Melbourne Sewage System Western Treatment plant Eastern treatment Plant Regional treatment plans

Western Treatment plant n Primary Treatment –Sludge n Grass Filtration n Land Filtration n Lagooning –Aerobic –Facultative

Primary Treatment n Screening n Sedimentation n Sludge Evaporation Evaporation Storage Storage Extraction Extraction

Grass Filtration n Soil type n Grass type n Bacteria n Result

Grass Filtration Concrete drain Earth drain Out In Clay soil Rye Grass Transpiration

Land filtration n Soil type –Friable n Grass type n Bacteria n Water evaporation / Transpiration –trees n Grazing –Recycling n Result –Best method

Land filtration Aerobic bacteria Anaerobic Bacteria

Lagooning

Digestion in Aquatic Environments n In stationary water two layers develop: – Upper Layer with the oxygen –oxygen being used up by aerobic and facultative bacteria. n CHO N S ---> CO 2 + NO 3 + SO 4 = n The bottom layer –No oxygen so anaerobic bacteria grow. –Digest organic mater ---> H2S, NH3 and CH4. –The bad smelling gases n Don’t escape to the environment n oxidised to H20, NO2-, SO4 and CO2 in the aerobic layer. n oxidised to H20, NO2-, SO4 and CO2 in the aerobic layer.

Digestion In a Pond

Dissolved Gases In Pond

Lagoon System

n Grass filtration can be saturated if too much water. n Lagoons can vary the though put by over 10 times n The more material put through the lagoons the faster the bacteria grow

Throughput in a Lagoon

Serpentine Lagoons

Lagoon at Werribee

Capture of Methane

Marine Disposal

Marine Digestion n A marine environment similar to lagoons. n If the affluent is discharges far enough out n BOD removed before any reaches the coast n Affluent must be primary treated. n The massive amount of non-salty water will alter the ecosystem n causing a different organisms to develop.