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The use of mixed microbial cultures (MMC) and organic wastes and wastewaters as feed sources is considered an appealing approach to reduce the current polyhydroxyalkanoates (PHAs) production costs. However, this method entails an additional hurdle to the PHAs downstream processing (recovery and purification). In the current work, the effect of a sodium hypochlorite (NaClO) pre-treatment coupled with dimethyl carbonate (DMC) or chloroform (CF) as extraction solvents on the PHAs recovery efficiency (RE) from MMC was evaluated. MMC were harvested from a sequencing batch reactor (SBR) fed with a synthetic prefermented olive mill wastewaster. Two different carbon-sources (acetic acid and acetic/propionic acids) were employed during the batch accumulation of polyhydroxybutyrate (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) from MMC. Obtained PHAs were characterized by 1H and 13C nuclear magnetic resonance, gel-permeation chromatography, differential scanning calorimetry, and thermal gravimetric analysis. The results showed that when a NaClO pre-treatment is not added, the use of DMC allows to obtain higher RE of both biopolymers (PHB and PHBV), in comparison with CF. In contrast, the use of CF as extraction solvent required a pre-treatment step to improve the PHB and PHBV recovery. In all cases, RE values were higher for PHBV than for PHB.

Altres ajuts: acords transformatius de la UAB Volatile fatty acids (VFAs) are a group of carboxylic acids considered as building block chemicals. Nowadays, commercial production of VFAs is performed using fossil fuel sources. As an alternative, acidogenic fermentation of wastes by mixed microbial cultures (MMC) is starting to be considered as a potential bioproduction process that would replace conventional production processes and contribute to the circular economy. Nevertheless, more research is needed to control the VFA production yields and to precisely drive the fermentation process to the production of a certain VFA or a mixture of VFAs, either by modifying the operational parameters or by appropriately tunning the substrate composition. Following this gap, this review starts screening the metabolic routes that yield VFAs by anaerobic fermentation. Subsequently, the effect of different operational parameters on VFA production yield and VFA composition distribution is extensively discussed depending on the organic composition of the waste in terms of proteins, carbohydrates and lipids. To the best of our knowledge, previous review articles analyzed the impact of these parameters for different types of wastes, but without specifically considering their organic composition in terms of proteins, carbohydrates and lipids. Afterwards, energy-based metabolic models are presented as the one of the best modelling approaches to predict VFA composition. Then, polyhydroxyalkanoates (PHAs) production by MMC is described since it is one of the most promising applications of waste derived VFAs. Finally, we highlight the research gaps that should be further investigated to develop a large scale VFA bioprocess based on MMC platform from waste streams.

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.

Unidad de excelencia María de Maeztu CEX2019-000940-M Altres ajuts: acords transformatius de la UAB A paradigm shift is needed in wastewater treatment plants (WWTPs) to progress from traditional pollutant removal to resource recovery. However, whether this transformation produces overall environmental benefits will depend on the efficient and sustainable use of resources by emerging technologies. Given that many of these technologies are still being tested at the pilot scale, there is a lack of environmental assessments quantifying their impacts and benefits. In particular, an integrated approach to energy and nutrient recovery can elucidate the potential configurations for WWTPs. In this study, we conduct a life cycle assessment (LCA) of emergent wastewater treatment technologies aimed at increasing resource circularity in WWTPs. We focus on increasing energy self-sufficiency through biogas upgrades and a more radical circular approach aimed at nutrient recovery. Based on a case-study WWTP, we compare its current configuration with (1) implementing autotrophic nitrogen removal in the mainstream and deriving most of the organic matter for biogas production, which increases the quality and quantity of biogas available for energy production; (2) implementing struvite recovery through enhanced biological phosphorus removal (EBPR) as a radical approach to phosphorus management, offering an alternative to mineral fertilizer; and (3) a combination of both approaches. The results show that incremental changes in biogas production are insufficient for compensating for the environmental investment in infrastructure, although autotrophic nitrogen removal is beneficial for increasing the quality of the effluent. Combined phosphorus and energy recovery reduce the environmental impacts from the avoided use of fertilizers and phosphorus and the nitrogen release into water bodies. An integrated approach to resource management in WWTPs is thus desirable and creates new opportunities toward the implementation of circular strategies with low environmental impact in cities.

