COMPACT MEMBRANES PLANT FOR MBR...

COMPACT MEMBRANES PLANT

FOR MBR PROCESS

Get water from wastewater

COMPACT MEMBRANES PLANT FOR MBR

CONVENCIONAL BIOLOGICAL WASTEWATER TRETMENT

Effluent not suitable for reuse

More space requirement. Larger footprint.

Loss of sludge due to denitrification process and sludge bulking.

Poor stability of water quality due to the sensitivity of the system to overloads, toxics and other factors.

Toxins affects the biomass generating high turbidity on the effluent.

Weaknesses of conventional activated sludge treatment system

PRETREATMENT AND PRIMARY SETTLEMENT

ACTIVATED SLUDGE CLARIFIER

RAW WATER

SLUDGE TREATMENT

EFFLUENT


MEMBRANE BIOREACTOR SYSTEM

MBR system is a water treatment process that combines biological degradation of suspended biomass and the separation of solid/liquid using membrane micro or ultrafiltration.

Membrane bioreactors are classified depending on the submerged membranes configuration:

Bioreactor with inside submerged membrane Membrane modules are submerged inside the biological tank where the biodegradation is carried out.

Bioreactores with outside submerged membrane Membranes modules are placed outside the bioreactor tank. The pump circulates the mixed liquor from the bioreactor to the membrane module or back.

Outside submerged membranes configuration is easier to operate and easier to manipulate, maintane and control as is an independent process. Outside submerged MBRs appeared later in time but quickly became the favored MBR design for municipal plants in Europe.

MBR systems with inside submerged membranes are very compact.


MBR PORCESS DESIGN

Air supply is required not only to provide oxygen to microorganism for biodegradation of pollutants, but also to detach solids from the surface of the membranes. This operation is carried out during relaxation cycles.

Water from the bioreactor is filtered through the membrane under pressure. The permeate without solids stored in Clean in Place Tank and the exceed water is ready to use. The solids grater than the porues membranes size are retened into the membrane tank, periodically sludge is recirculated to the bioreactor.

Filtration cycles are combined with relaxation cycles and backwashing cleaning. During backwashing operation, permeate water or chemicals are forced to pass through the membrane backflow in order to clean membrane pores and extend their lifetime. Intensive chemical cleaning can be performed soaking membrane in a chemical solution for a time.


MEMBRANE TECHNOLOGY

Membranes are classified depending on: • Geometry: plane, tubulars, espiral • Composition: organic ( polímers and organics copolimers) and inorganic (ceramic) • Filtration range (micro, ultra, nano )

Micro and ultrafiltration is the range of membranes used in MBR applications. And the most common geometries are plane membrane and hollow fiber membranes

Studies shown the high efficiency of ultrafiltration membranes to remove faecals coliforms (Till et al.,1998; Gander I al.2000). Other studies shown 100% of bacterial removal in permeate water ( Aroojo I al.,2005) using ultrafiltration membrane with pores size of 0,04micras.

Micro and ultrafiltration casues a physical barrear for bacteris and virus, it is the reason why is able to reach easly a resusable higher water quality comparing with a conventional biological system. Membrane technology is considered the safest system to reuse water.


AXG MEMBRANE TECHNOLOGY

AXG MEMBRANE PROPERTIES • Membranes material is Polyvinylidene fluoride known for their:

High chemical resistance High temperature resistance Strong physical-mechanical resistance

• High capacity antifouling • High flux per modules

• Low cleaning frequency thanks to Out-inside flux configuration

and air scouring operation. • Excellent quality of water due to a separation range of 0,03 μm

and uniformity of pores distribution. • Low energy cost thanks to ultra-low pressure-driven operation.

Hollow fiber membrane PVDF (Polyvinylidene fluoride) is wide used for MBR treatment system cause their properties makes them a good cost effective choice.


AXG MBR SYSTEM BENEFITS

Save 30% to 40% space requirements due to: Eliminate secondary clarifier and filtration for tertiary treatment. Smaller bioreactor required thanks to the high biomass concentration allowed

(10-20g/l)

Excellent effluent quality 99% Removal of MES and DQO Viruses, algae, fungi and protozoa removal

Water quality stability due to the independence of the process to pollutant load and kind, turbidity, sludge settlement among other variable factors.

Less sludge production due to the capacity to operate with long sludge age. More concentrated sludge to purge. Modular system, easy to enlarge. Minimal manual operation and maintenance.

Reduce footprint

The enormous advantages of MBR system compared with conventional wastewater treatment are obvious as their application has been increasing from 2005.


ACTIVATED SLUDGE AND MBR COMPARISON

PARAMETERS INFLUENT ACTIVATED SLUDGE

MBR

COD 520 mg/l ≤75 mg/l ≤15 mg/l

SS 110 mg/l ≤40 mg/l ≤1 mg/l

Total N 48,3 mg/l ≤30,2 mg/l ≤3,4mg/l

Total P 15 mg/l ≤7,9 mg/l ≤2,25 mg/l

Turbidity 34 NTU 15 NTU ≤1 NTU

Overall Investment and operating cost for both systems are comparable, even little more for the MBR system due to major electrical consumption and membrane cost. But, the fact that MBR allows to reuse effluent provides added value to the system, as a result, the investment is repaid in half of the time compared with activated sludge installations. MBR system is much environmental and economic sustainable than conventional activated sludge systems.

EFFLUENT QUALITY SPACE REQUIREMENTS

CAPACITY= 1500m3/d

MBR = 595 m2 ASP = 855,25 m2

COSTES EXPLOTACIÓN Y MANTENIMIENTO

Camparison of quality of water between activated sludge and MBR process[Hasar y Kinaci, 2004]


CASE OF STUDY – MBR SYSTEM INSTALLATION FOR EXISTING WWTP TO REUSE WATER


CASE OF STUDY – CAPACITY OF TREATMENT

Capacity: Daily flow =1.000 m3/d

Peak flow = 80 m3/h

Raw water: COD = 500 mg/l BOD5 = 300 mg/l SS = 200 mg/l NTK = 90 mg/l

E.Coli = 48 ufc/100 ml Effluent :

COD < 30 mg/l BOD5 < 10 mg/l SS < 1 mg/l

NTK < 15 mg/l E.Coli < 0 ufc/100 ml


CASE OF STUDY – TREATMENT PROCESS

Screening: Material: Acero inoxidable Width slot: 1 mm

Homogenization Volume: 300 m³ Mixers: 2 mixers

Anoxic tank: Second clarifier is modified to anoxic tank to remove nitrates. Tank volume : 250 m Equipment: 2 mixers Oxygen concentration: < 0,1 mg/l

Bioreactor: Organic matter removal and nitrification. Tank volume: 1.000 m³ Air supplied: 2.400 m³/h Number of Aerator: 600 Oxygen concentration: > 2 mg/l Biomass concentration: 8-10 g/l

Biological treatment

Pretreatment


CASE OF STUDY – TREATMENT PROCESS

Membrane filtration

Membrane cassettes: Material: stainless steel Dimensions: 1,6 x 1,4 x 1,7 m

Membrane tank: Material: stainless steel Dimensions: 7 x 2,4 x 2,7 m

Membrane module: Material: PVDF Separation range: Ultrafiltración (0,1 micras) PTM < 0,5 bar

COMPACT MEMBRANES PLANT FOR MBR...

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