What are pre-approved sewage systems?
There are two types of approvals that need to be met for the installation of on-site sewage treatment systems in unsewered areas of Queensland which are:
- Local government approval
- The specific treatment plant approval to ensure the Plumbing and Drainage Act 2018 regulations are met.
In Queensland, the Department of Housing and Public Works is responsible for home sewage treatment system approvals (systems catering for fewer than 21 persons).
To streamline the process of approvals the Department has pre-approved a range of wastewater treatment systems which meet the requirements. These are classified into the varying quality of effluent produced.
- Secondary
- Advanced secondary
- Advanced secondary with nutrient removal
Secondary quality effluent characteristics
To meet the ‘secondary’ requirements systems must:
- At least 90% of effluent samples over the test period must have a BOD5 (biological oxygen demand - an indirect measure of the sum of all biodegradable organic substances in the water) of less than or equal to 20g/㎥ with no sample greater than 30g/㎥.
- 90% of the samples taken must have total suspended solids of less than or equal to 30g/㎥, with no sample exceeding 45g/㎥.
- Where disinfection is provided - 90% of samples must have thermotolerant coliform (faecal coliforms) count not exceeding 200 organisms per 100ml, with no sample exceeding 1000 organisms per 100ml.
- Where chlorination is the disinfection process - total chlorine concentration is greater than or equal to 0.5g/㎥ and less than 2.0g/㎥ in 4 out of 5 samples.
Around 35 secondary effluent treatment systems have been pre-approved view the complete list here - business.qld.gov.au and speak to your wastewater specialist to find out which system would suit your property.
Advanced secondary quality effluent characteristics
To meet the ‘advanced secondary’ requirements systems must:
- 90% of samples must have BOD5 less than or equal to 10g/㎥ and no greater than 20g/㎥.
- 90% of samples must have total suspended solids less than or equal to 10g/㎥ and no sample greater than 20g/㎥.
- Where disinfection is provided - 90% of samples must have a thermotolerant coliform count not exceeding 10 organisms per 100ml with no sample exceeding 200 organisms per 100ml.
- Where chlorination is the disinfection process - total chlorine concentration is greater than or equal to 0.5g/㎥ and less than 2.0g/㎥.
Around 21 advanced secondary effluent treatment systems have been pre-approved for use in QLD view the complete list here - business.qld.gov.au and speak to your wastewater specialist to find out which system would suit your property.
Advanced secondary with nutrient removal
Compliance requirements for wastewater treatment systems which offer advanced secondary quality effluent with nutrient removal include:
- 90% of samples - BOD5 less than or equal to 10g/㎥ and no greater than 20g/㎥.
- 90% of samples - total suspended solids less than or equal to 10g/㎥ with no sample greater than 20g/㎥.
- Where disinfection is provided - 90% of samples have thermotolerant coliform count not exceeding 10 organisms per 100ml with no sample exceeding 200 organisms per 100ml.
- Where chlorination is the disinfection process - total chlorine concentration is greater or equal to 0.5g/㎥ and less than 2.0g/㎥ in 4 out of 5 samples.
- 90% of samples, with 95% confidence limits, the test period has a total nitrogen concentration of less than or equal to 10mg/l.
- 90% of samples, with 95% confidence limits, have total phosphorus concentration less than or equal to 5mg/l.
Seven advanced secondary with nutrient removal effluent treatment systems has been pre-approved for use in QLD view the full list here - business.qld.gov.au and speak to your wastewater specialist to find out which system would suit your property.