal is important for good

P removal (nitrification will take

place in warm climates; avoid

nitrate in anoxic zones)

PATHOGEN REMOVAL

Disinfection

(e.g. UV radiation)

Natural systems

(e.g. maturation ponds)

Barrier

(e.g. membrane)

Source: Everychina

• Pathogenic bacteria + viruses (inactivation)

• Protozoan cysts + helminth eggs (physical removal)

EXPECTED REMOVAL EFFICIENCIES FROM

MAJOR WASTEWATER TREATMENT

PROCESSES USED IN WARM-CLIMATE

DEVELOPING COUNTRIES

(personal interpretation)

PROCESSES

LEGEND IN GRAPHS

UASB reator only

Natural (extensive) system

Compact (intensive) system

System with additional steps

y/n = (yes/no) = with or without a certain step

Low, intermediate, high: three ranges of removal efficiencies

(for developing countries)

REMOVAL EFFICIENCIES - BOD

REMOVAL EFFICIENCIES - AMMONIA

REMOVAL EFFICIENCIES - NITROGEN

REMOVAL EFFICIENCIES - PHOSPHORUS

REMOVAL EFFICIENCIES – E. COLI

CONCLUDING REMARKS

WHAT IS THE BEST WASTEWATER

TREATMENT PROCESS?

• There is no best treatment process, each is site

specific and important.

• We have to be open to different alternatives.

• Good that we have many choices.

• We have to move on a stepwise manner.

THANK YOU VERY MUCH!