Statistical optimization of operating parameters of microbial electrolysis cell treating dairy industry wastewater using quadratic model to enhance energy generation

The performance of Microbial electrolysis cell (MEC) is affected by several operating conditions. Therefore, in the present study, an optimization study was done to determine the working efficiency of MEC in terms of COD (chemical oxygen demand) removal, hydrogen and current generation. Optimization was carried out using a quadratic mathematical model of response surface methodology (RSM). Thirteen sets of experimental runs were performed to optimize the applied voltage and hydraulic retention time (HRT) of single chambered batch fed MEC operated with dairy industry wastewater. The operating conditions (i.e) an applied voltage of 0.8 V and HRT of 2 days that showed a maximum COD removal response was chosen for further studies. The MEC operated at optimized condition (HRT- 2 days and applied voltage- 0.8 V) showed a COD removal efficiency of 95 ± 2%, hydrogen generation of 32 ± 5 mL/L/d, Power density of 152 mW/cm² and current generation of 19 mA. The results of the study implied that RSM, with its high degree of accuracy can be a reliable tool for optimizing the process of wastewater treatment. Also, dairy industry wastewater can be considered to be a potential source to generate hydrogen and energy through MEC at short HRT.     

Enhancement effect of zero-valent iron nanoparticle and iron oxide nanoparticles on dark fermentative hydrogen production from molasses-based distillery wastewater

This study investigates the effect of two different iron compounds (zero-valent iron nanoparticle: nZVI and iron oxide nanoparticles: nIO) and pH on fermentative biohydrogen production from molasses-based distillery wastewater. The nZVI and nIO of optimum particle sizes of 50 nm and 55 nm respectively were synthesized and applied for fermentative hydrogen (H₂) production. The addition of nIO & nZVI at (0.7 g/L, pH: 6) resulted in the highest H₂ yield, H₂ production rate, H₂ content and COD reduction. Moreover, the kinetic parameters of H₂ production potential (P) and H₂ production rate (R_m) increased to 387 mL, and 22.2 mL/h, respectively for nZVI, these values were 363 mL and 21.8 mL/h for nIO. The results obtained indicated the positive effect of nZVI and nIO addition on enhanced fermentative H₂ production. The addition of nZVI & nIO resulted in 71% and 69.4% enhancement in biohydrogen production respectively.     

铁碳填料对电镀清洗废水的微电解性能

以硫铁矿烧渣为主要材料制备了球形铁碳填料,并将其用于电镀清洗废水的处理。由交互正交试验结果可知,废水pH值是影响COD和氨氮去除率的主要因素,其次是废水pH值与铁碳填料添加量的交互作用和废水pH值与反应时间的交互作用。微电解的最佳工艺条件为:废水pH值2.50,铁碳填料的添加量15 g/L,反应时间30 min。此时,COD降低78.6%,氨氮降低15.0%,处理效果比商品铁碳填料的好。     

芬顿氧化-絮凝沉淀处理焦化废水应用研究

研究以"芬顿氧化+絮凝沉淀"组合工艺对某焦化厂的二级处理尾水进行深度处理,以小试优化条件用于实际尾水处理,考核指标为絮凝沉淀池最终出水COD。结果表明,组合工艺的优化运行条件:H2O2、Fe2+的质量浓度分别为210、185 mg/L,pH为3.5。在此条件下,实际尾水系统出水COD低于80 mg/L,能够满足GB 16171-2012的相关要求。     

PAM-粉煤灰体系在煤泥水絮凝沉降过程中的作用及机理

以煤泥水COD、SS、动电位、污泥比阻为切入点,分析了煤泥水的特点及难以絮凝沉降的原因,并研究了PAM-粉煤灰体系在混凝沉降作用中的机理。研究结果表明:PAM-粉煤灰法在最优条件下,清水分离率47%、沉降速度0.357 mm/s;上清液:pH=7.35,SS=55.57 mg/L,COD=37.72 mg/L;污泥比阻为0.062×10^15 m/kg,满足煤泥水循环标准。     

铜钼分离磁-浮联合新工艺研究

国内某含钼铜精矿，铜钼可浮性相近，单一浮选工艺所需药剂量大，废水COD高。针对矿石性质特点和规律，开发出了磁选-浮选联合工艺，相比单一浮选工艺，钼精矿中钼的回收率提高了2.87%；新工艺节省硫化钠60%以上，水玻璃、六偏磷酸钠和煤油节省40%以上，同时废水COD下降60%以上。新工艺具有明显的经济效益和环境效益，为该类型的铜钼矿的开发利用提供了新的技术方案。     

Fenton 絮凝工艺去除废水中的有机物试验

为了研究废水中有机物的去除问题，针对某企业含有机物废水进行了对比试验，采用了Fenton 絮凝联合工艺去除废水中的COD（化学需氧量）和浊度，考察了初始pH值、H2O2投加量、H2O2与Fe2+投加物质的量比、反应时间、絮凝剂投加量以及絮凝剂投加时的pH值对COD以及浊度去除效果的影响。结果表明，采用最佳工艺参数组合后，浊度去除率和COD的去除率分别为99.32%和97.27%。     

不同含量低污染水对人工湿地中细菌的影响研究

探究水平流人工湿地(HFCW)系统处理低污染水过程中,相同COD/ρ(TN)下不同碳氮含量对细菌群落结构的影响。结果表明,进水为较高碳氮含量的HFCW(HF1)和进水为较低碳氮含量的HFCW(HF2)对COD和TN的去除效率具有一定的差异,HF1和HF2对COD的去除效率分别为48.26%和28.89%,对TN的去除率分别为79.06%和81.87%。HF1中细菌的丰富度和多样性均高于HF2,HF1中富集的优势细菌为Chloroflexaceae、Comamonadaceae和Rhodocyclaceae,均具有异养反硝化功能,HF2中富集的优势细菌为Xanthomonadaceae和Rhodocyclaceae,其中Xanthomonadaceae具有自养反硝化功能。COD、NH4^+-N和NO3^--N对HF1中细菌群落的影响大于对HF2中细菌群落的影响,HF1中COD对细菌群落的影响大于NH4^+-N和NO3^--N。     

柿竹园多金属矿选矿废水处理试验研究

针对柿竹园多金属矿选矿废水量大、难沉降、pH值高、COD高等特点,研究了石灰沉降+ZJYH03氧化法、石灰沉降+漂白粉氧化法、石灰沉降+NaClO氧化法、聚合硫酸铁沉降+ZJYH03氧化法和石灰沉降+生物氧化法等废水处理工艺,并对比分析了各工艺的处理效果和药剂成本,结果表明: 聚合硫酸铁沉降+ZJYH03氧化法取得了较好的处理效果,该方法具有工艺简单、水质无色透明、药剂成本低等特点。