48
SEWAGE TREATMENT PROCESSES FOR WARM AND DEVELOPING COUNTRIES Marcos von Sperling ITB Webinar 07 July 2020 Federal University of Minas Gerais Brazil
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!
