Define Precisely - Environmental Services - Past Exam Paper, Past Exams for Environmental Science

Define Precisely - Environmental Services - Past Exam Paper, Past Exams for Environmental Science

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Main points of this past exam are: Define Precisely, Application, Operation, Design Philosophy, Operation, Multimedia, Anthracite, Dual Filter, Clean Bed Head Loss, Dioxins
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Microsoft Word - EBSEN_7_Y3 Environmental Services.doc

Cork Institute of Technology Bachelor of Engineering in Building Services Engineering - Award


Summer 2008 Environmental Services

(Time: 3 Hours) Instructions Answer any FIVE questions. All questions carry equal marks.

Examiners: Mr. W. M. Corr Mr. D. Leonard

Dr. M. Smyth

Q1. (a) Write a detailed note on the uses of activated carbon in water treatment.

Your note should address:

• Source, size, type, dose, uses

• Mode of application

• Mode of operation

(7 marks)

(b) Describe the design philosophy and operation of multimedia filter beds. (4 marks)

(c) Drinking water for a scheme to supply a town of 50,000 people is to be filtered through a

dual filter of anthracite and sand with design data as follows:

Table 1

Constituent Size mm Density g/cc Sphericity Depth mm Porosity %

Anthracite 1.3 1.60 0.52 720 45

Sand 0.65 2.65 0.75 360 55

(i) Size the bed As for a loading of 300 m3/day per m2. (3 marks)

(ii) Calculate the total clean bed head loss. (6 marks)

( ) eqs d


g K

L h

ψφ φ

ρ µ 6,1 23


= −


Take K = 5 µ = 0.001 Pa.S


Q2. (a) Write concise notes on dioxins and furans under the following headings:

(i) Origin and chemical composition, particularly in respect of incineration vs backyard

burning. (5 marks)

(ii) Toxicity and health effects and the controversies surrounding this topic. (6 marks)

(iii) Generation and Removal within the incinerator stages. (6 marks)

(b) Define precisely the terms DRE, LD50, and ELV in relation to this topic. (3 marks)

Q3. (a) Write brief notes on the following:

(i) The difference between L10 and LA,Eq as measures of noise. (3 marks)

(ii) Legislation on the wearing of ear protection. (3 marks)

(iii) The performance of commercially available ear protection. (3 marks)

(b) Write brief notes on:

(i) The design and construction of outdoor noise barriers. (3 marks)

(ii) The effectiveness of outdoor noise barriers. (3 marks)

(c) Noise levels in a plant room over an eight-hour shift are measured as:

Level, dBA Time, hrs

97 2

99 4

101 2

(i) Calculate LA,Eq. (3 marks)

(ii) How long may a worker remain in the room if the LA,Eq dose is not to exceed

90 dBA over 8 hours? (2 marks)



EqA t10logL .1010

10, ∑=


2 10

2 ,EqA,

1 ,EqA, 10LL T

Tlog TT



Q4. (a) Describe in detail the unit operations involved in the pre-treatment of municipal or

industrial wastewaters. (5 marks)

(b) Describe the operation and advantages of a sequencing batch reactor (SBR). (5 marks) (c) (i) Design a primary settling tank for the new (large) wastewater treatment plant at

Little Island. Assume a treatment load of 250,000 persons equivalent. (6

(ii) Sketch ideal and thermal stratified (dead zone) flow patterns along the tank. (4 marks)

Q5. (a) “On an international scale, Irish aquifers are relatively vulnerable to pollution”.

Describe the factors which lead to this conclusion; and those which alleviate the

consequences. (4 marks)

(b) Describe the Geological Survey of Ireland’s Vulnerability Mapping and Response as

applied to a landfill application. (5 marks)

(c) A gravel aquifer with thickness 12 m and permeability K = 15 m/d supplies a group

scheme from a single well at a rate of Q = 300 m3/day. The bed can be treated as water-

full but not confined.

An observation well located 100 m from the main well records a drawdown of 3.5 m

when the main well reaches steady flow.

A septic tank is proposed to be located 300 m from the main well.

(i) For the following data, determine if the septic tank lies within the recharge zone:

- Effective Annual Rainfall: 500 mm

- 80% Recharge to Groundwater

- Free-draining thin sandy soil overlay

- Recharge Area centred on well. (4 marks)

(ii) Will the septic tank lie within the drawdown zone if this is defined as exceeding

0.5 m? (5 marks)

  

 

− =



2 1

2 2

ln r r

hhKQ π

(iii) Would you recommend that permission be granted or refused for the septic tank?

(2 marks)


Q6. (a) Describe a temperature inversion and sketch the effect it has on atmospheric plume

dispersion. (4 marks) (b) It is estimated that a burning dump emits 3g/s of NOx. What is the concentration of NOx

directly downwind from this source at distances of 0.5 and 5 km on an overcast night

with a wind speed of 7 m/s? Assume the dump to be a ground-level point source with no

plume rise. (6 marks) (c) (i) The owner of the dump suggests things would be much better if a 20-m stack

were erected on the dump: it could then be considered a point source at an elevation

of 20 m. Repeat part (b) for this condition. (7 marks)

(ii) Is the owner right? (3 marks)

Refer to Table 6.1 and Figures 6.7 and 6.8

Q7. (a) Describe the operation of a typical MSW incinerator and list the key operating

parameters. (6 marks)

(b) Describe the content and disposal of the four key effluent streams. (5 marks)

(c) What technologies are available for flue gas treatment? (3 marks)

(d) MSW from a city of 200,000 households comprises combustible: water: inert in the ratio

50:30:20 by mass.

(i) Estimate the calorific value of the waste. Will it burn unassisted? (3 marks)

(ii) Estimate the primary energy output in MW. (2 marks)

(ii) How might the calorific value be increased in winter-time? (1 mark)



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