M1U1: Principles of Environmental Engineering

Question 1

Leads to the development of sludge deposits and anaerobic conditions

Answer 1

Suspended Solids

Question 2

Biological destabilization can lead to the depletion of natural oxygen resources and the development of septic conditions

Answer 2

Biodegradable Organics

Question 3

Communicable diseases can be transmitted by pathogenic microorganisms

Answer 3

Pathogens

Question 4

Can lead to algal growth and pollution of groundwater when discharged on land

Answer 4

Nutrients

Question 5

Organic and inorganic compounds selected on the basis of their known or suspected carcinogeniticy, mutagenicity, teratogenicity or high acute toxicity

Answer 5

Priority Pollutants

Question 6

Resist conventional methods of WW treatment. Low value of BOD: COD

Answer 6

Refractory Organics

Question 7

May cause poisoning; need to be removed when wastewater is to be reused

Answer 7

Heavy Metals

Question 8

Constituents such as Ca2+, Na+ and SOx added during water usage

Answer 8

Dissolved Organics

Question 9

Wastewater Treatment Methods

Answer 9

Preliminary
Primary
Secondary
Tertiary
Sludge Treatment

Question 10

Processes in Preliminary Treatment

Answer 10

Screening
Comminution
Grit Removal
Oil and Grease Removal

Question 11

abrasive in nature and will cause accelerated wear on pumps and sludge handling equipment with which it comes in contact with.

Answer 11

Grit

Question 12

Most common device use for Grit removal

Answer 12

Parshall Flumes and Palmer-Bowlus flumes

Question 13

dependable and cheap way to remove oil, grease and other hydrocarbons from water.

Answer 13

Skimmers

Question 14

Processes in Primary Treatment

Answer 14

Settling and Sedimentation

Question 15

to produce a clarified effluent simultaneous with production of concentrated sludge that can easily be handled and treated.

Answer 15

sedimentation

Question 16

Processes in Secondary/Biological Treatment

Answer 16

activated sludge
fixed-film reactors
lagoons
pond
systems

Question 17

They use the organics in wastewater as food supply and convert them into biological cells or biomass.

Answer 17

Microorganisms

Question 18

Types of Biological Culture

Answer 18

Suspended Growth
Attached Growth

Question 19

suspended in the wastewater as single cells or clusters (flocs)

Answer 19

Suspended Growth

Question 20

the biological mass formed when air is continuously injected into the wastewater.

As the microorganisms grow and are mixed by the agitation of the air, the individual organisms flocculate to form an active mass of microbes
(biologic floc) called

Answer 20

activated sludge

Question 21

This is the name given by Barnard (1975) to represent any anaerobic/aerobic sequence to promote BPR. A version of this process with multiple stages is patented as A/O ™ (anaerobic/aerobic).

Answer 21

Phoredox

Question 22

This is a proprietary modification of the A/O ™ process that provides internal recycle and an anoxic zone for denitrification

Answer 22

A2/O™

Question 23

This modification of the four-stage process provides for both denitrification and phosphorus removal. Uses a longer SRT thus increases the carbon oxidation capability.

Answer 23

Bardenpho (5 stage)

Question 24

It is similar to the A2/O ™ process with two exceptions. The return sludge is recycled to the anoxic stage instead of the aeration stage, and the internal recycle is from the anoxic stage to the anaerobic stage.

Answer 24

University of Cape Town (UCT)

Question 25

The six operational steps of the SBR denitrification process are retained, but the conditions are modified

Answer 25

Sequencing Batch Reactor (SBR)

Question 26

stabilization pond, oxidation pond or sewage lagoon; shallow earthen basin where wastewater is retained long enough for natural purification processes to provide treatment

Answer 26

Ponds

Question 27

distinguished from ponds in that oxygen is provided by artificial aeration

Answer 27

lagoons

Question 28

ponds, in which both aerobic and anaerobic zones exist, may be used as the total treatment system for municipal wastewater. They are assumed to be completely mixed reactors without biomass recycle.

