M1U1: Principles of Environmental Engineering Flashcards
Leads to the development of sludge deposits and anaerobic conditions
Suspended Solids
Biological destabilization can lead to the depletion of natural oxygen resources and the development of septic conditions
Biodegradable Organics
Communicable diseases can be transmitted by pathogenic microorganisms
Pathogens
Can lead to algal growth and pollution of groundwater when discharged on land
Nutrients
Organic and inorganic compounds selected on the basis of their known or suspected carcinogeniticy, mutagenicity, teratogenicity or high acute toxicity
Priority Pollutants
Resist conventional methods of WW treatment. Low value of BOD: COD
Refractory Organics
May cause poisoning; need to be removed when wastewater is to be reused
Heavy Metals
Constituents such as Ca2+, Na+ and SOx added during water usage
Dissolved Organics
Wastewater Treatment Methods
Preliminary
Primary
Secondary
Tertiary
Sludge Treatment
Processes in Preliminary Treatment
Screening
Comminution
Grit Removal
Oil and Grease Removal
abrasive in nature and will cause accelerated wear on pumps and sludge handling equipment with which it comes in contact with.
Grit
Most common device use for Grit removal
Parshall Flumes and Palmer-Bowlus flumes
dependable and cheap way to remove oil, grease and other hydrocarbons from water.
Skimmers
Processes in Primary Treatment
Settling and Sedimentation
to produce a clarified effluent simultaneous with production of concentrated sludge that can easily be handled and treated.
sedimentation
Processes in Secondary/Biological Treatment
activated sludge
fixed-film reactors
lagoons
pond
systems
They use the organics in wastewater as food supply and convert them into biological cells or biomass.
Microorganisms
Types of Biological Culture
Suspended Growth
Attached Growth
suspended in the wastewater as single cells or clusters (flocs)
Suspended Growth
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
activated sludge
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).
Phoredox
This is a proprietary modification of the A/O ™ process that provides internal recycle and an anoxic zone for denitrification
A2/O™
This modification of the four-stage process provides for both denitrification and phosphorus removal. Uses a longer SRT thus increases the carbon oxidation capability.
Bardenpho (5 stage)
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.
University of Cape Town (UCT)
The six operational steps of the SBR denitrification process are retained, but the conditions are modified
Sequencing Batch Reactor (SBR)
stabilization pond, oxidation pond or sewage lagoon; shallow earthen basin where wastewater is retained long enough for natural purification processes to provide treatment
Ponds