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• Pilot-scale MEC yielding 19.07 ± 0.46 L H 2 m−2 d−1 with industrial wastewater. • Up to 3.0-fold increase in hydrogen production using Ni-foam cathodes. • Energy efficiency of the process up to 133 % using Ni-foam cathodes. • Cathode configuration significantly affected the anodic microbial communities. Microbial electrolysis cells (MECs) have garnered significant attention as a promising solution for industrial wastewater treatment, enabling the simultaneous degradation of organic compounds and biohydrogen production. Developing efficient and cost-effective cathodes to drive the hydrogen evolution reaction is central to the success of MECs as a sustainable technology. While numerous lab-scale experiments have been conducted to investigate different cathode materials, the transition to pilot-scale applications remains limited, leaving the actual performance of these scaled-up cathodes largely unknown. In this study, nickel-foam and stainless-steel wool cathodes were employed as catalysts to critically assess hydrogen production in a 150 L MEC pilot plant treating sugar-based industrial wastewater. Continuous hydrogen production was achieved in the reactor for more than 80 days, with a maximum COD removal efficiency of 40 %. Nickel-foam cathodes significantly enhanced hydrogen production and energy efficiency at non-limiting substrate concentration, yielding the maximum hydrogen production ever reported at pilot-scale (19.07 ± 0.46 L H 2 m−2 d−1 and 0.21 ± 0.01 m3 m−3 d−1). This is a 3.0-fold improve in hydrogen production compared to the previous stainless-steel wool cathode. On the other hand, the higher price of Ni-foam compared to stainless-steel should also be considered, which may constrain its use in real applications. By carefully analysing the energy balance of the system, this study demonstrates that MECs have the potential to be net energy producers, in addition to effectively oxidize organic matter in wastewater. While higher applied potentials led to increased energy requirements, they also resulted in enhanced hydrogen production. For our system, a conservative applied potential range from 0.9 to 1.0 V was found to be optimal. Finally, the microbial community established on the anode was found to be a syntrophic consortium of exoelectrogenic and fermentative bacteria, predominantly Geobacter and Bacteroides , which appeared to be well-suited to transform complex organic matter into hydrogen. [Display omitted] [ABSTRACT FROM AUTHOR]

The boring giant clam Tridacna crocea is an evolutionary, ecologically, economically, and culturally important reef-dwelling bivalve targeted by a profitable ornamental fishery in the Indo-Pacific Ocean. In this study, we developed genomic resources for T. crocea. Using low-pass (=low-coverage, ~6×) short read sequencing, this study, for the first time, estimated the genome size, unique genome content, and nuclear repetitive elements, including the 45S rRNA DNA operon, in T. crocea. Furthermore, we tested if the mitochondrial genome can be assembled from RNA sequencing data. The haploid genome size estimated using a k-mer strategy was 1.31–1.39 Gbp, which is well within the range reported before for other members of the family Cardiidae. Unique genome content estimates using different k-mers indicated that nearly a third and probably at least 50% of the genome of T. crocea was composed of repetitive elements. A large portion of repetitive sequences could not be assigned to known repeat element families. Taking into consideration only annotated repetitive elements, the most common were classified as Satellite DNA which were more common than Class I-LINE and Class I-LTR Ty3-gypsy retrotransposon elements. The nuclear ribosomal operon in T. crocea was partially assembled into two contigs, one encoding the complete ssrDNA and 5.8S rDNA unit and a second comprising a partial lsrDNA. A nearly complete mitochondrial genome (92%) was assembled from RNA-seq. These newly developed genomic resources are highly relevant for improving our understanding of the biology of T. crocea and for the development of conservation plans and the fisheries management of this iconic reef-dwelling invertebrate. [ABSTRACT FROM AUTHOR]

[Display omitted] • Microbial electrolysis cell (MEC) hydrogen production at pilot scale (135L). • Continuous hydrogen production for 6 months with urban and synthetic wastewater. • High COD removal efficiency (>70%) under different operational conditions. • Hydrogen production up to 0.1 m3·m−3·d−1 by modifying operational parameters. • Potential energy-recovery alternative compared to activated sludge. Bioelectrochemical systems (BES) are becoming popular technologies with a plethora of applications in the environmental field. However, research on the scale-up of these systems is scarce. To understand the limiting factors of hydrogen production in microbial electrolysis cell (MEC) at pilot-scale, a 135 L MEC was operated for six months under a wide range of operational conditions: applied potential [0.8–1.1 V], hydraulic residence time [1.1–3.9 d], and temperature [18–30 °C], using three types of wastewater; synthetic (900 mg CODs L−1), raw urban wastewater (200 mg CODs L−1) and urban wastewater amended with acetate (1000 mg CODs L−1). The synthetic wastewater yielded the maximum current density (1.23 A m−2) and hydrogen production (0.1 m3 m−3 d−1) ever reported in a pilot scale MEC, with a cathodic recovery of 70% and a coulombic efficiency of 27%. In contrast, the use of low COD urban wastewater limited the plant performance. Interestingly, it was possible to improve hydrogen production by reducing the hydraulic residence time, finding the optimal applied potential or increasing the temperature. Further, the pilot plant demonstrated a robust capacity to remove the organic matter present in the wastewater under different conditions, with removal efficiencies above 70%. This study shows improved results compared to similar MEC pilot plants treating domestic wastewater in terms of hydrogen production and treatment efficiency and also compares its performance against conventional activated sludge processes. [ABSTRACT FROM AUTHOR]

Abstract Sulfur oxide emissions can lead to acidic precipitation and health concerns. Flue gas desulfurization (FGD) systems treat these emissions generating a wastewater with high-sulfate content. This work is the first attempt to treat this effluent with bioelectrochemical systems (BES) in order to recover elemental sulfur, a technology that allows the treatment of several wastewaters that lack of electron donor. The sulfate treatment and elemental sulfur recovery have been studied in a biocathode with simultaneous sulfate reduction to sulfide and partial sulfide oxidation, comparing the performance obtained with synthetic and real wastewater. A decrease of the sulfate removal rate (SRR) from 108 to 73 mg S-SO 4 2− L−1 d−1 was observed coupled to an increase in the elemental sulfur recovery from 1.4 to 27 mg S-S0 L−1 d−1. This elemental sulfur recovered as a solid from the real wastewater represented a 64% of the theoretical elemental sulfur produced (the elemental sulfur corresponded to a 72% of the solid weight). In addition, microbial communities analysis of the membrane and cathode biofilms and planktonic biomass showed that the real wastewater allowed a higher growth of sulfur oxidizing bacteria (SOB) adapted to more complex waters as Halothiobacillus sp. while decreasing the relative abundance of sulfate reducing bacteria (SRB). Graphical abstract Unlabelled Image Highlights • Treatment of sulfate from real flue gas desulfurization wastewater in a biocathode • Slight decrease of sulfate removal rate from synthetic to real wastewater • 64% of sulfate removed was recovered as elemental sulfur with a purity of 71.8%. • Simultaneous growth of SRB and SOB allows high elemental sulfur production from sulfate. [ABSTRACT FROM AUTHOR]

Basturk et al. (2021) focus on the treatment of medical laboratory wastewater by the advanced oxidation process of electro-Fenton. Finally, Azimi et al. (2021) propose a method for the treatment of wood industry wastewater that combines coagulation, flocculation, decantantion, and Fenton process. The Editor's Choice paper is the review article by Adeola and Forbes (2021) describing available treatment technologies for the removal of polycyclic aromatic hydrocarbons (PAH). [Extracted from the article]

Marine organisms with a pelagic stage are often assumed to display minor population structure given their extended larval development and subsequent high long-distance dispersal ability. Nonetheless, considerable population structure might still occur in species with high dispersal ability due to current oceanographic and/or historical processes. Specifically, for the wider Caribbean and Gulf of Mexico, theoretical and empirical considerations suggest that populations inhabiting each of the following areas should be genetically distinct: Panama, Belize, Southwest Florida (Tampa), and Southeast Florida (Fort Pierce). This study tests the hypothesis of significant genetic differentiation in Palaemon floridanus populations across the wider Caribbean and Gulf of Mexico. Population level comparisons were conducted using sequences of the mt DNA COI. In agreement with predictions, AMOVA and pairwise FST values demonstrated population differentiation among most pairs of the studied populations. Only Panama and East Florida populations were genetically similar. An isolation-with-migration population divergence model (implemented in IMA2) indicated that population divergence with incomplete lineage sorting can be invoked as the single mechanism explaining genetic dissimilarity between populations from the east and west coast of Florida. Historical demographic analyses indicated demographic expansion of P. floridanus in some localities [recent in Panama and ancient in East Florida and the wider Caribbean (entire dataset)] but constant population in other localities (in Belize and West Florida). This study rejects the idea of panmixia in marine species with high long-distance dispersal ability. Contemporary and historical processes might interact in a complex manner to determine current phylogeographic patterns. [ABSTRACT FROM AUTHOR]

