***Data underlying the PhD thesis: Ecophysiology of N2O-emitting microbial communities***
Authors: N. Roothans, M.C.M. van Loosdrecht, M. Laureni
Department of Biotechnology, Faculty of Applied Sciences, Delft University of Technology

Contact Information: 
M. Laureni
Sanitary Engineering, Faculty of Civil Engineering and Geosciences, Delft University of Technology
m.laureni@tudelft.nl


*** General description ***
This dataset contains operational data collected from laboratory bioreactors (Delft) and a full-scale wastewater treatment plant (Amsterdam-West), 
as part of the PhD Thesis of N. Roothans (2024). The data was collected between October 2020 and August 2022. This data was only included in publications 
as graphics, so it is here provided in table 
format.

Publications associated to the datasets:
https://doi.org/10.1093/ismejo/wrae116
https://doi.org/10.1101/2024.04.17.589950

This research was funded by the Dutch Foundation for Applied Water Research (Stowa), Hoogheemraadschap Hollands Noorderkwartier, and Waterschap de Dommel.


*** Objectives ***
The experiments were performed to gain deeper insights into complex nitrogen-converting microbial communities in lab- and full-scale.


*** Data collection and file description ***

1) ------ Chapter2_Reactor_Data.xlsx ------

Two denitrifying communities were enriched in lab-scale bioreactors to investigate aerobic denitrification under alternating oxic and anoxic conditions. 
The data was collected between May and August 2022. The reactors ran continuously with NO3- as electron acceptor, and acetate, propionate, and butyrate as 
electron donor and carbon source. The concentrations of O2, N2O, and CO2 in the off-gas were continuously monitored online (every minute) by a Rosemount 
NGA 2000 off-gas analyser (Emerson). The concentrations of NH4+, NO2-, and NO3- in the influent and effluent supernatant were spectrophotometrically measured 
with the Gallery Discrete Analyzer (Thermo Fisher Scientific) or cuvette test kits (Hach Lange) immediately after sampling or within 24h after storage at 4 oC. 
The concentrations of acetate, propionate, and butyrate in the influent and effluent supernatant were measured after storage at -20 oC by high-pressure liquid 
chromatography (Vanquish Core HPLC, Thermo Fisher Scientific) using an Aminex HPX-87H column (300 x 7.8 mm) (Bio-Rad), calibrated with solutions ranging from 
0 to 250 mM.

Terminology:
	R4    - bioreactor submitted to  4 oxic-anoxic cycles per day
	R32   - bioreactor submitted to 32 oxic-anoxic cycles per day 
	X     - biomass
	Stdev - standard deviation
	c     - concentration
	R     - conversion rate (mmol/h)
	Mw    - molecular weight (g/mol)
	µ     - biomass specific growth rate (Cmmol/Cmmol/h)
	COD   - chemical oxygen demand (soluble organic carbon - acetate, propionate, butyrate)

The data was divided in different sheets according to their content. Calculations are detailed in the publication (https://doi.org/10.1093/ismejo/wrae116).
	Cycling_times: 			effective period in each cycle during which each reactor was anoxic or oxic. Oxic conditions were assumed when the dissolved 
					oxygen was above 1% air saturation.
	Rates: 				daily conversion rates for each compound were calculated from influent and effluent concentrations. The "cleaning" column 
					marks the days in which the bioreactors were cleaned.
	Rates_STDEV:			errors of the rates propagated from concentration measurements.
	Biomass_estimation:		Calculations to estimate the rates and concentration of biomass in each reactor.
	Dissolved concentrations: 	Concentrations measured in the influent and effluent of the reactor, and calculation of the respective rates. Nitrogen
					samples were measured at the end of the anoxic period and at the beginning and end of the oxic period. "Fin" stands for
					the volumetric influent flow of the nitrogen (N) and carbon (C) media, and the total including added acid and base.
	Nitrification_batches:		Concentrations and sampling times of the nitrification batches.
	Cycle_concentrations:		Concentration profiles of nitrogen species throughout a few oxic-anoxic cycles.
	Daily_profiles_N2O:		Dissolved N2O and O2 in each reactor measured every minute for 24h on selected days.


2) ------  Chapter3_Activities_Data.xlsx ------

The maximum nitrification and denitrification activities of full-scale activated sludge were measured every two weeks between January 2021 and May 2022. 
Samples were collected from the aerated compartment of the monitored full-scale activated sludge reactor and stored in two litre glass bottles in the fridge 
for a maximum of four hours. The sludge was transported under cold conditions (never reaching a temperature above 10 oC) and immediately placed in a 3 L jacketed 
glass bioreactor with a 2 L working volume (Applikon, Getinge). The batch activity tests were sequentially performed on the same day in the following order: N2O, 
NO2- and NO3- reduction (denitrification), and NH4+ and NO2- oxidation (nitrification). Samples were taken every 3, 5, 10 or 15 min (depending on the length of 
the batches). The concentrations of NH4+, NO2- and NO3- in the filtered supernatant were spectrophotometrically measured using the GalleryTM Discrete Analyzer 
(Thermo Fisher Scientific) or cuvette test kits (LCK339, LCK342 and LCK304, Hach Lange). The volatile suspended solids concentration (ash content subtracted 
from the dried biomass), measured in triplicate, was taken as proxy for the biomass concentration. The dissolved N2O concentrations were monitored and recorded 
every minute with a standard N2O-R microsensor (customized concentration range 0.4 – 2 mM, Unisense) and a picoammeter PA2000 (Unisense). The dissolved N2O 
concentrations were calculated using the average of all calibrations performed 1-2 days before every batch series.

Terminology:
	VSS - Volatile suspended solids (proxy for biomass concentration)
	θ   - Microbial activity temperature coefficient
	NIT - nitrification
	DEN - denitrification
The data was divided according to their content. Calculations are detailed in the publication (https://doi.org/10.1101/2024.04.17.589950).
	Rates:				Rates calculated from the concentration profiles by linear regression.
	T_variation:			Rates obtained at 5, 10, 15, and 25 degrees Celsius, and calculation of the temperature coefficient.
	[X]_[Y]_batches:		Concentrations measured during each batch test, with [X] the nitrogen species used as substrate (NH4+, NO2-, NO3-, N2O), 
					and [Y] the nitrogen cycle process measured (NIT - nitrification or DEN - denitrification). For N2O, the calibration line
					used to convert signal (pA or Al1) to concentration is also indicated.
	N2O_production:			N2O produced during each batch.


3) ------ Chapter3_WWTP_Data.xlsx ------

The operational data of the Amsterdam-West wastewater treatment plant was collected by Waternet between October 2020 and July 2022. Daily averages of each 
parameter were calculated by averaging values collected every minute.

Terminology:
	NIT - Nitrification tank
	FCT - Facultative tank
	DNT - Denitrification tank
	TSS - Total suspended solids
	SVI - Sludge volume index
The data was divided in two sheets. Details can be found in the publication (https://doi.org/10.1101/2024.04.17.589950).
	Daily averages:			Containing all operational data of the wastewater treatment plant measured on a daily basis. Only the gas flow of the 
					reactor offgas is represented as a single average value. The N2O (kgN/d) was calculated from the concentration of N2O in
					the offgas (ppm) and the overall gas flow (m3/h).
	Daily profiles:			Concentration of nitrogen compounds and oxygen in the nitrification tank measured every 15 minutes on selected days.


