Water and wastewater

What is meant by water stress and how do this vary across different parts of the world?

Describe the urban water cycle, focus closely on the parts of the cycle that require intervention by Civil Engineers

Explain how the provision of water and wastewater services are regulated in the UK. List the regulators and their functions.

Explain the key differences between a combined and separate sewer system, and the key advantages and disadvantages of each system.

Explain the difference between point sources and non-point sources of pollution.

Provide example of point sources and non-point sources of pollution.

List two nutrients of major concern for a natural receiving water body.

Define biochemical oxygen demand, describe the procedure for determining BOD, in particular the temperature and duration used in the testing procedure.

Explain the difference between CBOD and NBOD, use a sketch.

Why are suspended sediments problematic in receiving waters?

Explain what is meant by “emerging pollutants” and why they are causing
particular concern.

Explain, using equations and sketches the concept of “instantaneous” mixing when
applied to a control volume.

Explain using a sketch the impact of BOD on a natural river.

Describe what is meant by the “DO sag”. Explain what processes cause this phenomenon.

What physical processes control the value of the coefficients that describes the deoxygenation rate and the re-aeration rate in natural rivers.

If the wastewater is treated to a higher level before discharge would you expect the critical point to move upstream or downstream from its original position?

List and explain the purpose of the various processes that you would expect to see within a water treatment plant.

List typical water quality parameters used to characterise raw water.

What is pH, what does it represent?

Define turbidity, describe how it is often measured in a laboratory environment.

Define total suspended solids, describe how it is often measured in a laboratory.

Define Hardness, what is the impact of this parameter on supplied potable water.

Explain the difference between coagulation and floculation.

Explain how coagulation works, how does the use of alum help to cause coagulation?

Describe the physical differences between Type I, Type II and Type III settling.

Describe how a dissolved air flotation tank operates and why it is advantageous to use such a system compared to a Type I
settling tank.

Define Hardness in potable water, what is meant by Carbonate Hardness and NonCarbonate Hardness.

Explain the five different processes that can occur in filtration.

Explain how a rapid sand filter works and is operated, describe typical loading rates for a rapid sand filter and explain why they are higher than for a more traditional slow sand filter

What is the aim of disinfection in the water treatment cycle, state 6 characteristics of a good disinfectant. List typically used disinfecting agents.

Describe the treatment processes commonly found in waste water treatment plants in the UK. List all the important processes and explain why each process is
important.

What is meant by dry weather flow, how is it calculated? What is the daily flow rate
used in the design of wastewater treatment plants in the UK?

Name and describe the typical pollutants that wastewater treatment plants aim to
remove.

Describe the three types of settlement processes found in wastewater treatment
plants. Clearly explain the differences between the processes.

Describe any external factors which may impact on the reliable running of a mixed aerated sludge system.

Describe two different systems that can be used to aerate wastewater. List the
advantages and disadvantages of each system.

List the advantages and disadvantages of the activated sludge process.

List the advantages and disadvantages of trickling filters.

List typical processes used to de-water sludge and explain how the processes
work.

Describe the global water cycle, list all the important processes and explain why this is considered a closed system as regards water. Discuss the availability of freshwater for use.

When designing a sedimentation tank, what impact does the following have: Larger particles compared with smaller particles, same density, and Type I settling;

When designing a sedimentation tank, what impact does the following have: A 3-meter deep tank compared with a 5-meter deep tank.

When designing a sedimentation tank, what impact does the following have: Mineral particles as opposed to organic particles of the same particle size

When designing a sedimentation tank, what impact does the following have: Particles with a single settling velocity, as compared to particles with a distribution of settling velocities with a mean value equal to the particles with a single settling velocity.

When designing a sedimentation tank, what impact does the following have: Different water temperatures, e.g. 5°C vs. 20°C

Ewden Water Treatment Works is connected to two impounding reservoirs. Explain the purpose of the two reservoirs. What characteristics of the raw water does the treatment plant at Ewden focus on? Explain the processes used to deal with these characteristics.

What quantities of solids and BOD are removed in primary, secondary and tertiary treatment?

Describe the main features to be
incorporated into the design of primary
sedimentation tanks to achieve efficient solids removal. Give examples of two types of tank and state typical value of suspended solids and BOD5 reductions.

Design criteria for Primary sedimentaion

Design criteria for Secondary sedimentation

Give some possible solutions to water stress.

List conventional water pollutants.

List emerging pollutants.

What is meant by oxygen demand?

List sources of oxygen demanding material.

What two things effect the amount of molecular oxygen dissolved in water (DO)?

What is BOD and why is it useful?

What are the standard conditions for BOD analysis?

What does 'L' represent?

What is ThOD and how is it determined?

What is COD and why is it useful?

What are the advantages and disadvantages of COD analysis?

Describe the stages behind eutrophication.

Whats are total dissolved solids?

What are the sources/concentration influences of salts?

Why are salts a bad influence on the water cycle?

What are suspended solids and how are they measured?

List some toxic and hazardous substances.

What are the 3 processes in the transformation of BOD in a river?

How do you develop the DO sag curve?

What are the primary objectives of water treatment?

What are the characteristics of GW?

What are the characteristics of surface water?

What is turbidity, how is it used and how is it measured?

Why is pH an important part of water quality?

What is water hardness?

What is E.coli used to measure and why?

Describe the coliform test.

Describe the 4 water quality parameters

What type of tank is used for coagulation?

What type of tank is used for floculation?

List some typical coagulants.

Why are coagulants needed?

Describe the 3 flocculation mechanisms.

What are diluted suspensions?

What are concentrated suspensions?

What is dissolved air flotation?

What are the dissolved air flotation key parameters?

What are the advantages of dissolved air flotation?

What is water softening?

How can you easily identify hard water?

What is alkalinity?

Describe the process of filtration.

What are the 5 mechanisms of filtration?

Slow sand filtration

Rapid sand filtration

Describe the back wash process.

What are the considerations when choosing a site for a WwTP?

Whats the maximum amount of water to the treatment works?

Whats the maximum flow that can receive full treatment?

What is the suspended growth process?
(activated sludge)

What is the attached growth process? (aerobic biofilm)

2 treatment methods for the activated sludge process

2 treatment methods for the aerobic biofilm process

Why are wetlands used as a biological treatment method?

How to choose mode of BOD decomposition?

What are the effects of temperature in the biological treatment phases?

Describe the activated sludge process.

What happens in the aeration tank?
(activated sludge)

What happens in the settling tank?
(activated sludge)

What is sludge age?

What is sludge bulking?

What is foaming?

What are the Advantages and Disadvantages of
Activated sludge process?

Describe the biofilm process.

What is the structure of biofilm?

What are trickling filters?

List the advantages and disadvantages of trickling filters.

What sort of problems can we face when using trickling filters?

How can the problems with trickling filters be overcome?

Why is tertiary treatment needed?

What are the 4 steps to sludge processing?

Aerobic or anaerobic digestion?
(stabilisation)

How can sludge be thickened?

What is sludge conditioning?

What is the sludge de-watering process?

How can we reduce the volume of sludge?