Acidogenic fermentation of wastes produces volatile fatty acid (VFA)-rich streams that can be used as low-cost carbon sources for polyhydroxyalkanoate (PHA) production. In this study, an inoculum collected from an anaerobic reactor of a municipal WWTP was conditioned to suppress methanogenic activity. The heat-shock conditioning method of the inoculum proved to be more efficient than acid and alkaline conditioning methods for methanogen inhibition. Then, the pre-conditioned inoculum was used to determine the acidogenic potential of different wastes: three waste activated sludge (WAS) samples generated at different sludge retention times (SRTs, 2, 7 and 14 days), olive mill wastewater (OMW), glycerol, apple pomace (AP) and winterization oil cake (WOC). Batch tests were performed in quintuplicate at 37°C and pH 7. A higher degree of acidification was observed for high-rate activated sludge (2 days of SRT) (69%), followed by olive mill wastewater (OMW) (43%), while the lowest was for glycerol (16%). The results for the winterization oil cake (WOC) samples interestingly elucidated a high content of propionic acid with a high odd-to-even ratio (0.86) after fermentation. Feeding the VFA profile obtained from WOC into a PHA production system led to a significant production of 0.64 g PHA g− 1 C with 30% polyhydrobutyrate (PHB) to 69% polyhydroxyvalerate (PHV) as monomeric units of HB-co-HV, decoupling the need for a related carbon source for co-polymer production.

Altres ajuts: acords transformatius de la UAB Altres ajuts: LIFE14/ENV/ES/000633 The use of high-rate activated sludge (HRAS) reactors for the removal of COD in urban wastewater treatment plants (WWTPs) has been investigated because its potential contribution to energy generating WWTPs. A one-year operation period of a pilot plant treating the effluent of the primary settler of a full-scale WWTP was analyzed. The HRAS pilot plant operated without iron salts addition at temperatures between 12 and 28 ºC at an average organic loading rate 2.8 ± 0.5 kg COD m-3 d-1 and with an average inflow COD concentration of 330 ± 86 mg O2 L-1. The influence of sludge retention time (SRT) on COD recovery and biomethane potential of the produced sludge was investigated and compared to the full scale WWTP performance. The highest observed sludge yield coefficient and biomethane potential of the sludge were achieved at SRT of 0.6 days. The weak point of the HRAS performance at STR of 0.6 days is the high loss of organic matter in the effluent due to the limited efficiency of the solids separation in the secondary settler. At higher SRT (in the range 1.0-2.1 days), the secondary settler efficiency and the COD recovery are higher than those achieved at SRT of 0.6 days but part of the inlet ammonium can be nitrified in the HRAS system at temperatures above 20 ºC. A detailed energy balance indicated that two-thirds reduction of aeration requirements and one-third increase of biogas production could be achieved in a plant configuration in which HRAS is coupled to autotrophic biological nitrogen removal (BNR) compared to the heterotrophic BNR configuration, yielding a net energy production of ca. 0.1 kWh m-3 of treated water.

Altres ajuts: acords transformatius de la UAB Biases on molecular techniques used to study microbial communities in the anammox process are not always considered. This work aimed to evaluate different molecular approaches to study bacterial communities in an anammox reactor treating real urban wastewater at mainstream conditions. 16S rRNA amplicon sequencing with different primer sets, metagenomics, and qPCR were evaluated. An enriched anammox reactor feed with synthetic wastewater was used as a positive control. We reported that, despite its in silico coverage, the universal primers 515F-909R had, in fact, very low coverage (1%) of the Planctomycetota phylum. The functional genes approach showed a taxonomic resolution at the species level, although genomic database updates are a bias to be considered. From the phylogenetic analysis, coherence among the approaches was obtained. Primers targeting anammox 16S rRNA and hydrazine synthase genes in qPCR showed consistency in the quantification, making them useful for comparing similar investigations. According to the results, recommendations on the biomolecular approach to be used were outlined.

