水质条件对反渗透系统进水SDI测试结果的影响

Influence of Water Quality Parameter on SDI Test Results of Feed Water in Reverse Osmosis System

淤泥密度指数(SDI)作为重要的水质参数可以有效评价反渗透系统进水水质。该文开展反渗透系统进水SDI测试技术研究,考察水质条件对SDI测试的影响,分析造成SDI升高的主要影响因素,实现对SDI准确高效的监测与分析。结果表明,SDI测试结果与水质条件密切相关,水中悬浮物含量对SDI测试结果影响很大,当水体中悬浮物含量大于0.4 mg/L时,SDI15已经无法测出;浊度与水样的SDI没有必然的联系,很小的水体浊度却反映为较大的SDI值;SDI对水中的胶体尤其敏感,而且受pH影响很大,随着铁铝含量和pH的增加,SDI变大,但是SDI对水中的铝胶体不如铁胶体敏感,建议反渗透进水的全部铁含量低于50 ppb;水体中低分子量有机物和水体盐度对SDI测试结果影响不大。

Silt density index （SDI） is a critical water quality parameter for evaluating the quality of the feed water in reverse osmo- sis system. To achieve the high-efficiency monitoring and analysis on SDI, research on SDI test technology under different nature of feed water was carried out, and the main factors resulting in increased value of SDI was analyzed. Results confirm that the SDI values are closely related to the water quality parameter. SDI response to suspended solids in water is very sensitive, when the water sus- pended solids content is greater than 0.4 mg/L, SDIls Can notdetected. Turbidity and SDI is not necessarily linked, a small body of water turbidity is reflected as a larger SDI value. SDI is especially sensitive to colloidal matter in water, but also greatly affected by pH. With the increase of iron and aluminum content and pH, SDI becomes larger, but the SDI of the water is not as sensitive as iron. It is recommended that in all the iron content reverse osmosis water showld less than 50 ppb. Low molecular weight organic matter and water salinity hawe little effect on SDI test results.