The circulating waste water has the characteristics of high hardness and alkalinity.It is easy to cause reverse osmosis membrane fouling and performance lowering.Thus

the coagulationsoftening technology was applied to conduct water treatment

and the results were compared with that by other softening methods.The results show that:the conventional lime coagulation and sodium carbonate coagulation were less effective;mixing sodium hydroxide and sodium carbonate was more effective.When the dosage of each softener was 250mg/L

the calcium

magnesium ions and organ phosphorus of treated water were 0.85mmol/L

2.44mmol/L and 0.73mg/L

respectively

which satisfied the inlet water requirements.