To explore the changes in the microbial community structure during the recovery process of an anammox reactor after a temperature shock, the 454-pyrosequencing technique was used. The temperature shock reduced the nitrogen removal rate up to 92% compared to that just before the temperature shock, and it took 70 days to recover a similar nitrogen removal rate to that before the temperature shock (ca. 0.30 g N L−1 d−1). Pyrosequencing results indicated that microbial diversity in the reactor decreased as the reactor progressively recovered from the temperature shock. Anammox bacteria were accounted as 6%, 35% and 46% of total sequence reads in samples taken 13, 45 and 166 days after the temperature shock. These results were in agreement with N-removal performance results and anammox activity measured in the reactor during the recovery process. An anammox specific primer was used to precisely determine the anammox species in the biomass samples.

A sequencing batch reactor (SBR) was inoculated with p -nitrophenol-degrading activated sludge to biodegrade a mixture of monosubstituted phenols: p -nitrophenol (PNP), PNP and o -cresol; and PNP, o -cresol and o -chlorophenol. Settling times were progressively decreased to promote biomass granulation. PNP was completely biodegraded. The PNP and o -cresol mixture was also biodegraded although some transitory accumulation of intermediates occurred (mainly hydroquinone and catechol). o -Chlorophenol was not biodegraded and resulted in inhibition of o -cresol and PNP biodegradation and complete failure of the SBR within a few days. The biomass had very good settling properties when a settling time of 1 min was applied: sludge volume index (SVI 5 ) below 50 mL g −1 , SVI 5 /SVI 30 ratio of 1 and average particle size of 200 μm.

Long-term operation (390 days) of a continuous airlift reactor with aerobic granular biomass was successfully applied to treat a highly complex wastewater composed of: ammonium (1000 mg N L−1), o-cresol (100 mg L−1), phenol (100 mg L−1), quinoline (50 mg L−1) and salts (16 g salts L−1). High nitrogen loading rate (1.1 g N L−1 d−1) and organic loading rate of 0.7 (g COD L−1 d−1) were achieved for the simultaneous nitritation and complete biodegradation of the aromatic compounds. The successful operation of the granular airlift reactor can be related to (i) the growth of specialized microorganisms in the aerobic granules and (ii) the continuous feeding regime. Aerobic granules were maintained stable in spite of the high salinity conditions. Dissolved oxygen (DO) concentration and DO/ammonium concentrations ratio were the key parameters to select a suitable effluent for anammox or heterotrophic denitrification via nitrite. Besides, nitrous oxide emissions were related to the DO concentration in the reactor.

Granular sludge aggregates are particular types of biofilms that display significantly different metrics and physical-chemical characteristics than activated sludge flocs. The efficiency of intensified processes using granular sludge relies on the application of selection pressures. Operational conditions are engineered to force microorganisms to form specific intrinsic physiological, phenotypic, and metabolic traits for granulation and high-rate biological removal of nutrients and/or recalcitrant organic matter. Granular sludge and conventional activated sludge share a core microbiome, while the distribution of the underlying populations can significantly differ in relative abundance and localization in the architecture of granules and flocs. Analogous ecological principles of microbial selection apply from activated sludge to granular sludge ecosystems with the essential difference that granules are governed by diffusion limitations through which different redox potentials are created on micrometre scale. Integrating the microbiology dimension together with the physical–chemical features of granules in engineering practice will make a difference at process level, besides offering new opportunities for bioaugmentation of granules in existing infrastructure. With this review article we critically examine the macro-scale factors impacting granulation, the physical-chemical characteristics of granular sludge, and fundamental and applied questions driven by the microbial ecology of granular sludge, to generate useful concepts for process design and evaluation in engineering practice.

