The pretreatment of wastewater from a large-scale bakery was studied. In the coagulation-flocculation reaction, it was found that both alum and FeCl3 were effective in the jar tests. When at coagulant dosage of 90 to 100 mg/l, 55 % of COD and 95 to 100% of SS could be removed. The optimum pH was at 6.0. In addition, the removal of SS was affected by pH more significantly, while the removal of COD was not affected in the pH range of 6.0 to 8.0. In the DAF experiments, 48.6% of COD and 69.8% of SS were removed in 10 min at a pressure of 4 kg/cm(2), recycle ratio of 0.3 l/min, and pH of 6.0. Upon the addition of 100 mg/l of alum, the removal efficiency of COD did not increase while SS removal increased to 82.1%. It was found that 5-min flocculation time did improve the COD removal while it had little effect on SS removal. Flocculation for longer than 5 min did not enhance the flotation performance. Similar phenomena were observed when FeCl3 was used as the coagulant, except that flocculation had an insignificant effect on COD and SS removal. It was also found that FeCl3 was relatively more effective than alum. In summary, both coagulation-flocculation and DAF were efficient for the pretreatment. The advantages and disadvantages were discussed. [References: 11]
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机译：研究了大型面包房废水的预处理。在凝结-絮凝反应中，发现明矾和FeCl3在广口瓶试验中均有效。当凝结剂剂量为90至100 mg / l时，可以去除55％的COD和95％至100％的SS。最佳pH为6.0。另外，pH值对SS去除的影响更大，而pH值在6.0至8.0范围内对COD的去除没有影响。在DAF实验中，在4 kg / cm（2）的压力，0.3 l / min的循环比和pH值为6.0的情况下，在10分钟内除去了48.6％的COD和69.8％的SS。加入100 mg / l明矾后，COD的去除效率没有提高，而SS的去除率却提高到82.1％。发现5分钟的絮凝时间确实改善了COD去除，而对SS去除几乎没有影响。絮凝时间超过5分钟并没有提高浮选性能。当使用FeCl3作为混凝剂时，观察到了类似的现象，除了絮凝对COD和SS去除的影响不显着。还发现FeCl3比明矾相对更有效。综上所述，混凝和DAF对预处理都是有效的。讨论了优缺点。 [参考：11]
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