Final Report Summary - CARBALA (CARbon BALAncing for nutrient control in wastewater treatment)
The objective of the Carbala project was to promote the transfer of knowledge in the field of wastewater treatment through an exchange programme among ten research teams; early and senior researchers were involved in research activities and training related to the development and testing of new process configurations for wastewater treatment. While during the initial two-years period, research activities were mainly focused on innovative unit processes, during the second period (year three and four) the process investigated were scaled up or gradually combined into wastewater treatment systems optimized with respect to wastewater characteristics and environmental conditions.
The partners’ research teams are composed mainly by bioprocess engineers, modellers, biotechnologists, technology developers and microbiologist, and their expertise is complementary with regards to:
- the unit processes investigated: anammox and denitrification with sulphide; biological phosphorus removal with a focus on denitrifying phosphorus accumulating bacteria; anaerobic digestion and co-digestion; fungi applied to recalcitrant compounds removal and aerobic granular biomass applications.
- the ability of representing the studied phenomena: activated sludge modelling, microbial ecosystems characterisation and energy and carbon footprint assessment;
- the context of reference: environmental and economic situation; domestic or industrial wastewater; small or large wastewater treatment plants;
- facilities (analytical instruments, laboratories, pilot/full scale plants).
The project deal with the need, typical of “state of the art” wastewater treatment, for biodegradable carbon, either for heterotrophic denitrification and biological phosphorous removal or anaerobic digestion, which is often not sufficiently present in the wastewater itself. External carbon sources are not only expensive, but their application increases both the production of excess sludge and the energy and carbon footprint of the treatment, eventually reducing the potential production of biogas.
The new process configurations evaluated were selected with aim of balancing the use of organic compounds in order to maximize the role of anaerobic processes while, at the same time, operating biological nitrogen and phosphorus removal; this will allow to decrease of the carbon footprint of the treatment, while maintaining the desirable effluent quality.
The most significant findings and the achievements of the research activities are related to the following topics:
• granular biomass selection and stability;
• free nitrous acid (FNA) inhibition on anoxic and aerobic P removal in hybrid suspended and attached biomass systems (IFAS);
• on-line continuous titrimetry for biological nitrification process control (tested also at full scale);
• denitrification and denitritation with sulphide as electron donor;
• effect of selecting conditions and of inhibiting compounds on anammox bacteria kinetics;
• reactor design for fungi application in non-sterile conditions to remove recalcitrant compounds;
• anaerobic digestion and co-digestion of tannery sludge and waste;
• role and modelling of external carbon source in denitrification;
• microbial ecology in pilot and full scale bioreactors;
• activated sludge modelling adaptation to simulate unit processes as well as complex full scale industrial wastewater treatment plants.
Including journal papers and conference proceedings, more than seventy works have been already published by Carbala network, and several others are submitted or in preparation.
The partners’ research teams are composed mainly by bioprocess engineers, modellers, biotechnologists, technology developers and microbiologist, and their expertise is complementary with regards to:
- the unit processes investigated: anammox and denitrification with sulphide; biological phosphorus removal with a focus on denitrifying phosphorus accumulating bacteria; anaerobic digestion and co-digestion; fungi applied to recalcitrant compounds removal and aerobic granular biomass applications.
- the ability of representing the studied phenomena: activated sludge modelling, microbial ecosystems characterisation and energy and carbon footprint assessment;
- the context of reference: environmental and economic situation; domestic or industrial wastewater; small or large wastewater treatment plants;
- facilities (analytical instruments, laboratories, pilot/full scale plants).
The project deal with the need, typical of “state of the art” wastewater treatment, for biodegradable carbon, either for heterotrophic denitrification and biological phosphorous removal or anaerobic digestion, which is often not sufficiently present in the wastewater itself. External carbon sources are not only expensive, but their application increases both the production of excess sludge and the energy and carbon footprint of the treatment, eventually reducing the potential production of biogas.
The new process configurations evaluated were selected with aim of balancing the use of organic compounds in order to maximize the role of anaerobic processes while, at the same time, operating biological nitrogen and phosphorus removal; this will allow to decrease of the carbon footprint of the treatment, while maintaining the desirable effluent quality.
The most significant findings and the achievements of the research activities are related to the following topics:
• granular biomass selection and stability;
• free nitrous acid (FNA) inhibition on anoxic and aerobic P removal in hybrid suspended and attached biomass systems (IFAS);
• on-line continuous titrimetry for biological nitrification process control (tested also at full scale);
• denitrification and denitritation with sulphide as electron donor;
• effect of selecting conditions and of inhibiting compounds on anammox bacteria kinetics;
• reactor design for fungi application in non-sterile conditions to remove recalcitrant compounds;
• anaerobic digestion and co-digestion of tannery sludge and waste;
• role and modelling of external carbon source in denitrification;
• microbial ecology in pilot and full scale bioreactors;
• activated sludge modelling adaptation to simulate unit processes as well as complex full scale industrial wastewater treatment plants.
Including journal papers and conference proceedings, more than seventy works have been already published by Carbala network, and several others are submitted or in preparation.