Polyhydroxyalkanoates (PHAs) are biopolyesters accumulated as carbon and energy storage materials under unbalanced growth conditions by various microorganisms. They are one of the most promising potential substitutes for conventional non-biodegradable plastics due to their similar physicochemical properties, but most important, its biodegradability. Production cost of PHAs is still a great barrier to extend its application at industrial scale. In order to reduce that cost, research is focusing on the use of several wastes as feedstock (such as agro-industrial and municipal organic waste and wastewater) in a platform based on mixed microbial cultures. This review provides a critical illustration of the state of the art of the most likely-to-be-scale-up PHA production processes using mixed microbial cultures platform and waste streams as feedstock, with a particular focus on both, upstream and downstream processes. Current pilot scale studies, future prospects, challenges and developments in the field are also highlighted.

Aquest article pertany al grup de recerca GENOCOV. https://ddd.uab.cat/collection/genocov Heterotrophic denitrification of nitrite (denitritation) with phenol as the only organic carbon source was successful achieved in an Upflow Sludge Blanket (USB) reactor with granular biomass. High nitrite removal (over 95%) and complete biodegradation of phenol were obtained at low COD/N ratio (2.5 ± 0.1) and at high nitrogen and organic loading rates (0.6 ± 0.1 g N L⁻¹ d⁻¹ and 1.6 ± 0.3 g COD L⁻¹ d⁻¹ at 30 C, respectively). The granulation remained stable throughout the operational period with an average granule size of 0.80 ± 0.08 mm and 95% of the biomass with a diameter higher than 0.2 mm. The denitrifying granular biomass was also able to use nitrate as electron acceptor after one year consuming exclusively nitrite. However, the granular biomass was not able to use o-cresol as electron donor although phenol and nitrite degradations were not affected by the presence of o-cresol and the granules remained stable. Most of the genera identified in the granules after one year operation of the anoxic USB reactor were denitrifying bacteria able to use nitrite and nitrate as electron acceptors and aromatic compounds as electron donors. The results presented in this study open the possibility of designing a new process for the treatment of complex wastewaters contaminated with aromatic compounds.

A new protocol for polyhydroxyalkanoates (PHA) extraction from mixed microbial cultures (MMCs) is proposed. PHA-accumulating capacity of the MMC was selected in a sequencing batch reactor (SBR) fed with a synthetic effluent emulating a fermented oil mill wastewater (OMW). The highest recovery yield and purity (74 ± 8% and 100 ± 5%, respectively) was obtained when using NH4-Laurate for which operating conditions of the extraction process such as temperature, concentration and contact time were optimized. Best conditions for PHA extraction from MMC turned to be: i) a pre-treatment with NaClO at 85 °C with 1 h of contact time, followed by ii) a treatment with lauric acid in a ratio acid lauric to biomass of 2:1 and 3 h of contact time.

The effect of salinity over granular biomass treating a mixture of aromatic compounds (phenol, o-cresol and p-nitrophenol) was evaluated in a continuous airlift reactor. To mimic an industrial wastewater, increasing concentrations (from 2.0 to 29.0 g salts L(-1)) of a mixture of salts (MgSO4, NaCl, KCl, CaCl2 and NaHCO3) were introduced in the influent. The gradual salinity increase led to a good acclimation of the biomass obtaining complete biodegradation of the aromatic compounds and no accumulation of metabolic intermediates. However, a deterioration of the morphology of aerobic granules with a complete loss of granulation after 125 days was produced at 29.0 g salts L(-1). At that moment, anaerobic granules were added to promote granulation and after 50 days new aerobic granules were formed. These new aerobic granules remained stable for more than 100 days at the highest salinity condition with 100% removal of the mixture of aromatic compounds.

The short-term effect of several aromatic compounds ( o -cresol, p -nitrophenol, o -chlorophenol and quinoline) was evaluated over granular anammox sludge cultivated over 2 years in a Sequencing Batch Reactor (SBR). The anammox granular sludge had an average size of 1.0 ± 0.2 mm and was enriched in Brocadia sp. Specific Anammox Activity (SAA) batch tests with this granular biomass were carried out in the presence of o -cresol, p -nitrophenol, o -chlorophenol, quinoline and their mixtures. The anammox biomass was never exposed to the tested aromatic compounds, prior to the SAA tests. The concentration and the mixture of aromatic compounds had a strong effect over the loss of the anammox activity. The higher the concentrations of the aromatic compounds, the higher the reduction of the SAA. Quinoline and p -nitrophenol have a lower negative effect compared to o -cresol and o -chlorophenol. The Luong inhibition model seems to adjust better the inhibition of anammox biomass by the tested aromatic compounds. Depending on the aromatic compound, toxic or inhibitory effect was measured. o -Cresol and o -chlorophenol caused a toxic effect whereas p -nitrophenol and quinoline produced an inhibitory effect. In general, synergistic effects were observed when mixtures of aromatic compounds were studied.

