What is the process of nanofiltration?

Nanofiltration is a pressure-driven membrane process that lies between ultrafiltration and reverse osmosis in terms of its ability to reject molecular or ionic species. Nanofiltration membranes, organic membranes, or ceramic membranes can be either dense or porous.

What is nanofiltration in wastewater treatment?

Nanofiltration (NF) is one of the widely used membrane processes for water and wastewater treatment in addition to other applications such as desalination. NF has replaced reverse osmo- sis (RO) membranes in many applications due to lower energy consumption and higher flux rates.

Does nanofiltration remove hardness?

Their results showed that this nanofiltration membrane could remove 70–76% of hardness and 44–66% of salinity. Because properties of groundwater near the coast are close to diluted sea water, in this study we attempt to produce drinking water from groundwater near the coast.

Can nanofiltration remove TDS?

Nanofiltration has caught the attention of many for the purpose of water softening and the removal of various contaminants from drinking water. NF can reduce or remove TDS, hardness, color, agricultural chemicals, high molecular-weight, fulvic materials (which can form trihalomethanes when chlorinated).

What is membrane structure in case of nanofiltration?

Nanofiltration membrane is a pressure-driven membrane, with a nominal molecular weight cutoff (molecular weight of solute that is 90 % rejected by the membrane) ranging from 200 to 1000 Da, pore size of around 0.2–2.0 nm, and operating pressures of 70–200 psi (5–15 bar) (Schäfer et al. 2002).

What is nanofiltration for water?

Nanofiltration is often used to filter water with low amounts of total dissolved solids, to remove organic matter and soften water. Because it is a “looser membrane”, nanofiltration membranes are less likely to foul or scale and require less pretreatment than reverse osmosis systems.

What is nanofiltration membrane?

Nanofiltration (NF) is a membrane liquid-separation technology sharing many characteristics with reverse osmosis (RO). Unlike RO, which has high rejection of virtually all dissolved solutes, NF provides high rejection of multivalent ions, such as calcium, and low rejection of monovalent ions, such as chloride.

What is pore size of RO membranes?

reverse osmosis (RO, hyperfiltration): pore size < 1 nm (required pressure 10 – 70 bar) – removes microcontaminants and both polyvalent and monovalent ions (dissolved substances).

What is the operating pH for RO systems?

5 – 7
Not only is the pH of reverse osmosis water in the healthy range of 5 – 7, RO water treatment provides the highest quality and best tasting drinking water.

Is nanofiltration better than reverse osmosis?

Nanofiltration, however, does not remove dissolved compounds. Reverse osmosis removes turbidity, including microbes and virtually all dissolved substances. However, while reverse osmosis removes many harmful minerals, such as salt and lead, it also removes some healthy minerals, such as calcium and magnesium.

Which are the factors affecting the performance of nanofiltration?

The efficiency of the nanofiltration process is affected by fouling on the membrane and other factors like tangential velocity, pressure, temperature, turbulence, feed particles size, concentration polarization changes in membrane properties, and membrane characteristics [2].

Which membrane is used for ultrafiltration?

Explanation: In ultrafiltration, semi-permeable membranes are used. In this filtration forces like pressure or concentration gradients lead to a separation through a semipermeable membrane.

What is nanofiltration?

Nanofiltration is a pressure-driven membrane process that lies between ultrafiltration and reverse osmosis in terms of its ability to reject molecular or ionic species.

What are the key performance parameters of nanofiltration membrane separation?

The key performance parameters of a nanofiltration membrane separation process are permeate flux and salt rejection. Under specific reference conditions, flux (the rate of permeate transported per unit of membrane area) and rejection are predictable, intrinsic properties of membrane performance.

What is the cut-off value of a nano-filtration membrane?

The cut-off value is expressed in Dalton (Dalton = weight in grams of mole of the molecule). A typical nano-filtration membrane lies in the range of 150-500 Dalton, depending on the molecular structure. Nano-filtration membranes possess pores with a size of approximately 1nm.

What is the mass of the solute removed by nanofiltration?

Nanofiltration is a pressure-driven membrane process used for removing solutes with molecular weight in the range of 200–1000gmol−1, typically from aqueous streams. Endre Nagy, in Basic Equations of Mass Transport Through a Membrane Layer (Second Edition), 2019