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The use of microfluidic electrochemical reactors has been introduced several decades ago, but their application in the field of wastewater treatment is more recent (2010). The parallel development of electrochemical advanced oxidation processes (EAOPs) as promising technologies for effluent treatment make them good candidates to be implemented as thin film cells. This allows favoring the mass transfer, which is particularly interesting for heterogenous electro‐oxidation. Moreover, the energy requirement is reduced, while there is possibility to treat low‐conductivity solutions. This review intends to provide instructions on the main operating parameters to be optimized during the EAOPs treatment. Directions on engineering aspects have been given to overcome the main drawbacks of microreactors, such as fouling, scaling, and low treatment capacity, based on recent encouraging results given in literature. The promising development of hybrid processes that combine electroseparation with electroconversion would also benefit from such reactor designs. [ABSTRACT FROM AUTHOR]

Extended statistical entropy analysis (eSEA) is used to assess the nitrogen (N) removal performance of the wastewater treatment (WWT) simulation software, the Benchmarking Simulation Model No. 2 (BSM No. 2 ). Six simulations with three different types of wastewater are carried out, which vary in the dissolved oxygen concentration (O2,diss.) during the aerobic treatment. N2O emissions generated during denitrification are included in the model. The N-removal performance is expressed as reduction in statistical entropy, ▵ H, compared to the hypothetical reference situation of direct discharge of the wastewater into the river. The parameters chemical and biological oxygen demand (COD, BOD) and suspended solids (SS) are analogously expressed in terms of reduction of COD, BOD, and SS, compared to a direct discharge of the wastewater to the river (▵ EQrest). The cleaning performance is expressed as ▵ EQnew, the weighted average of ▵ H and ▵ EQrest. The results show that ▵ EQnew is a more comprehensive indicator of the cleaning performance because, in contrast to the traditional effluent quality index (EQ), it considers the characteristics of the wastewater, includes all N-compounds and their distribution in the effluent, the off-gas, and the sludge. Furthermore, it is demonstrated that realistically expectable N2O emissions have only a moderate impact on ▵ EQnew [ABSTRACT FROM AUTHOR]

Classical culture media, as well as domestic and/or industrial wastewater treated by biological processes, have a complex composition. The on-line and/or in situ determination of some substances is possible, but expensive, as sample collection and pre-treatment are often necessary with strict rules of sterility. More global methods can be used to detect rapidly “accidents” such as the appearance of an undesirable by-product in a fermentation broth or of a toxic substance in wastewater. These methods combine a “hard” part, for sensing, and a “soft” part, for data treatment.Among potential “hard” candidates, spectroscopy can be the basis for non-invasive and non-destructive measuring systems. Some of them have been already tested in situ: ultra-violet–visible, infra-red (mid or near), fluorescence (mono-dimensional, two-dimensional or synchronous), dielectric, while others, more sophisticated, such as mass spectrometry, coupled or not to pyrolysis, nuclear magnetic resonance and Raman spectroscopy, have been proposed.All these methods provide spectra, i.e. large sets of data, from which meaningful information should be rapidly extracted, either for analysis or fingerprinting. The recourse to data-mining techniques (the “soft” part) such as principal components analysis, projection on latent structures or artificial neural networks, is a necessary step for that task.A review of techniques, mostly based on spectroscopy, with examples taken in the bioengineering field in general is proposed. [Copyright &y& Elsevier]

The robustness of the control strategies developed in the COST 624 benchmark has been tested against the sophistication of the model describing the hydraulic behaviour of the biological reactor of a wastewater treatment plant by activated sludge. In such a large biological reactor of the channel type, hydrodynamics are intermediate between plug flow and well mixed and are function of the liquid flow rate and the aeration intensity. It could be noted in the various tested scenarios that ammonia was the most affected pollution parameter for effluent quality control. However no large effect of the hydrodynamics could be observed, suggesting that the actual benchmark is indeed a good tool for a first assessment of the efficiency of control schemes. [Copyright &y& Elsevier]

The paper introduces the philosophy and current status of a benchmark for the evaluation of control strategies in wastewater treatment plants and also the forthcoming developments and future perspectives. The work has been carried out within the framework of two COST Actions (682 and 624) and in close collaboration with the IWA Task Group on Respirometry. The benchmark is a platform-independent simulation environment defining a plant layout, a simulation model, influent loads, test procedures and evaluation criteria. Several different research teams have contributed to the development of the benchmark and have obtained results using several simulation platforms (GPS-X™, MATLAB/SIMULINK™, SIMBA®, WEST®, FORTRAN code, etc.). A short introduction to the six scientific papers of this special section dealing with various aspects of the COST benchmark simulation model is also given. [Copyright &y& Elsevier]

