黑水虻转化厨余垃圾过程中病原菌灭活规律的研究与综合评价

黑水虻能够有效取食厨余垃圾等有机固体废弃物,其自身转化为昆虫蛋白和脂肪等生物质,将厨余垃圾转化为虫沙有机肥,处理过程是一种有机固体废弃物的资源化新方法.为评估黑水虻处理厨余垃圾的效率与安全性,本课题研究黑水虻在厨余垃圾处理过程中,对大肠杆菌O157：H7（EC）、鼠伤寒沙门氏菌（ST）及金黄色葡萄球（SA）的灭活能力,评价黑水虻体内的抑菌因子,分析3种病原菌对黑水虻生长增重及厨余转化效率的影响.经过18 d的黑水虻处理,研究发现：①第0和第6 d两次以6.4~7.1 log₁₀ CFU·g^-1的浓度向厨余垃圾中分别接种EC、ST和SA以后,EC经4~6 d处理被全部灭活、ST经3~4 d处理被全部灭活,SA经6 d处理,浓度下降到1.9~2.6 log₁₀ CFU·g^-1,但不能被全部灭活,病原菌的灭活效率呈现EC=ST>SA的趋势（p < 0.001）,且黑水虻体内无EC、ST或SA残留;②厨余垃圾降解过程中,初期和中期pH值主要呈现酸性（4.0~5.3）,对抑制EC、ST和SA起到了促进作用,后期pH值呈中性至弱碱性;③黑水虻对于EC和ST能够产生自身免疫抑制因子,且抑制活性ST>EC,但对SA无明显的免疫抑制能力,SA的灭活主要依赖于黑水虻肠道菌群的竞争性抑制作用;④黑水虻的体长、体重、预蛹率、产率,以及厨余垃圾的生物转化率和减量化率未受病原菌存在的影响,18 d后EC组、ST组和SA组的预蛹率均达到在80%以上,厨余减量化率分别达到74.0%、79.1%和78.5%,生物转化率分别达到13.0%、13.2%、19.4%.综上,黑水虻能够在彻底灭活EC、ST,99%灭活SA的同时,高效降解厨余垃圾（减量化率>74%）,并转化为虫体有机质（虫产率>10%）,是一种高效卫生的厨余垃圾资源化方法.今后的研究中,还需要加强以金葡菌为代表的抗逆性病原菌的灭活机制的探讨.     

Anaerobic digestion in mesophilic and room temperature conditions: Digestion performance and soil-borne pathogen survival

Tomato plant waste(TPW) was used as the feedstock of a batch anaerobic reactor to evaluate the effect of anaerobic digestion on Ralstonia solanacearum and Phytophthora capsici survival. Batch experiments were carried out for TS(total solid) concentrations of 2%, 4% and 6% respectively, at mesophilic(37 ± 1°C) and room(20–25°C) temperatures. Results showed that higher digestion performance was achieved under mesophilic digestion temperature and lower TS concentration conditions. The biogas production ranged from 71 to 416 L/kg VS(volatile solids). The inactivation of anaerobic digestion tended to increase as digestion performance improved. The maximum log copies reduction of R. solanacearum and P. capsici detected by quantitative PCR(polymerase chain reaction) were 3.80 and 4.08 respectively in reactors with 4% TS concentration at mesophilic temperatures. However, both in mesophilic and room temperature conditions, the lowest reduction of R. solanacearum was found in the reactors with 6% TS concentration, which possessed the highest VFA(volatile fatty acid) concentration. These findings indicated that simple accumulation of VFAs failed to restrain R. solanacearum effectively, although the VFAs were considered poisonous. P. capsici was nearly completely dead under all conditions. Based on the digestion performance and the pathogen survival rate, a model was established to evaluate the digestate biosafety.     