Previous studies assessing the environmental impacts of drinking water supply networks have considered a bottom-up approach, analysing single case studies. This paper presents a top-down approach for the assessment of the operational phase of a water supply network. A representative sample of 50 cities was statistically analysed to find relations between different variables regarding electricity and water consumption linked with the environmental impacts of the network. The results show that some of the variables are clearly related to the relative energy consumption of the network. Such is the case for population size, where small municipalities have up to 14 times higher relative electricity consumption compared with medium-sized municipalities (1.15E-2 as opposed to 8.3E-4 kWh/m3 registered water km of network) due to case-specific factors such as a strong gradient between a water tank and the consumption point. Similarly, the cases showing low population density exhibit 7 times higher relative electricity consumption because of the longer distances that must be covered and the correlation between population density and size. The values found for greenhouse gas (GHG) emissions derived from the energy consumption are consistent with results from previous studies: on average, 5.53 kg of CO2 eq. emissions/inhabitant·year are released, but the variability is very high, ranging from 0.005 to 67.8 kg of CO2 eq. emissions/inhabitant·year. No clearly significant correlations were found between the relative water demand and variables such as seasonality or income per capita, which might indicate that water consumption depends on individual decisions of the population rather than on the variables assessed. Models for the estimation of water demand, length of network and electricity consumption were defined. However, the modelling of electricity consumption presented more difficulties because of its high variability. A protocol for data collection should be defined and implemented in the future to enable the analysis of more high quality case studies and for the definition of more accurate and reliable models.

Aerobic granular sludge is presented as an alternative technology to conventional activated sludge processes for the treatment of low-strength wastewaters. Results obtained with granular aerobic reactors at laboratory scale are promising but, there are few studies carried out at pilot scale. Therefore, more information about the stability of granules and their performance at larger scale is needed to establish if aerobic granulation could be a feasible treatment. With this aim, a 100 L granular sequencing batch reactor (GSBR) operating at high loading rate and treating low-strength wastewater for simultaneous carbon, nitrogen and phosphorus removal was operated for 11 months. Mature granules prevailed in the GSBR during a period of 5 months (from days 150 to 330), with a SVI 30 of 13 ± 6 mL g −1 TSS, a granule density around 114 ± 5 g TSS L −1 and an average particle size of 2.4 mm. The biological nitrogen removal with mature granules was mainly performed via nitrite, probably due to the large granule size achieved. Nitrification efficiency was higher than 75% and occurred simultaneously with denitrification during the aerobic phase of the GSBR. A progressive accumulation of P-salts (probably apatite), was found from days 150 to 300, which could enhance the destabilization of granules at the end of the experimental period.

A granular airlift reactor enriched in ammonia oxidizing bacteria (AOB) was operated at 10 °C performing stable partial nitritation in the long-term. The reactor treated a synthetic low-strength influent during 250 days with an average nitrogen loading rate of 0.63 ± 0.06 g N L(-1) d(-1). Nitrate production was barely detected, being the average concentration in the effluent of 0.6 ± 0.3 mg N-NO3 L(-1). Furthermore, a suitable effluent for a subsequent reactor performing the anammox process was achieved. A maximum specific growth rate as high as 0.63 ± 0.05 d(-1) was determined by performing kinetic experiments with the granular sludge in a chemostat and fitting the results to the Monod model. Pyrosequencing analysis showed a high enrichment in AOB (41 and 65% of the population were identified as Nitrosomonas genus on day 98 and 233, respectively) and an effective repression of nitrite oxidizing bacteria in the long-term. Pyrosequencing analysis also identified the coexistence of nitrifying bacteria and heterotrophic psychrotolerant microorganisms in the granular sludge. Some psychrotolerant microorganisms are producers of cryoprotective extracellular polymeric substances that could explain the better survival of the whole consortia at cold temperatures.

