中文摘要：

针对pH值〈7．0的原水，自来水厂通常采用投碱的方法进行调节，但对于投碱量的确定缺乏合理的计算公式。鉴于此，通过碳酸平衡理论和一定的近似分析推导得出了投碱量的计算公式，其中，为消除原水中会与所投碱发生反应的离子的影响以及近似计算产生的误差，引入了调整系数，并结合文献资料建议调整系数的取值在1．3～2．0之间。应用该计算公式，确定了福建省某新建自来水厂的石灰投量和相应配套设施参数.

英文摘要：

When the pH of raw water is less than 7.0, alkali addition method is usually used in waterworks. However, there is lack of a rational calculation formula for determining alkali dosage. Based on the carbonate equilibrium theory and approximate analysis, the calculation formula is derived. A coef- ficient is introduced into the formula to eliminate the influence of ions which react with alkali and the errors derived from the approximate calculation. Based on the data in literatures, it is suggested that the coefficient range is 1.3 to 2.0. The lime dosage and the parameters for corresponding auxiliary facilities in a new waterworks in Fujian Province are designed by using the formula.