A novel fuzzy-logic control strategy minimizing N2O emissions

Abstract

A novel control strategy for achieving low NO emissions and low effluent NH concentration is here proposed. The control strategy uses the measurements of ammonium and nitrate concentrations in inlet and outlet of the aerobic zone of a wastewater treatment plant to calculate a ratio indicating the balance among the microbial groups. More specifically, the ratio will indicate if there is a complete nitrification. In case nitrification is not complete, the controller will adjust the aeration level of the plant in order to inhibit the production of NO from AOB and HB denitrification. The controller was implemented using the fuzzy logic approach. It was comprehensively tested for different model structures and different sets of model parameters with regards to its ability of mitigating NO emissions for future applications in real wastewater treatment plants. It is concluded that the control strategy is useful for those plants having AOB denitrification as the main NO producing process. However, in treatment plants having incomplete NHOH oxidation as the main NO producing pathway, a cascade controller configuration adapting the oxygen supply to respect only the effluent ammonium concentration limits was found to be more effective to ensure low NO emissions.

Minimizing membrane bioreactor environmental footprint by multiple objective optimization

“…A value of RNAT less than 1.0 gNO3 gNH4 -1 represents a good balance between AOB and NOB. This value was obtained for the optimal solution, confirming the low nitrification efficiency for the system under study (Boiocchi et al, 2017b), which has also influenced the N2O formation during the nitrification/denitrification processes. Only negligible OffgasN2O and DE emission were found from the anaerobic and anoxic reactors, since the greater part of N2O has been produced during the nitrification ( Figure 5).…”

“…At high SRTs biomass endogenous decay rate dominates since most carbon has been oxidized. This will limit the denitrification rate, thus contributing to N2O emissions(Boiocchi et al, 2017b). OffgasCO2 increases with an increase of SRT.…”

Assessment of Full-Scale N2O Emission Characteristics and Testing of Control Concepts in an Activated Sludge Wastewater Treatment Plant with Alternating Aerobic and Anoxic Phases

“…Although long-term measurement campaigns and relevant analyses have been reported 12 , the insights obtained are largely dependent on the plant/process design applied and the control strategy involved and cannot be generalized to all types of WWTPs. With respect to N 2 O control strategies, only limited work 4 based on model simulations has been reported 13 . The numerous N 2 O models available are seldom calibrated or verified using highly dynamic full-scale data in the long term 11 , thus bringing high uncertainty to the validity of the model-based N 2 O control strategies.…”

Organic carbon recovery modeling for a rotating belt filter and its impact assessment on a plant-wide scale

“…bacteria (NOB) model and denitrifcation models are adopted from the literature [26,27,28] as implemented and evaluated by Boiocchi et al [35]. The details of the rate expressions for each pathway and the model parameters used for our study (plant-wide simulation) are provided in the SI (Table 3, 4, 5, 6) and the Boiocchi et al [35].…”