Continuous feeding operation of an airlift reactor and its inoculation with mature aerobic granules allowed the successful treatment of a mixture of aromatic compounds (p-nitrophenol, o-cresol and phenol). Complete biodegradation of p-nitrophenol, o-cresol, phenol and their metabolic intermediates was achieved at an organic loading rate of 0.61 g COD L(-1)d(-1). Stable granulation was obtained throughout the long-term operation (400 days) achieving an average granule size of 2.0 ± 1 mm and a sludge volumetric index of 26 ± 1 mL g(-1) TSS. The identified genera in the aerobic granular biomass were heterotrophic bacteria able to consume aromatic compounds. Therefore, the continuous feeding regimen and the exposure of aerobic granules to a mixture of aromatic compounds make possible to obtain good granulation and high removal efficiency.

The influence of temperature (140 and 160 ◦ C) and oxygen partial pressure (2 and 9 bar) on the continuous catalytic wet air oxidation (CWAO) over activated carbon (AC) has been investigated for the removal of phenol, o-cresol and 2-chlorophenol in aqueous solutions. Seventy-twohour tests were performed in a fixed bed reactor in trickle flow regime. A commercial AC was employed as catalyst. The pollutant elimination effectiveness, the distribution of major reaction products and the AC behaviour were studied for each compound. Also, respirometric screening tests were completed to the effluents before and after each CWAO experiment to assess the biodegradability enhancement. The results show that pollutant disappearance, chemical oxygen demand (COD) removal, total organic carbon (TOC) abatement and biodegradability enhancement (fraction of COD readily biodegradable, %CODRB) were very sensitive to temperature but rather independent of the oxygen partial pressure (PO2 ). On the contrary, AC catalyst preservation was strongly influenced by both temperature and pressure. For instance, for phenol CWAO at 2 bar of PO2 ,a s temperature increased from 140 to 160 ◦ C, phenol conversion increased from 45% to 78%, COD removal from 33% to 65%, TOC abatement from 21% to 62% and %CODRB from 4% to 36%. Similar behaviour was found for the other model compounds tested, although the level of refractoriness was rather different. © 2007 Elsevier B.V. All rights reserved.

The aim of this work is to study the viability of the H2O2 Promoted Catalytic Wet Air Oxidation (PP-CWAO) process, using activated carbon (AC) as catalyst, to increase the biodegradability of phenolic aqueous solutions. Seventy-two hours experiments were performed in a trickle bed reactor at 140 8C and 2 bar of oxygen partial pressure. Feed concentrations, in terms of theoretical chemical oxygen demand (ThCOD), were 11.8 g COD l � 1 for phenol, 12.6 g COD l � 1 for o-cresol and 8.0 g COD l � 1 for p-nitrophenol. Air was used as main oxidant and 20% of the stoichiometric amount of H2O2needed for pollutant complete mineralisation was added as oxidation promoter. Adding H2O2to the CWAO process not only increases pollutant removal but also leads to higher mineralisation of the remaining oxidation products. For instance, removal of phenol, o-cresol and p-nitrophenol increase from 45, 33 and 15% in the CWAO process to 64, 64 and 49% in the PP-CWAO process. In addition, the PP-CWAO process leads to better biodegradability enhancements, when compared to CWAO, as demonstrated by the respirometric tests. However, it is still necessary to improve the oxidation step in order to assure more biodegradable effluents that could be combined with a subsequent biological wastewater plant. # 2007 Elsevier B.V. All rights reserved.

