Energy Consumption for Nutrient Removal from High-Nitrate and High-Phosphorus Wastewater in Aerobic and Anaerobic Bioelectrochemical Reactors

Abstract

An attempt was undertaken to determine indicators of energy consumption in bio-electro reactors (BERs) i.e., an aerobic rotating electrobiological disc contactor (REBDC) and an anaerobic sequencing batch biofilm reactor (SBBR), during contaminant removal from soilless tomato cultivation wastewater having a specific composition, i.e., high nitrate and phosphorus concentrations and low COD. Because of this specificity, the energy consumption during the treatment process was characterized by a cumulative indicator for simultaneous removal of phosphorus and nitrates—EEINUTRIENTSrem (electric energy consumption per unit of removed nutrient load, expressed as kWh/kgNUTRIENTSrem). Four values of direct current density were tested: 0.63, 1.25, 2.5, and 5.0 A/m2. The indicator values were compared at a hydraulic retention time (HRT) of 24 h. The study demonstrated that the values of electric energy consumption per unit of removed nutrient load determined in the anaerobic SBBR ranged from 30 to 464 kWh/kg NUTRIENTSrem and were lower than the values obtained in the aerobic REBCD, i.e., 80–1380 kWh/kg NUTRIENTSrem.

Energy Production in Microbial Fuel Cells (MFCs) during the Biological Treatment of Wastewater from Soilless Plant Cultivation

“…The electrical energy generated in the form of a direct electric current could also be harnessed in DW electrocoagulation or in the bioelectrochemical treatment stage. The usefulness of both direct and alternating current in DW treatment has been confirmed in previous studies [32].…”

“…Electric current consumption using the Rotating Electrobiological Disk Contactor ranged from 118 to 2170 kWh/kgN (removed nitrogen) and from 104 to 9456 kWh/kgP (removed phosphorus) depending on the electrical current density (from 0.62 to 10.0 A/m 2 ) and the wastewater hydraulic retention time (from 4 to 24 h). In the case of another solution, namely Sequencing Batch Biofilm Reactor, the energy consumption ranged from 49 to 144.5 kWh/kgN (removed nitrogen) and from 82 to 787 kWh/kgP (removed phosphorus) depending on the electric current density used (0.62-5.0 A/m 2 ) at HRT 1d [32]. At the same time, DW is effectively pre-treated upon the precipitation of mainly phosphorus with calcium and magnesium ions already at pH > 7.5 [33].…”

Anammox with alternative electron acceptors: perspectives for nitrogen removal from wastewaters

“…The numbers indicate that up to 50% of the total energy supplied in a conventional WWTPs is used to satisfy the aeration demand for carbon and nitrogen oxidation processes (Gude et al 2015 ; Ghimire and Gude 2019 ). Another study suggests that the contribution of biotreatment processes to total electric power consumption may reach up to 80% (Rodziewicz et al 2022 ). In fact, it is expected that its consumption will be higher in the future due to the increase in pollutant load and stringent environmental regulations (Wang et al 2019 ).…”

“…Likewise, the external carbon sources for the denitrification process can lead to operating costs of up to € 3.64/kg N removed (Arias et al 2018 ). In a typical WWTP with nitrification-denitrification, the energy consumption can reach 14.6 kWh/kg N removed (Panepinto et al 2016 ; Wang et al 2019 ; Rodziewicz et al 2022 ). In a simulation model, energy consumption during N removal can reach 52 kWh/kg N removed using indicators for loads of total nitrogen removed from dairy wastewater in biological processes (Żyłka et al 2021 ).…”

The Influence of the Duration of Exposure to Direct Current on the Treatment Efficiency of Wastewater from Soilless Tomato Cultivation in a Bio-Electrochemical Reactor

“…The course and efficiency of many of them depends on the presence of intermediate or final products of processes which commenced at the beginning of the cycle. Most of these processes are affected by the current flow between the electrodes [23]. The literature presents data on the operation of bio-electrochemical reactors, in which the current is supplied during the entire cycle [9,[12][13][14][15][16][17].…”