Via anerobic stabilisation of sludge and recovery of methane gas, wastewatertreatment plants can achieve significant energysavings.
But how to properly handle the increased internal return flow of nitrogen, which arises with the sludge dewatering effluent?
This new study by Thomas Baumgartner, Lydia Jahn et al. compared different treatment processes and found that:

• sidestream treatment at single-stage WWTPs does not display an energetic advantage
• the deammonification process has a much lower carbon demand compared with mainstream SDE treatment, which is a great benefit for single-stage activated sludge plants with high effluent requirements regarding N removal or a limited capacity of the aeration system
• pre-treatment in sidestream via nitritation and the further treatment of nitrite-rich effluent in the first stage of a two-stage WWTP reduces the oxygen demand for COD respiration and is therefore the most favourable strategy to achieve an energy-efficient wastewater treatment with savings of approx. 8% of aeration energy

The paper provides data and plant-specific loads, which will support operators and planners in evaluating the best suitable treatment option for each plant.
For further results and details check the full openaccess publication:

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