• No compensation of anodic H + with cathodic OH− at 50 µm at sufficiently high current. • Short distance (50 µm) could lead to high degradation yield with higher current. • With 50 µm, it still required higher energy to reach similar degradation efficiency. • A distance of 500 µm led to higher degradation, lower scaling and chlorate formation. The influence of a range of inter-electrode distances from 50 µm to 1 mm has been investigated for the first time, in order to assess to possibility to maximize the degradation and mineralization efficiency, while minimizing the cathode scaling and the inorganic by-products formation. Tylosin has been selected as representative pharmaceutical pollutant in wastewater, while the influence of Ca2+, HCO 3 −/CO 3 2− and Cl− was carried out. Advanced electro-oxidation with boron-doped diamond (BDD) anode and stainless-steel cathode was implemented to treat this synthetic effluent in a scalable filter-press reactor operated in a recirculated batch flow-by mode. The first interesting feature is that cathodic OH− and anodic H+ formations were not counterbalanced at short micro-distances (50 µm), meaning that electro-precipitation (until 50 % of CaCO 3 precipitation) and degradation/mineralization (until 100 %) could still occur at such range of distance. Secondly, the gain of mass transfer at the shorter distance (50 µm) couldn't counteract the higher energy needed to achieve similar degradation efficiency compared to the distances of 500 µm and 1 mm. Lastly, too high distances such as 1 mm suffer from lower mass transfer compared to sub-millimetric distances. Thus, an intermediate distance of 500 µm led to better performance in terms of tylosin degradation (100 % of degradation, 39 % of mineralization), while minimizing electro-precipitation (26 % of CaCO 3 cathodic precipitation) and unwanted inorganic chlorinated by-products formation (ClO 3 − = 2.8 mg L−1). This was obtained at a current density of 0.1 mA cm−2, leading to lower energy requirement (0.018 kWh g-tylosin−1). In these low-current conditions the formation of perchlorate could be avoided. [ABSTRACT FROM AUTHOR]

The rare earth element (REE) contamination of urban wastewater, which was collected from open sewers and the inlet of a wastewater treatment plant in Cotonou (Benin), was assessed. The drinking water distributed to the inhabitants of Cotonou and water samples from private wells were also analyzed. The sampling occurred between October and December 2016 and the samples were analyzed by ICP-MS. Although the only magnetic resonance imaging facility in Cotonou opened in November 2016, pollution by anthropogenic gadolinium (Gd), which is included in phase contrast agents, was observed: there was 30–620 times more Gd in wastewater samples than in drinking and well water samples. Europium was another REE presenting positive anomalies. It is hypothetized than the europium came from the leachates of solid waste piles in the street. In the absence of any wastewater treatment, the REEs found in the wastewater are spread to the aquatic environment. It would be interesting to monitor the wastewater REEs over the long term. So far, the aquifers used for water provision have not been polluted by the anthropogenic REEs. Image 1 • Anthropogenic rare earth elements anomalies were found in Cotonou (Benin). • Even without magnetic resonance imaging gadolinium was found in wastewater. • Contamination by europium likely related to leachates from solid waste piles. [ABSTRACT FROM AUTHOR]

The fate of inorganic nitrogen species has been studied for the first time in electro-Fenton (EF) conditions in acid media. A redox cycle is first obtained and validated with a kinetic model in synthetic solution and highlights the removal of nitrite that is quickly oxidized into nitrate while the reduction conditions are sufficient to reduce nitrate into ammonium cation. However, NH 4 + and gaseous nitrogen accumulate in such solution. The study in reclaimed municipal wastewater emphasize the removal of NH 4 + with formation of chloramines in the presence of initial chloride ions, a species widely present in wastewater effluent. Contrastingly, NO 3 − remain constant all along the electrolysis even after 2.1 Ah L −1 . The oxidation conditions were not sufficient to produce perchlorate while chlorate accumulated in solution. Therefore, it limits the use of EF for direct use for drinking water purpose but could be considered as complementary treatment for wastewater reuse applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Anodic •OH role in cathodic electro-precipitation is investigated for the first time. • Anodic •OH reacts with CO 3 2– and decrease cathodic CaCO 3 electroprecipitation yield. • A new model is proposed to predict evolution of cathodic CaCO 3 electroprecipitation. Electrochemical systems are attracting increasing interest in environmental protection as relatively sustainable processes, particularly in wastewater treatment and reuse. However, cathode scaling in electrochemical processes for wastewater treatment is a major issue that is often overlooked. It is proposed for the first time to investigate the anodic contribution towards CaCO 3 electroprecipitation phenomena under the advanced electrooxidation conditions applied to remove organic biorecalcitrant pollutants. The contribution of the reaction of the hydroxyl radical (•OH) with carbonates, which reduces cathodic scaling at a micrometric interelectrode distance (500 µm) and at a high current density (16 mA cm−2), is described in detail. In addition, the anti-scaling effect of local anodic acidification should be considered. A new kinetic model of electroprecipitation fits the experimental curves well (root mean square error (RMSE) < 0.19 for Ca2+) and confirms this anodic role, combined with the gas hindrance and scale detachment induced by gas bubble electrogeneration at sufficiently high current intensities. [ABSTRACT FROM AUTHOR]

