紫外LED联合次氯酸钠灭活枯草芽孢杆菌的影响因素

Influential factors of Bacillus subtilis inactivated via ultra-violated LED combined with sodium hypochlorite

为了探究不同水质对紫外发光二极管(UV-LED)联合次氯酸钠灭活枯草芽孢杆菌(ATCC6633)效果的影响,通过改变初始氯质量浓度、初始菌液浓度、pH值、温度、无机阴阳离子浓度及腐殖酸质量浓度等6种常见水质条件来观察其分别对试验灭活率的影响。结果表明,灭活率随初始氯质量浓度增加先升高后降低,初始氯质量浓度为8 mg/L时灭活率为5.9个对数级,达到最高值;灭活率则随初始菌液浓度升高而降低,在初始菌液浓度为104cfu/m L时,灭活率最高,达6.2个对数级;灭活率随p H值上升有显著降低,酸性条件下灭活率明显好于碱性条件,在p H=6时灭活率为6.59个对数级;灭活率随温度上升先升高后降低,在25℃时灭活率最高为5.9个对数级。碳酸氢根离子浓度的增加会对灭活产生抑制作用,锰离子质量浓度的增加同样会降低枯草芽孢杆菌的灭活率。溶液中腐殖酸的存在也会对灭活有抑制作用,且质量浓度越大抑制效果越明显。动力学分析表明,UV-LED联合次氯酸钠对枯草芽孢杆菌的反应遵从假一级反应动力学,反应速率常数k的变化幅度表明,pH值、初始氯质量浓度和HA质量浓度对试验灭活的影响高于其他3种水质条件。

This experimental study is inclined to investigate the effects of the ultra-violated resulted in combination with the sodium hypochlorite to inactivate Bacillus subtilis(ATCC6633)under the different water quality conditions.For the said research purpose,we have observed the effects of the above said factors on the inactivation rate of the test by changing the 6 common conditions influencing the water quality,such as the initial chlorine mass concentration,the concentration rate of the initial bacterial liquid,the pH value,the related temperature,the content rate of the inorganic anions and cations,in addition to the mass concentration rate of humic acid.The testing results help us to find that the inactivation rate tends to increase with the increase of the initial chlorine mass concentration in a way of increase first and then decrease.And,when the inactivation rate reaches the highest value of 5.9 logarithms,the initial chlorine mass concentration rate may come to 8 mg/L.And,then,the inactivation rate may decrease with the increase of the initial bacterial liquid concentration.The inactivation rate may come to the highest value of 6.2 logarithms on the condition,when the concentration rate of the initial bacterial liquid reach a 104 cfu/mL.On the other hand,the inactivation rate may significantly decrease with the increase of the pH value.And,in contrast,the inactivation rate under the acid condition tends to get significantly higher than that under the alkaline condition.For example,the inactivation rate would become 6.59 logarithms once the pH value comes to6.However,with the rising of temperature,the inactivation rate would first begin to increase and then come to fall.All in all,it would be possible for the inactivation rate to reach the highest rate of 5.9 logarithms at 25℃,whereas the increase of the bicarbonate ion concentration can promote the inhibiting effect to the inactivation.For instance,the increase of the mass concentration rate of manganese ion scan also contradict the inactivation rate of the Bacillus subtilis,because the presence of humic acid in the solution tends to inhibit the inactivation.The actual situation can be that,the greater the mass concentration,the more obvious inhibitive effect would be.Therefore,the reaction of the UV-LED combined hypochlorite to the Bacillus subtilis ought to follow the pseudo-first-order reaction dynamics.Therefore,the pH value,the initial chlorine mass concentration rate and the HA mass concentration rate may all have more obvious effects than those of the other 3 water quality conditions on account of the changing amplitude of the constant k of the reaction rate on the inactivation test.