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In this study, a newly developed nitrogen (N) and phosphorus (P) recovery process using a membrane contactor termed NPHarvest was tested with different liquid waste streams in large-scale trials. Ammonia was captured in ammonium sulfate form using a hydrophobic membrane, while phosphorus was precipitated as sludge using alkali precipitation and coagulation processes. The tested streams were selected to cover the potential liquid waste streams for nitrogen recovery and included two different mesophilic digester reject waters, landfill leachate, and separately collected urine. The NPHarvest pilot was tested with hydraulic loads in the range of 12–133 L/h. Nitrogen recovery efficiency reached a maximum of 92.5% with the reject water of mesophilic digester and a maximum ammonia flux of 481.1 mg/L.h was obtained with a urine stream. A mass transfer coefficient was calculated for the four tested wastewater streams using two different approaches, resulting in two value ranges in the order of 10−3 and 10−7 m/s. It was found that the mass transfer coefficient decreased with increase in the initial nitrogen concentration. The recovery of phosphorus varied between 79% and 97%. The quality of ammonium sulfate was evaluated by employing comprehensive tests that included vegetative cells and coliphages, harmful metals, and organic micropollutant measurements. These measurements confirmed that ammonium sulfate meets the Finnish legislation requirements for agricultural use. The use of a diluted acid wash was proven to be sufficient for maintaining membrane surface properties and was confirmed by the observed insignificant loss of hydrophobicity and the mild development of fouling. Finally, the competitiveness of NPHarvest compared to existing processes was confirmed through a detailed cost analysis.
Juho Uzkurt Kaljunen; Raed A. Al-Juboori; Anna Mikola; Ilaria Righetto; Irene Konola. Newly developed membrane contactor-based N and P recovery process: Pilot-scale field experiments and cost analysis. Journal of Cleaner Production 2020, 281, 125288 .
AMA StyleJuho Uzkurt Kaljunen, Raed A. Al-Juboori, Anna Mikola, Ilaria Righetto, Irene Konola. Newly developed membrane contactor-based N and P recovery process: Pilot-scale field experiments and cost analysis. Journal of Cleaner Production. 2020; 281 ():125288.
Chicago/Turabian StyleJuho Uzkurt Kaljunen; Raed A. Al-Juboori; Anna Mikola; Ilaria Righetto; Irene Konola. 2020. "Newly developed membrane contactor-based N and P recovery process: Pilot-scale field experiments and cost analysis." Journal of Cleaner Production 281, no. : 125288.
In this study, the microbial community of nitrifying activated sludge adapted to Finnish climate conditions was studied to clarify the microbial populations involved in low-temperature nitrification. Microbial community analysis of five full-scale wastewater treatment plants (WWTPs) showed several differences compared to WWTPs from other countries with a similar climate. In particular, very low abundance of ammonium oxidizing bacteria (AOBs) (altogether ˂ 0.25% of total community) as well as typical NOBs (˂0.35%) and a high abundance of orders Cytophagales and Micrococcales was observed in all Finnish WWTPs. To shed light on the importance of autotrophic and heterotrophic nitrifying processes, laboratory studies of activated sludge were carried out with a presence of and a lack of organic carbon in wastewater at 10 ± 1 °C. Two different sludge retention times (SRTs) were compared to determine the effect of this operational parameter on low-temperature nitrogen removal. The important role of previously reported Candidatus Nitrotogaarctica for nitrite oxidizing in cold climate conditions was confirmed in both full-scale and laboratory scale results. Additionally, potential participation of Dokdonella sp. and Flexibacter sp. in nitrogen removal at low-temperatures is proposed. Operation at SRT of 100 days demonstrated more stable and efficient nitrogen removal after a sharp temperature decrease compared to 14 days SRT.
Antonina Kruglova; Jenni Kesulahti; Khoi Minh Le; Alejandro Gonzalez-Martinez; Anna Mikola; Riku Vahala. Low-Temperature Adapted Nitrifying Microbial Communities of Finnish Wastewater Treatment Systems. Water 2020, 12, 2450 .