Highlights: [•] Development of new control strategies for enhancing P-removal in WWTP. [•] Performance comparison of optimized open loop operation to the new control structures. [•] Control loops based on COD addition to the anaerobic reactor allow stable EBPR. [•] Optimized controllers allowed lower effluent pollutants and minimal operational costs. [Copyright &y& Elsevier]

Achievement of partial nitrification relies on the different characteristics of the microorganisms involved in the two steps of nitrification (AOB, ammonium oxidizing bacteria and NOB, nitrite oxidizing bacteria). Several configurations and conditions have been used to achieve partial nitrification taking into account their different responses in front of some environmental conditions like pH, temperature (T), dissolved oxygen (DO) and the inhibitory compounds free ammonia (FA) and free nitrous acid (FNA). This work is a theoretical study about the utilization of a control strategy based on controlling OUR by manipulating the influent flow-rate together with additional changes in T, pH or DO for achieving stable partial nitrification. Two different configurations were simulated. Configuration A consisted of three continuous stirred-tank reactors in series plus a settler, while configuration B consisted of a single reactor with the same total volume and a settler. The developed control system was shown as a good tool to achieve partial nitrification with both configurations. Nevertheless, configuration A showed better results and partial nitrification was obtained even under theoretically unfavourable conditions as T = 15°C, pH = 8.3 and DO = 3mgO2 L-1. [ABSTRACT FROM AUTHOR]

Caridean shrimps display a wide variety of sexual systems, including the newly discovered protandric simultaneous hermaphroditism. Protandric simultaneous hermaphroditism is known only from seven species of Lysmata, and it is not clear if this condition is fixed within the genus or if Lysmata includes species that are simply protandric or gonochoric (with separate sexes). This study uses anatomical data, aquarium experiments, and field observations to demonstrate that Lysmata nayaritensis is another protandric simultaneous hermaphrodite. It is shown that, despite occurring in the tropics, this species fits into the "crowd" species category, with high densities in the field and that the field sex ratio is highly male-biased. Information on the sex allocation and sexual system of more species needs to be examined before these observations can be put into a comparative context within the genus. [ABSTRACT FROM AUTHOR]

Abstract: The modelling of the nitrification process of high-strength ammonium wastewater must be designed to consider it as a two-step reaction with substrate inhibition. Consequently, kinetic and stoichiometric parameters of both steps are required. In this work, the second step in the nitrification process was studied: a biological nitrite oxidation model was formulated, calibrated and validated using only oxygen uptake rate (OUR) measurements. The model included biomass growth and substrate inhibition. First, the biomass yield coefficient for nitrite-oxidising biomass was determined. Then, a respirometric experiment with one nitrite pulse of 500mgN–NO2 − L−1 was performed to estimate the rest of the model parameters. The practical identifiability study showed that the parameters were strongly correlated. Hence, a new experimental design consisting of two consecutive pulses and a delayed third one was designed to improve the parameter identifiability. Both experimental designs were compared using contour plots of the objective function and optimal experimental design criteria for parameter estimation. It was concluded that the parameter identifiability was improved with the new experimental design. Finally, the estimated parameters were validated and the pH effect on the inhibition coefficient was evaluated. [Copyright &y& Elsevier]

Bioelectrochemical systems provide a promising tool for the treatment of acid mine drainage (AMD). Biological sulphate reduction powered with electrical energy consumes acidity and produces sulphide, which can precipitate metals. However, the produced sulphide and the changes in pH resulting from the biological processes affect the efficiency and the environmental impacts of this treatment significantly. In this work, the effects of pH and sulphur speciation on the sulphate reduction rate (SRR) and comprehensive AMD treatment were evaluated in two-chamber microbial electrolysis cells at a cathode potential of −0.8 V vs. NHE. The increase of initial sulphate concentration from below 1000 mg to above 1500 mg S-SO 4 2–/L increased SRR from 121 ± 25 to 177 ± 19 mg S-SO 4 2–/L/d. SRR further increased to 347 mg S-SO 4 2–/L/d when the operation mode was changed from batch to periodical addition of sulphate and acidity (363 mg S-SO 4 2–/L/d and 22.6 mmol H+/L/d, respectively). The average SRR remained above 150 mg S-SO 4 2–/L/d even at pH above 8.5 and with the total dissolved sulphide concentration increasing above 1300 mg S-TDSu/L. Operation at pH above 8 enabled the recovery of over 90% of the sulphur as dissolved sulphide and thus assisted in minimising the formation and release of toxic H 2 S. ga1 • Sulphate and sulphide concentrations and pH influence sulphate reduction rate (SRR). • Periodical sulphate and acidity addition increased SRR above 300 mg S-SO 4 2–/L/d. • Operation at pH above 8 helped to minimise the emissions of toxic H 2 S. • Desulfomicrobium norvegicum -dominated biofilm tolerated >2 g S-TDSu/L and pH > 8.5. [ABSTRACT FROM AUTHOR]

[Display omitted] • Effective ammonium recovery in continuously-fed MECs from N-rich waste streams. • Achieved high 33 g N /m 2 /d recovery with low 4.5 kWh/kg N energy consumption. • Current density limits higher ammonium recovery. • Biofilm bacteria's metabolism is notably affected by 2.5 gN-NH 4 +/L ammonium. Microbial electrolysis cells (MEC) have been identified as an energy efficient system for ammonium recovery from wastewater. However, high ammonium concentrations at the anode can have inhibitory effects. This work aims to determine the effects on current generation performance and active ammonia nitrogen recovery in wastewater containing 0.5 to 2.5 g N-NH 4 +/L. The study also evaluates the effect of two cathode materials, stainless steel (SS-MEC) and nickel foam (NF-MEC). When the concentration of ammonium in the feed was increased from 0.5 to 1.5 g N-NH 4 +/L the maximum current density increased from 3.2 to 3.9 A/m2, but a further increase to 2.5 g N-NH 4 +/L inhibited the biofilm activity, decreasing the current density to 0.5 A/m2. The maximum ammonium removal and recovery efficiencies were 71 % and 33 % at 0.5 g N-NH 4 +/L. The SS-MEC exhibited more energy efficient ammonium recovery compared to the NF-MEC, requiring 3.6 kWh/kg N,recovered at 0.5 gN-NH 4 +/L. The highest ammonium recovery rate of 33 g N /m2/d (1.5 gN-NH 4 +/L) was obtained with an energy consumption of 4.5 kWh/kg N,recovered. Conversely, a lower recovery rate (10 g N /m 2 /d for 2.5 gN-NH 4 +/L) resulted in reduced energy consumption at 2.1 kWh/kg N,recovered. This highlights the inherent trade-off between energy consumption and efficient ammonium recovery in the process. [ABSTRACT FROM AUTHOR]

Nemertean worms belonging to the genus Carcinonemertes have been tied to the collapse of crab fisheries in the northeastern Pacific Ocean. A new species is described from egg masses of two commercial crabs, Cancer porteri and Romaleon setosum, inhabiting the central-north Chilean coast. This is the first species of Carcinonemertes described from the southeastern Pacific Ocean. Total body length of Carcinonemertes camanchaco sp. nov. ranged from 2.38 to 4.93 and from 4.29 to 8.92 mm, in males and females, respectively. Among others, traits that distinguish this new species from other previously described congeneric species include: presence of two gonad rows on each side of the intestine, a simple (not decorated) mucus sheath, and a relatively wide stylet basis. Maximum likelihood and Bayesian inference phylogenetic analyses distinguished this new species from all other species of Carcinonemertes with available cox1 sequences in GenBank. Prevalence and mean (± SD) intensity of C. camanchaco sp. nov. was 24% and 2.6 (± 2.07) worms per egg mass in C. porteri and 38.1% and 3.8 (± 2.4) worms per egg mass in R. setosum. The formal description of this new species represents the first step towards the understanding of this worm's impact on the health of crab fisheries in the southeastern Pacific Ocean. [ABSTRACT FROM AUTHOR]

