SWIM and Horizon 2020 Support Mechanism...Ammonia removal by air stripping can reduce ammonia...
Transcript of SWIM and Horizon 2020 Support Mechanism...Ammonia removal by air stripping can reduce ammonia...
This Project is funded by the European Union
SWIM and Horizon 2020 Support Mechanism Working for a Sustainable Mediterranean, Caring for our Future
Development of Landfill Leachate Treatment Sequence
Presented by:
Mr. Abderrahmane MALOUM, Biogas and Leachate Expert – SUEZ GROUP
SWIM and Horizon 2020 SM Title of Meeting
June 25th 2018, Beirut, Lebanon
Lecture 8
Outline Leachate Treatment Options How to choose a solution? Development of Landfill Leachate Treatment Sequence Different treatment sequences Two-stage suspended growth reactors SBR + BAC filter and denitrification process Biological treatment + RO Microfiltration/RO MBR-UV/ozone-RO Ammonia stripping + MBR + Ozonation
Other combinations Bio-Reactor + UF Bio-Reactor + UF + RO Bio-Reactor + UF + RO + Evaporation
Leachate Treatment Options
How to choose a treatment solution
Leachate Flow
Leachate Quality
Discharge Limits
Labour Skills (Operating Complexity according to the Treatment Solution (Often need Laboratory studies, summary Design, detail Design) To confirm the solution
Energy (biogas
valorisation,
Thermal
recovery, Biogas
availability,..)
Space
contraints
Balance CAPEX/OPEX
• Physico-Chemical processes
• Biological Treatment
• Membranes (RO, NF)
• Thermal Treatment (Evaporation)
• Zero Liquid Discharge (EVALIX)
How to choose a solution? 1- Sketchy Design Leachate Volume Leachate Quality, Discharge quality/Regulation
2- Main Factors Biogas recovery, energy Cost Local/national Regulation, Place Availability Town Planning
2- Other factors Environment Impact (Emissions, …) Reagent availability locally, Operating Skills
CAPEX OPEX Residues Evaluation (Quantity/Quality) Emissions (Liquid/gaz) Implementation
Solution 1 Solution 2 Solution X
Leachate Treatment Solution
Development of Landfill Leachate Treatment Sequence
A single treatment technology is not efficient for leachate
treatment due to the complexity involved in treating it having a varied composition and characteristics.
Leachate treatment entails the integration of several processes.
The coupling of units for the development of treatment sequences should be modular to allow maximum flexibility in order to vary the order of arrangement and the addition/removal of unit operations.
This effectively creates different treatment lines and thus can be better adapted to the changing qualitative conditions of the leachate.
Treatment
sequences
Sequencing batch
reactor (SBR) –
biological activated
carbon (BAC) filter and
denitrification process
Microfiltration/reverse
osmosis
Two-stage suspended
growth reactors
MBR-UV/ozone-reverse
osmosis
Ammonia stripping,
MBR and ozonation
Different treatment sequences
Biological treatment and
reverse osmosis
1
2
3
4
5
6
1-Two-stage suspended growth reactors
Two-stage suspended growth reactors
Source: Asian Institute of Technology (2004). State of the Art Review Landfill Leachate Treatment, Thailand
A single-stage activated sludge process is incapable of removing residual refractory organics, which remain after stabilization of biodegradable organics.
The existence of a second stage process can maintain organisms acclimatized to refractory organic compounds and for further degradation.
A treatment sequence comprising of an anaerobic reactor followed by aerobic process where biodegradable refractory organics and nitrogen compounds are simultaneously removed could be effective in treating a young and middle aged leachate.
Powdered activated carbon (PAC) could also be added to enhance biological treatment efficiency and remove refractory organic compounds to enhance nitrification.
Finally, a denitrification reactor can be introduced with an addition of external carbon source.
