To ensure the quality of rivers and natural waters, administration bodies must protect them from untreated or insufficiently treated waste water to avoid the presence of organic impurities, inorganic pollutants, nutrients, microorganisms and micropollutants.
To achieve an energy efficient waste water treatment, public administration bodies should:
- have the capacity to treat at least twice the dry weather waste water flow (in case of rain or thawing)
- treat the waste water at nitrifying conditions, and perform denitrification and phosphorus removal
- remove suspended solids by sand filtration in the case of sensitive receiving water bodies or other tertiary treatment such as activated carbon filtration or oxidation with chlorine-free oxidising agents in order to reduce micropollutants
- monitor online organic compounds (total organic carbon), ammonia, nitrate and phosphorus in the case of plant capacities of more than 100,000 population equivalents or a daily inflow of BOD5-load of more than 6000 kg
- stabilise primary and excess sludge in anaerobic digesters and to use the produced biogas for on-site electricity production and sludge drying at least for plants with a capacity of more than 100,000 population equivalents or a daily inflow BOD5-load of more than 6000 kg
- dry the anaerobically stabilised sludge and send it to incineration or co-incineration plants meeting the standards according to the Industrial Emissions Directive; in the case of small plants, the mechanically de-watered sludge can be sent to central sludge-drying plants
- use energy efficient fine bubble aeration systems in the biological stage, and energy efficient pumps and screw lifters, and recover biogas from anaerobic digestion of primary and excess sludge and use it in energy efficient turbines producing electricity and heat to be fully used for plant operation.