Background: Stomatopod crustaceans are aggressive marine predators featuring complex compound eyes and powerful raptorial appendages used for "smashing" or "spearing" prey and/or competitors. Among them, parasquilloids (superfamily Parasquilloidea) possess eyes with 2-3 midband rows of hexagonal ommatidia and spearing appendages. Here, we assembled and analyzed the complete mitochondrial genome of the parasquilloid Faughnia haani and explored family- and superfamily-level phylogenetic relationships within the Stomatopoda based on mitochondrial protein coding genes (PCGs). Results: The mitochondrial genome of F. haani is 16,089 bp in length and encodes 13 protein coding genes (PCGs), 22 transfer RNA genes, 2 ribosomal RNA genes, and a control region that is relatively well organized, containing 2 GA-blocks, 4 poly-T stretches, various [TA(A)]n-blocks, and 2 hairpin structures. This organized control region is likely a synapomorphic characteristic in the Stomatopoda. Comparison of the control region among superfamilies shows that parasquilloid species are more similar to gonodactyloids than to squilloids and lysiosquilloids given the presence of various poly-T stretches between the hairpin structures and [TA(A)]n-blocks. Synteny is identical to that reported for other stomatopods and corresponds to the Pancrustacea ground pattern. A maximum-likelihood phylogenetic tree based on PCGs revealed that Parasquilloidea is sister to Lysiosquilloidea and Gonodactyloidea and not to Squilloidea, contradicting previous phylogenetic studies. Conclusions: The novel phylogenetic position of Parasquilloidea revealed by our study indicates that 'spearing' raptorial appendages are plesiomorphic and that the 'smashing' type is either derived (as reported in previous studies) or apomorphic. Our results raise the possibility that the spearing raptorial claw may have independently evolved twice. The superfamily Parasquilloidea exhibits a closer relationship with other stomatopod superfamilies with a different raptorial claw type and with dissimilar numbers of midband rows of hexagonal ommatidia. Additional studies focusing on the assembly of mitochondrial genomes from species belonging to different genera, families, and superfamilies within the order Stomatopoda are warranted to reach a robust conclusion regarding the evolutionary history of this iconic clade based on mitochondrial PCGs. [ABSTRACT FROM AUTHOR]

A systematic comparison framework for selecting the best retrofitting alternative for a water resource recovery facility (WRRF) is proposed in this work. The procedure is applied comparing different possible plant configurations to retrofit an existent anoxic/oxic (A/O) WRRF (Manresa, Spain) aiming to include enhanced biological phosphorus removal (EBPR). The framework for comparison was built on system analysis using a calibrated IWA ASM2d model. A multicriteria set of performance variables, as the operational and capital expenditures (OPEX and CAPEX, respectively) and robustness tests for measuring how fast the plant configuration refuses external disturbances (like ammonium and phosphate peak loads), were used for comparison. Starting from the existent WRRF, four plant configurations were tested: single A2/O (only one anoxic reactor converted to anaerobic), double A2/O (two anoxic reactors converted to anaerobic), BARDENPHO, and UCT. The double A2/O plant configuration was the most economical and reliable alternative for improving the existent Manresa WRRF capacity and implementing EBPR, since the effluent quality increased 3.8% compared to the current plant configuration. In addition, the double A2/O CAPEX was close to €165,000 which was at the same order of the single A2/O and lower than the BARDENPHO and UCT alternatives. Practitioner points: Four configurations including EBPR were evaluated for retrofitting an A/O WRRF.A new multicriteria comparison framework was used to select the best configuration.Up to 13 criteria related to effluent quality, robustness and costs were included.A single function based on the combination of all the criteria was also evaluated. [ABSTRACT FROM AUTHOR]

Several industrial activities produce wastewater with high sulfate content that can cause significant environmental issues. Although bioelectrochemical systems (BESs) have recently been studied for the treatment of sulfate contained in this wastewater, the recovery of elemental sulfur with BESs is still in its beginnings. This work proposes a new reactor configuration named BES-EC, consisting of the coupling of a BES with an electrochemical cell (EC), to treat this type of wastewater and recover elemental sulfur. The reactor consisted of four electrodes: i) an abiotic anode, ii) a biocathode for the autotrophic sulfate reduction, iii) an anode of an electrochemical cell (EC) for the partial oxidation of sulfide to elemental sulfur (the biocathode and the EC anode were placed in the same chamber) and iv) an abiotic EC cathode. Several cathode potentials and sulfate loads were tested, obtaining high sulfate removal rates (up to 888 mg SO 4 2−-S L−1 d−1 at −0.9 V vs. SHE with a specific energy consumption of 9.18 ± 0.80 kWh kg−1 SO 4 2−-S). Exceptionally high theoretical elemental sulfur production rates (up to 498 mg S0-S L−1 d−1) were achieved with the EC controlled at a current density of 2.5 A m−2. Electron recovery around 80% was observed throughout most of the operation of the integrated system. In addition, short experiments were performed at different current densities, observing that sulfate removal did not increase proportionally to the higher applied current density. However, when the BES was controlled at 30 A m−2 and the EC at 7.5 A m−2, the proportion of elemental sulfur produced corresponded to 92.9 ± 1.9% of all sulfate removed. Unlabelled Image • Sulfate is treated in a novel bioelectrochemical integrated configuration. • High sulfate removal rates with a maximum up to 888 mg SO 4 2−-S L−1 d−1 is observed. • High sulfur production rate up to 498 mg S0-S L−1 d−1 has been obtained. • Electron recoveries around 80% were achieved with the integrated system. [ABSTRACT FROM AUTHOR]

Bioelectrochemical systems (BESs) are being studied as an alternative technology for the treatment of several kinds of wastewaters with a lack of electron donor such as high-strength sulfate wastewaters. This study evaluates different parameters that influence the simultaneous sulfate reduction and sulfide oxidation in an autotrophic biocathode: ion-exchange membrane (IEM), cathodic pH and cathode potential. Two different membranes were studied to evaluate sulfate and sulfide adsorption and diffusion from the cathode to the anode, observing that a cation-exchange membrane (CEM) widely decreased these effects. Three different cathode pH (5.5, 7 and 8.5) were studied in a long-term operation observing that pH = 7 was the optimal for sulfate removal, achieving reduction rates around 150 mg S-SO 4 2- L −1 d −1 . Microbial community analysis of the cathode biofilm demonstrated a high abundance of sulfate-reducing bacteria (SRB, 67% at pH 7, 60% at pH 8.5 and 42% at pH 5.5), mainly Desulfovibrio sp. at pH 5.5 and 7 and Desulfonatronum sp. at pH 8.5. The cathode potential also was studied from −0.7 to −1.2 V vs. SHE achieving sulfate removal rates higher than 700 mg S-SO 4 2- L −1 d −1 at cathode potentials from −1.0 to −1.2 V vs. SHE. Also, the highest cathodic recovery and the highest sulfur species imbalance were observed at a cathode potential of −1.0 V vs. SHE, which indicated a higher elemental sulfur production. [ABSTRACT FROM AUTHOR]

This work evaluates the performance and stability of a continuous anaerobic/aerobic A-stage system with integrated enhanced biological phosphorus removal (A-stage-EBPR) under different operational conditions. Dissolved oxygen (DO) in the aerobic reactor was tested in the 0.2–2 mgDO/L range using real wastewater amended with propionic acid, obtaining almost full simultaneous COD and P removal without nitrification in the range 0.5–1 mgDO/L, but failing at 0.2 mgDO/L. Anaerobic purge was tested to evaluate a possible mainstream P-recovery strategy, generating a P-enriched stream containing 22% of influent P. COD and N mass balances indicated that about 43% of the influent COD could be redirected to the anaerobic digestion for methane production and 66% of influent NH 4 +-N was discharged in the effluent for the following N-removal B-stage. Finally, when the system was switched to glutamate as sole carbon source, successful EBPR activity and COD removal were maintained for two months, but after this period settleability problems appeared with biomass loss. Microbial community analysis indicated that Propionivibrio , Thiothrix and Lewinella were the most abundant species when propionic acid was the carbon source and Propionivibrio was the most favoured with glutamate. Thiothrix, Hydrogenophaga, Dechloromonas and Desulfobacter appeared as the dominant polyphosphate-accumulating organisms (PAOs) under different operation stages. [Display omitted] • Long-term maintenance of an A-stage-EBPR under selected operational conditions. • The system operated good at range 0.5–1 mg DO/L, but failed at 0.2 mg DO/L. • Anaerobic purge led to 43% of the influent COD being sent to anaerobic digestion. • Glutamate as carbon source was only feasible for 60 days due to settleability issues. • Propionivibrio was the most abundant species during the whole operational process. [ABSTRACT FROM AUTHOR]

