Industrial wastewater treatment with a bioelectrochemical process: assessment of depuration efficiency and energy production

Abstract Development of renewable energy sources, efficient industrial processes, energy/chemicals recovery from wastes are research issues that are quite contemporary. Bioelectrochemical processes represent an eco-innovative technology for energy and resources recovery from both domestic and industrial wastewaters. The current study was conducted to: (i) assess bioelectrochemical treatability of industrial (dairy) wastewater by microbial fuel cells (MFCs); (ii) determine the effects of the applied organic loading rate (OLR) on MFC performance; (iii) identify factors responsible for reactor energy recovery losses (i.e. overpotentials). For this purpose, an MFC was built and continuously operated for 72 days, during which the anodic chamber was fed with dairy wastewater and the cathodic chamber with an aerated mineral solution. The study demonstrated that industrial effluents from agrifood facilities can be treated by bioelectrochemical systems (BESs) with >85% (average) organic matter removal, recovering power at an observed maximum density of 27 W m−3. Outcomes were better than in previous (shorter) analogous experiences, and demonstrate that this type of process could be successfully used for dairy wastewater with several advantages

In situ groundwater remediation with bioelectrochemical systems: A critical review and future perspectives

Groundwater contamination is an ever-growing environmental issue that has attracted much and undiminished attention for the past half century. Groundwater contamination may originate from both anthropogenic (e.g., hydrocarbons) and natural compounds (e.g., nitrate and arsenic); to tackle the removal of these contaminants, different technologies have been developed and implemented. Recently, bioelectrochemical systems (BES) have emerged as a potential treatment for groundwater contamination, with reported in situ applications that showed promising results. Nitrate and hydrocarbons (toluene, phenanthrene, benzene, BTEX and light PAHs) have been successfully removed, due to the interaction of microbial metabolism with poised electrodes, in addition to physical migration due to the electric field generated in a BES. The selection of proper BESs relies on several factors and problems, such as the complexity of groundwater and subsoil environment, scale-up issues, and energy requirements that need to be accounted for. Modeling efforts could help predict case scenarios and select a proper design and approach, while BES-based biosensing could help monitoring remediation processes. In this review, we critically analyze in situ BES applications for groundwater remediation, focusing in particular on different proposed setups, and we identify and discuss the existing research gaps in the field. Keywords: Bioelectrochemical systems, In situ treatment, Groundwater remediation, Bioelectroremediation, Denitrification, Microbial electrochemical technologie

Sewage Sludge Biorefinery for Circular Economy

Sewage sludge processing and disposal have a significant weight on the energy and economic balances of wastewater treatment operations and contribute substantially to greenhouse gas emissions related to wastewater processing. Despite this, sewage sludge contains substantial recoverable resources in the form of energy and useful molecules. The current challenge, other than reducing the environmental and economic impacts of its disposal, is to recover energy and materials from this waste stream, implementing a biosolid-centered circular economy with the greatest possible added value. A number of options along these lines exist, and others are being investigated, ranging from biological processes, thermochemical technologies, bioelectrochemical processing, biorefineries and others. Recoverable resources comprise biogas from sludge fermentation, liquid and solid end products (e.g., biodiesel and biochar) and valuable nutrients (N and P). This paper presents a state of the art of biorefinery, with emphasis on recent developments in non-conventional resource recovery from EBSS streams for sludge-based circular economy implementation. Expectations and limitations, including technological readiness, of these technologies are discussed

An Integrated Mathematical Model of Microbial Fuel Cell Processes: Bioelectrochemical and Microbiologic Aspects

Microbial Fuel Cells (MFCs) represent a still relatively new technology for liquid organic waste treatment and simultaneous recovery of energy and resources. Although the technology is quite appealing due its potential benefits, its practical application is still hampered by several drawbacks, such as systems instability (especially when attempting to scale-up reactors from laboratory prototypes), internally competing microbial reactions, and limited power generation. This paper is an attempt to address some of the issues related to MFC application in wastewater treatment with a simulation model. Reactor configuration, operational schemes, electrochemical and microbiological characterization, optimization methods and modelling strategies were reviewed and have been included in a mathematical simulation model written with a multidisciplinary, multi-perspective approach, considering the possibility of feeding real substrates to an MFC system while dealing with a complex microbiological population. The conclusions drawn herein can be of practical interest for all MFC researchers dealing with domestic or industrial wastewater treatment

Sewage Sludge Biorefinery for Circular Economy

Sewage sludge processing and disposal have a significant weight on the energy and economic balances of wastewater treatment operations and contribute substantially to greenhouse gas emissions related to wastewater processing. Despite this, sewage sludge contains substantial recoverable resources in the form of energy and useful molecules. The current challenge, other than reducing the environmental and economic impacts of its disposal, is to recover energy and materials from this waste stream, implementing a biosolid-centered circular economy with the greatest possible added value. A number of options along these lines exist, and others are being investigated, ranging from biological processes, thermochemical technologies, bioelectrochemical processing, biorefineries and others. Recoverable resources comprise biogas from sludge fermentation, liquid and solid end products (e.g., biodiesel and biochar) and valuable nutrients (N and P). This paper presents a state of the art of biorefinery, with emphasis on recent developments in non-conventional resource recovery from EBSS streams for sludge-based circular economy implementation. Expectations and limitations, including technological readiness, of these technologies are discussed

Operation of a 2-Stage Bioelectrochemical System for Groundwater Denitrification

Nitrate groundwater contamination is an issue of global concern that has not been satisfactorily and efficiently addressed, yet. In this study, a 2-stage, sequential bioelectrochemical system (BES) was run to perform autotrophic denitrification of synthetic groundwater. The system was run at a 75.6 mgNO3−-N L−1NCC d−1 nitrate loading rate, achieving almost complete removal of nitrate (>93%) and Total Nitrogen (TN) (>93%). After treatment in the first stage reactor values of effluent nitrate compatible with the EU and USA limits for drinking water (<11.3 and 10 mgNO3−-N L−1, respectively) were achieved. Nitrite and nitrous oxide were observed in the first stage’s effluent, and were then successfully removed in the second stage. The observed nitrate removal rate was 73.4 ± 1.3 gNO3−-N m−3NCC d−1, while the total nitrogen removal rate was 73.1 ± 1.2 gN m−3NCC d−1. Specific energy consumptions of the system were 0.80 ± 0.00 kWh m−3, 18.80 ± 0.94 kWh kgNO3−-N−1 and 18.88 ± 0.95 kWh kgN−1. Combination of two denitrifying BES in series herein described proved to be effective