This study examines the feasibility of coupling a Catalytic Wet Air Oxidation (CWAO), with activated carbon (AC) as catalyst, and an aerobic biological treatment to treat a high-strength o-cresol wastewater. Two goals are pursued: (a) To determine the effect of the main AC/CWAO intermediates on the activated sludge of a municipal WasteWater Treatment Plant (WWTP) and (b) To demonstrate the feasibility of coupling the AC/CWAO effluent as a part of the influent of a municipal WWTP. In a previous study, a high-strength o-cresol wastewater was treated by AC/CWAO aiming to establish the distribution of intermediates and the biodegradability enhancement. In this work, the biodegradability, toxicity and inhibition of the most relevant intermediates detected in the AC/CWAO effluent were determined by respirometry. Also, the results of a pilot scale municipal WWTP study for an integrated AC/CWAO-aerobic biological treatment of this effluent are presented. The biodegradation parameters (i.e. maximum oxygen uptake rate and oxygen consumption) of main AC/CWAO intermediates allowed the classification of the intermediates into readily biodegradable, inert or toxic/ inhibitory compounds. This detailed study, allowed to understand the biodegradability enhancement exhibited by an AC/CWAO effluent and to achieve a successful strategy for coupling the AC/CWAO step with an aerobic biological treatment for a high-strength o-cresol wastewater. Using 30%, as COD, of AC/CWAO effluent in the inlet to the pilot scale WWTP, the integrated AC/CWAO-biological treatment achieved a 98% of total COD removal and, particularly, a 91% of AC/CWAO effluent COD removal without any undesirable effect on the biomass. � 2006 Elsevier Ltd. All rights reserved.

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.

Sewers are known as longitudinal reactors where gases such as methane, nitrous oxide and hydrogen sulphide can be produced. However, gaseous emissions have been mainly assessed in wastewater treatment plants (WWTP). This article presents a critical review of studies that quantify the generation of these gases in sewers and aims to identify the existing research gaps. Differences in sampling methods and site selection, as well as a limited number of studies, result in incoherent comparisons. To address some of these gaps, sampling campaigns were conducted in two Spanish cities. Results showed that wet wells were the most important sources of gases with concentrations up to 321 μg CH4 Lair−1 and 6.8 μg N2O Lair−1. Regarding emission factors, in the case of Calafell, the estimated annual emissions were 18.6 kg CH4 year−1 and 0.3 kg H2S year−1 in summer and 3.8 kg CH4 year−1 and 0.5 kg H2S year−1 in winter. About Betanzos, these values were 24.6 kg CH4 year−1 and 0.5 kg N2O year−1 in summer and 10 kg CH4 year−1 in winter. The summer campaign resulted in greater gas concentration than in the winter season for both cities, suggesting that temperature is a key parameter. We conclude that gas emissions from sewers are significant compared to those of WWTPs resulting in an important contribution to the carbon footprint. Further work needs to be done to assess the gas production along the entire sewer networks, which can result in very different emission factors depending on the sewer components.

The final publication is available at Springer via http://dx.doi.org/10.1007/s11269-015-0958-2 The environmental impacts resulting from sewer networks are best analysed from a life-cycle perspective to integrate the energy requirements into the infrastructure design. The energy requirements for pumping wastewater depend on the configuration of the city (e.g., climate, population, length of the sewer, topography, etc.). This study analyses and models the effect of such site-specific features on energy consumption and related effects in a sample of Spanish cities. The results show that the average annual energy used by sewers (6.4 kWh/capita and 0.014 kWh/m3 of water flow) must not be underestimated because they may require up to 50 % of the electricity needs of a typical treatment plant in terms of consumption per capita. In terms of Global Warming Potential, pumping results in an average of 2.3 kg CO2eq./capita. A significant positive relationship was demonstrated between the kWh consumed and the length of the sewer and between other factors such as the population and wastewater production. In addition, Atlantic cities can consume 5 times as much energy as Mediterranean or Subtropical regions. A similar trend was shown in coastal cities. Finally, a simple predictive model of the electricity consumption was presented that considers the analysed parameters.