The two-stage A/B WWTP configuration is being studied as a possible wastewater treatment with low energy consumption or even with a net energy generation. The first phase, A-stage, is designed to remove organic matter at very short Sludge Retention Time (SRT), while the B-stage is based on autotrophic nitrogen removal. However, P-removal in the A/B process usually only relies on precipitation. This work studies the potential inclusion of Enhanced Biological Phosphorus Removal (EBPR) in the A-stage phase. For this aim, the long-term operation of three different Sequencing Batch Reactors (SBR) enriched in Accumulibacter at low SRT was thoroughly monitored for more than three months each one. This work shows that EBPR can be sustained with a minimal SRT of 3.6 d at 25 °C. Lower values, SRT = 3 d, led to the PAO washout because of a reduction in P-release and P-uptake, an increase of the VSS/TSS ratio and a decrease of the P/C ratio. The Y obs could be related to the SRT with the parameters Y = 0.39 ± 0.05 gCOD X ·g −1 COD S and k D = 0.06 ± 0.04 d −1 which leads to a 24% increase of biomass yield when SRT was reduced from 10 to 4 d. [ABSTRACT FROM AUTHOR]

A fuel cell sensor was demonstrated as a low cost on-line monitoring tool for hydrogen producing microbial electrolysis cells (MECs) at lab scale. Hydrogen produced in the MEC was oxidized at the anode of the fuel cell generating electricity that could be easily monitored. The total electrical current obtained was proved to correlate with the hydrogen supplied (r 2 0.99) and was equally efficient as other reference analytical methodologies based on gas chromatography. Signal was repetitive (2.3% variation coefficient, n = 12) and did not show interferences by the presence of other compounds like methane and carbon dioxide. The fuel cell was coupled to single and double chamber MECs validating its applicability as on-line monitoring portable device for quantifying hydrogen production. The use of the fuel cell as an on-line hydrogen sensor offers an alternative to more complex methodologies and offers the possibility to implement control systems and optimization strategies. [ABSTRACT FROM AUTHOR]

Treatment of high-strength sulfate wastewaters is becoming a research issue not only for its optimal management but also for the possibility of recovering elemental sulfur. Moreover, sulfate-rich wastewater production is expected to grow due to the increased SO 2 emission contained in flue gases which are treated by chemical absorption in water. Bioelectrochemical systems (BESs) are a promising alternative for sulfate reduction with a lack of electron donor, since hydrogen can be generated in situ from electricity. However, complete sulfate reduction leads to hydrogen sulfide as final sulfur compound. This work is the first to demonstrate that, in addition to an efficient sulfate-rich wastewater treatment, elemental sulfur could be recovered in a biocathode of a BES under oxygen limiting conditions. The key of the process is the biological oxidation of sulfide to elemental sulfur simultaneously to the sulfate reduction in the cathode using the oxygen produced in the anode that diffuses through the membrane. High sulfate reduction rates (up to 388 mg S-SO 4 2− L −1 d −1 ) were observed linked to a low production of sulfide. Accumulation of elemental sulfur over graphite fibers of the biocathode was demonstrated by energy dispersive spectrometry, discarding the presence of metal sulfides. Microbial community analysis of the cathode biofilm demonstrated the presence of sulfate-reducing bacteria (mainly Desulfovibrio sp.) and sulfide-oxidizing bacteria (mainly Sulfuricurvum sp.). Hence, this biocathode allows simultaneous biological sulfate reduction and biological sulfide oxidation to elemental sulfur, opening up a novel process for recovering sulfur from sulfate-rich wastewaters. [ABSTRACT FROM AUTHOR]

The development of the Smart-Plant Decision Support System (SP-DSS) is presented, which helps to find the optimal water resource recovery facility (WRRF) configuration for a specific case. A general plant superstructure is defined to allow the evaluation of different combinations among the available process unit options, considering technical, economic, and environmental impact criteria. The complete evaluation is based on a five-step framework: (i) design problem set-up, (ii) wastewater inflow generation, (iii) superstructure generation and plant-wide model simulation under dynamic conditions, (iv) estimation of multi-criteria objective values (greenhouse gas emissions, accumulation of effluent violations, effluent quality index, net present value, system readiness level and plant land area), and (v) design configuration multi-criteria sorting with the technique for order of preference by similarity to ideal solution (TOPSIS). SP-DSS application is shown comparing the mainstream shortcut enhanced phosphorus and polyhydroxyalkanoate (PHA) recovery (SCEPPHAR) technology with a conventional anaerobic/anoxic/aerobic (A2O) configuration for a medium size WWTP (Manresa, Spain). The comparison shows both configurations allow meeting discharge limits, and among other criteria, the SCEPPHAR novel configuration, with respect to A2O, shows higher pollutant contents in the effluent (3.30 vs 2.34 gPoll/m3), higher capital expenditures (CAPEX 0.191 vs 0.130 €/m3), lower operational expenditures (OPEX 0.397 vs 0.515 €/m3), lower required tariff (0.654 vs 0.674 €/m3) and higher greenhouse gas emissions (GHG 0.19 vs 0.14 kgCO 2 /m3). Overall, TOPSIS sorting indicates A2O is still the best configuration for this specific case. • Automatic comparison of water resource recovery facility (WRRF) configurations. • Smart plant decision support system (SP-DSS) eases technical and economic comparisons. • Process units and control systems can be described by static or dynamic models. • User can concentrate on scenario set-up and analysis of multicriteria results. • A case-study compares three possible configurations for a medium size WRRF. [ABSTRACT FROM AUTHOR]

The present work aims at understanding the performance of bioelectrochemical systems when subjected to different starvation periods, which is very relevant in view of their industrial application or use as biosensor. The results show that both microbial fuel cells (MFC) and microbial electrolysis cells (MEC) could resist starvation periods up to 10–11 days without any significant decrease in their performance when endogenous consumption was enabled by closing the circuit in MFC or applying an external voltage in MEC. By contrast, starvation periods longer than 5 days in both MFC and MEC when the flow of electrons from the anode to the cathode was not permitted thereby avoiding endogenous consumption, led to a reversible decrease in the cells performance. A longer starvation period of 21-days under open-circuit caused an irreversible performance loss of the MFC. [ABSTRACT FROM AUTHOR]

• Mainstream P-recovery can be successfully implemented in WWTPs with EBPR. • High extraction ratio increases P recovery but hinders PAO activity. • A P-recovery efficiency of 60% is the top long-term limit goal for these systems. • Mainstream P-recovery can help the treatment of low COD/P ratio influents. Phosphorus (P), an essential nutrient for all organisms, urgently needs to be recovered due to the increasing demand and scarcity of this natural resource. Recovering P from wastewater is a feasible and promising way widely studied nowadays due to the need to remove P in wastewater treatment plants (WWTPs). When enhanced biological P removal (EBPR) is implemented, an innovative option is to recover P from the supernatant streams obtained in the mainstream water line, and then combine it with liquor-crystallisation recovery processes, being the final recovered product struvite, vivianite or hydroxyapatite. The basic idea of these mainstream P-recovery strategies is to take advantage of the ability of polyphosphate accumulating organisms (PAO) to increase P concentration under anaerobic conditions when some carbon source is available. This work shows the mainstream P-recovery technologies reported so far, both in continuous and sequenced batch reactors (SBR) based configurations. The amount of extraction, as a key parameter to balance the recovery efficiency and the maintenance of the EBPR of the system, should be the first design criterion. The maximum value of P-recovery efficiency for long-term operation with an adequate extraction ratio would be around 60%. Other relevant factors (e.g. COD/P ratio of the influent, need for an additional carbon source) and operational parameters (e.g. aeration, SRT, HRT) are also reported and discussed. [ABSTRACT FROM AUTHOR]