Inactivation of Cryptosporidium by ozone and cell ultrastructures

The fluorescence staining method and scanning electron microscopy (SEM) were used to study the effect of ozone (O3) inactivating Cryptosporidium in water and cell ultrastructures variation to shed light on the mechanism of inactivation preliminarily.Results indicated that O3 had a stronger inactivating capability.When the concentration of O3 was above 3.0 mg/L and the contact time was up to 7 min,a significant inactivating effect could be achieved.The turbidity on inactivation effects was also found to be statistically significant in artificial water.With increases in turbidity,the inactivating effect decreased.Inactivation rate improved with a temperature increase from 5 to 25°C,but decreased beyond this.The inactivating capability of O3 was found to be stronger under acidic than that under alkalic conditions.When the concentration of organic matter in the reaction system was increased,the competition between Cryptosporidium and organics with O3 probably took place,thereby reducing the inactivation rate.In addition,the cellular morphology of Cryptosporidium varied with different contact times.At zero contact time,cells were rotundity and sphericity,at 60 sec they became folded,underwent emboly,and burst at 480 sec,the cell membrane of Cryptosporidium shrinked and collapsed completely.     

Inactivated properties of activated carbon-supported TiO2 nanoparticles for bacteria and kinetic study

The activated carbon-supported TiO₂ nanoparticles (TiO₂/AC) were prepared by a properly controlled sol-gel method. The effects of activated carbons (AC) support on inactivated properties of TiO₂ nanoparticles were evaluated by photocatalytic inactivation experiments of Escherichia coli. The key factors affecting the inactivation efficiency were investigated, including electric power of lamp, temperature, and pH values. The results show that the TiO₂/AC composites have high inactivation properties of E. coli in comparison with pure TiO₂ powder. The kinetics of photocatalytic inactivation of E. coli was found to follow a pseudo-first order rate law for TiO₂/AC composites, and kinetic behavior could be described in terms of a modified Langmuir-Hinshelwood model. The values of the adsorption equilibrium constants for the bacteria, K_c, and for the rate constants, k_r, were certainly depended on TiO₂ content. At 47 wt.% TiO₂ coatings with the highest rate constant, the K_c and k_r were 1.17 × 10⁻⁸L/cfu and 1.43 × 10⁶ cfu/(L·min), respectively. The variety of parameters shows significant effects on inactivation rate. The outer layer of bacteria decomposed first resulting in inactivation of cell, and with further illumination, the cells nearly decomposed.     

Effects of UV/Ag-TiO2/O3 advanced oxidation on unicellular green alga Dunaliella salina: Implications for removal of invasive species from ballast water

The UV/Ag-TiO2/O3 process was investigated for ballast water treatment using Dunaliella salina as an indicator. Inactivation curves were obtained, and the toxicity of e uent was determined. Compared with individual unit processes using ozone or UV/Ag-TiO2, the inactivation e ciency of D. salina by the combined UV/Ag-TiO2/O3 process was enhanced. The presence of ozone caused an immediate decrease in chlorophyll a (chl-a) concentration. Inactivation e ciency and chl-a removal e ciency were positively correlated with ozone dose and ultraviolet intensity. The initial total residual oxidant (TRO) concentration of e uent increased with increasing ozone dose, and persistence of TRO resulted in an extended period of toxicity. The results suggest that UV/Ag-TiO2/O3 has potential for ballast water treatment.     

镧沸石对磷和重金属的吸附与底泥钝化性能

矿业开采加工排放的重金属污染物会进入底泥中,与其中的磷形成复合污染.然而,目前关于底泥钝化的研究多数仅针对单一污染物.考察了新型钝化剂——镧沸石对P、Zn和Pb的吸附性能,及其对疏浚底泥中相应污染物的钝化效果,并通过脱附实验、X射线光电子能谱（XPS）和X射线衍射（XRD）研究了其吸附机制.结果表明,镧沸石对P、Zn和Pb的最大吸附量分别为53.76、27.70和123.45mg ·g^-1;预吸附Zn和Pb对镧沸石的除磷性能影响不大,但Zn和Pb的吸附会受到预吸附抑制.投加质量分数0.83%和1.66%的镧沸石后底泥中的P、Zn和Pb均向稳定态/生物难利用形态转化.P、Zn和Pb都可以通过形成内圈络合物被镧沸石吸附,此外静电作用和表面沉淀也分别会对Zn和Pb的吸附形成贡献.投加镧沸石可实现疏浚底泥中磷和重金属的钝化.     

