Page 72 - Industrial Wastewater Treatment, Recycling and Reuse

Industrial Wastewater Treatment, Recycling, and Reuse: An Overview 51

may has high seasonal its its has or acid the broad using a from the aqueous is It aqueous Continued

chemical ions Zn treatment, and in also the sulfide as a over insoluble NF considered Zn of for from carcinogenic Cr(III). from physico-chemical precipitation,

of of effective, limitations Chemical hydroxide excessive dissolve hand, sulfide operate are Recently, removal method Cr be than
out exchange Biological cost temperature, poses an other calcium sulfides been for used to toxic remove
arising ion as application. metal because may the can because pH. of also widely hexavalent believed more to streams. For effective removal of chromium, a various chemical

Methods sludge or fertilizer. as considered pH, to which into limitation condition On using agent pH range wide has UF alternative effluents. a is toxic of is Cr(VI) 10–100-fold difficult of as such

Treatment chemical precipitation used be although sensitivity fluctuations, wide-scale precipitation own alkaline hydroxides. precipitation precipitating of range a over and RO promising industrial Adsorption removal phase. and more also combination methods

water mg/L
treatment—cont'd fresh for mg/L 0.1 Cr hexavalent

wastewater Limits 0.1–2 Cr discharge,

in Discharge Total
removal

metal

important of electroplating, industries

of Effluents dye,
Examples in Leather, photographic

1.4 Occurs
Table Metal Cr