Platinum is one of the most widely used catalysts in the cathode of Microbial Electrolysis Cells (MECs) to overcome the relatively slow kinetics of hydrogen evolution, even though it is not economically feasible on a large scale. This work aims at developing, applying, characterizing, and optimizing two novel Pt-functionalized inks with promising characteristics: Pt@rGO based on reduced graphene oxide and Pt@Graphitene based on a home-made material named Graphitene, which showed improved performance at a lower cost. The Pt-functionalized materials were deposited on carbon cloth and used as cathode electrode in a single chamber MEC. These materials provided 47% increase in Pt functionalization over commercial inks. Moreover, surface areas of 10.76 m2/g and 24.40 m2/g and electroactive areas of 0.10 cm2/cm2 and 0.16 cm2/cm2 were determined for Pt@Graphitene and Pt@rGO, respectively, a difference caused by structural defects in the case of the Pt@rGO, which slightly improved its performance compared to Pt@Graphitene. Thus, the experimental results reached ca. 0.8 mA/cm2, a 43% higher intensity than that obtained using conventional commercial inks. [Display omitted] • Reduced graphene oxide (Pt@rGO) and novel graphitene (Pt@Graphitene) were functionalized with Pt. • Pt-functionalized graphene-based materials tested as cathodes for MECs. • Higher surface (24.40 m2/g) and electroactive (1.14 cm2) area for Pt@rGO. • Both materials showed 47% more platinum functionalization than commercial inks. • Functionalized coating MECs had higher performance than those using commercial inks. [ABSTRACT FROM AUTHOR]

The modelling of the enhanced biological phosphorus removal (EBPR) process is a recent focus of interest. The pH profile is a promising output variable for EBPR modelling as it is very sensitive to the consumption or production of acid and base species (e.g. phosphate or VFA). pH-based EBPR modelling is based on the assumption that phosphorus is released and taken up as H2PO4 ¿, but this assumption has not been experimentally confirmed yet with enriched EBPR biomass. Therefore, the objective of this work was to assess the species in which P is released and taken up under different pH conditions. Several batch experiments were performed with an enriched culture of Accumulibacter (around 70±10% of total microorganisms). The total observed proton production, inorganic carbon, ammonium, phosphate and VFA were measured to evaluate the titrimetric contribution of anaerobic P-release and aerobic P-uptake over the total observed proton production. The results show that the only phosphorus form involved in P-release and P-uptake is equivalent in terms of proton production to H2PO4 ¿ in the pH range of 6.5¿8.5. Finally, proton production and pH in several SBR cycles were modelled and resulted in good agreement with the experimental profiles. [Copyright &y& Elsevier]

Abstract: Polyhydroxyalkanoate (PHA) is a biodegradable plastic synthesised by bacteria as energy and carbon storage material. PHA production is mostly based on pure cultures operated under sterile conditions, which increase the costs of this biopolymer. The use of inexpensive mixed culture biomass, such as activated sludge, to produce biodegradable plastics from renewable waste streams has been proposed as an alternative. The effect of carbon sources (acetate, propionate, butyrate and glucose) on the type and quantity of PHA synthesis obtained with different enhanced biological phosphorus removal (EBPR) microbial communities enriched with acetate and propionate are reported in this work. Two sequencing batch reactors (SBRs) were seeded with biomass withdrawn from a non-EBPR wastewater treatment plant (WWTP). The same operational conditions were kept, but using acetate or propionate as the sole carbon source of each reactor. These conditions produced two microbial communities with different P-removal capacity. The results presented in this study show the effect of the carbon source on the PHA composition (amount of polyhydroxybutyrate (PHB), polyhydroxyvalerate (PHV) and polyhydroxy-2-methylvalerate (PH2MV)), which differed not just between substrates but also between the two EBPR communities used. In addition, some monomers not always analysed contribute significantly to the total amount of PHA, especially when using butyrate, showing that if they are not considered this can lead to erroneous calculated yields. [Copyright &y& Elsevier]

Abstract: Recently, some research in the field of enhanced biological phosphorus removal (EBPR) has been focused on studying systems where the electron donor (substrate) and the electron acceptor (nitrate or oxygen) are present simultaneously. This can occur, for example, in a full scale wastewater treatment plant during heavy rainfall periods when the anaerobic hydraulic retention time is temporarily shortened. To study this situation that could induce EBPR failure, the operation of a sequencing batch reactor (SBR) working under alternating anaerobic–aerobic conditions with an enriched EBPR population (50% Candidatus Accumulibacter phosphatis and less than 1% Candidatus Competibacter phosphatis) was shifted to strict aerobic operation. Seven cycle studies were performed during the 11 days of aerobic operation. Net P-removal was observed in this aerobic SBR during the first 4 days of operation but the system could not achieve net-P removal after this period, although the microbial composition, in terms of percentage of Accumulibacter and Competibacter, did not change significantly. The observed changes in the different compounds analysed (phosphorus, acetate, glycogen and PHB) as well as in the OUR profile indicate that metabolic changes are produced for the adaptation of PAO to aerobic conditions. [Copyright &y& Elsevier]

The sea louse Caligus rogercresseyi is the most important pathogen causing "caligidosis" in the Chilean salmon industry. In this study, using cox1 gene, we evaluate the genetic variation of C. rogercresseyi from farmed Salmo salar along a latitudinal range (40°–52°S) in south Chile to determine whether morphological differences are explained by genetic or environmental factors. Female parasites were randomly collected from S. salar at five farms. Body variation was examined using multivariate analyses and genetic heterogeneity was explored with AMOVA. C. rogercresseyi exhibited significant morphometric variability among sites and parasites collected from >54°S were the longest ones. Parasites did not show genetic structure among farms. Thus, C. rogercresseyi infesting salmons is panmictic along an extensive latitudinal range in south Chile. The same genetic pattern can be explained by the frequent movement of parasitized S. salar among farms in that region. Phenotypic plasticity in parasites could be explained by natural or aquaculture‐mediated environment variability. C. rogercreseyi from 54°S could favor the local spread of this disease, suggesting an immediate health risk for the recent salmon industry in that region. Further research is required to confirm genetic homogeneity of this parasite along its geographical distribution using more powerful markers (e.g. SNPs). [ABSTRACT FROM AUTHOR]

• Enhanced Biological Phosphorus Removal (EBPR) at short sludge retention time (SRT) • A-Stage EBPR is achieved as a high-rate anaerobic/aerobic system at low SRT = 4d • No nitrification is observed operating at aerobic DO = 0.5 mg/L and SRT = 4d • 64% of entering COD is diverted to biomass for energy recovery • 69% of N in the influent remains as NH 4 + in the effluent for the B-stage treatment Recovering energy from wastewater in addition to its treatment is a hot trend in the new concept of water resource recovery facility (WRRF). High-rate systems operating at low solid retention time (SRT) have been proposed to meet this challenge. In this paper, the integration of Enhanced Biological Phosphorus Removal (EBPR) in an anaerobic/aerobic continuous high-rate system (A-stage EBPR) was evaluated. Successful P and COD removal were obtained operating at SRT 6, 5 and 4 days treating real wastewater, while a further decrease to 3 days led to biomass washout. The best steady state operational conditions were obtained at SRT = 4d, with high removal percentage of P (94.5%) and COD (96.3%), and without detecting nitrification. COD mineralization could be reduced to 30%, while 64 % of the entering carbon could be diverted as biomass to energy recovery. Regarding nitrogen, about 69±1% of the influent N was left as ammonium in the effluent, with 30% used for biomass growth. The aerobic reactor could be operated at low dissolved oxygen (DO) (0.5 mg/L), which is beneficial to decrease energy requirements. Biochemical methane potential (BMP) tests showed better productivity for the anaerobic sludge than the aerobic sludge, with an optimal BMP of 296±2 mL CH 4 /gVSS. FISH analysis at SRT = 4d revealed a high abundance of Accumulibacter (33±13%) and lower proportion of GAO: Competibacter (3.0±0.3%), Defluviicoccus I (0.6±0.1%) and Defluviicoccus II (4.3±1.1%). Image, graphical abstract [ABSTRACT FROM AUTHOR]

