Green synthesis of biocidal silver-activated charcoal nanocomposite for disinfecting water

We report for the first time the green synthesis of silver nanoparticles using West Indian cherry (Malpighia emarginata) extract known for its high vitamin C content. UV–visible spectroscopy, powder X ray diffraction (PXRD), dynamic light scattering (DLS), scanning electron microscopy (SEM) and energy dispersive X ray spectroscopy (EDX) analysis were used to characterise silver nanoparticles. Silver nanoparticles thus synthesised exhibit antimicrobial activity against gram-negative bacteria such as Pseudomonas aeruginosa, Escherichia coli, and gram-positive bacteria such as Bacillus subtilis and Staphylococcus aureus. The antimicrobial property of nanoparticles thus synthesised was applied in the production of silver-activated charcoal nanocomposite towards fabrication of antimicrobial water filtration columns. The microbial filtration efficiency of the nanocomposite was found to be higher compared to virgin activated charcoal even with reusage.     

水处理工程的消毒方法比较

在水处理中,消毒工艺的目的主要是杀死对人体健康有害的病原微生物,常用的方法有氯消毒、次氯酸钠消毒、二氧化氯消毒、臭氧消毒、紫外线消毒和活性氧消毒剂法等。文章重点分析以上消毒方法的机理及各自的优缺点,为工程选择提供理论依据。     

污水处理厂利用次氯酸钠消毒实验研究

粪大肠菌群是污水处理厂出水的一个重要指标,次氯酸钠是一种真正的高效、广谱、安全的强力灭菌、杀病毒药剂。固戍污水处理厂通过实验投加不同量的次氯酸钠溶液,使出水水质粪大肠菌群数不超过最高允许排放浓度,并得出最佳的投加量。     

医疗机构废水处理研究与应用

文章通过对南昌市某医疗机构废水处理工程运行特性进行研究,工程运行结果表明:采用水解酸化+生物接触氧化+ClO2消毒工艺对医疗废水进行处理,工艺运行稳定,出水水质可以达到《医疗机构水污染物排放标准》(GB18466-2005)中的浓度限值,吨水处理费用仅为1.35元。     

复合二氧化氯的制备及其用于城市污水回用消毒

在酸性环境中通过NaCl电解协同NaClO2化学氧化方法制备的复合二氧化氯溶液中ClO2和自由氯浓度分别达到70%和20%左右,系统地研究了电流密度(A)、NaClO2与NaCl质量比(B)、电解时间(C)对复合溶液中组分浓度和质量百分数的影响,并将复合溶液用于城市污水二级处理出水的消毒。结果表明,复合溶液中自由氯的浓度主要受因素C和A的影响,ClO2的浓度主要受因素C和B的影响,而A对副产物ClO2-和ClO3-的影响最大。总大肠菌群数在105~108个.L-1的城市污水二级处理出水采用复合溶液消毒时,当其中ClO2投加量为4 mg/.L-1,自由氯含量不低于1.20mg.L-1,经30min接触后出水生物学指标满足GB/ T18920-2002 的要求。既降低了消毒剂的使用量,又减少了消毒副产物ClO2-的生成。     

Antimicrobial Efficacy of a Novel Eucalyptus Oil,Chlorhexidine Digluconate and Isopropyl Alcohol Biocide Formulation

Effective surface disinfection is a fundamental infection control strategy within healthcare. This study assessed the antimicrobial efficacy of novel biocide formulations comprising 5% and 2% eucalyptus oil (EO) combined with 2% chlorhexidine digluconate (CHG) and 70% isopropyl alcohol (IPA) contained within a wipe. The efficacy of this novel antimicrobial formulation to remove and eliminate methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli and Candida albicans from steel surfaces was investigated. Adpression studies of pre-contaminated wipes were also utilised to assess their potential to induce cross-contamination between hard surfaces. Furthermore, the bactericidal nature of the EO-formulation was established in addition to time-kill. The EO-containing formulations demonstrated bactericidal antimicrobial efficacy against all microorganisms and did not induce surface cross-contamination. There was no significant difference (p < 0.05) between the 5% and 2% EO formulations in their ability to remove microorganisms from steel surfaces, however both significantly (p < 0.05) removed more than the control formulations. Microbial biofilms were eliminated within 10 min (p < 0.05) when exposed to the EO formulations. Our novel EO-formulation demonstrated rapid antimicrobial efficacy for potential disinfection and elimination of microbial biofilms from hard surfaces and may therefore be a useful adjunct to current infection control strategies currently employed within healthcare facilities.     

人工快渗工艺设计的若干问题探讨

人工快渗工艺在三峡库区小城镇污水处理厂的应用十分广泛,在广泛调查的基础上,对人工快渗工艺中的调节池设计、砂滤池反冲洗排水处理、人工快渗池设计、曝气方式改良、污水消毒和污泥处理等关键技术问题进行了总结和探讨,对比分析了各种具体设计形式的利弊,并提出了一些合理化设计的建议。     

自由氯、氯胺和顺序氯化对饮用水消毒效果的试验研究

研究了自由氯、氯胺和顺序氯化三种消毒方式对大肠埃希氏菌和粪肠球菌的灭活效果.结果表明,自由氯浓度越高,对细菌的灭活速率和最终灭活率越大;氯胺浓度越高,对细菌的灭活速率和最终灭活率越大;顺序氯化消毒效果优于单独使用自由氯或氯胺时的消毒效果.同时,还探讨了pH和温度对三种消毒方式的影响.     

水解酸化/生物接触氧化/ClO2消毒处理中小型医院废水的效果分析

采用水解酸化/生物接触氧化/ClO2消毒处理某中小型医院废水,当进水COD、BOD5、SS、氨氮质量浓度分别为190～300 mg/L、80～150 mg/L、42～56 mg/L、≤14.87 mg/L粪大肠菌群(MPN)≥25 000 L-1时,去除率分别为74%～83%、89%～93%、71%～81%、≥32.7%和99.6%～99.7%,工程出水达到国家医疗机构水污染物排放标准(GB18466-2005)排放标准。因此,该工艺处理中小型医院废水具有较好的实际运用价值和明显的经济效益。     

Disinfection of Biologically Treated Municipal Wastewater using Electrochemical Process

The present study demonstrates the application of Al-Al electrode combination for electrochemical disinfection of biologically treated municipal wastewater (BTMW) of Sewage Treatment Plant. A glass chamber of 2 liter volume was used for the Electrochemical (EC) process using two electrode plates of aluminum (Al-Al) with DC power supply at different operating conditions of current density (CD), operating time (OT), inter electrode distance (IED), electrode area (EA), initial pH, and settling time (ST). The maximum removal of total coliforms (TC) (99.99%) and total bacteria (TB) (99.87%) from BTMW was achieved with the optimum operating conditions of CD (2.65 A/m²), OT (40 mins.), IED (0.5 cm), EA (160 cm²), initial pH (7.5), and ST (60 min.). The efficiency of the EC process for disinfection of BTMW was strongly affected by the CD, OT, IED, EA, pH, and ST. These effects can be explained by the formation of the reactive species such as OH^?, and ClO₂^?·during the electrochemical process. Under optimal operating conditions, the operating cost was found to be 1.01 $/m³ in terms of the electrode consumption (23.71 x 10^?5 kg Al/m³) and energy consumption (101.76 kwh/m³).