Two-stage suspended growth reactors
for young to medium age landfill
Clarifier Extended Aeration/
Nitrification
Extended Aeration/
Nitrification
Carbon source
Denitrification
Return sludge
Clarifier
To sludge drying bed
Sludge to Digester
Return sludge
Anaerobic Digester/Equalization
basin
Gas
Clarifier
Effluent
Two-stage suspended growth reactors
Source: Asian Institute of Technology (2004). State of the Art Review Landfill Leachate Treatment, Thailand
As the landfill age increases, the leachate characteristics changes and treatment sequence could be subsequently changed.
The second aerobic reactor could be converted into an ammonia-stripping column to compensate the increase in ammonia and incomplete nitrification in the first aerobic zone.
The denitrification zone can be used for recarbonation and pH adjustment of the effluent from the ammonia stripping phase.
The process could be effective in removing biodegradable and refractory organics, heavy metals, nitrogen and phosphorus. However, this scheme would not be efficient in removal of dissolved solids.
Two-stage suspended growth
reactors for old landfill
Clarifier Extended Aeration/
Nitrification
Recarbonation
Clarifier
To sludge drying bed
Sludge to Digester
Return sludge
Anaerobic Digester/Equalization
basin
Gas
Clarifier
Effluent
Lime
Clarifier
Air stripping of Ammonia
2-Sequencing batch reactor (SBR) - biological activated
carbon (BAC) filter
Sequencing batch reactor (SBR) - biological activated carbon (BAC) filter
Source: Asian Institute of Technology (2004). State of the Art Review Landfill Leachate Treatment, Thailand
Treatment process with pre-treatment using an anaerobic reactor (equalization take place ) followed by coagulation-flocculation (heavy metal precipitation occurs) and subsequently by SBR-BAC filter and denitrification process could be successful in treating young and middle aged leachate.
The SBR would enrich the microbial population with desired metabolic capabilities, stability and settling characteristics in which both the biodegradable and refractory organics could be removed.
The biological activated carbon would help in creating a biofilm to metabolize refractory organics and initiate nitrification of the residual ammonia. The nitrate nitrogen would be removed in the denitrification tank.
SBR-BAC and denitrification
process for young to
medium age landfill
Clarifier
Denitrification
To sludge drying bed
Anaerobic Digester/
Equalization basin
Gas
Clarifier
Effluent
Chemicals
Flocculation
Sludge to Digester
SBR
BAC
Two-stage suspended growth reactors
Source: Asian Institute of Technology (2004). State of the Art Review Landfill Leachate Treatment, Thailand
With an increase in the landfill age, the facility could be upgraded by the addition of granular activated carbon columns.
SBR-BAC and denitrification process for old landfill
Clarifier
Denitrification
To sludge drying bed
Anaerobic Digester/
Equalization basin
Gas
ClarifierEffluent
Chemicals
Flocculation
Sludge to Digester
SBR
BAC GAC
3-Biological treatment and Reverse Osmosis
Biological treatment and reverse osmosis
Source: Asian Institute of Technology (2004). State of the Art Review Landfill Leachate Treatment, Thailand
A treatment sequence that is capable of removing mineralized material should include anaerobic digestion (stabilizes the waste), suspended growth biological waste treatment (degrades the biological matter), partial softening, filtration and reverse osmosis.
The effluent is polished in a gravity filter and dematerialized in RO unit, thus achieving an effluent devoid of dissolved salts and low in organics.
Leachate treatment with biological treatment and reverse osmosis
for young to medium age landfill
Return sludge
Clarifier Aerobic treatment
Gas
Sludge to Digestion RO Concentrate
RO Permeate
Granular Filter Media Anaerobic
Digester
Influent
Two-stage suspended growth reactors
Source: Asian Institute of Technology (2004). State of the Art Review Landfill Leachate Treatment, Thailand
With increase in age, the biological treatment could be replaced by coagulation-precipitation process followed by re-carbonation, filtration and RO.
Leachate treatment with biological treatment and reverse
osmosis for old landfill
Recarbonation
Chemical treatment
Gas
To drying bed RO Concentrate
RO Permeate
Granular Filter Media
M
Anaerobic Digester
Influent
Clarifier
4-Microfiltration/reverse osmosis
Microfiltration/reverse osmosis
Source: Asian Institute of Technology (2004). State of the Art Review Landfill Leachate Treatment, Thailand
The combination of microfiltration and reverse osmosis could also lead to a well-developed treatment sequence.
