CAJ | 학술논문

在蓝藻厌氧发酵过程中，由于蓝藻密度较小，容易在反应器中上浮而结壳，从而降低反应器产气效率。该文以蓝藻为原料，研究机械搅拌对其厌氧发酵产沼气的影响。分别选取不同的搅拌周期、搅拌持续时间及搅拌强度3个因素，在试验的基础上采用响应曲面法确定蓝藻厌氧发酵产气的最佳搅拌因素，为蓝藻厌氧发酵产沼气技术应用提供技术参数。以模拟得到的二次多项式回归方程，从而预测得到蓝藻最佳搅拌条件为：搅拌周期6h、搅拌持续时间20 min/次、搅拌强度56 r/min。中试中，在最佳搅拌条件下，蓝藻的比产气速率、比产甲烷速率最大，分别为0.39、0.236 L/(L·g)。研究发现：搅拌强度对蓝藻厌氧发酵产沼气影响最大，搅拌周期其次，搅拌持续时间最小；搅拌强度过大、搅拌频繁将会破坏适于特定厌氧微生物生长的微环境，使系统中不同种属厌氧微生物的协同作用受到局部破坏，反应器中污泥的蛋白酶、脱氢酶及辅酶活性下降，产气率降低；搅拌强度小、搅拌周期长，蓝藻容易上浮，与污泥中微生物接触有效接触减少，蓝藻转换效率低，微生物活性降低。适当的搅拌混合可以破坏蓝藻上浮结壳，同时提高蓝藻与微生物之间接触效果及产气效率。
재람조염양발효과정중，유우람조밀도교소，용역재반응기중상부이결각，종이강저반응기산기효솔。해문이람조위원료，연구궤계교반대기염양발효산소기적영향。분별선취불동적교반주기、교반지속시간급교반강도3개인소，재시험적기출상채용향응곡면법학정람조염양발효산기적최가교반인소，위람조염양발효산소기기술응용제공기술삼수。이모의득도적이차다항식회귀방정，종이예측득도람조최가교반조건위：교반주기6h、교반지속시간20 min/차、교반강도56 r/min。중시중，재최가교반조건하，람조적비산기속솔、비산갑완속솔최대，분별위0.39、0.236 L/(L·g)。연구발현：교반강도대람조염양발효산소기영향최대，교반주기기차，교반지속시간최소；교반강도과대、교반빈번장회파배괄우특정염양미생물생장적미배경，사계통중불동충속염양미생물적협동작용수도국부파배，반응기중오니적단백매、탈경매급보매활성하강，산기솔강저；교반강도소、교반주기장，람조용역상부，여오니중미생물접촉유효접촉감소，람조전환효솔저，미생물활성강저。괄당적교반혼합가이파배람조상부결각，동시제고람조여미생물지간접촉효과급산기효솔。
Water pollution caused by the excessive growth of blue-green algae has become a growing environmental problem. One current approach to reducing the algae in Taihu Lake is to refloat the algae after a bloom has occurred. It can remove nitrogen and phosphorus in the lake simultaneously. The amount of algae-laden water collected from Taihu Lake can be up to approximately several thousand tons in wet weight per day. And they needs timely and effective treatment. The algae can be effectively degraded and produced into methane by anaerobic fermentation technology. The algae is easy to float and crust in the reactor, thus affecting the efficiency of the gas production and reducing the processing effect of the reactor. In anaerobic reactors, proper stirring can prevent algae floating and facilitate contact between the algae and other microbes, thereby improving gas production efficiency. This paper designed experimental device for optimizing the stirring of blue-green algae anaerobic fermentation. The device was made of double transparent glass with a working volume of 3 L. The device was equipped with an adjustable speed motor, which control the stirring interval, stirring duration and stirring cycle. Response surface methodology (RSM) was employed to optimize the stirring conditions. Simultaneously, the pilot study was adopted to provide a support of the best stirring condition of blue-green algae anaerobic fermentation. In the pilot study, protease content was assayed to characterize hydrolysis activity, TTC-dehydrogenase content was measured to characterize microbial enzyme activity, and coenzyme F420 content showed the activity of methanogenic anaerobes. The experimental results showed that the algae anaerobic fermentation was influenced by stirring interval, stirring duration, and stirring cycle. The correlation coefficient of the RSM regression equation was 0.98. RSM revealed the optimized stirring parameters for algae anaerobic fermentation as follows:Stirring intensity 56 r/min, stirring duration 20 min, and stirring cycle 6 h. Under these conditions, the proportional rates of gas and methane production in the pilot study were maximized at 0.39 and 0.236 L/(g·d), respectively. It was demonstrated that RSM methodology could be applied to the stirring process in larger-scale algae anaerobic fermentation reactors. Levels of protease, dehydrogenase, and coenzyme F420 were higher in optimized stirring parameters than other conditions. Stirring intensity was the main factor affecting biogas production by anaerobically fermenting algae. Stirring cycle exerted a secondary effect, while the effect of stirring duration was minor. Excessively intense and frequent stirring destroy the micro-environment of anaerobic microbial growth, partially disrupting the synergy between different anaerobic species. Conversely, an excessively weak stirring or prolonged stirring cycle lead to float of algae in the reactor, forming an upper algal layer. And the algal layer hinder the discharge of gas from the reactor. Meanwhile, less effective contact between algae and the microbes leads to the decrease of algae degradation rate.