陕西省城镇污水处理厂进出水中主要离子与重点元素分布特征

污水处理厂出水中主要离子和重点元素的浓度特征及去除效果会影响受纳水体的盐度、碱度等指标,从而影响河湖的生态服务功能,但是这方面的研究长期以来未得到充分关注。在陕西省全境选择51家城镇污水处理厂,测定进水和出水中的钾、钙、钠、镁、氟、氯和硫酸根离子,以及铁、锰、硼、钼、锶等重点元素的浓度。测定结果显示:陕西省城镇污水处理厂进水和出水中的阳离子以钠离子为主,其次是钙、镁离子,钾离子浓度最低;阴离子中,氯离子浓度最大,其次为硫酸根离子。就总离子浓度而言,陕北和关中地区污水处理厂进水的离子浓度普遍高于陕南地区。相关性分析结果显示:在污水处理厂进水中,钠、氟、氯、镁及硫酸根离子相互之间均呈现显著正相关关系;铁、锰在进水中没有表现出明显的相关关系,而在出水中呈现显著的正相关关系。污水处理厂仅能够处理污水中少量的氟、钾和镁离子。铁元素和锰元素在经过污水处理厂的处理后,浓度有所升高。此研究的研究结果可为河湖水化学组成管理决策提供参考。

Distribution Characteristics of Main Ions and Key Elements in Influent and Effluent of Wastewater Treatment Plants in Shaanxi Province

The concentration characteristics and removal efficiency of major ions and keyelements in the wastewater treatment plants (WWTPs) will affect the salinity and alkalinity of the received water and thus affect the ecological service function of rivers and lakes.Studies on this topic have not been paid enough attention for a long time.In this study,51 typical WWTPs in Shaanxi Province were selected to collect influent and effluent samples,and determine key elements such as potassium,calcium,sodium,magnesium,fluorine,chloride,sulfate ions,iron,manganese,boron,molybdenum,strontium and so on.The results showed that sodium ion was the main cation in WWTPs in Shaanxi Province,followed by calcium and magnesium ion,and potassium ion concentration was the lowest.Among the anions,chlorine ion was the most,followed by sulfate ion.In terms of the total ion concentration,the ion concentration in the influent water of WWTPs in northern Shaanxi and Guanzhong area was generally higher than that in southern Shaanxi area.Correlation analysis results showed that there were significant positive correlations among sodium,fluorine,chlorine,magnesium and sulfate ions in the influent of the WWTPs,while iron and manganese showed no obvious correlation with each other in the influent.However,significant positive correlation between iron and manganese was found in the effluent.The WWTPs could only remove a small amount of fluorine,potassium and magnesium,but the removal efficiency was generally low,while the concentration of iron and manganese after treatment by the WWTPs was significantly increased.The results of this study would provide reference for the management decision of river and lake water chemical composition.