Mbr-c1 Fundamentals Of Mbr

MBR Course Fundamental of MBR Processes & Introduction to Process Design Tools October 16 & 17, 2012 Hamid Rabie

Function of a WWTP Removal of particulate materials • sand • hairs, fibrous materials • other solids Biodegradation of undesired components • • • •

carbon nitrogen sulphur phosphorus

CO2 + biomass N2 + biomass biomass biomass

Solid liquid separation

Waste water

WWTP

Effluent

• biomass rejection • Microbial rejection • standard sedimentation: 10,000 CFU/ml (colony forming unit: cfu)

Surplus sludge (biomass)

Fundamentals of Bio-Reactor Processes Wastewater

Effluent

Solid - Liquid Separation • Settling • Filter media • Membrane Biological Process

Engineered systems to: Accumulate microorganisms for oxidation of electron donor pollutants. Convert soluble pollutants to large particles (biomass) for separation.

Sludge

Fundamentals of Bio-Reactor Processes Pollutant Measurement Biological Reaction Process Name O2 Carbonaceous BOD, COD Organic → CO2 + cells BOD Removal O2 Ammonia N - NH3 Nitrification NH → NO − + cells 3

3

Condition Aerobic Aerobic

Nitrate

TN

NO3−  → N 2 + cells

Denitrification

Phosphorous

TP

P → cells

Bio-P Removal Anaerobic

BOD / Nit

Aerobic

BOD / Nit / Denit

Anoxic

Aerobic

BOD / Nit / Denit Bio-P

Anaerobic

Anoxic

Anoxic

Aerobic

First Use of Membranes in Biological WWT Effluent treatment with membrane technology – tertiary treatment

S

GF

PC

Raw wastewater

S GF PC BS

BS

ST

DC

MT

Permeate

Effluent

= = = =

Step screen Grid and fat removal Primary clarifier Biological step

ST = Sedimentation tank DC = Third cleaning step (e.g. filtration) MT = Membrane technology

Membranes at the End of WWT Process Tertiary treatment Always end of the processes

additional costs to conventional technology; additional footprint required

Low solid concentration tolerance in membrane stage

no hair and fibrous material allowed requires easy sludge management

Mostly dead end filtration mode

Pressurized membrane systems or Submerged membrane systems

Sensitive against fouling components

fouling components come in direct contact with membrane surfaces; often additional flocculation required; operation difficult to optimize

Interesting for existing WWTP that need disinfection or reuse Almost similar to surface water treatment (need for coagulant)

Changes in the MBR System Membrane bioreactor (MBR)

S

GF

FS

PC

BS

Raw wastewater

S GF FS BS

BS

MT

ST

TC Combination of biological step and solid liquid separation

Permeate

= = = =

Step screen Grid and fat removal Fine screen Biological step

MT = Membrane technology

Effluent

MBR vs. Conventional Activated Sludge Conventional Activated Sludge System

Incoming Wastewater

PreTreatment

Anoxic Zone

Aerobic Zone

Settling Tank Effluent In case of Tertiary More processes; e.g. sand filter

RAS

Membrane Bioreactor (MBR) Incoming Wastewater

PreTreatment

Anoxic Zone

Aerobic Zone

MF/UF

RAS

Effluent

MBR Reduces the Footprint

Eliminate all clarifiers

Replace with membrane systems Membranes

Major Differentiations of MBR Technology

Stable Biological Treatment Process

Activated Sludge Process

MBR

Membrane Filtration

Absolute Solids Separation

• Replaces conventional clarification; requires less footprint • Combines physical barrier of a membrane with biological treatment • Produces high quality effluent at all times • Comparable to tertiary treatment; then LCC is ≤ conventional technologies

membrane

key component to this market

Advantages of MBR over Conventional Better effluent quality

Increased Efficiency

> 95%, 98% and 99.9% for COD, BOD, SS removal

All bacteria retained, cold weather nitrification

Effluent TSS independent of bioreactor efficiency

Insoluble P retained reducing chemical addition for P removal

High MW organics are retained and bio-degraded

High MLSS (1-2%), greater organic loads and less sludge production

Improved biological reactions (due to longer SRT, shear, etc.)

Compact systems, less footprint Sludge digestion within bioreactor

Process Control Complete separation between HRT and SRT Accurate control over sludge age, development of slow-growing microorganisms (nitrifiers)

Modular expansion Absorbs variation and fluctuations in incoming flow and organic loads

Market Areas for MBR Technology Space limitation reuse; high quality High & variable salt content

pulp & paper

municipal wastewater

textile industry

tank cleaning

pharmacy industry

beverage industry

industrial laundries

Membrane Bioreactors

dairy industry

High & variable salt content

High COD content

petrochem industry

vegetable industry

leachate fruit industry

High COD content

Slaughter -house / rendering

chemical industry

High ammonia content

Drivers of MBR Market & Technology Increasing regulatory standards especially regarding disinfectant byproducts and waterborne pathogens

Limited supply tap into alternative supplies such as water re-use

Growth in Membrane Technology Growing demand due to population growth, new infrastructure in developed countries, and aging infrastructure in industrialized countries

Technological innovation development of low cost, high quality water treatment solutions

Main Configurations for MBR Technology Tubular modules

Hollow fiber modules

Plate modules

Inside/Out Filtration (Pressurized Vessel)

Outside/In Filtration Immersed (Vacuum)

Outside/In Filtration Immersed (Vacuum)

