Where does the large volume of waste water needing treatment come from?

From urban lifestyles, such as homes and businesses, and from industrial processes.

Explain why waste water must be treated before it is released into the environment.

It contains harmful microbes and organic matter that would pollute rivers and harm the organisms living in them.

Explain why sewage is treated in several separate stages rather than one.

Each stage removes a different kind of material, working from large solids through to dissolved organic matter and microbes.

Suggest why a sewage works must handle a much greater volume of liquid after heavy rain.

Rainwater drains into the sewers, so the volume of waste water arriving at the works increases.

AQA GCSE Chemistry 8462

Atomic Structure and the Periodic Table

Topic overview Atoms, elements and compounds Word equations, symbols and balanced equations Mixtures From the plum pudding model to the nuclear model Bohr, Chadwick and the modern model of the atom Relative electrical charges of subatomic particles Size and mass of atoms Relative atomic mass and electronic structure The periodic table Development of the periodic table Metals and non-metals Group 0 Group 1 Group 7 Transition metals, and how they differ from Group 1

Bonding, Structure, and the Properties of Matter

Topic overview Chemical bonds, including metallic bonding Ionic bonding Ionic compounds Covalent bonding and how it is represented The three states of matter and changes of state Predicting state, state symbols, and the limits of the particle model Properties of ionic compounds Properties of small molecules Polymers and giant covalent structures Properties of metals and alloys, and why metals conduct Diamond and graphite Graphene and fullerenes Sizes of particles and their properties Uses of nanoparticles

Chemical Analysis

Topic overview Pure substances Formulations Chromatography Tests for hydrogen, oxygen, carbon dioxide and chlorine Flame tests Metal hydroxides Tests for carbonates, halides and sulfates Flame emission spectroscopy

Chemical Changes

Topic overview The reactivity series Metal oxides, extraction, and redox in terms of electrons Acids reacting with metals, neutralisation and salts Soluble salts The pH scale and neutralisation Titrations Strong and weak acids The process of electrolysis, and molten ionic compounds Using electrolysis to extract metals Electrolysis of aqueous solutions Representation of reactions at electrodes as half equations

Chemistry of the Atmosphere

Topic overview The Earth's early atmosphere How oxygen increased and carbon dioxide decreased The gases in today's atmosphere, and which are greenhouse gases Human activities which contribute to an increase in greenhouse gases in the atmosphere Global climate change and carbon footprints Atmospheric pollutants from fuels, and their effects

Energy Changes

Topic overview Exothermic and endothermic reactions Everyday uses, and investigating temperature change Reaction profiles The energy change of reactions Cells and batteries Fuel cells

Organic Chemistry

Topic overview Crude oil, hydrocarbons and alkanes Fractional distillation and petrochemicals Properties of hydrocarbons Cracking, and testing alkenes with bromine water Why cracking is useful, and equations for it Structure and formulae of alkenes Reactions of alkenes Alcohols Carboxylic acids Addition polymerisation Condensation polymerisation Amino acids, DNA and naturally occurring polymers

Quantitative Chemistry

Topic overview Conservation of mass and balanced chemical equations Relative formula mass and concentration of solutions Mass changes when a gas is involved, and measurement uncertainty Moles Amounts of substances in equations, and balancing using moles Limiting reactants Percentage yield Atom economy Using concentrations of solutions in mol/dm Use of amount of substance in relation to volumes of gases

The Rate and Extent of Chemical Change

Topic overview Measuring the mean rate of a reaction Rate from graphs, and the gradient of a tangent Factors which affect the rates of chemical reactions Collision theory and activation energy Catalysts Reversible reactions and dynamic equilibrium The effect of changing conditions on equilibrium The effect of changing concentration The effect of temperature changes on equilibrium The effect of pressure changes on equilibrium

Using Resources

Topic overview Using the Earth's resources and sustainable development Producing potable water in the UK Desalination, and analysing water samples Waste water treatment Alternative methods of extracting metals Life cycle assessment Ways of reducing the use of resources Corrosion and its prevention Alloys as useful materials Glass, clay ceramics and polymers Composites, and comparing materials The Haber process Production and uses of NPK fertilisers

Using Resources

Waste water treatment

3 things to know
Paper 2

Overview

Where waste water comes from and why it must be treated, what sewage and industrial waste need removed, screening, sedimentation into sludge and effluent, anaerobic and aerobic treatment, and comparing ground, salty and waste water as sources.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

Which water source is easiest to make potable and why, what extra does sea water need, and rank ground, sea and waste water.

Key term

What must be removed from sewage and agricultural waste water?

Key term

How does the treatment of industrial waste water differ from that of sewage?

Questions from this subtopic

Each one with the model answer underneath.

1
Where does the large volume of waste water needing treatment come from?
Model answer
From urban lifestyles, such as homes and businesses, and from industrial processes.
2
Explain why waste water must be treated before it is released into the environment.
Model answer
It contains harmful microbes and organic matter that would pollute rivers and harm the organisms living in them.
3
What must be removed from sewage and agricultural waste water?
Model answer
Organic matter and harmful microbes.
4
How does the treatment of industrial waste water differ from that of sewage?
Model answer
Industrial waste water may also need harmful chemicals removed, as well as organic matter.
5
Explain why sewage is treated in several separate stages rather than one.
Model answer
Each stage removes a different kind of material, working from large solids through to dissolved organic matter and microbes.
6
Suggest why a sewage works must handle a much greater volume of liquid after heavy rain.
Model answer
Rainwater drains into the sewers, so the volume of waste water arriving at the works increases.

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Atomic Structure and the Periodic Table

Bonding, Structure, and the Properties of Matter

Chemical Analysis

Chemical Changes

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