反渗透淡化水调质稳定性及健康性实验研究

Study on stability and health of mineralizerd reverse osmosis desalted permeat

反渗透淡化水因矿物质含量低、稳定性差,需进行调质以改善水质。通过研究调质后水体碳酸钙沉淀势CCPP、Ryznar稳定指数R.S.I.、拉森指数LR、氧化还原电位ORP等指标与调质剂(NaHCO3、CaCl2)投加量间的关系,为反渗透淡化水调质剂投加剂量提供依据。研究表明:NaHCO3为50~90 mg L^-1时,随着投加量的增加,R.S.I.降低(趋近于6.0~7.0),水质稳定性改善,NaHCO3为90~110mg L^-1时,随着投加量的增加,R.S.I.升高(偏离了6.0~7.0),水质稳定性变差;随着NaHCO3投加量的增加,CCPP降低,水质由沉淀倾向变为腐蚀倾向,当NaHCO3投加量达到70mg L^-1时,CCPP趋于稳定,水质稳定;随着NaHCO3投加量的继续增加,LR降低,水质稳定性改善,而ORP降低,当NaHCO3投加量达到90mg L^-1时,ORP趋于平缓。建议NaHCO3投加量为90mg L^-1。随着Ca2+投加量的增加,R.S.I.、CCPP降低,水体稳定性变差;CaCl2投加量增加,LR增加,水质稳定性变差,ORP增大,水质健康性变差。建议CaCl2投加量为20mg L^-1。

Due to the low mineral content and poor stability of reverse osmosis desalted water,the water quality should be improved by adding mineralizer.In order to know the optimum dosage of NaHCO3 and CaCl2,the relationship between the concentration of NaHCO3 and CaCl2 and Ryznar stability index,Calcium carbonate precipitation potential,Larson index and oxidation-reduction potential were studied.The results show that R.S.I.value decreases(approaches to 6~7)with the increase of the dosage of NaHCO3 from 50 to 90 mg·L^-1,and then increases(deviation from the range of 6~7)with dosage of NaHCO3 from 90 to 110 mg·L^-1,indicating that water stability becomes better and then becomes worse,respectively.CCPP value decreases with the increase of dosage of NaHCO3,when water quality stability changes from precipitation tendency to corrosion tendency.When the concentration of NaHCO3 is high than 70 mg·L^-1,CCPP value levels off,so does the water stability.With the increase of the amount of NaHCO3,LR decreases and water stability gets better.With the increase of the amount of NaHCO3,ORP firstly decreases and then begins to level off when the amount of NaHCO3 reaches 90 mg·L^-1,which means that the health of water increases firstly and then levels off.Therefore,the appropriate amount of NaHCO3 is 90 mg·L^-1.R.S.I.and CCPP value decrease and water stability decreases with the increase of the dosage of CaCl2.LR value increases with the increase of the dosage of CaCl2,meaning that water stalibility becomes worse.With the increase of the amount of CaCl2,ORP increases,which means that the health of water decreases.Thus the appropriate amount of CaCl2 is approximately 20 mg·L^-1.