Robinione overstreeti is a bopyrid isopod endemic to the Gulf of Mexico that inhabits the branchial chamber of the ghost shrimp Callichirus islagrande. Information on this host–parasite association is scant. This study describes population and reproductive features of R. overstreeti and its host. A total of 90 (9.97%) out of 903 individuals of C. islagrande collected from Tamiahua lagoon, Veracruz, Mexico, between April 2012 and October 2013, were parasitized by R. overstreeti. Parasite prevalence in male and female ghost shrimps was similar. However, no parasitized ovigerous females of C. islagrande were recorded, suggesting that R. overstreeti is a parasitic castrator. Host and parasite body sizes were positively correlated suggesting early host infestation by parasites and simultaneous growth of the host and parasite. Parasitic isopods frequently inhabited the same branchial chamber (n = 77) of ghost shrimps as adult male-female pairs. Females were occasionally found with supernumerary juveniles and cryptoniscus larvae in the same host individual, and rarely solitarily. Furthermore, the body size of paired adult male and female parasites was tightly correlated suggesting long-term 'social' monogamy in R. overstreeti. Fecundity in R. overstreeti varied between 1668 and 9884 embryos female−1 and increased with female body size. [ABSTRACT FROM AUTHOR]

The design of new wastewater treatment plants with the aim of capturing organic matter for energy recovery is a current focus of research. Operating with low sludge residence time (SRT) appears to be a key factor in maximizing organic matter recovery. In these new configurations, it is assumed that phosphorus is chemically removed in a tertiary step, but the integration of enhanced biological phosphorus removal (EBPR) into these short-SRT systems seems to be an alternative worth studying. A key point of this integration is to prevent the washout of polyphosphate accumulating organisms (PAO) despite the low SRT applied. However, the minimum SRT required to avoid PAO washout depends on temperature, due to its effects on reaction kinetics, gas transfer rates, biomass growth and decay rates. This work includes a wide range of short and long-term experiments to understand these interactions and shows which combinations of SRT and temperature are detrimental to PAO growth. For example, an EBPR system operating at 20 °C and SRT = 5 d showed good performance, but EBPR activity was lost at 10 °C. EBPR operated at SRT = 10 d had 86% P removal at 20 °C but decreased to 71% at 15 °C and progressively lost its activity at lower temperature. The temperature coefficient obtained for PAO show a low degree of temperature dependence (θ = 1.047 ± 0.014), and should be considered when designing short-SRT systems with EBPR. Image 1 • Study of long-term and short-term effects of SRT and temperature on EBPR. • Operation is evaluated at different SRT (3.5–15) and T (10-20 °C). • EBPR rates have a medium dependence on T (θ = 1.047 ± 0.014). • Using correct T coefficients is essential for designing A-stage systems with EBPR. • A correlation SRT-T is reported to calculate the minimum SRT required for PAO. [ABSTRACT FROM AUTHOR]

The new paradigm in wastewater treatment aims at diverting as much organic matter as possible to anaerobic digestion to boost energy recovery (i.e. biogas production) and to decrease operational costs (i.e. aeration requirements and sludge generation). To achieve this, short sludge retention time (SRT) systems could be implemented in the first stage of the wastewater treatment plants (WWTPs) that include biological phosphorus removal. This enables efficient removal of both carbon and phosphorus. This paper focuses on the biochemical methane potential (BMP) that could be reached when using bio-P sludge with different polyhydroxyalkanoate (PHA) content obtained under different SRTs and under anaerobic and aerobic environments. The PHA content of the biomass increased from 3.15 to 9.80 mmol C/g VSS when the SRT was decreased from 15 to 5 days and, on average, anaerobic sludge contained 45% more PHA than the aerobic sludge. BMP was correlated with the PHA content, following an approximate linear trend: BMP (mL CH 4 /g VSS) = 240 + 15.3 * PHA (mmol C/g VSS), independently of SRT and the anaerobic or aerobic extraction. The maximum BMP obtained was 401 mL CH 4 /g VSS with the biomass with the highest PHA content (9.80 mmol C/g VSS). When operating at low SRT and purging from the anaerobic phase, 28% of the influent COD content could be recovered as methane. This represented up to 2.5 times more energy than in the more conventional scenario tested: operating at high SRT with conventional aerobic purge. Image 1075 • BMP for Bio-P sludge is linearly correlated to its PHA content. • BMP (mLCH 4 /gVSS) can be calculated as 240 + 15.3 * PHA (mmolC/gVSS). • The correlation of BMP and the PHA content in bio-P sludge is independent of SRT. • PHA increased from 3.15 to 9.80 mmolC/gVSS when SRT decreased from 15 to 5 days. • 28% of influent COD was recovered as CH 4 purging from anaerobic phase at low SRT. [ABSTRACT FROM AUTHOR]

• TAN recovery via BES as a low-energy intensive alternative to conventional systems. • The TAN recovery rate highly depends on the current density produced. • Challenges for scale-up: nature/quantity of carbon source and NH 4 + concentration. • Describing fundamentals of BES TAN recovery: stripping, absorption or precipitation. Due to the anticipated rise in demand for ammonia, the search for viable methods for its recovery has intensified in recent years, as traditional ammonia production is a high energy intensive process. Bioelectrochemical systems (BESs) offer an alternative solution for ammonia recovery since they have shown lower energy demand (in terms of kJ g−1N recovered) at lab-scale than other methodologies. In BESs, the bioelectrochemically generated current drives the transport of NH 4 + from the wastewater to a concentration chamber through a cation exchange membrane before its subsequent recovery. This paper describes the fundamentals and opportunities for bioelectrochemical ammonia recovery (either by stripping, absorption, or precipitation) in different BES devices such as microbial fuel cells, microbial electrolysis cells, microbial desalination cells and bioelectroconcentration cells and compares the performance of all the reported experimental works so far. Moreover, the most critical challenges (low current density, nature and quantity of the carbon source, inlet ammonium concentration, use of membranes, energy yield and recovery efficiency) have been detailed and discussed in view of better understanding the current bottlenecks for its scale-up and, thus, for its prompt industrial adoption. [ABSTRACT FROM AUTHOR]

Abstract Enhanced Biological Phosphorus Removal (EBPR) is based on the enrichment of sludge in polyphosphate accumulating organisms (PAO). Candidatus Accumulibacter is the bacterial community member most commonly identified as PAO in EBPR systems when volatile fatty acids (VFA) are the carbon source. However, it is necessary to understand the role of non- Accumulibacter PAO in the case of wastewater with low VFA content. This work shows the first successful long-term operation of an EBPR system with glutamate as sole carbon and nitrogen source, resulting in the enrichment of sludge in the genus Thiothrix (37%), the family Comamonadaceae (15.6%) and Accumulibacter (7.7%). The enrichment was performed in an anaerobic/anoxic/oxic (A2/O) continuous pilot plant, obtaining stable biological N and P removal. This microbial community performed anaerobic P-release with only 18–29% of the observed PHA storage in Accumulibacter -enriched sludge and with slight glycogen storage instead of consumption, indicating the involvement of other carbon storage routes not related to PHA and glycogen. Thiothrix could be clearly involved in P-removal because it is able of accumulating Poly-P, probably without PHA synthesis, but with glutamate involvement. On the other hand, Comamonadaceae could participate in degradation of glutamate and denitrification, but its involvement in P-uptake cannot be reliably concluded. Graphical abstract Unlabelled Image Highlights • Glutamate can be used as sole carbon and nitrogen source for EBPR. • P was successfully removed with low PHA and glycogen involvement. • The enrichment was more stable in an A2/O plant than in a SBR. • Enrichment of bio-P sludge with Thiothrix and Comamonadaceae was observed. • Thiothrix is the main candidate to be involved in P-removal using glutamate [ABSTRACT FROM AUTHOR]

