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Chemical Engineering and Clean Water

by YPU Admin on March 3, 2016, Comments. Tags: chemical engineering, Engineering, Research, UoM, and water

Introduction

Hello, I’m Emily, a second year PhD student in Chemical Engineering at the University of Manchester. I have always been a keen scientist studying Chemistry, Biology and Maths at A-level before coming to the University of Manchester in 2010 to study Chemical Engineering. I completed my four year Integrated Master’s degree before continuing on with my studies by beginning a PhD in September 2014.  

My research focuses on the development of fuel cells, in particular Microbial Fuel Cell which uses bacteria found in waste water to clean wastewater whilst generating small quantities of electricity. The main purpose of this research is to identify and develop a system of cleaning waste water which is less harmful to the environment compared with methods currently used. 

In Depth…

Every day we use water. To drink, to cook, to clean, etc. We are very lucky that when we turn on our taps at home the water that comes out is clean and safe to use. However, when the water leaves our homes it is contaminated and cannot be used again unless it’s cleaned. So, how do we clean this water?

Current methods of treating wastewater are expensive as they either require large quantities of air to be pumped through the system (activated sludge reactors) or large areas of land for large reactors (trickle filter bed). They also produce large quantities of waste sludge which requires further treatment. The quantity of energy required for pumping, the damage to large areas of land and the production of sludge also makes this technology damaging to the environment highlighting a further need for a better method of cleaning water. An alternative is the use of microbial fuel cells.

Microbial fuel cells use the bacteria found in wastewater and starve it of oxygen. This prevents the bacteria from breathing and forces them to ferment, break down organic materials in water, in order to gain energy and survive. As the organic materials are broken down protons and electrons are formed. This occurs on one side of a fuel cell called an anode. These newly formed ions are forced to travel from the anode side of the fuel cell to the other side, called the cathode, following two separate routes routes. In between the sides of the fuel cell is a proton exchange membrane, this allows the movement of protons from one side to the other but blocks the movement of electrons. Meanwhile the electrons flow through wires externally of the fuel cell from one side to the other. The ions are then able to re-join on the cathode side; here they are mixed with oxygen to produce clean water.

This movement of ions is able to generate small quantities of electricity. The anaerobic nature of the anode greatly reduces the quantity of sludge produced which reduces the amount of further treatment required. The reduction of waste sludge, reduction of energy needs and the production of electricity make microbial fuel cells an ideal alternative to current wastewater treatment systems. As well as its use as an alternative wastewater treatment system, other research is ongoing which uses this technology specifically for power production or as bio-sensors.

Going Further

This is a great website for general information on what it’s like to be a chemical engineer and how to become one: http://www.whynotchemeng.com/

This is the official blog by students in the School of Chemical Engineering and Analytical Science; it highlights work by both staff and students:  http://www.mub.eps.manchester.ac.uk/ceasblog/

This blog highlights work being done in fuel cell technology and is run by the Governments Office of Energy, Efficiency and Renewable Energy: http://energy.gov/eere/hydrogen-fuel-cells-blog

Another blog about different types of Microbial Fuel Cells and how they work: http://www.sciencebuddies.org/blog/2014/03/microbial-fuel-cells-on-the-hunt-for-renewable-energy.php

A short video explaining microbial fuel cells by Bruce Logan, a world leader in this research: https://www.youtube.com/watch?v=ZotwUJAb8R4

 

Developing environmentally friendly fuel

by YPU Admin on June 25, 2015, Comments. Tags: biofuel, biotechnology, computing, electricity, enzymes, hydrogen, maths, oxygen, Physics, redox, Research, and water

Introduction

My name is Nick and I am a first year PhD student at the Manchester Institute of Biotechnology. At school I studied physics, maths and computing at A-level and then went on to study physics at the University of Manchester (BSc and MSc). My PhD research involves trying to find out how the structure of redox enzymes affects their redox potential. The redox potential is an important factor that needs to be considered in the design of biofuel cells. Biofuel cells use enzymes to help produce electricity from hydrogen and oxygen, with water as a waste product.

In depth

The redox potential (E0) tells you how likely a chemical species will accept an electron. When a chemical species accepts and electron, we say it has been reduced. The more positive the redox potential, the more likely it is that a chemical species will accept an electron and be reduced. The below reaction has a positive redox potential, so a copper ion will tend to accept an electron to become a copper atom.  

Cu+  +  e-  ↔  Cu  (E0 = +0.52V)

A chemical species may have a negative redox potential. This means it is more likely to lose an electron. When a chemical species loses an electron we say is has been oxidised. The more negative the redox potential, the more likely it is that a chemical species will lose an electron and be oxidised. The below reaction has a negative redox potential, so a sodium atom will tend to lose an electron to become a sodium ion.

Na+  +  e-   ↔  Na    (E0 = -2.71V)

Enzymes are a type of biological molecule which catalyse (increase the rate of) the chemical reactions that sustain life. Redox enzymes contain a metal ion which can either be reduced or oxidised. They help control the rate of many different reactions which involve the transfer of electrons. The structure of the enzyme around the metal ion influences the redox potential of the metal ion. Below is an image of an enzyme called Azurin, which has a Cu2+ ion in its active site.  The way in which the Azurin is bound to the copper ion affects how easily it can accept an electron.

You might be familiar with the idea that electricity is the flow of charge particles. For example, electrons flow in the wires that make up the electrical devices we use. Electricity can be made in many different ways, some more environmentally friendly than others. Biofuel cells utilise enzymes to help make electricity using hydrogen and oxygen and producing water as the only waste product. The redox enzymes help transfer the electrons through the cell which generates electricity. One enzyme takes electrons from hydrogen and passes them through the cell. The other enzyme collects the electrons and then uses them to make water.

My research involves working out how the structure of the enzymes changes their redox potential. The idea is to produce a computer program that will be able to adapt the structure of an enzyme so its redox potential is perfectly tuned for use in biofuel cells. I also plan to make the enzymes and experimentally measure their redox potentials, to prove the computer program works.

Going further

Manchester Institute of Biotechnology: http://www.mib.ac.uk/

What are enzymes? http://www.chem4kids.com/files/bio_enzymes.html

What are redox reactions? http://www.bbc.co.uk/bitesize/higher/chemistry/reactions/redox/revision/1/

Fuel cells: http://en.wikipedia.org/wiki/Fuel_cell

Biofuel cells: http://en.wikipedia.org/wiki/Enzymatic_biofuel_cell

Could biofuel cells be developed for use in our bodies? http://www.bbc.co.uk/news/technology-15305579