Our clients understand that any water used in their operations eventually has to go somewhere. However, choosing the best option for effluent disposal is not always simple.
Figuring out how to dispose of effluent depends on a few factors. The initial questions asked are typically:
What sort of wastewater is being disposed (e.g. treated domestic sewage, industrial trade waste)?
Roughly how much wastewater needs to be disposed?
Is it possible to connect to the local municipal sewer? Where is the nearest connection to sewer?
How much land on the site could be reserved for irrigation?
Is there a natural environment (i.e. a waterway) nearby that could take the effluent if treated sufficiently?
The driving factor to decide the disposal method is often the quality of the effluent. Although discharging wastewater to an established sewer network normally requires the user to meet quality requirements, these requirements are much lower compared to land disposal methods or disposal to a creek or waterway.
Connecting to an existing sewer network is the simplest option if a sewer main is nearby. A connection to a sewer main must be installed, and provided that the discharge meets sewer acceptance criteria, the rest is managed by the sewer owner. Simple! If the discharge doesn’t meet the acceptance criteria a small treatment plant may be required. These can be as simple as a sedimentation chamber or screen, to as complicated as a digester or dissolved air flotation.
For businesses in Brisbane and Ipswich, releasing more than just human waste (i.e. trade waste), the requirement is to comply with Queensland Urban Utilities’ sewer acceptance criteria, and to obtain a trade waste approval. In other regions, the compliance is still with the respective owner of the sewer network, be it the local council or a water authority.
When a connection to sewer isn’t possible, irrigation (or an alternative land disposal method) can be a suitable solution. The main requirement for disposal via land irrigation is available land area. The thought of reserving prime real estate for getting rid of wastewater can be difficult for some to stomach, but in reality, we find that many of our clients are not near a sewer connection because they are operating on lots sized in the hectares, and are generally comfortable with dedicating some land to irrigation.
The amount of land required is based upon the effluent quality, soil type, depth to groundwater, plant type and a few other factors and is generally to be designed by a qualified person. In Queensland a piece of software called MEDLI (the Model for Effluent Disposal via Land Irrigation) is generally used to support applications that include effluent disposal to land. Specific rules vary state-by-state, but disposal systems of sufficient size (greater than 21 Equivalent Persons in Queensland) generally require an approval from the state environmental regulator (the Department of Environment and Heritage Protection or DEHP in Queensland).
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