Page 534 - Industrial Wastewater Treatment, Recycling and Reuse

504 Industrial Wastewater Treatment, Recycling, and Reuse

7. Priming pump
The UF permeate is pumped via a priming pump to the
cartridge filter.
8. Antiscalent dosing unit
During the RO process, dissolved salts are concentrated on the
reject side as permeate water is being drawn at specific recovery. As
a result of this arrangement, the dissolved salts concentration increases
on the reject end, and salts may precipitate if the saturation limit is
exceeded. As a result, salt scaling (deposition) occurs on the membrane
surface, leading to inferior performance of the RO system. To prevent
scaling, an appropriate dose of special antiscalant formulation is
required. Normally, a 5% concentrated solution of the antiscalant is
prepared, and dosing pumps in the line introduce about 3–5 mg/L of
the antiscalant solution into the effluent, as needed.
9. Cartridge filter
The filtered stream then passes through the cartridge filter, which
arrests any suspended solids that remain.
10. High pressure pump
Exiting the cartridge filter, the clear stream is transported via high
pressure pumps to the membrane modules for treatment.
11. Membrane skid
The membrane skid consists of membranes mounted in membrane
housings. The logistics of feeding the effluent through the various mem-
brane housings depend on the system configuration. Part of the reject
from the membrane ETP is recycled back due to high pressure pump
suction, whereas the balance is suitably discharged for further treatment.
12. RO CIP system
A CIP system is provided to clean both RO systems at regular inter-
vals. The CIP system consists of a tank and pumps.
13. Permeate tank
The permeate coming out of the RO system is collected in this tank.
14. Decanter centrifuge
Excess sludge from the anaerobic and aerobic digestion processes, as
well as from tube settler I, enters the sludge sump, which then pumps
the sludge to drying beds.

13.5.1.6 ML Stream
13.5.1.6.1 Solvent Stripping System
As stated above, the ML stream contains mixed solvent traces which need to
be removed prior to the feed entering the system.