EcoLanTM MBR Membrane Module Replacement Case

Project Overview

Project name: A mine bathing wastewater treatment project

Number of MBR membrane elements: 80pcs EcoLan TM EL M-5080

Water production capacity: 750m3/day

MBR module replacement date: June 2022

System process flow: Mine bathing wastewater → Regulating tank → Anaerobic tank → Aerobic tank → EcoLan MBR tank → Clear water tank → Effluent reuse

Produced water quality: turbidity ≤ 1NTU, TSS ≤ 10mg/L

Design feed water quality

The feed water of the MBR system is the product water of the pretreatment unit, and the following criteria need to be met.

Number Control index Maximum limit
1 pH value ≤10
2 COD ≤1000mg/L
3 BOD ≥120mg/L
4 TSS ≤100mg/L
5 TDS 600~5000mg/L
6 NH3-N ≤35mg/L
7 Hardness ≤600mg/L

EcoLan’s membrane module specifications and technical parameters

To maintain the regular and stable operation of the MBR system, we developed the following plan to replace the MBR membrane module with a treatment capacity of 750 m³/day, based on a preliminary understanding of the industrial wastewater quality of this project.

Number Item Name Technical Specifications Remark
1 Treating water Mine bathing wastewater
2 Capacity 750m³/day
3 Designed flux 15L/(㎡·h) Instantaneous flux(25℃)
4 Design effluent quality Level 1A(GB18918-2002) Requires normal pretreatment
5 MBR membrane Curtain hollow fiber membrane
6 Membrane material PVDF + PET
7 Pore size 0.1μm
8 Filament inner/outer diameter 1.5/2.6mm
9 Filtration accuracy 0.1μm
10 Filtration mode Submerged suction filtration (Out to In)
11 Expected life ≥2 years
12 Tensile strength ≥200N
13 Max pH value 2~12
14 Tolerable residual chlorine concentration 3000ppm
15 Oil content requirement
Mineral oil: ≤3mg
16 Sealing material polyurethane adhesive
17 Active membrane area 34m2/pc
18 Membrane size 1250*30*2000mm
19 Quantity 80pcs

Phase II and Phase III membrane modules are 2200mm and 2520mm long, 1680mm and 2170mm in width, and 2027mm in height, based on the project’s existing membrane modules. See the below chart for details.

Two EcoLan membrane modules of 2520 x 1500 x 2700 mm are proposed to be replaced to fit the available space in the on-site membrane tank. It will allow the production of 750 m³/day for more than two years. A diagram of the new MBR modules is shown in the figure below.

The membrane module is easy to install and remove, the hollow fiber membrane sheet does not break or peel, the flux is stable, and it can withstand high-pressure water backwash. The recommended backwash pump flow rate is 75.6 m³/h, the aeration blower volume is 7.5 m³/min, and the system online cleaning pump flow rate is 10.08 m³/h.

MBR membrane module operating conditions

Item Unit Parameters
PH value / 6-9
Working temperature 5-35
Mineral oil content mg/l <3
TMP Mpa -0.01 ~ -0.05
Backwashing pressure Mpa ≤ 0.2
MLSS mg/l 4000-12000
Operating mode / Filtration 8~12min, stop 1~2min
Aeration Air-to-water volume ratio (10~15):1

Cleaning of MBR membrane modules

Option A

Water backwashing
Chemicals for cleaning Concentration Cleaning frequency Cleaning duration
Clear water or product water 1 to 2 times water production 4~6 times a day 1~5 minutes (per series), backwash pressure: 0.05 to 0.2Mpa, max. not exceeding 0.5Mpa
CIP (Clean in place)
Chemicals for cleaning Concentration Cleaning frequency Cleaning duration
NaClO 100-500ppm Every 1-3 months of running 60 minutes((per series)
Citric acid, HCl 0.1-0.2% Every 1-3 months of running 60 minutes((per series)
COP (Clean out of place)
Chemicals for cleaning Concentration Cleaning frequency Cleaning duration
NaClO 1000-2000mg/L 1 time in 5~6 months 8~12 hours((per series)
NaOH and Oxidizing agents NaOH: 0.1mol/L~0.5mol/L,Oxidizing agents : 200 mg/L 1 time in 5~6 months 8~12 hours((per series)
Citric acid 1-3% 1 time per half-year 8~12 hours((per series)

Note:

① COP cleaning is only considered when TMP cannot be restored by CIP cleaning, which can be done once in 3 months to once a year. According to the high hardness of the incoming water, which is prone to scaling situations, we propose adjusting the frequency and concentration of acid cleaning according to the actual condition.

②After chemical cleaning, it should be rinsed with water sufficiently before use. It is necessary to rinse with water between changing chemicals when using multiple chemicals for cleaning.

Option B

Maintenance cleaning (low-concentration fluid cleaning)
Chemicals for cleaning Concentration Cleaning frequency Cleaning duration
NaClO 300-500mg/L 1-2 times per week 60 minutes((per series)
Recovery cleaning (high-concentration liquid cleaning)
Chemicals for cleaning Concentration Cleaning frequency Cleaning duration
NaClO 1000mg/L 1-2 times per month 60~90 minutes((per series)
Citric acid 0.5-1% 1-2 times per month 60~90 minutes((per series)
Soak clearing
Chemicals for cleaning Concentration Cleaning frequency Cleaning duration
NaClO 1000-2000mg/L 1~2 times per year 8~12 hours((per series)
NaOH and Oxidizing agents NaOH: 0.1mol/L~0.5mol/L,Oxidizing agents : 200 mg/L 1 time in 5~6 months 8~12 hours((per series)
Citric acid 1-2% 1~2 times per year 8~12 hours((per series)

MBR System Operation and Maintenance

To ensure the stable and regular operation of the MBR system, the customer must do the following in the operation process.

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