The first step of precipitation and microfiltration provides a simple pre-treatment (removal of toxic metals and suspended solids) for the RO unit and thus produces a high quality effluent free of solids and dissolved organics.
However, similar to other membrane processes, the system is susceptible to fouling, antifouling strategies needs to be evaluated.
The process is suitable for leachates of all ages.
MF and RO process for leachate treatment
Chemical treatment
RO Concentrate(Recirculation)
EffluentMInfluent
Flow Equalization Microfiltration Reverse Osmosis
Solids
Filter Press
5-MBR-UV/ozone-reverse osmosis
MBR-UV/ozone-reverse osmosis
Source: Asian Institute of Technology (2004). State of the Art Review Landfill Leachate Treatment, Thailand
The basic technologies selected in the study were: Membrane bioreactor for biological treatment by aerobic oxidation and nitrification; UV/ozone for increasing biodegradability and for partial removal of organic residuals, as
well as breaking down and partially oxidizing low degradable molecules; and Reverse osmosis treatment for the elimination of dissolved solids and reducing of organic
load.
MBR-UV/ozone-RO process for leachate treatment
MBR UV/ozone Reverse osmosis
Influent Effluent
MBR-UV/ozone-reverse osmosis
Source: Asian Institute of Technology (2004). State of the Art Review Landfill Leachate Treatment, Thailand
UV/ozone process was more efficient when
placed after MBR process in young leachate and
before MBR process in the old leachate
MBR followed by RO proved to be the most
promising treatment sequence. Removal efficiencies
of 96 - 99% could be obtained and the effluent could
be directly discharged into the environment
The biological pre-treatment of the leachate
ensured a better quality permeate from the RO
unit and prolonged the life span of the RO unit
by reducing fouling effects and treatment costs
By incorporating RO as a post-treatment to MBR
process, UV/ozone is not required
6-Ammonia stripping, MBR and ozonation
Ammonia stripping, MBR and ozonation
Source: Asian Institute of Technology (2004). State of the Art Review Landfill Leachate Treatment, Thailand
Ammonia removal by air stripping can reduce ammonia concentration from 2,000 - 200 mg/L.
Ammonia stripping as pre-treatment also has an advantage of reducing refractory compounds, thereby reducing the COD by precipitation when the pH is adjusted.
If pre-treatment of ammonia stripping fails, shock loading will occur caused by ammonia in the biological system, making it difficult for the floc to settle down.
Adoption of membrane system to replace the clarifier in the activated sludge process since membranes can retain total solids until the sludge recovers from the shock loading of ammonia.
Ammonia stripping, MBR and ozonation process for leachate treatment
MBR Ozonation Influent
Effluent Ammonia stripping
Ammonia stripping, MBR and ozonation
Source: Asian Institute of Technology (2004). State of the Art Review Landfill Leachate Treatment, Thailand
A possible approach to increase leachate biodegradability
is to ozonate either the mixed liquor or effluent streams
from the membrane bioreactor
To maintain a constant MLSS as well as breakdown of high
molecular weight refractory compounds into simpler
molecules, which increases the nutrients within the reactor
To Increases the overall biodegradability within the
bioreactor and improves the effluent quality to create a
zerodischarge system
To eliminates the capital and operational costs associated
with the treatment of sludge in its disposal facility prior to
discharge
Other combinations
Process Treatment combination
BioReactor UF
NF
RO Evaporator
Treated Water
Treated Water
Treated Water
Leachate quality at different steps of treatment
1 2 3 4 5
+ Bio-Reactor
+ UF
=
Combination Bio-Reactor & UF
+ =
Combination Bio-Reactor + UF + RO
NF
RO +
+ =
Combination Bio-Reactor + UF + RO + EVAPORATION
+
Evaporater