Abstract Phosphorus recovery is usually based on the chemical precipitation of struvite from the supernatant comming from anaerobic digestion of surplus sludge of wastewater treatment plants. However, the recovery of phosphorus from the mainstream would be very beneficial to the operation of the plant. This work represents a step forward in this challenge. The configuration of a sequencing batch reactor performing Enhanced Biological Phosphorus Removal (EBPR) was modified to include the extraction of a P-rich supernatant after a settling period. The liquid extracted after the anaerobic phase has the highest phosphorus concentration in all the reactor cycle and is therefore suitable for implementing P-recovery strategies. This is the first experimental system operated under this configuration and in a long-term basis (more than one year) under different influent COD/P ratios with good performance and stability. This work shows experimentally that up to 60% of the P could be extracted without a deleterious effect on EBPR. The system could even operate at high COD/P ratio (7.5) with high activity. Finally, anaerobic supernatant extraction was linked to anaerobic sludge purging and it was demonstrated that higher methane production (24.3%) was obtained compared to the default case with the sludge purged at the end of the aerobic phase. Highlights • Long-term assessment of the EBPR2 configuration for P-recovery from mainstream line. • 60% P-recovery with anaerobic supernatant extraction without adverse effect on EBPR. • Long-term good performance under low influent COD/P ratio with high EBPR activity. • 24.3% higher methane production with sludge purged at anaerobic phase vs aerobic. [ABSTRACT FROM AUTHOR]

[Display omitted] • Comprehensive assessment of adding a SSSF in a A 2 O with a COD-limited influent. • Higher P and N removal capacity obtained without compromising COD removal. • Satisfactory EBPR with a low influent COD/P of only 26.3 (S2EBPR) vs 32.6 (A 2 O). • A lower effluent quality (2.0 ± 1.6 mgP/L) was observed due to the extra P load. • SSSF involved a reduction on the waste sludge production vs A 2 O. The implementation of a side-stream sludge fermenter (SSSF) has been identified as a possible solution to improve the performance of an anaerobic/anoxic/aerobic (A 2 O) configuration when treating low COD wastewater. This study systematically evaluated the effects of incorporating a SSSF into an A 2 O configuration (side-stream enhanced biological phosphorus removal, S2EBPR) for P/N/COD removal under a limited influent COD (COD INF) condition. The performance of the S2EBPR (with the SSSF receiving 6% of the recycled activated sludge and operating with a hydraulic retention time (HRT) of 2.4 d) and A 2 O were compared under the same limited COD INF (350 mg/L) condition. S2EBPR improved the amount of P removed (26.6%) under a low influent COD/P of only 26.3 compared with A 2 O of 32.6, and enhanced denitrification (11%) without compromising full ammonium and COD removal. However, the P LOAD to the plant increased due to the P-release in SSSF, resulting in higher effluent P concentration. The methane and energy recovery indexes were around 45% lower than those of A 2 O. Sequencing analysis revealed a high abundance of PAO in accordance to its higher P removal. This study represents a comprehensive evaluation of the S2EBPR configuration and provides an assessment of its suitability. [ABSTRACT FROM AUTHOR]

Nitrous oxide (N 2 O), a significant contributor to the greenhouse effect, is generated during the biological nutrient removal in wastewater treatment plants (WWTPs). Developing mathematical models estimating the N 2 O dynamics under changing operational conditions (e.g. dissolved oxygen, DO) is essential to design mitigation strategies. Based on the activated sludge models (ASM) structure, this work presents an ASM2d-N 2 O model including all the biological N 2 O production pathways for a municipal anaerobic/anoxic/oxic (A 2 /O) WWTP with biological removal of organic matter, nitrogen and phosphorus, and its application in different dynamic scenarios. Three microbial N 2 O production pathways were considered: nitrifier denitrification, hydroxylamine oxidation, and heterotrophic denitrification, with the first two being activated by ammonia oxidizing bacteria (AOB). A stripping effectivity (SE) coefficient was added to reflect the non-ideality of the stripping model. Partial nitrification and high N 2 O production via nitrifier denitrification were observed when the range of DO in the aerobic compartment was 1.8 to 2.5 mg·L −1 . It could imply that low aeration strategies lead to low overall carbon footprint provided complete nitrification is not hindered. The model predicted high N 2 O emissions when low DO (∼1.1 mg L −1 ) and high ammonium concentration concurred. With the AOB prevailing over the nitrite oxidizing bacteria (NOB), nitrite was accumulated, triggering the activation of the nitrifier denitrification pathway. After suddenly increasing the influent ammonium load, the AOB had a greater growth compared to the NOB and the same pathway was considered as N 2 O hotspot. Especially under conditions promoting partial nitrification (i.e. low DO) and raising the stripping effect importance (i.e. high SEs), the highest N 2 O emission factors were predicted. [ABSTRACT FROM AUTHOR]

Nitrous oxide (N 2 O) is an important pollutant which is emitted during the biological nutrient removal (BNR) processes of wastewater treatment. Since it has a greenhouse effect which is 265 times higher than carbon dioxide, even relatively small amounts can result in a significant carbon footprint. Biological nitrogen (N) removal conventionally occurs with nitrification/denitrification, yet also through advanced processes such as nitritation/denitritation and completely autotrophic N-removal. The microbial pathways leading to the N 2 O emission include hydroxylamine oxidation and nitrifier denitrification, both activated by ammonia oxidizing bacteria, and heterotrophic denitrification. In this work, a critical review of the existing literature on N 2 O emissions during BNR is presented focusing on the most contributing parameters. Various factors increasing the N 2 O emissions either per se or combined are identified: low dissolved oxygen, high nitrite accumulation, low chemical oxygen demand to nitrogen ratio, slow growth of denitrifying bacteria, uncontrolled pH and temperature. However, there is no common pattern in reporting the N 2 O generation amongst the cited studies, a fact that complicates its evaluation. When simulating N 2 O emissions, all microbial pathways along with the potential contribution of abiotic N 2 O production during wastewater treatment at different dissolved oxygen/nitrite levels should be considered. The undeniable validation of the robustness of such models calls for reliable quantification techniques which simultaneously describe dissolved and gaseous N 2 O dynamics. Thus, the choice of the N-removal process, the optimal selection of operational parameters and the establishment of validated dynamic models combining multiple N 2 O pathways are essential for studying the emissions mitigation. [ABSTRACT FROM AUTHOR]

Enhanced Biological Phosphorus Removal (EBPR) of urban wastewaters is usually limited by the available carbon source required by Polyphosphate Accumulating Organisms (PAO). External carbon sources as volatile fatty acids (VFA) or other pure organic compounds have been tested at lab scale demonstrating its ability to enhance PAO activity, but the application of this strategy at full-scale WWTPs is not cost-effective. The utilization of industrial by-products with some of these organic compounds provides lower cost, but it has the possible drawback of having inhibitory or toxic compounds to PAO. This study is focused on the utilization of crude glycerol, the industrial by-product generated in the biodiesel production, as a possible carbon source to enhance EBPR in carbon-limited urban wastewaters. Crude glycerol has non-negligible content of other organic compounds as methanol, salts, VFA and long chain fatty acids (LCFA). VFA and methanol have been demonstrated to enhance PAO activity, but there is no previous study about the effect of LCFA on PAO. This work presents the operation of an EBPR SBR system using crude glycerol as sole carbon source, studying also its long-term stability. The effect of LCFA is evaluated at short and long-term operation, demonstrating for the first time EBPR activity with LCFA as sole carbon source and its long-term failure due to the increased hydrophobicity of the sludge. [ABSTRACT FROM AUTHOR]

• The IWA-BSM2 was extended to account for chemical precipitation and N 2 O emissions. • Detailed indirect and direct CO 2 (biogenic/non-biogenic) emissions were also included. • Control strategies balance plant performance, nutrient recovery and GHG mitigation. • Lowest emissions: control of NH 4 ++ N 2 O in aerobic reactors and struvite recovery. In this study, a plant-wide model describing the fate of C, N and P compounds, upgraded to account for (on-site/off-site) greenhouse gas (GHG) emissions, was implemented within the International Water Association (IWA) Benchmarking Simulation Model No. 2 (BSM2) framework. The proposed approach includes the main biological N 2 O production pathways and mechanistically describes CO 2 (biogenic/non-biogenic) emissions in the activated sludge reactors as well as the biogas production (CO 2 /CH 4) from the anaerobic digester. Indirect GHG emissions for power generation, chemical usage, effluent disposal and sludge storage and reuse are also included using static factors for CO 2 , CH 4 and N 2 O. Global and individual mass balances were quantified to investigate the fluxes of the different components. Novel strategies, such as the combination of different cascade controllers in the biological reactors and struvite precipitation in the sludge line, were proposed in order to obtain high plant performance as well as nutrient recovery and mitigation of the GHG emissions in a plant-wide context. The implemented control strategies led to an overall more sustainable and efficient plant performance in terms of better effluent quality, reduced operational cost and lower GHG emissions. The lowest N 2 O and overall GHG emissions were achieved when ammonium and soluble nitrous oxide in the aerobic reactors were controlled and struvite was recovered in the reject water stream, achieving a reduction of 27% for N 2 O and 9% for total GHG, compared to the open loop configuration. [Display omitted] [ABSTRACT FROM AUTHOR]

