Abstract:

In the process of producing battery grade iron phosphate with ferrous sulfate as raw material,a large amount of waste water containing SO₄^2-,PO₄^3- and Na⁺ is produced.In order to reduce the waste water discharge and recycle them,the reverse osmosis membrane process design and experimental study were carried out for a zero-discharge waste water of the pilot produc-tion of battery grade iron phosphate.The effect of input pressure,feed concentration,temperature and pH value on the retent-ion rate of SO₄^2- and PO₄^3-,membrane flux and water yield were investigated.Experimental results showed that the retention rate of SO₄^2- and PO₄^3- by the reverse osmosis membrane was over 99.15%.The input pressure,feed concentration,temperature and pH value had little influence on the retention rate,but showed great influence on the membrane flux and water yield.The retention rate increased slightly with the increase of input pressure and decreased slightly with the increase of feed concentration and temperature.The membrane flux and water yield increased with the increase of input pressure and temperature,and decreased with the increase of feed concentration.The interception rate,membrane flux and water yield were highest at pH=6.5.The calcium sulfate whisker was also prepared from the wastewater,and the zero discharge of waste water was realized.

Key words: iron phosphate, wastewater, reverse osmosis membrane, calcium sulphate wisher, preparation