Being an internationally accepted standard for the activated sludge modeling, the Activated Sludge Model No.1 (ASM1) was used to simulate the treatment of paper mills effluent in an industrial full-scale sequencing batch reactor (SBR). Key characteristic parameters were estimated and corrected with the wastewater temperature: maximum heterotrophic growth rate μ H (9.69/day), heterotrophic yield Y H (0.625 g cell COD/g COD oxidized) and heterotrophic decay rate b H (1.98/day). The wastewater chemical oxygen demand (COD) was fractionated as slowly biodegradable substrate X S (20%), particulate inert organic matter X I (58%), readily biodegradable substrate S S (18%) and soluble inert organic matter S I (4%). Finally, the SBR operation was simulated with field data from the paper mill. The average relative error of the simulated effluent COD was 12.7%. The results showed that the ASM1 could be reasonably used in the papermaking wastewater treatment simulation. [ABSTRACT FROM AUTHOR]

Abstract: The tertiary treatment of paper mill wastewaters was investigated by testing the effect of batch electrocoagulation for 90min with two parallel iron or aluminum plates at two values of the current density (100 and 150A/m2). Dissolved organic carbon removal ranged between 24% and 46%, and chemical oxygen demand removal ranged between 32% and 68%. UV–visible spectroscopy showed a reduction of the aromaticity of the treated effluent. The process was also very efficient for the removal of lignin-based pollution, characterized by the fluorescence of humic substances. Arsenic was selected as an example of a non-organic micropollutant and was also satisfactorily removed (from 4 to 0.5μg/L). The settling characteristics of the sludge obtained after the electrocoagulation treatment were also evaluated. The sludge aptitude to settling is better with Fe electrodes than with Al electrodes. The experimental results obtained in the present study indicate that electrocoagulation treatment can be very effective and was capable of improving the paper mill wastewaters’ quality downstream of the biological treatment. [Copyright &y& Elsevier]

The solid waste of olive oil extraction processes (olive pomace, OP) was converted into activated carbon (AC) by treating it with NaOH and then encapsulating it within sodium alginate (SA) in beads by crosslinking (SA-AC beads). The prepared SA-AC beads were utilized as an adsorbent for the elimination and recovery of phenolic compounds (PCs) from olive mill wastewater (OMWW) following a zero liquid and waste discharge approach to implement and promote the circular economy concept. The novel AC and SA-AC beads were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and Brunauer, Emmett and Teller (BET) analysis. The adsorption performance of these beads was evaluated in batch and fixed-bed reactors operated in a concurrent flow system. The results revealed that an adsorption capacity of 68 mg g−1 was attained for 4000 mg L−1 phenolic compounds. The kinetics of the adsorption process of the PCs fit a pseudo second-order model, and the most likely mechanism took place in two stages. The adsorption isotherm conformed to the Langmuir model, representing the monolayer adsorption of the phenolic compounds. The dynamic models were used, and they accurately represented the breakthrough curves. Considering PC recovery and process reusability, a regeneration experiment of SA-AC beads was carried out in fixed-bed reactors. SA-AC beads showed a high percentage desorption >40% using ethanol and were efficient after several cycles of OMWW treatment and phenol recovery. [Display omitted] • Porous beads based on activated carbon from olive pomace was prepared. • The removal efficiency of phenolic compounds using beads improved significantly. • The adsorption kinetics, isotherms and thermodynamic were studied. • Breakthrough curves from fixed-bed adsorption columns were evaluated and modeled. • 40% recovery of phenolic compounds using ethanol was achieved. [ABSTRACT FROM AUTHOR]