Performances des membranes de Filmtec

21 décembre, 2008
15:21

Performance de quelques membranes FILMTEC	SW30HR	BW30	XLE	NF270
Feed pressure (psi)	370	150	70	50
Feed pressure (bar)	25	10	5	3.5
Rejection (%)
Sodium chloride NaCl	99.7	99.4	98.6	45
Calcium chloride CaCl2	99.8	99.4	98.8	50
Magnesium sulfate MgSO4	99.9	99.7	99.2	99.3

 

À 18 GFD (30 l/m2h), 2,000 mg/l de NaCl, 25°C, pH 7-8, 10% taux de recouvrement parélément de 40 ».

Performance des membranes:

1. 1. As a general rule, membranes with a high water permeability (low feed pressure) also havea higher salt permeability compared to membranes with lower water permeability. The permeability of solutes decreases (the rejection increases) with an increase in the:
   3. degree of dissociation: weak acids, for example lactic acid, are rejected much better at higher pH when the dissociation is high
   4. ionic charge: e.g. divalent ions are better rejected than monovalent ions
   5. molecular weight: higher molecular weight species are better rejected
   6. nonpolarity: less polar substances are rejected better
   7. degree of hydration:highly hydrated species, e.g. chloride, are better rejected than less hydrated ones, e.g. nitratedegree of molecular branching: e.g. iso-propanol is better rejected than n-propanol. ( )Concentration de sel traité (attendu dans le perméat)
   8. BW ——5000 (50)
   9. SW ——3000 – 15000 (150)
   10. SWHR -10000 – 50000 (500)
   11. TW—— 5000 (50)
   12. NF —— 1000 (500)

• TDS que les membranes de Filmtec peuvent supporter:

Molecular weight cut-off ( from Filmtec)

The RO membrane acts as a barrier to all dissolved salts and inorganic molecules, as well as organic molecules with a molecular weight greater than approximately 100. Rejection of dissolved salts is typically 95% to greater than 99%.

Nanofiltration (NF) : Organic molecules with molecular weights greater than 200-400 are rejected. Also, dissolved salts are rejected in the range of 20-98%. Salts which have monovalent anions (e.g. sodium chloride or calcium chloride) have rejections of 20-80%, whereas salts with divalent anions (e.g. magnesium sulfate) have higher rejections of 90-98%.

We don’t have specific MWCO information for our different NF products, but perhaps the following will give you some guidance:

FILMTEC NF90 Elements: Removal of TOC, nitrates, pesticides, herbicides, hardness, iron, salts.

>97% MgSO4 rejection 85 – 95% NaCl rejection

FILMTEC NF270 Elements: Removal of color, TOC, medium to low calcium passage, high salt passage.

>97% MgSO4 rejection 40-60% CaCl2 rejection

FILMTEC NF200 Elements: Removal of TOC, atrazine, medium calcium passage, medium to high salt passage.

97% MgSO4 rejection 35 – 50% CaCl2 rejection

Les tailles des trains de membranes sont généralement conçues en incrément de 0,5 mgd ou plus. La taille des trains est généralement limitée à 2,5 mgd

Les systèmes sont généralement conçues avec un nombre d »étages variant de 1 à 3.Les étages de membranes

Les taux de recouvrement (TR) se situent dans les intervalles suivants:

Pas de recirculation:

1 étages: TR / 50%

2 étages: 50%/TR/75%

3 étages: TR\75%

• Lavage des membranes
  • Formulations utilisées en MF eau de surface
  • Acides
  • 1) 2% acide citrique
  • 2) 0,05% HCl + 0,15% EDTA
  • 3) 0,05% H2SO4 + 0,15% EDTA
  • La formulation 3 s’est avérée plus efficace
  • Base
  • 1) 2% NaOH + 1% Surfactant
  • 2) 2% NaOH + 0,5% H2O2 + 0,15% EDTA
  • La formulation 2 s’est avérée plus efficace
• Voir les articles Elimelech sur lavage NF270 et NF90 (dans fichier lavages)
  • Membrane fouling Elimelech
  • Formulation: 1 nM EDTA / 1% SDS (ou 10 mM/L et plus / pH 11. Semble plus efficace que EDTA + NaOH pour la MOD selon Elimelech.
  • Le PH 11 est assuré par l’ajout de NaOH. L’activité de SDS n’est pas lié au pH, mais celui de l’EDTA, oui. L’EDTA n’est totalement déprotoné qu’à pH proche de 11. Ceci est nécessaire pour pour capter les cations bivalents jouant le rôle de pont entre la membrane et la matière organique.
  • pH solution de EDTA: autour de 4.8.
  • pH solution de SDS: autour de 9.
  • SDS: Sodium dodecyl sulfate (SDS or NaDS) (CH3(CH2)11OSO3Na) (FW 288.38), aussi connu sous le nom de sodium lauryl sulfate (SLS), est un surfactant ionique.
• Formulation utilisée efficacement pour laver membranes RO:

 

• 0.15% (w) Na percarbonate
• 0.12–0.13% (w) NaDBS
• pH 11.7–11.9(w/NaOH)
• Sodium dodecylbenzenesulfonate (NaDBS)
• Formule Sodium Percarbonate: 2Na2CO3
• 3H2O2
• Molecular formula : 2Na2CO3 3H2O2
• Molecular Weight: 314
• Appearance : White granule, odorless
• Bulk Density : 0.92~1.08(g/ml)
• Active Oxygen(AO) : 12% or more
• PH(1% solution) PH(1% aq.soln.) : 10~11
• Solubility(g/100g water) : 12 (5oC); 14 (20oC); 18.5 (40oC)
• Autres formulations

• Cleaning solution	Foulants	Metal	Inorganic	Biological	Organics	Silica	Results at
  	sparsely soluble inorganic salts	oxides	colloids(silt)	matter			Dhekelia D.P.
  2.5% (w) citric acid pH 4.0 (w/NH4OH)	Effective	Effective	Effective				Not effective
  0.5–0.75% (w) P3Ultrasil 53			Effective				Not effective
  pH 10.8-11.0(w/NaOH)
  0.2–0.25% Na2S2O4	Effective	Preferred					Some effect on
  							RO1–4
  NaOCl, 140 g/m³ active Cl2				Effective	Effective		Not effective
  PH 11.5–12.0 (w/NaOH)
  1.0% (W) NaHMP		Effective	Effective		Effective		Not effective
  0.15% (w) Na percarbonate			Preferred	Effective	Effective	Effective	Very effective
  0.12–0.13% (w) NaDBS pH
  11.7–11.9(w/NaOH)
  0.5–1.0% (w) Permaclean 67			Effective		Effective		Not effective
  pH 10.5–11.0 (w/NaOH)
  Sodium carbonate							Not effective
  High pH–NaOH PH 11.7						Prefitted	Very little effect

NF270 90 pore size Elimelech Retention of Emerging Water and Wastewater imstec054.pdf

1. D. Nghiem1,2,a#, A. I. Schäfer2,b, M. Elimelech1,c

http://www.membrane.unsw.edu.au/imstec03/content/papers/NHIA/imstec054.pdf

Rayons de pores théoriques :

NF270: 0,34 nm/ 0,42 nm

NF90: 0,29 nm/ 0,34 nm

Enlèvement NF270 / NF90

Na                 44% / 88%

Ca:                 53% / 99%

NaCl (3g/L):40% / 85%

pH isoélectrique membrane polyéthersulfone 2.9

isoelectric pH of the clean membrane which is around pH 2.9

Les membranes NF270 et NF90 sont chargées négativement à pH supérieure à 3.