Treatment of Waste H2O b.stev

the USED H 2 O of a COMMUNITY ie: kitchen sink/ tub/ toilet shower/ laundry/ industry CORRECT treatment is necessary to health SAVES exposure to infectious organisms THEN the H 2 O is returned to waterway s

CORRECT treatment is necessary to health

SAVES exposure to infectious organisms

THEN the H 2 O is returned to waterway s

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

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

- mend ruptures

- install new seals

- check apparatus

- upgrade areas

SCREENING FINE SCREENS intercept : solids plastics paper leaves 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 :

solids plastics

paper

leaves

wood

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 remain suspended (Water Care Services Ltd, 2008)

AUTOMATIC scrapers collect this from a sloped floor removed offsite SEDIMENTATION FLUID & ORGANIC SOLIDS slowly 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, 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 & CO 2 gas

Activated sludge Trickling filters Oxidation ponds Polishing ponds DISINFECTION Irrigation Wetlands Outlet THE PROCESS

bacteria strip out, organic pollutants This DECREASES the concentration of pollutants in the ,” WASTEWATER ,”. ACTIVATED SLUDGE wastewater after the,”sedimentation,” : aerated with O 2 & saprotrophic bacteria (Water Care Services Ltd, 2008)

An example of an activated sludge tank:

TRICKLING FILTERS

ALGAE & BACTERIA mature the H 2 O and an anaerobic sludge layer settles OXIDATION PONDS MOST COMMON SYSTEM used in NZ 4 – 6 week stage of treatment Large pond/s where the H 2 O 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 algal solids left in the H 2 O after having ,” settled out .”

UV gives high quality product the harbour first : the H 2 O 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 O 2 & electricity are used = O 3 removes colour from the H 2 O NOT used in NZ easy & effective in disuse over UV - due to the environmental impacts OZONE (American Chemistry Council, 2005) ALSO:

destroys many microbes

O 2 & electricity are used = O 3

removes colour from the H 2 O

NOT used in NZ

easy & effective

in disuse over UV - due to

the environmental impacts

USED FOR: septic tank & oxidation pond effluent &, secondary/tertiary stages of treatment WETLANDS 5 – 10 day flow through a ,”wetland,” - plants rooted in soil of a shallow pond BACTERIA settle to plant stems and aeration of H 2 O transfers the process

IRRIGATION H 2 O from the treatment plant can be used for IRRIGATION purposes THOUGH much care is needed to ensure the 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=107 Science 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