AMA StyleAntonina Kruglova, Jenni Kesulahti, Khoi Minh Le, Alejandro Gonzalez-Martinez, Anna Mikola, Riku Vahala. Low-Temperature Adapted Nitrifying Microbial Communities of Finnish Wastewater Treatment Systems. Water. 2020; 12 (9):2450.
Chicago/Turabian StyleAntonina Kruglova; Jenni Kesulahti; Khoi Minh Le; Alejandro Gonzalez-Martinez; Anna Mikola; Riku Vahala. 2020. "Low-Temperature Adapted Nitrifying Microbial Communities of Finnish Wastewater Treatment Systems." Water 12, no. 9: 2450.
Microplastic (MP) removal by coagulation/flocculation followed by settling was studied in a secondary wastewater treatment plant (WWTP) effluent matrix. MP concentration in size range <10 µm in wastewater is currently unknown due to the exclusion of this size range in many studies and due to difficulties in MP quantification. WWTP effluent samples were spiked with a known amount of polystyrene spheres of two different sizes 1 µm and 6.3 µm. The samples were treated with inorganic and organic coagulants typically used in WWTPs, i.e., ferric chloride, polyaluminum chloride, and polyamine. The effect of pH was studied with ferric chloride by changing the pH from 7.3 to 6.5. In this study, MP removal was monitored using flow cytometry. The role of chemicals in MP removal at WWTPs has not been in the focus of previously reported MP studies. Our results showed that all tested coagulants enhanced the removal of MPs with dosages applicable to tertiary treatment. The highest removal efficiency obtained was 99.4%, and ferric chloride and polyaluminum chloride were more efficient than polyamine. Performances of ferric chloride and polyaluminum chloride were close to each other, with a statistically significant difference at a certain dosage range. Our findings suggest that chemical coagulation plays a key role in the removal of MPs, and the process can be optimized by selecting the right coagulant and pH.
Katriina Rajala; Outi Grönfors; Mehrdad Hesampour; Anna Mikola. Removal of microplastics from secondary wastewater treatment plant effluent by coagulation/flocculation with iron, aluminum and polyamine-based chemicals. Water Research 2020, 183, 116045 .
AMA StyleKatriina Rajala, Outi Grönfors, Mehrdad Hesampour, Anna Mikola. Removal of microplastics from secondary wastewater treatment plant effluent by coagulation/flocculation with iron, aluminum and polyamine-based chemicals. Water Research. 2020; 183 ():116045.
Chicago/Turabian StyleKatriina Rajala; Outi Grönfors; Mehrdad Hesampour; Anna Mikola. 2020. "Removal of microplastics from secondary wastewater treatment plant effluent by coagulation/flocculation with iron, aluminum and polyamine-based chemicals." Water Research 183, no. : 116045.
We mapped a large-scale wastewater treatment plant onto a complex network and we investigated how the structural properties of the graph evolve in time as the facility is operated. The Viikinmäki plant is mapped onto a dependence network in which the nodes are online process measurements and interconnectivity between nodes encodes pairwise correlations between the corresponding time series, as estimated over moving-windows. In this initial study, the construction of a graph of Viikinmäki is presented and results are discussed with the goal of understanding its usability as model for process interactions and encoder of latent structures.
Francesco Corona; Michela Mulas; Anna Mikola; Anna Kuokkanen; Mari Heinonen; Riku Vahala. Network representation and analysis of a large-scale wastewater treatment plant. IFAC-PapersOnLine 2019, 52, 364 -369.
AMA StyleFrancesco Corona, Michela Mulas, Anna Mikola, Anna Kuokkanen, Mari Heinonen, Riku Vahala. Network representation and analysis of a large-scale wastewater treatment plant. IFAC-PapersOnLine. 2019; 52 (1):364-369.
Chicago/Turabian StyleFrancesco Corona; Michela Mulas; Anna Mikola; Anna Kuokkanen; Mari Heinonen; Riku Vahala. 2019. "Network representation and analysis of a large-scale wastewater treatment plant." IFAC-PapersOnLine 52, no. 1: 364-369.
