1. Integrated Sludge Management
SLUDGE to ENERGY
Integrated Sludge Management
p2m berlin GmbH Sustainability from Berlin Excellence for Water and Environment.
Hubertus Schrage, Hubertus Soppert; p2m berlin GmbH 1

2. Engineering Company of Berlinwasser Group
p2m berlin GmbH
Engineering Company of Berlinwasser Group
We offer expertise in the fields of:
Drinking Water Supply
Stormwater Management
Sewer Systems
Wastewater Treatment
Sludge Management
Project Management
Landscaping
International Consulting

3. Our Activities in ACWUA Countries
Algeria
Kingdom of Bahrain
Jordan
Kuwait
Qatar
Kingdom of Saudi Arabia

4. Introduction Rising Need for Sludge Management:
Awareness of sewage treatment has risen in the Middle East
Connection of households to the public sewage still increasing significantly
Extension of wastewater treatment produces increases sewage sludge volumes
No comprehensive sludge management strategies available in most countries
Sustainable strategies for sludge disposal have to be developed in the near future
Stricter regulations require improvement of existing systems

5. Introduction Main Keys to Sustainable Sludge Management:
Sustainable Sludge Reuse/Disposal Routes
Land availability
Existing industries
Existing agriculture/landscaping
Waste to Energy Concepts (Energy Recovery)
Biogas
Mono-Incineration (sludge only)
Co-Incineration (cement industry, solid waste)
Sludge Treatment Options depend on the above 2 key factors

6. Sludge Reuse/Disposal Options
Sludge Drying and Disposal in Landfill a NOT SUSTAINABLE SOLUTION
Sludge Drying and use in agriculture and landscaping a MOSTLY SUSTAINABLE SOLUTION
limited by long term soil contamination with: heavy metals, pharmaceutical/medical residues (hormones, antibiotics, etc.), micro-plastics
must ensure Pathogen Removal before reuse (sanitation and disinfection)
European regulations are changing further limiting sludge reuse in agriculture due to public health and safety concerns
Sludge Mono-Incineration and Re-use of Ash in Landfill a LIMITED SUSTAINABLE SOLUTION
limited long-term, but can be short/mid-term solution due to reduced waste product volumes, P-recovery possible if stored accordingly
Sludge Mono-Incineration and Re-use of Ash in Construction (Admixture to concrete, asphalt, etc.) a SUSTAINABLE SOLUTION
Sludge Co-Incineration and Re-use (e.g. Cement Industry) a SUSTAINABLE SOLUTION

7. Sludge Disposal in GCC & Middle East
Mostly sludge drying and disposal in landfills a NOT SUSTAINABLE SOLUTION
Limited reuse in agriculture and landscaping
sludge quality concerns (Pathogens, Heavy Metals),
limited/insufficient land availability
a LIMITED SUSTAINABILITY limited by climate & geology, farmland availability, cultural concerns and acceptance
Agricultural Reuse
Gravity Thickener
Natural Dewatering
Drying Area

8. Sludge Disposal in Europe

9. Sludge Disposal in Germany
Sludge was historically re-used in agriculture
In the 1960s and 1970s capacity of wastewater treatment facilities started increasing
Lack of regulations in sludge disposal a malpractice
First German regulation on sludge disposal in 1982
Regulation with regards to Sludge Treatment (EU Urban Waste Water Treatment Directive 91/271/EEC, Sewage Sludge Directive 86/278/EEC) regulating quality concerns
Changing of regulations in Germany to limit agricultural reuse due to long-term soil contamination and public health concerns: amendment of the German Sewage Sludge Ordinance (AbfKlärV)
In the future in Germany all sewage sludge will be incinerated with full energy recovery – ash reuse and Phosphorus recovery

10. Sludge Disposal in Germany Disposal on Landfills
Until 1980s sludge could be disposed:
in mono-landfills for sludge alone
in landfills for combined disposal
Since 1992 sludge disposal only allowed on multi-disposal landfills
Since 2005 disposal of organic waste is only allowed if content of volatile organic solids < 5% a Cannot be met by digested and/or dried sludge a Sludge disposal in landfills is no longer economical – not being used in Germany

11. Sludge Disposal in Germany Disposal in Agriculture
Sanitation Options for pathogen Removal as per Sewage Sludge Ordinance (AbfKlärV):
Heating (pasteurization, thermal conditioning – longer at temperatures > 70°C for 1 hour)
Aerobic-Thermophilic Sludge stabilization (ATS)
Composting – long term
Adding Lime or pH increase - Ca(OH)2
Thermal drying (short term at temperatures exceeding 100°C)
Incineration
NEW Sewage Sludge Ordinance (AbfKlärV) amendment expected to restrict agricultural reuse even further!

