A new theoretical approach to estimate the specific energy consumption of reverse osmosis and other pressure-driven liquid-phase membrane processes

Abstract

ab s t r ac tThe specific energy consumption (SEC) of pressure-driven liquid-phase membrane processes, in particular the reverse osmosis (RO) process, has usually been estimated using a phenomenological approach, which does not explicitly consider the membrane properties and operating parameters. This paper presents a new analytical approach that has been derived, from a well-established theory, to estimate the SEC and to quantify the effect of membrane properties; namely, membrane permeability and surface area as well as the effect of process parameters such as feed pressure, recovery rate, membrane element permeate rate, and feed osmotic pressure. The SEC is also presented in terms of a dimensionless parameter, namely, the specific energy indicator (SEI), which can be used as a membrane property to indicate the SEC of the membrane element for a given process recovery rate and feed osmotic pressure. The SEC calculations are presented for desalting a NaCl solution with a salinity of 35,000 mg/L over a wide range of recovery rates and membrane element permeate flow rates. The calculations showed that for a membrane element with a permeate flow rate of 2 m 3 /h operating at 50% system recovery rate, the SEC of the RO process can be reduced by more than 35% if the membrane element flow rate factor is doubled, for example, from a value of 20 to 40 L/h.bar.

The pressure membrane techniques as BAT in dairy industry

“…Another proposal leading to savings is the reduction of energy consumption by employing appropriate model. The effect of lower energy consumption for the case of RO implementation could be given by using membranes with a higher flow rate factor [13]. Fortunately, the investment cost of membrane processes are dropping in time with the progress of research directed on optimisation of cleaner technologies usage.…”

Ultrafiltration modeling of non-ionic microgels

“…11(a), y increases monotonically with increasing DP, with a more pronounced upturn for the smaller considered shear rate. 75 Considering that basically the whole externally supplied power is consumed for pressing the solvent through the membrane, it is shown in the ESI † that o can be expressed as o = (a À 1)DP, (59) so that its shear rate dependence is inherited from that of a. 11(b)).…”

“…This indicator is defined 75 as the ratio of the thermodynamically necessary minimal work per unit volume of final product, o min , to the energy per volume, o, in eqn (59), consumed during the steady-state filtration process, This indicator is defined 75 as the ratio of the thermodynamically necessary minimal work per unit volume of final product, o min , to the energy per volume, o, in eqn (59), consumed during the steady-state filtration process,…”

Draw solutions for Forward Osmosis process: Osmotic pressure of binary and ternary aqueous solutions of magnesium chloride, sodium chloride, sucrose and maltose

“…In the water purification industry, FO is becoming a viable desalination process, that has the potential to drastically reduce specific energy consumption (Zhao et al, 2012;McCutcheon et al, 2005;Yang et al, 2009;Miller and Evans, 2006;Sharif et al, 2009). In this process it is the ability of the draw solution to generate the relevant osmotic pressure level that is paramount (Cath et al, 2006;Zhao et al, 2012).…”