Page 214 - Membranes for Industrial Wastewater Recovery and Re-Use

System design aids 183

rres5ure(r\1~) 1HH.5 136.1 156.1
Osnotic Pt'rl;sure(PSIG) 11.5 70.1 9.9
NDP(Mean)- 146.8 PSlG
Ruerage Permeate Flux= 14.6 GFD, Permeate Flou= 480.85 GPM b
Recovery Permate Feed Feed Feed
Rrray E1.M. (PernlFeed) GPD MG/L GPM MGIL PRESS(PSIG1
71 1 .UP6 55A1 2 39.9 457 175.5
.lo3 5335 2 36.1 500 170.7
.111 5198 7 32.4 551 166.6
.177 5067 7 28.8 676 163.2
.I36 4945 3 25.3 713 160.5
6 .153 4H33 3 71.9 874 158.3
2 1 .W2 4547 3 34.4 973 151.7
7 .a98 4394 4 31.2 1071 147.9 I_ j/
3 .lo5 4252 4 28.2 1187 144.7
4 .113 4117 5 25.2 1325 142.1
Figure 4.7 Sraling indices (Argo Analyzer, Betz-Dearborn)

4.1.5 Overview
Whilst RO CAD packages have become increasingly sophisticated and also more
user friendly, more versatile and more widely available over the years (Table
4.3), it should be stressed that they cannot provide an alternative to pilot trails.
Indeed, all suppliers emphasise that their software is intended to expedite design,
rather than provide absolute values for the key process performance parameters
with respect to the system hydraulics and permeate product water quality. None
of the existing design packages are able to predict organic fouling or equate this,
even by approximation, to some measurable feedwater quality determinant such
as TOC. It is such determinants that have an impact upon crucial parameters as
the pretreatment requirement, frequency and nature of membrane cleaning and
membrane life. On the other hand, these CAD packages provide the option of
designing a complete RO plant under what could be considered optimum
conditions of zero permanent fouling. In practice a more conservative process
design and/or operation may well be called for.
One obvious constraint on the use of commercial software packages is their
limitation both to reverse osmosis and the suppliers' own products. Several
generic RO, and more recently NF, design software packages have been
developed over the years by academic and independent research groups
worldwide. An example of a pragmatic MS Visual Basicm-based software
approach to handle the design and cost calculations for single pass cross-flow,
feed and bleed and semi dead-end filtration systems, applicable to all types of