超声灭活饮用水中隐孢子虫研究

为研究超声对饮用水中隐孢子虫(Cryptosporidium parvum)的灭活情况,考察了超声频率、功率、pH值和温度对灭活率的影响,通过形态学观察初步探讨了超声灭活隐孢子虫的机制,并进行了灭活动力学分析.结果表明,低频有利于隐孢子虫灭活,19.8kHz, pH7.2,温度(20±1)℃条件下超声15min灭活率可达92.5%,频率升高灭活率反而下降.在本实验条件下,超声功率103W对隐孢子虫的灭活效果与151W的相近,pH值对超声灭活隐孢子虫的影响不大,36℃超声灭活15min灭活率为95.6%,而在9℃下超声15min灭活率为88.3%,水温升高有利于灭活.灭活前后的形态学变化表明超声空化作用导致细胞膜破坏,细胞质流出从而起到灭活孢囊的效果.超声灭活隐孢子虫遵循假一级反应动力学,灭活隐孢子虫以低频率高功率的效果最好,可认为隐孢子虫的灭活以超声空化的强度为主.     

控制水体隐孢子虫的研究进展

介绍了隐孢子虫病的症状和传播途径 ,并着重论述控制水体隐孢子虫卵囊的化学灭活方法。     

铬离子对SBR工艺活性污泥毒性作用研究

针对重金属铬离子对SBR工艺系统中活性污泥的毒性作用,通过检测不同初始污泥容积指数(SVI)下SBR工艺活性污泥在不同铬负荷下的COD值、挥发性污泥浓度以及受铬离子影响的污泥容积指数(SVI),研究重金属铬离子对活性污泥的毒性作用以及对SBR工艺系统处理污水的影响。研究表明,重金属铬离子会导致SBR工艺系统出水COD升高;将铬离子对活性污泥的毒性作用按照挥发性污泥(MLVSS)铬负荷可划分为耐受范围、非耐受范围、细胞失活范围以及细胞分解范围。耐受范围铬负荷低于约30 mg Cr3+/gMLVSS,此范围内铬离子对于活性污泥的毒性作用不大,不致于导致系统出水水质变差;非耐受范围铬负荷在约30~65 mg Cr3+/g MLVSS,在铬离子作用下系统出水COD值明显高于对照系统;细胞失活范围铬负荷在约70~100 mg Cr3+/gMLVSS范围内,SVI大幅下降,微生物部份死亡和失活,出水COD尽管有一些下降,但与进水COD相比差不了多少;细胞分解范围铬负荷在约100 mg Cr3+/gMLVSS以上,微生物大量死亡,部分死亡细胞分解,系统出水COD值因微生物的死亡分解而超出进水COD值,受铬离子影响的系统SVI值大幅度降低。     

固载型TiO2光催化反应器对富营养水体杀藻作用研究

以泡沫镍作为载体，利用电沉积技术将纳米TiO₂负载在泡沫镍上，制成固载型TiO₂光催化反应器。研究表明，经过光催化反应器处理的富营养水体，30 h内叶绿素a由96.2 mg/m³降至2.2mg/m³，下降率达97.6％，而未负载纳米TiO₂普通泡沫镍材料，在同样光强的紫外灯照射下，叶绿素a下降率为74.3％，表明紫外光照射虽然也具有一定的杀藻功能，但是光催化反应才是藻类被杀灭的主要原因。利用9.54 m³景观喷水池进行杀藻中试，光催化反应器也同样表现出优异的杀藻性能，12 d内叶绿素a由18.7 mg/m³降至1.9mg/m³，下降率达到89.8％，水体由浓绿变为清澈见底，这表明光催化反应器具有很强的杀藻能力，通过有效杀灭富营养水体中藻类、控制藻类基数，对应急处理城市景观水、湖泊等富营养水体和突发性藻华，提高生物-生态法处理效率，改善城市水环境具有十分重要的意义。