Types Of Reactor Designs Research Articles

Micro-structured copper and nickel metal foams for wastewater disinfection: proof-of-concept and scale-up

It is necessary to disinfect treated wastewater prior to discharge to reduce exposure risks to humans and the environment. The currently practiced wastewater disinfection technologies are challenged by toxic by-products, chemicals and energy demand, a range of effectiveness limitations, among other concerns. An effective, eco-friendly, and energy-efficient alternative disinfection technique is desirable to modernize and enhance wastewater treatment operations. Copper and nickel micro-structured metal foams, and a conventional copper mesh, were evaluated as disinfecting surfaces for treating secondary-treated wastewater contaminated with coliform bacteria. The micro-structured copper foam was adopted for scale-up study, due to its stable and satisfactory bactericidal performance obtained over a wide range of bacterial concentrations and metal-to-liquid ratios. Three scales of experiments, using two types of reactor designs, were performed using municipal wastewater to determine the optimal scale-up factors: small lab-scale batch reactor, intermediate lab-scale batch reactor, and pilot-scale continuous tubular reactor experiments. The performance was evaluated with the aim of minimizing metal material requirement with respect to bactericidal efficiency and leaching risks at all scales. Copper foam, at or above optimal conditions, consistently inactivated over 95 % of total coliforms, fecal coliforms and E.coli in wastewater at various scales, and leachate copper concentrations were determined to be below Canadian guideline values for outfall. This study successfully implemented the “structure” strategy of process intensification, and opens up the possibility to apply micro-structured copper foam in a range of other water disinfection systems, from pre-treatment to point-of-use, and should thus become a topic of further research.

Environmental Effects of Fusion Power Plants. Part I: Effluents Other than Tritium

Radioactive and nonradioactive effluents are released routinely during normal operation of near-term commercial fusion power reactors. Nonradioactive effluents are essentially the same as those released at conventional steam-electric power plants. Radioactive effluents consist of activated corrosion products and tritium. Most radioactive releases originate from liquid-waste processing systems and from ventilation systems of various buildings where radioactivity may become airborne. These effluents have some potential for environmental impact; however, the significance of the impact depends in part on the concentration and release rate of the effluent. The type of reactor design (e.g., tokamak, mirror, etc.) has minimal influence on activation product releases. Activation products released are influenced primarily by the materials chosen for structural components, and the quantities released are influenced primarily by the coolant choice.