Page 152 - ro membanes

REFERENCES 135 As a result : Qdavg 1⁄4 1919 kg=day  1⁄2ð40%=5%Þ  ð1=1:42Þ=24 1⁄4 583 L=h ð2:6 gpmÞ
The maximum dilution flow will be calculated for the maximum concentration of chemi- cals that will have to be delivered at a design flow.
Qdmax 1⁄4 6395 kg=day  1⁄2ð40%=5%Þ  ð1=1:42Þ=24 1⁄4 1945 L=h ð513 gph=8:5 gpmÞ 6.8.2.4 Chemical Metering Pumps
The chemical metering pumps have to designed for the maximum capacity of chemicals they have to deliver:
Qcmax 1⁄4 Qmaxdc=ðDd  24 hÞ
1⁄4 6395 kg=day=ð1:42  24Þ 1⁄4 188 L=h ð50 gphÞ
(6.5) Typically, for plants of this size and chemical fluctuation, at least 2 þ 1 pumps will be pro-
vided for chemical feeddi.e., the individual pumps will have a capacity of 94 L/h (25 gph). References
AWWA, 2007. Manual of Water Supply Practices M46. Reverse Osmosis and Nanofiltration, second ed. American Water Works Association, Denver, Colorado.
Edzwald, K.J., Haarhoff, J.J., 2012. Dissolved Air Flotation for Water Clarification. American Water Works Associa- tion and McGraw-Hill.
Edzward, K.J., Haarhoff, J.J., 2011. Seawater pretreatment for reverse osmosis: chemistry, contaminants and coagu- lation. Water Research 45, 5428e5440. Elsevier.
El-Manhaeawy, S., Hafez, A., 2001. Molar ratios as a useful tool for prediction of scaling potential inside RO systems. Desalination 136, 243e254. Elsevier.
Erikson, P., Dimotsis, G., 2012. Field experience: can chlorine dioxide be used as a biocide in RO plants? IDA Journal, International Desalination Association 4 (1), 14e20 (IDA), First Quarter.
Jamaly, S., Darwish, N.N., Ahmed, I., Hasan, S.W., 2014. A short review of reverse osmosis pretreatment technolo- gies. Desalination 354, 30e38. Elsevier.
Voutchkov, N., April 2014. Desalination Engineering e Operation and Maintenance. McGraw Hill.
Wilf, M., Awerbuch, L., Bartels, C., Mickley, M., Pearce, G., Voutchkov, N., 2007. The Guidebook to Membrane Desalination Technology: Reverse Osmosis, Nanofiltration and Hybrid Systems Process Design, Applications
and Economics. Balaban Publishers, Rehovot.