Murwillumbah Wastewater Treatment Plant  
     
The Murwillumbah Wastewater Treatment Plant was designed to service a population of 16000 people. It was completed in 2000 and the cost of the plant and reticulation was $10 million. 75% was funded by Council and 25% from the State Government. 

  • The treatment plant has been designed to treat 3.84 ML/day.

  • In 2010 dry weather flow was about 2.8 ML/day.

Murwillumbah WWTP is located on the banks of the Rous River. The reticulation network in Murwillumbah is based on a conventional gravity system with pump stations.

Features of the Plant include:

  • The inlet works comprise a main channel fitted with a mechanical step screen, grit chamber, storm overflow chamber and a flow divider to split the flows downstream of the inlet works.

  • Two intermittently decantering extended aeration tanks (EAT’s), each with a design capacity of 8000 equivalent persons.

  • Two concrete lined in-ground balance ponds.

  • Chemical dosing facilities for phosphorus removal and pH correction with bunded storage area.

  • ·UV disinfection facilities.

  • ·Deodorisation bed and blower to extract and treat foul air from the inlet works.

  • ·Amenities

  • ·Blower facility for aeration

  • Tertiary Treated Effluent System

Inlet Works

Looking past inlet works to plant

Treatment

  • The treatment process is an activated sludge process.

  • The amount of phosphorus is reduced by the addition of Alum (Aluminium Sulfate) to the process.

  • Volume limit for the discharge of liquid waste is 14000 kL/day.

  • Load limiting applies to this plant

Looking across in-ground balance pond to extended aeration tank (EAT)

Tertiary Treated Effluent System

In 2007 the Tertiary treated effluent system was built to reuse the majority of wastewater at Condong Sugar Mill.  It comprises an in-line filter, 2 membrane tanks (3ML/day), balance tank, UV system and permeate pumps, blowers and storage tanks

Chemicals used include Citric Acid and Sodium Hypochlorite for membrane cleaning, Sodium Metabisulphite for dechlorination of wash water and Chlorine for final disinfection.

Tertiary Treated Effluent Facility

Reuse water is called for on demand from Condong Sugar Mill and reuse is approximately 30 percent of total flows.

A high quality effluent is being produced using this system and any effluent not required by Condong Sugar Mill is discharged into the Rous River directly opposite the treatment plant as per licence conditions.

Looking down at membranes in one of the membrane tanks

The EPA licence limits (582) are listed on the following table for all flows up to three times the average dry weather flow.

Parameter

Units

90th Percentile Concentration

100th Percentile Concentration

Requirements for environmental discharge (to Rous River)

Biological Oxygen Demand

mg/L

10

20

Non Filterable Residues

mg/L

15

30

Total Nitrogen

mg/L as N

10

20

Ammonia

mg/L as N

2

5

Total Phosphorous

mg/L as P

0.5

1

Oil & Grease

mg/L

5

10

Faecal coliforms

cfu/ 100 mL

200

600

pH

-

Range 6.5 to 8.5
(This page was last edited on Monday March 14, 2011 )