•

X-Flow / Pentair

•

GE-Zenon

•

Kubota

•

Berghof

•

Mitsubishi

•

Toray

•

Koch Membrane

•

Siemens-Memcor

•

Huber

•

Koch Membrane-Puron

•

A3 Gmbh

•

Micronet PF

MBR with Tubular Modules Cross Flow Membrane Filtration Pressure Pump

External cross flow MBR

DN

MF

N RC

RL

Pressure

modules cross flow operation Feed side Permeate side

Module Length

RC RL MF N DN

recirculation return line membrane filter Nitrification De-nitrification

Cross Flow Membrane Filtration for MBR – Tubular Membrane (Inside/Out Filtration)

Concentrated Waste

Feed

Membrane Support Material

Permeate (Clean Water)

Cross Flow Membrane Filtration for MBR – Tubular Membrane • Original “work-horse” in MBR applications; used horizontal configuration • Large diameter membrane tube and high recirculation flow rate and high TMP served to eliminate potential for plugging with biomass • Membrane designed to operate at MLVSS levels > 50,000 mg/l • Energy intensive on large flow rates (> 300,000 gpd) • Low packing density (requires large footprint for large flow rates) • New tubular systems from X-Flow uses air plugs in vertical tubes operating at lower pressures

Tubular MBR Configurations X-Flow Airlift

• MLSS: 12-50 g/L

• MLSS: 8.0-12 g/L

• Flux: 50-150 lmh

• Flux: 30-50 lmh

• High energy consumption:

• Lower energy consumption:

(1.5-4.0 kWh/m3)

(0.3-1.0 kWh/m3)

• Continuous

• Discontinuous

• TMP: 1.0-5.0 bar

• TMP: 0.2-0.6 bar • More valves & complexity

MBR with Submerged (Immersed) membranes

submerged membranes

Vacuum Pump Waste water Permeate

Biological sludge Air

Basic of Immersed MBR Train 1.Biological reactor 2.Membranes 3.Permeate pump & blower 4. Control panel 5. Permeate & air piping

5 1

2

3

4

Immersed Membrane Filtration (hollow fiber) Membrane

Permeate to Top Header (Puron has no top header) Support Material (e.g. Zenon, MPF, Puron)

Aeration Bubbles (for fluid agitation)

Suction

Outside/In Filtration

Coarse Bubble Diffuser

Bulk Fluid (Concentrate)

Coarse Bubble Diffuser Permeate to Bottom Header (Siemens has no bottom header)

Immersed Hollow Fibers in Operation Module Installation with crane

Submerged module in operation air injection phase

Immersed Membrane Filtration (flat sheet) To suction Suction

Panel

Air bubbles between membrane panels

Air diffusers

MBR with submerged modules different tank configurations Internal submerged MBR

DN

N

RC RL MF N DN

MF

RC

External submerged MBR (Preferred)

DN

N

MF RC

RL

recirculation return line membrane filter Nitrification dnitrification

Key Aspects of MBR Products For superior technological and economical performance, should consider:

Membrane structure and characteristics Module design and features Aeration system & sludge management Membrane tank hydraulics Membrane filtration process and system design

Classification of membrane processes

Pressure difference in [bar]

Saline solutions Viruses

Bacteria

100 RO

10

Nanofiltration

Ultrafiltration 1

Microfiltration

0,1 0,0001

0,001

0,01

0,1

1,0

Particle size in [µm] Membrane pore size range from different suppliers for MBR

10,0

Sand filtration

100

Comparison of microorganisms vs membrane pore size

E. Coli ~ 0,5 - 1,5 µm

B. Subtilis ~ 0,3 µm

MS2-Virus (Coliphage) ~ 0,025 µm poresize ~ 0,01 µm

ultrafiltration

poresize ~ 0,2 µm

microfiltration

MBR provides better effluent quality

Parameter

MBR

convent. plant

Solids

mg/l

0

10 –15

COD

mg/l

< 30

40 – 50

Ptotal with precipitation

mg/l

< 0,3

0,8 – 1,0

g/l

< 20

<5

MLSS content in aeration tank

Key Requirements for Membrane Properties Material requirements hydrophilicity - good wetability with water low fouling tendency chemical and thermal stability mechanical stability Morphological requirements narrow pore distribution minimized number of defects high porosity low hydraulic resistance high bonding of membrane to support material Economic requirements cost-effective materials cost-effective production

Different Types of Membranes & Structures (SEM of Membrane Surfaces) Zenon

Toray

Kubota

Mitsubishi

2 µm

2 µm

2 µm

3 µm •

Avg. Pore: 0.1 µm

•

Avg. Pore: 0.03 µm

•

Avg. Pore: 0.4 µm

•

Avg. Pore: 0.2 µm

•

PVDF high MW

•

PVDF low MW

•

Chlorinated PE

•

PVDF low MW

•

Asymmetric

•

Asymmetric

•

Symmetric

•

Asymmetric

•

Coated on fabric

•

Coated on a support •

Coated on fabric

•

Double coating

•

Coated on support

10 µm

Asymmetric Structure

Membrane Skin/Surface

Introduction to Design Tools

Key Elements of MBR Process Design • Full step by step biological reaction analysis and mass balances such as: • Carbon, Phosphorous, Nitrogen, etc • Sludge production • Aeration and nutrient requirements •

Step by step process mass balances and all necessary sizing such as: • Pumping and coarse screen • Sand and fat removal • Fine screen • Equalization • All dosing systems • Different biological steps • Sludge treatment • Membrane systems: filtration tank, configuration, RAS, sludge g=feed, aeration capacity, blower sizes, pump sizes, chemical dosing, etc

System Configuration

Step by Step Process Calculations

Step by Step Process Calculations

Process Trends for Different Key Parameters