Answer 28

Facultative ponds and lagoons

Question 29

used in plug flow where compressed air is injected

Answer 29

air diffusers

Question 30

larger surface area per volume of air; 2 – 2.5mm bubble diameter

Answer 30

fine bubble diffuser

Question 31

less maintenance but poorer oxygen transfer; upto 25mm diameter

Answer 31

Coarse bubble diffuser

Question 32

used in completely mixed reactors employing high-speed impellers

Answer 32

mechanical aerators

Question 33

organisms attach themselves to the medium and grow into dense films of a viscous, jelly-like nature.

Answer 33

attached growth

Question 34

uses randomly packed solid medium where wastewater is passed over the biofilm in intermittent doses;

Answer 34

trickling filter

Question 35

uses modular synthetic media of high porosity and low weight such as light weight flat PVC sheets in alternating patterns/deep trickling filters

Answer 35

biotowers

Question 36

uses rotating disks partially submerged in the wastewater. The medium moves the biofilm alternately through water and air thus also maintains aerobic condition.

Answer 36

Rotating biological contactors (rbc)

Question 37

these processes were called “advanced wastewater treatment” because they employed techniques that were more advanced than secondary treatment methods.

Answer 37

tertiary treatment

Question 38

processes involved in tertiary treatment

Answer 38

nutrient removal organic material removal ion exchange reverse osmosis

Question 39

present in precipitation resulting from soluble and particulate nitrogen forms that are scrubbed from the atmosphere;

Answer 39

nitrogen

Question 40

effects of discharges

Answer 40

*Eutrophication leading to depletion of DO from nitrification and bio-stimulation * Ammonia toxicity to aquatic life * Reduction in the suitability of water for re-use

Question 41

biological oxidation of ammonium by chemoautotrophic bacteria

Answer 41

nitrification

Question 42

microorganism used in nitrification

Answer 42

nitrobacter

Question 43

biological reduction of nitrate to nitrogen gas by heterotrophic bacteria

Answer 43

denitrification

Question 44

from phosphate-rich rocks and organic decomposition

Answer 44

phosphorus

Question 45

Phosphorus removal process

Answer 45

chemical precipitation biological removal

Question 46

primary microorganisms responsible for P removal. They utilize volatile fatty acids (VFA) in the influent wastewater under anaerobic conditions by releasing stored P.

Answer 46

acinetobacter

Question 47

microorganism starvation (stressed state)

Answer 47

anoxic/anaerobic

Question 48

storage of P exceeding their normal need (luxury uptake)

Answer 48

aerobic

Question 49

processes in sludge treatment and disposal

Answer 49

stabilization dewatering

Question 50

basic processes of sludge treatment

Answer 50

preliminary operations thickening stabilization conditioning dewatering reduction

Question 51

sludge processing

Answer 51

conditioning thickening stabilization disinfection sludge dewatering solids reduction beneficial use system biosolids disposal

Question 52

removes soluble compounds

Answer 52

elutriation

Question 53

releases bound water and destroys biological cells

Answer 53

thermal conditioning

Question 54

generally restricted to biological solids; achieved by extended aeration, maintaining the m.o. in the endogenous respiration

Answer 54

aerobic digestion

Question 55

for primary sludge

Answer 55

anaerobic digestion

Question 56

consist of facultative and anaerobic bacteria. They ferment soluble organic solids to acids and alcohols of low molecular weights

Answer 56

acid formers

Question 57

consist of strict anaerobic bacteria that convert acid and alcohols along with H and CO2 to CH4

Answer 57

methane formers

Question 58

addition of Ca(OH)2 or CaO to sludge to raise pH to about 11 or above

Answer 58

lime stabilization

Question 59

aerobic to a certain degree and takes 30-40 days

Answer 59

composting

Question 60

use of belt filter, vacuum filter, plate and frame filter press

Answer 60

filtration

Question 61

dewatering by evaporation or percolation through the sludge bed or underlying media.

Answer 61

drying in drying beds

Question 62

this is common in industrial plants with available land

Answer 62

sludge lagoons

Question 63

for cold climates

Answer 63

sludge freezing beds

Question 64

combination of thermal cracking & condensation reactions; oil from sludge (OFS) and gasification

Answer 64

pyrolysis

Question 65

vitrified sludge can be used as material for floorings.

Answer 65

vitrification