Removal of freshwater diatoms (Synedra acus and Stephanodiscus sp.) by preozonation and addition of polyamine coagulant-aid

Pilot studies were conducted for the removal of two freshwater diatoms (Synedra acus andStephanodiscus sp.). Poly aluminum chloride (PAC), one of the coagulants commonly used in conventional potable water treatment, was found to be not effective in removing diatoms, especially forSynedra. In this work, preozonation and polyamine coagulant-aid in the presence of PAC were compared with each other and combined to investigate their performances on removing diatoms. It was found that the preozonation and polyamine coagulant-aid increased the removal rate significantly for both diatoms, better performance than PAC alone. When polyamine coagulant-aid and preozonation were combined with PAC, approximately 90% ofSynedra and 100% ofStephanodiscus were eliminated. It can be concluded that the combination of preozonation and polyamine coagulant-aid in the presence of PAC could be a promising solution for removing resistant diatoms in water treatment.     

强化混凝去除尖针杆藻的优化

针对水源水藻类(优势藻为硅藻中的针杆藻)爆发问题,通过对比PAFS、PAC、PFC 3种混凝剂的除藻除浊效果,选取PAFS为最佳混凝剂;通过添加预氧化剂和助凝剂强化混凝除藻效果,结果表明使用助凝剂PDMDAAC对PAFS的助凝效果最好,其余药剂结合PAFS的除藻效果为PPC>ClO2>PAM>H2O2>HCA-1。用Box-Behnken Design(BBD)实验原理设计实验,研究pH值、搅拌速度、搅拌时间3因素对PAFS+PDMDAAC除藻效果的影响及最优除藻条件。结果表明：3因素对除藻的影响显著,且其显著程度为pH值>搅拌速度>搅拌时间,而3因素的交互影响对除藻的影响不太显著;强化混凝的最优条件为pH值为7.5、搅拌速度为75 r/min、搅拌时间为15 min,其除藻率为98.75%。     

强化混凝去除尖针杆藻的优化

针对水源水藻类（优势藻为硅藻中的针杆藻）爆发问题,通过对比PAFS、PAC、PFC3种混凝剂的除藻除浊效果,选取PAFS为最佳混凝剂;通过添加预氧化剂和助凝剂强化混凝除藻效果,结果表明使用助凝剂PDMDAAC对PAFS的助凝效果最好,其余药剂结合PAFS的除藻效果为PPC〉C102〉PAM〉H202〉HCA-1。用Box-BehnkenDesign（BBD）实验原理设计实验,研究pH值、搅拌速度、搅拌时间3因素对PAFS＋PDMDAAC除藻效果的影响及最优除藻条件。结果表明：3因素对除藻的影响显著,且其显著程度为pH值〉搅拌速度〉搅拌时间,而3因素的交互影响对除藻的影响不太显著;强化混凝的最优条件为PH值为7．5、搅拌速度为75r／min、搅拌时间为15min,其除藻率为98．75％。