h2o recycle
DESCRIPTION
TRANSCRIPT
Treatment of Waste H2O
b.stev
the USED H2O of a COMMUNITY
ie: kitchen sink/ tub/ toilet shower/ laundry/ industry
o CORRECT treatment is necessary
to health
o SAVES exposure to infectious
organisms
THEN the H2O is returned to
waterways
PRIMARY: infiltration/ screening/ grit removal/
sedimentation
SECONDARY: anaerobic digestors (organic waste)
activated sludge/ trickling filters/
oxidation ponds (H2O) TERTIARY: disinfection/ wetlands/ irrigation
WASTEWATER system starts as
a complex network of pipes &
junctions that feed the material
and fluid to the treatment plant
PIPES last 20-50yrs:dependent upon material used
THE SYSTEM EXPERIENCES LOAD INCREASE FROM:
tree roots cracks
poor design installation
deterioration flood
PRIMARY TREATMENT
This load increase is known as,”INFILTRATION,”.
Maintenance is constant to :- mend
ruptures
- install new
seals
- check
apparatus
-- upgrade
areas
PREVENTS SEWER overflow and seeping
into the soil/ drains and the environment
SCREENINGFINE SCREENS intercept :
o solids plastics
o paper
o leaves
o wood
DRUM SHAPE revolves: 3 mm screens
of stainless steel that catches the debris
DEBRIS is transported offsite to a landfill
Arrival at the treatment plant :
PUMPED AIR in the FLUID
generates motion This reduces density & allows grit to settle
in HOPPERS
GRIT REMOVAL TANKS
This: GRIT, is removed offsite
ORGANIC SOLIDS ORGANIC SOLIDS remain suspended
(Water Care Services Ltd, 2008)
AUTOMATIC scrapers collectthis from a slopedsloped floorfloor removed offsite
SEDIMENTATION
FLUID & ORGANIC SOLIDS slowlyslowly
flow within big tanks, this
settles the “organic solids”
SEDIMENTATION
ANAEROBIC DIGESTORS
ACTIVATED SLUDGE
Process of Separation
[organic waste]
[wastewater]
37.5C & acid forming bacteria
breakdown organic materials
organic acids
ANAEROBIC DIGESTORS
BIOGAS: collected to generate POWER,POWER, contributes to the electricity demand in the plant
THE GAS is collected – called,”BIOGAS,”
(Water Care Services Ltd, 2008)
NEXT: methane forming bacteria utilise acids
produce methane & CO2 gas
Activated sludge
Trickling filters
Oxidation ponds
Polishing ponds
DISINFECTION
Irrigation
Wetlands
Outlet
THE PROCESS
bacteria strip out, organic
pollutants
This DECREASESDECREASES the
concentration
of pollutants in the ,”
WASTEWATERWASTEWATER,”.,”.
ACTIVATED SLUDGE
wastewaterwastewater after
the,”sedimentation,”
: aeratedaerated with O2 & saprotrophic
bacteria
(Water Care Services Ltd, 2008)
An example of an activated sludge tank:
TRICKLING FILTERS
ALGAE & BACTERIA mature the H2O
and an anaerobic sludge layer settles
OXIDATION PONDS
MOST COMMON SYSTEM used in NZ4 – 6 week stage
of treatment Large pond/s
where the H2O is,”settled
out.”
(Water Care Services Ltd, 2008)
Most effective method is to utilise, SERIES of cells, in the process
ALSO: remaining time it takes for the
human intestinal bacteria to die off
POLISHING PONDS
5 -10 day process: settles the algalalgal solids
left in the H2O after having,”settled out.”
UV gives high quality product the harbour
first: the H2O passes through sand filters
that extract particles to:
DISINFECTION
15 microns
254nm quartz tube lamp of 300W is used
Mangere Site has 7776 UV LAMPS
(Water Care Services Ltd, 2008)
CHLORINE
destroys many microbes
O2 & electricity are used = O3
removes colour from the H2O
NOT used in NZ
easy & effective
in disuse over UV - due to
the environmental impacts
OZONE
(American Chemistry Council, 2005)
ALSO:
USED FOR:
septic tank & oxidation pond effluent
&, secondary/tertiary stages of
treatment
WETLANDS5 – 10 day flow through a ,”wetland,” -
plants rooted in soil of a shallow pond
BACTERIA settle to plant stems and aeration of H2O transfers the process
IRRIGATION
H2O from the treatment plant can be used for IRRIGATION purposes
THOUGH much care is needed to ensurethe soil & vegetation is not suscepted
to microbial contamination from this.
VERY dependent: toxcity
hazard
involved with the use of land &
timing of the crops to be
grown
Bibliography
Disinfection of wastewater. (n.d). Retrieved September 18, 2008, from http//: www.me.vccs.edu/courses/ENV149/disinfectionb.htm - 5k
American Chemistry Council.Inc. (2007). Chlorine chemistry division- wastewater disinfection. Retrieved September 18, 2008, from http//: www.americanchemistry.com/s chlorine/sec content.asp?CID=1198& DID=4534&CTYPEID=107Science Learning Hub. (2008). Disinfection of wastewater.sciencelearn.hub. Retrieved September 18, 2008, from http//:www.sciencelearn.org.nz /contents/you_me_and_uv/nz_research/disinfecting_wastewater-25k
Ministry of Environment. (2005). Client. Retrieved September 18, 2008, from http//:www.nzwwa.org.nz/Guideline%20for%20Oxidation %20Ponds%202005%20Final…-
Global Water Instrumentation.Inc. (2007). Inflow and infiltration of sanitary sewer systems. Retrieved September 18, 2008, from http//:www. globalw.com/support/inflow.html – 33k
Natural Resource Management and Environmental Department. (2007). Retrieved September 18, 2008, from http//:www.fao.org/docrep/t0 551e07.htm – 129k