Influence of Oil

Influence  of  Oil-­‐Containing  Raw  Water  in  Flat-­‐Sheet  MBR  Opera<on  

Marcelo  Bueno  –  Toray  Brazil  

Content

•  Objectives

•  MBR Basics

•  Adopted Technology (submerged flat sheet)

•  Experimental devices

•  Experimental conditions

•  Results

•  Conclusions

Objectives

What is the level of tolerance of fats and oils in an MBR plant? Not only during design phase, but also during the operation phase unusual presence of oil can be considered as a possible risk. It was with this in mind that we decided to carry out some specific tests in our laboratory.

MBR performance was examined using raw water that included various types of oil (biodegradable and non-biodegradable). Milk fat and vegetable oil (salad oil) were chosen as the biodegradable oils, while three industrial oils with different kinematic viscosities were chosen as the non-biodegradable oils.

A laboratory-scale experiment was conducted using the mini module with the ultrafiltration PVDF flat-sheet membrane.

- Combines membrane technology with biological treatment - Replaces conventional clarification, aeration and filtration into a single step

Conventional Multi-Step Tertiary Treatment Process

Influent  

Screen   Primary  Clarifier  

(Optional)  

Aeration  Basin  

Secondary  Clarifier  

Sand  Filter  

Effluent  for  Discharge  or  Reuse  

Influent  

Screen   Membrane  Bioreactor  (MBR)  

High  Quality  Effluent  for  Discharge  or  Reuse  or  Recycle  

MBR Simplified Treatment Process

Reverse  Osmosis  (RO)  

Extremely  High  Quality  Effluent  for  Industrial  Use  

High  Quality  Effluent  for  Direct  Feed  to  RO  

MBR Basics

Adopted Technology – Flat Sheet

Permeate

Supporting

Panel

Air Bubble

Membrane

Feed Water

Experimental Devices

Mini membrane element “A4” 0.029 m2 filtration area

MODULE Bacteria

Permeate

Air

Standard module (TMR140-100S) with 100 membrane elements

1,4m2 each – total 140m2

PVDF Element

0,08µm Pore size

Experimental Devices

MBR Tank 30 L (each)

Experimental Conditions

The artificial sewage was prepared with organic sources of sodium acetate and acetic acid as well as inorganic sources of nitrogen and phosphorous. The Table shows the test oil characteristcs: - Milk (4.0% fat) and salad oil were selected as the biodegradable oils. - Three industrial oils with different viscosities were selected as the non-biodegradable oils. These are widely used as raw materials and lubricants.

Experimental Conditions

Table shows the operational conditions of the experiment. The filtration flux was set to 11.3 LMH (0.27 m/d) on average. The operational cycle was 9 min “On” followed by 1 min “Off,” so that the activated sludge would not cake on the membrane surface.

Experimental Conditions

With biodegradable oils, the oil concentrations and BOD-SS loadings were changed. The milk and salad oil each were tested under several conditions:

Experimental Conditions

With non-biodegradable oils, the oil concentration was fixed and the kinematic viscosity was varied:

Lab MBR Results BOD-SS loading of the milk was kept nearly constant while the BOD of its oil concentration was increased. Pressure remained constant for more than 20 days.

BOD-SS loading of salad oil was at 0.20-0.30 kgBOD/kg-SS and oil concentration was increased to 7,100 mg/L a rapid decrease in the suction was observed after 19-20 days in operation.

Lab MBR Results

TMP

[kPa

] No change

TMP increased after 32days

TMP increased after 19days

TMP

[kPa

] TM

P [k

Pa]

Chemical cleaning

Chemical cleaning

Viscosity of the oil seems to be one of the critical factors affecting sludge filterability

Chemical cleaning

[days]

Low viscosity Oil

Middle viscosity Oil

High Viscosity Oil

Conclusions

•  Stable operation of the MBR was observed when the raw water containing biodegradable oils was treated with the appropriate biological loading.

•  It was found that non-biodegraded and residual oil that enter the activated sludge may cause membrane fouling in cases of higher biological loading.

•  It would be difficult to derive precise guidelines from the limited amount of test in laboratory, or even from a much larger mix of fats and oils.

•  Some useful indications were obtained as when treating raw water containing non-biodegradable oil, MBR performance depends upon the kinematic viscosity of the oil. It was also found that oil with higher viscosity (higher molecular weight) causes greater fouling in shorter periods.

Obrigado !

www.toraywater.com

Marcelo Bueno (+5511) 98843-3886 / (+5511) 25579-1505

[email protected]