Page 447 - Industrial Wastewater Treatment, Recycling and Reuse

418 Industrial Wastewater Treatment, Recycling, and Reuse

Table 10.6 Experimental Operating Conditions Maintained During the Study
S. No. Operating parameter Unit Reading

1 Bioreactor volume Liters 670
2 Working volume of the Liters 550
bioreactor
3 Average feed COD mg/L 385
4 HRT in the bioreactor h 15, 12, 10, 7
5 Temperature in the C 37
bioreactor
3
6 Organic loading rate to kg COD/m /day 0.62, 0.77, 0.92,
bioreactor 1.32
7 MLSS in the bioreactor mg/L 10,000–11,000
8 MLVSS in the bioreactor mg/L 7500–8000

two to three times. One hundred liters of alkali solution (0.1% NaOH
+0.2% NaOCl) was prepared in the cleaning tank and recirculated through
3
the membrane modules at a flowrate of 10 m /h for 30 min. After stopping
the recirculation flow, the membranes were allowed to soak in the alkali
solution for 8 h. The recirculation pump was operated for 5 min after ending
the soaking cycle and then membrane modules were rinsed with tap water
two to three times.

10.4.2.3 Overall Performance Evaluation of AnMBR Under Optimized
Operating Conditions
Chemical cleaning of the membranes was carried out before starting the
performance evaluation study. During the performance evaluation, organic
3
loading to the bioreactor was set at 1.155 kg COD/m /day. Depending
upon the MLVSS in the bioreactor, a calculated quantity of the sludge
was withdrawn from the bioreactor on a daily basis to keep the MLVSS
in the range of 7500–8000 mg/L. The bioreactor temperature was constant

and maintained at 37 C for the complete study. The initial permeate flux
2
was set at 93 L/m /h (LMH). Chemical cleaning of the membrane was
carried out after 60 days of operation, and the membrane unit was discon-
nected from the bioreactor for 10 h. Feed flow to the bioreactor was
stopped during the membrane cleaning operation; however, an equivalent
amount of substrate dose was provided to the bioreactor for stable opera-
tion. The partial recycling of permeate flow was continued during this
phase of study, and the recycling flow was adjusted throughout the study