influence of oil
TRANSCRIPT
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