An Activated Sludge Model #3 (ASM3)-based, pseudo-mechanistic model describing nitrous oxide (N2O) production was created in this study to provide more insight into the dynamics of N2O production, consumption, and emissions at a full-scale wastewater treatment plant (WWTP). N2O emissions at the studied WWTP are monitored throughout the plant with an FT-IR analyzer, while the developed model encountered N2O production in the biological reactors via both ammonia oxidizing bacteria (AOB) nitrification and heterotrophic denitrifiers. Additionally, the stripping of N2O was included by applying a KLa-based approach that has not been widely used before. The objective was to extend the existing ASM3-based model of the plant and assess how well the full-scale emissions could be predicted with the selected model. The validity and applicability of the model were tested by comparing the simulation results with the comprehensive online data. The results show that the ASM3-based model can be successfully extended and applied to modelling N2O production and emissions at a full-scale WWTP. These results demonstrate that the biological reactor can explain most of the N2O emissions at the plant, but a significant proportion of the liquid-phase N2O is further transferred during the process.
Kati Blomberg; Pascal Kosse; Anna Mikola; Anna Kuokkanen; Tommi Fred; Mari Heinonen; Michela Mulas; Manfred Lübken; Marc Wichern; Riku Vahala. Development of an Extended ASM3 Model for Predicting the Nitrous Oxide Emissions in a Full-Scale Wastewater Treatment Plant. Environmental Science & Technology 2018, 52, 5803 -5811.
AMA StyleKati Blomberg, Pascal Kosse, Anna Mikola, Anna Kuokkanen, Tommi Fred, Mari Heinonen, Michela Mulas, Manfred Lübken, Marc Wichern, Riku Vahala. Development of an Extended ASM3 Model for Predicting the Nitrous Oxide Emissions in a Full-Scale Wastewater Treatment Plant. Environmental Science & Technology. 2018; 52 (10):5803-5811.
Chicago/Turabian StyleKati Blomberg; Pascal Kosse; Anna Mikola; Anna Kuokkanen; Tommi Fred; Mari Heinonen; Michela Mulas; Manfred Lübken; Marc Wichern; Riku Vahala. 2018. "Development of an Extended ASM3 Model for Predicting the Nitrous Oxide Emissions in a Full-Scale Wastewater Treatment Plant." Environmental Science & Technology 52, no. 10: 5803-5811.
Recent studies have indicated that the emissions of nitrous oxide, N2O, constitute a major part of the carbon footprint of wastewater treatment plants (WWTPs). Denitrification occurring in the secondary clarifier basins has been observed by many researchers, but until now N2O emissions from secondary clarifiers have not been widely reported. The objective of this study was to measure the N2O emissions from secondary clarifiers and weigh the portion they could represent of the overall emissions at WWTPs. Online measurements over several days were carried out at four different municipal WWTPs in Finland in cold weather conditions (March) and in warm weather conditions (June–July). An attempt was made to define the conditions in which N2O emissions from secondary clarifiers may occur. It was evidenced that large amounts of N2O can be emitted from the secondary clarifiers, and that the emissions have long-term variation. It was assumed that part of the N2O released in secondary clarification was originally formed in the activated sludge basin. The emissions from secondary clarification thus seem to be dependent on conditions of the nitrification and denitrification accomplished in the denitrification–nitrification process and on the amount of sludge stored in the secondary clarifiers.
Anna Mikola; Mari Heinonen; Heta Kosonen; Maarit Leppänen; Pirjo-Liisa Rantanen; Riku Vahala. N2O emissions from secondary clarifiers and their contribution to the total emissions of the WWTP. Water Science and Technology 2014, 70, 720 -728.
AMA StyleAnna Mikola, Mari Heinonen, Heta Kosonen, Maarit Leppänen, Pirjo-Liisa Rantanen, Riku Vahala. N2O emissions from secondary clarifiers and their contribution to the total emissions of the WWTP. Water Science and Technology. 2014; 70 (4):720-728.
Chicago/Turabian StyleAnna Mikola; Mari Heinonen; Heta Kosonen; Maarit Leppänen; Pirjo-Liisa Rantanen; Riku Vahala. 2014. "N2O emissions from secondary clarifiers and their contribution to the total emissions of the WWTP." Water Science and Technology 70, no. 4: 720-728.