12. Process Type
Method
Description
Reaching treatment temperature through heating
Sludge pasteurization
The sludge is kept at a temperature exceeding 70 °C for 60 minutes .
Thermal conditioning
Thermal conditioning is performed at 15 bar at a minimum, a minimum temperature of 80 °C, and for at least 45 minutes in a sludge reaction tank .
Reaching treatment temperature through spontaneous heating/ chemical reaction heating
Aerobic-thermophilic sludge stabilization (ATS)
Exothermic microbial breakdown and digestion processes are triggered by active air/oxygen input, resulting in heating and a pH increase to around 8 in sewage sludge. ATS systems that are run semi-continuously need to be composed of two stages at a minimum. Only with a minimum temperature of 55 °C and at least 22 hours of treatment time in a second tank can sufficient reduction of harmful organisms be assured .
Sludge composting in windrows or reactors
Microbial aerobic rotting allows for sludge composting. The heat needed for this process is supplied by breakdown process itself. Elements such as straw and wood shavings are added to the sludge. Baseline water content ranging from 40 to 60 % is ideal for a successful composting process .
Adding unslaked quicklime
Adding CaO to dewatered sewage sludge heats the mixture (secondary to exothermic reactions of calcium oxide and the water therein) to 55 °C at a minimum, provided that the reactor has adequate thermal insulation. Also, the baseline pH needs to be 12.8 at a minimum and dwell time must be at least three hours, during which a minimum temperature of 55 °C must be maintained .
pH value increase
Adding calcium hydrate during sludge conditioning
Adding Ca(OH)2 in the guise of quicklime or the like can result in a pH increase, and also reduces harmful-organism concentrations. A minimum of 0.2 kg Ca(OH)2/kg dry mass must be added and the baseline pH of the quicklime-sewage sludge mixture needs to be 12.8 at a minimum. The mixture needs to be stored for at least three months prior to use .
Long term storage processes that reduce concentrations of harmful organisms
Treatment carried out in
plant beds
Reeds or tule absorb and mineralize the organic elements in liquid sludge, resulting in a soil-like substrate containing the organic elements from the sludge and the rotted roots. The reed helps to aerate the substrate and promotes sludge dewatering thanks to its high evaporation capacity. The process is best carried out in modular treatment beds that are loaded in phases, which allows for minimum dwell times and load-free periods .
Drying processes
High temperature thermal drying
The sewage sludge is dried by heating the air, water or other drying medium to a temperature exceeding 100 °C .

13. Sludge Disposal in Germany Incineration
As result of severe legislative regulations incineration has been widely applied in Germany
Reduction of sludge quantity to the inorganic content (ashes) by incinerating the organic matter
Possible Re-use of remaining Product in Construction Industry
Possible Re-use with Co-Incineration (e.g. Cement Industry)
Removal of contaminants from the exhaust gases in accordance with 17. BImSchV (German Federal Immision Control Act)

14. Sludge Disposal in Germany
Landfill 0%
Landscaping 13%
Agriculture 30%
Incineration 55%
Source: Umwelt Bundesamt – Federal Ministry for Environment

15. Energy Recovery Options
Sludge Digestion and Biogas production a Energy from Biogas
Sludge Digestion plus Incineration a Energy from Biogas, Heat Recovery from Incineration
Sludge Mono-Incineration a Energy and Heat Recovery from Incineration (e.g. steam turbine)
Sludge Drying and Co-Incineration with solid waste or in industry (e.g. cement, power, etc) a Energy from Incineration

16. Sludge to Energy Digestion + Biogas Incineration
Sludge thickening by gravity
Mechanical sludge thickening
Anaerobic sludge digestion
Thermal sludge drying
Final Product: Dried Sludge
Energy Recovery from Biogas Incineration
Electricity
Heat
Only about 40-50% of Organic Matter is converted to Biogas Overall Energy Efficiency is therefore only about half