• Tracer experiments helped identify plant hydraulics for reliable modelling. • Sensitivity analysis helped to reveal an optimal parameter subset. • ASM2d-N 2 O model was successfully calibrated to describe a full-scale urban WWTP. • Trends in both nutrients removal and N 2 O emissions were described. Nitrous oxide (N 2 O) is a greenhouse gas (GHG) emitted during biological nitrogen removal from wastewater treatment plants (WWTPs). Some modelling tools have been proposed to predict N 2 O emissions during the design and operation of WWTPs. In this study, the novel ASM2d-N 2 O model, which accounts for the production of N 2 O in nutrient removal WWTPs, was used to study the associated emissions from a full-scale WWTP with two independent lines. Firstly, the hydraulics of the WWTP was characterized by a residence time distribution test, showing the flow was equally divided into the two treatment lines (49.3 vs. 50.7%), that each reactor worked as an ideal continuous stirred tank reactor and the secondary settler model flux was similar to a plug-flow reactor. The ASM2d-N 2 O model was then calibrated using experimental data obtained under dynamic conditions. A global sensitivity analysis was used to select, among 59 model parameters, five candidates that resulted to be related to nitrifying organisms. Different parameter subsets up to four parameters were evaluated, being the subset [µ NOB , q AOB_AMO , K O2_NOB , K NO2_NOB ] the best, achieving 53.3% reduction of the calibration cost function. The model fit obtained provided a reasonably description of nutrients and N 2 O emission trends, considering the inherent operational variability suffered in full-scale WWTPs. Finally, a simulation-based study showed that, for the given WWTP and operational conditions, an unbalanced distribution of flow-rate between the two treatment lines did not result in a significant increase on N 2 O emissions. The results obtained show that this model can be a suitable tool for predicting N 2 O emissions in full-scale WWTPs, and can therefore be used to find operational conditions that help to minimise these emissions. [ABSTRACT FROM AUTHOR]

The elimination capacity of gaseous H 2 S biofiltration can be limited either by mass transfer or bioreaction in the biofilm. Assessment of the biological activity of immobilized cells (biofilm) usually implies morphological and physiological changes during the adaptation of cells to respirometric devices operated as suspended cultures. In this study, respirometry of heterogeneous media is advised as a valuable technique for characterizing mass transport and biological activity of H 2 S-oxidizing biofilms attached on two packing materials from operative biotrickling filters. Controlled flows of liquid and H 2 S-containing air were recirculated through a closed heterogeneous respirometer allowing a more realistic estimation of the biofilm activity by the experimental evaluation of the oxygen uptake rate (OUR). Specific maximum OUR of 23.0 and 38.5 mmol O 2 (g biomass min) −1 were obtained for Pall rings and polyurethane foam, respectively. A mathematical model for the determination of kinetic-related parameters such as the maximum H 2 S elimination capacity and morphological properties of biofilm (i.e., thickness and fraction of wetted area of packing bed) was developed and calibrated. With the set of parameters obtained, the external oxygen mass transport to the wetted biofilm was found to limit the global H 2 S biofiltration capacity, whereas the non-wetted biofilm was the dominant route for the gaseous O 2 and H 2 S mass transfer to the biofilm. Oxygen diffusion rate was the limiting step in the case of very active biofilms. [ABSTRACT FROM AUTHOR]

Metopaulias depressus is a non-marine crab endemic to Jamaica that dwells in rainforest bromeliads and exhibits elaborate active parental care behavior. Current genomic resources on M. depressus are rare, limiting the understanding of its adaptation to terrestrial life in species that evolved from marine ancestors. This study reports the complete mitochondrial genome of M. depressus assembled using Sanger sequencing. The AT-rich mitochondrial genome of M. depressus is 15,765 bp in length and comprises 13 protein-coding genes (PCGs), 2 ribosomal RNA genes, and 22 transfer RNA genes. A single 691 bp-long intergenic space is assumed to be the control region (CR) or D-loop. A set of selective pressure analyses indicate that the entirety of the PCGs experience purifying selection. Cox1, cox2, nad5, cox3, and atp6 experience strong purifying selection, and atp8 experiences weak purifying selection compared to the rest of the PCGs. The secondary structures of most tRNA genes exhibit a standard 'cloverleaf' structure, with the exception of trnS1, which lacks the dihydroxyuridine (DHU) arm but not the loop, the trnH gene, which lacks the thymine pseudouracil cytosine (T) loop but not the arm, and trnM, which exhibits an overly developed T loop. A maximum likelihood phylogenetic analysis based on all PCGs indicated that M. depressus is more closely related to the genera Clistocoeloma, Nanosesarma, and Parasesarma than to Chiromantes, Geosesarma, and Orisarma. This study contributes to deciphering the phylogenetic relationships within the family Sesarmidae and represents a new genomic resource for this iconic crab species. [ABSTRACT FROM AUTHOR]

Enhanced biological phosphorus removal (EBPR) is an efficient and sustainable technology to remove phosphorus from wastewater. A widely known cause of EBPR deterioration in wastewater treatment plants (WWTPs) is the presence of nitrate/nitrite or oxygen in the anaerobic reactor. Moreover, most existing studies on the effect of either permanent aerobic conditions or inhibition of EBPR by nitrate or free nitrous acid (FNA) have been conducted with a " Candidatus Accumulibacter" or Tetrasphaera -enriched sludge, which are the two major reported groups of polyphosphate accumulating organisms (PAO) with key roles in full-scale EBPR WWTPs. This work reports the denitrification capabilities of a bio-P microbial community developed using glutamate as the sole source of carbon and nitrogen. This bio-P sludge exhibited a high denitrifying PAO (DPAO) activity, in fact, 56% of the phosphorus was uptaken under anoxic conditions. Furthermore, this mixed culture was able to use nitrite and nitrate as electron acceptor for P-uptake, being 1.8 μg HNO 2 –N·L−1 the maximum FNA concentration at which P-uptake can occur. Net P-removal was observed under permanent aerobic conditions. However, this microbial culture was more sensitive to FNA and permanent aerobic conditions compared to " Ca. Accumulibacter"-enriched sludge. [Display omitted] • A glutamate-fed bio-P sludge used nitrite/nitrate as electron acceptor for P-uptake. • Total P-uptake inhibition by FNA was observed at 2 μg HNO 2 –N L−1. • P-uptake rate was reduced by 72% at an initial concentration of 83 mg N–NO 3 - L−1. • Our bio-P sludge was more sensitive to oxygen than Accumulibacter -enriched cultures. [ABSTRACT FROM AUTHOR]

Abstract: The main objective of this work was the design of different effluent quality controllers and a cost controller for WWTPs. This study was based on the relative gain array (RGA) analysis applied to an anaerobic/anoxic/aerobic (A2/O) configuration of a simulated WWTP, with combined removal of organic matter, nitrogen and phosphorus. The RGA analysis was able to point out the best pairing amongst the input and the output control variables of the plant to design low order and decentralized effluent quality controllers, such as proportional-integral controllers for each variable of interest (ammonium, nitrate and phosphate). In a second step, a cost controller to automatically search for the most economic setpoints of the effluent quality controllers was implemented based on the best decentralized control structure tested. The simulated plant was operated under different control modes that chronologically represent control configurations becoming gradually more complex: (i) in open loop; (ii) with dissolved oxygen (DO) control in the last aerobic reactor only; (iii) with the effluent quality controllers active; (iv) with the effluent quality controllers active and automatically receiving the setpoints from a cost controller. The effluent quality controllers alone and the cost control together with effluent quality controllers could save up to 42,000 Euros/year and 225,000 Euros/year, respectively, when compared to the operating costs of the plant operating with DO control (a reduction of 2.5% and 13% of the operating costs, respectively). The cost controller proved to be a good tool for automating the search of the most profitable setpoints of the effluent quality controllers for a given cost setpoint. [Copyright &y& Elsevier]