Electrolysis is performed in what is called an electrolytic cell (see figure 7.4). The essential parts of an electrolytic cell are the positive and negative electrodes which are connected to a source of electricity. The positive electrode is termed an anode and the negative electrode is as cathode. Whether the anode is positive or negative depends upon the definition. The defin we will not follow in “The anod is the electrica t which oxidation ; the cathode is the electrode where reduction occurs”. In electrolytic cell as shown in the diagram anode is positive and cathode is negative. However, in electrochemical Or galvanic cell such as battery, the anode is negative and the cathode is positive. The electric current flows into and out of the solution via electrodes. Conventially, 

the current (flow of electrons) enters the cell at cathode and leaves at anode. can a present a loss of materials. More trees would BULL u make paper (deforestation results). By reusing waste materials that is ¢ recycling actually helps to reduce the problem of solid wasté dispo , Many industries like electroplating produce wastes that contain 

metals. Recovery of these metals from the wastes not only helps to conserve the metal (a non-renewable resource) but also helps to reduce environmenta 

pollution. 

Broken glass bottle, cups and jars can be crushed and recycled. The used of crushed in the malt glass to make old containers saves materials. As thig process requires less fuel, there is also an indirect saving of energy ang cost. Similarly, the recycling of other materials, such as aluminium cane 

and bottle caps, can save materials, energy and money. Indirect saving of energy through recycling means conserving fossil fuels which can be used C 

to supply energy in other important industrial processes. - 

19.3.7 Biological principle of sewage treatment: Sewage is the waste liquid which comes from our houses, industries and other parts of villages, towns and cities. These include urine and faeces, toilet papers, detergents, oil and many other chemicals. 

Sewage should not be allowed to run into rivers or the sea, before: is treated. This is because it harms the people and degrade the environmen Untreated sewage is called raw sewage.