17. 100% of Organic Matter (Fuel) removed during Incineration
Sludge to Energy
Incineration
Sludge thickening by gravity
Mechanical sludge thickening/dewatering
Thermal sludge drying (partial)
Sludge Incineration
Final Product: Ash
All organic substances burned and transfered to:
Electricity
Heat
100% of Organic Matter (Fuel) removed during Incineration

18. Overview Sludge Treatment - Process Steps
Raw Sludge

19. Process Steps Sludge Thickening/ Dewatering
Equipment/Technology:
Gravity Thickener (space requirement)
Mechanical Thickener (Belt Press, Centrifuge)
Mechanical Dewatering (Centrifuge)
Degree of Dewatering depends on further process steps:
Digestion a 8% DS
Drying only a 20-25% DS
Drying and Incineration a 20-25% DS

20. Process Steps Digestion
Equipment/Technology:
Anaerobic Digester
Biogas Storage
Dewatering after digestion

21. Process Steps Sludge Drying
Equipment/Technology:
Solar Drying (open drying beds, covered drying beds)
Thermal Drying
Degree of Dewatering/Drying depends on Dis-
posal (and Net Calorific Value of incoming Sludge):
Agriculture  90-95% DS
Landfill  90-95% DS
Co-Incineration  90-95% DS
Mono-Incineration  % DS
Source: Umwelt Bundesamt – Federal Ministry for Environment

22. Process Steps Sludge Incinerators
Equipment/Technology:
Fluidized Bed furnace
Granular (pellets) furnace
Multiple-hearth
Cycloid
Pyrolysis
Degree of Dewatering/Drying :
100% DS
Final Product is Ash

23. Sludge Incineration Plant Ruhleben, Berlin
Owner: Berliner Wasserbetriebe
Fluidized Bed Incinerator:
No of lines: 3
Sludge feed capacity: 3.7 tDS/h (each line)
DS-content: 24 – 30 %
Calorific value: < 3,000 kJ/kg
Firing rate (in total): 39 MW
Steam regeneration (in total): 47.5 t/h
Steam temperature: 460 °C
Electrical energy (in total): 7.8 MW
Additional fuel consumption: 120 – 1,200 kg/h of oil

24. National Masterplan for Sanitary Engineering
Sludge Management, Bahrain
Client: Ministry of Works
Period: 09/2008 – 02/2010
Project data:
Population about 1 million
Identifying investment needs for the next 30 years
Proposed measures
Currently dried sludge disposal in land fill
Insufficient land for agricultural reuse
Sludge incineration and potential reuse adopted as sustainable sludge management solution for major STPs (Tubli WPCC, Muharraq STP)
Partial reuse in agriculture/ landscaping desired (minor STPs to produce dried sludge)

25. Sewage Treatment Plant Muharraq, Bahrain Sludge Incineration Plant
Client: Ministry of Works
Project Period: 09/ /2014
Contractor: Samsung
Project Data:
BOO model for Sewage Treatment Plant 100 T m³/d
Contract volume 225 Mio. €
Sludge Incineration Plant
For future wastewater flow of up to 160 T m³/d
2 sludge drying and incineration lines
Currently ash is disposed at local landfill

26. Tubli Water Pollution Control Centre, Bahrain Sludge to Energy
Client: Ministry of Works, Kingdom of Bahrain
Period: 09/2007 – 2016
Project data:
Expansion and rehabilitation to 400,000 m³/d
SBR, filtration, ozonation and sludge incineration
Sludge incineration:
Currently sludge is dried to 90% and disposed off in local landfill – approx. 45 tDS/d
New sludge treatment with dewatering, drying and incineration of up to 114 tDS/d
Electrical energy approx. 15 GWh/a
Partial stream for agriculture reuse will be possible

27. Sludge Management - A Way Forward
Sludge Quality: Control what comes into the sewage network inputs
a stop “everything can go in the sewers”
Diversify sludge treatment and reuse options
a stop landfill disposing of dewatered sludge
Implement sustainable sludge management strategies
Safe reuse in agriculture landscaping
Energy recovery and sustainable disposal as
Fertilizer,
Construction ad-mixture
Nutrient/ Phosphorus recovery

28. Vielen Dank Thank you 谢谢 Merci