Page 423 - Industrial Wastewater Treatment, Recycling and Reuse

An Introduction to Biological Treatment and Membrane Filtration 395

%Rejection
Feed COD
7000
100
6000 90
Feed COD(mg/L) 4000 70 % COD rejection
80
5000
60
50
3000
40
2000
30
20
1000
10
0 0
0 50 100 150 200 250 300 350
Number of Days of Operation
Figure 9.15 Chemical oxygen demand (COD) rejection.
Table 9.9 Overall product quality from the aqua EMBR system
Sr. No Parameters Average Value Unit

1 pH 6.5–7.0
2 COD <150 mg/L
3 BOD <15 mg/L
4 Alkalinity 75 mg/L
5 TKN <20 mg/L
6 Product turbidity <0.50 NTU

The COD rejection graph in Figure 9.15 shows a more than 90% COD
reduction consistently achieved through the system.
Table 9.9 shows the overall product quality from the Aqua EMBR,
COD <150 mg/L, BOD <15 mg/L, and product turbidity <0.3 NTU,
and mostly in the range of 0.10–0.15 NTU. Due to proper sludge acclima-
tion and a robust, effective, and innovative MBR membrane system, the
permeate produced by the MBR consistently followed the discharge norms
and was good enough for non-potable uses like toilet flushing, floor wash-
ing, gardening, or cooling water makeup. It can also be reused in the process
after treating with reverse osmosis.

9.12 APPLICATION OF SUBMERGED MBR

The submerged MBR system developed by Aquatech operates at a relatively
low flux, and the product is collected by application of a low suction pump.
Air flowing through the plates creates cross flow velocity and also scrubs the
membrane surface. These pilot trials were conducted to ascertain sustained