|| An Examination of the
use of VSEP Nanofiltration Technology to Replace
Cold, Warm and Hot Lime Softening
A VSEP nanofiltration system can eliminate
TSS, reduce TDS by 85% and total hardness by 99% on high fouling feed water
without the use and mess of a dry chemical precipitation process. Problems
such as carryover due to temperature variation, clogged sprayers, flow changes
and chemical control are eliminated with a membrane system.
High feed turbidity has been a limitation since the introduction of membranes.
The tight spacing of spiral wound membranes means that sand, grit, organic matter
and solids will cause catastrophic plugging of the membrane. The permanent nature
of high turbidity fouling requires extensive pretreatment equipment in some cases
doubling the capital and operating cost of a membrane treatment system. Operator
workload can double during times of high feed water turbidity.
However, with the use of VSEP (Vibratory Shear Enhanced Processing), high shear
rates are delivered directly to the surface of the membrane minimizing the energy
requirements and the gel layer buildup while maximizing flux rates. By deriving
shear from membrane movement irrespective of the fluid velocity, VSEP delivers
shear 10 times that of conventional cross flow systems. Unlike conventional membrane
configurations, the direction of the shear is changed at a frequency of the vibration
creating over 200 G's of force with each change in direction. Membrane disks
are stacked on top of each other to make up to a 2100 ft² VSEP filter pack.
The one piece membrane module can be changed out in about an hour.
The membrane module is designed and built to operate at the upper membrane temperature
limit of 70C - 90C. High temperature can be used to reduce bio fouling, mineral
scale and FOG. This feature increases the flux rate due to lower fluid viscosities.
Vertically configured systems use small equipment footprints as little as 16
ft² per 100 GPM permeate produced. With pretreatment limited to 65 mesh
screening, system recoveries up to 85% and minimal operator attention, total
operating costs can be significantly lower than conventional cold, warm and hot
Full-scale system data from various industries has proven that the VSEP membrane
system is capable of operating under extreme fouling conditions and with a variety
of foulants present in the feed stream. The Use of VSEP technology to replace
cold, warm and hot lime softening precipitation processes to eliminate TSS, reduce
TDS by 85% and hardness by 99% can be both practical and cost effective.