Wastewater treatment plant operators, from both government utilities and industry, are faced with the challenge of minimising operating and capital costs while ensuring that they meet regulatory discharge limits relating to public health and environmental impacts.
Removal of nitrogen and phosphorus from wastewater treatment processes are the key effluent discharge reporting metrics for operators. In many situations, the addition of a carbon supplement assists in this process.
Raw sewage contains an amount of available carbon that can be utilised by bacteria to perform various processes during the sewage treatment process. The carbon performs an important part in the process because even though it needs to be eventually removed (because it imposes a biological oxygen demand (BOD) on receiving waters), the carbon is also an essential energy source required to remove other nutrients such as nitrogen and phosphorous from the water before discharge.
Your plant may require a carbon supplement if it has one or more of the following:
- High nitrogen levels in discharges (these limits are regulated by the EPA and/or local and state authorities in all states of Australia
- Influent has low levels of naturally occurring COD (this can be affected by the composition of influent from residential and industrial wastewater, or may be impacted by weather conditions)
- Loss of active biomass
- A plant’s design, capacity loading, and processing time
- A reduction in available COD due to processes e.g. removal of biomass for the purpose of energy generation.