In a world with an increasing urban population, analysing the construction impacts of sanitation infrastructures through Life Cycle Assessment (LCA) is necessary for defining the best environmental management strategies. In this study, the environmental impacts of one linear meter of sewer constructive solution were analysed for different pipe materials and diameters used in Southern Europe; a unit of different sewer appurtenances (pump, manhole and inspection chamber) was also considered. The impacts of the pipe materials were compared considering different lifespan periods and high-density polyethylene (HDPE) turned out to be the worst option, being polyvinyl chloride (PVC) and concrete the most favourable ones. Few data are available on the material and energy flows in the installation stage; therefore, a comparative analysis of trenches with sand and concrete bedding was conducted. The results show that the installation stage represents up to 80 % of the total life-cycle impact of the constructive solutions. Concrete pipes with half-concrete/half-sand bedding are the best option and produce 20–30 % of the impact of HDPE pipes with concrete bedding. Hence, designers should focus not only on the pipe but also on the trench model. A methodology was presented to enable the impact aggregation of the different sewer elements, and Betanzos (Spain) was selected to conduct a pilot study in small cities. In the future, studies will need to incorporate the use and maintenance stage, as it is not standard and varies according to the physical features of the cities. Finally, this study provides basic concepts for developing eco-efficiency indicators.

Industrial wastewater treatment plants must operate properly during the transient-state conditions often found in the industrial production. This study presents the performance of simultaneous partial nitritation and o-cresol biodegradation in a continuous aerobic granular reactor under sequentially alternating pollutant (SAP) scenarios. Three SAP scenarios were imposed during the operation of the granular reactor. In each one, a secondary recalcitrant compound (either p-nitrophenol (PNP), phenol or 2-chlorophenol (2CP)) were added for a short period of time to the regular influent containing only ammonium and o-cresol. Partial nitritation and o-cresol biodegradation were not inhibited by the presence of PNP or phenol and both compounds were fully biodegraded. On the contrary, the presence of 2CP strongly inhibited both processes within 2 days. However, the reactor was recovered in a few days. These findings demonstrate that treatment of complex industrial wastewaters with variable influent composition is feasible in a continuous aerobic granular reactor.

El títol de la versió pre-print de l'article és: Environmental assessment of a drinking water transport and distribution network in small to medium cities and application to a case study network Until now, few studies had focused on the environmental impact of the construction phase of a drinking water transport and distribution network (DWTDN). Using the life cycle assessment (LCA) methodology, this article compares the environmental impact of pipes made of different materials as constructive solutions for the DWTDN. Two pipe diameters (90 and 200 mm) commonly used in small to medium-sized cities are analysed. The results show that polyvinyl chloride (PVC), high density polyethylene (HDPE) and low density PE have similar environmental impacts in the case of 90 mm pipe diameter. In the case of 200 mm pipe diameter, ductile iron (DI) and glass fibre reinforced polyester show higher environmental impacts than HDPE and PVC, which in the case of DI are between 3 and 11 times higher than those of HDPE for all the midpoint impact categories. Regarding the different construction phases, installation has a higher percentage of environmental impact for 90 mm pipe diameter (40-68% for HDPE in all the impact categories) than for 200 mm pipe diameter (24-57% for an HDPE) due to the difference in the amount of material required for the manufacture of the pipe. The assessment methodology was applied to calculate the environmental burdens derived from a case study. The impact of the different elements of the case study network has been added to obtain the global impact. The potential reduction of the environmental impacts of the case study has been calculated substituting the whole actual network by less impacting constructive solutions. A potential reduction of between 6 and 16% of the impact has been found for the case study, although the savings might be greater in networks with greater abundance of more impacting pipe materials such as DI. This methodology allows the improvement of the network and the design of more eco-efficient DWTDN.

Several chemical industries produce wastewaters containing both, ammonium and phenolic compounds. As an alternative to treat this kind of complex industrial wastewaters, this study presents the simultaneous partial nitritation and o-cresol biodegradation in a continuous airlift reactor using aerobic granular biomass. An aerobic granular sludge was developed in the airlift reactor for treating a high-strength ammonium wastewater containing 950 ± 25 mg N-NH4(+) L(-1). Then, the airlift reactor was bioaugmented with a p-nitrophenol-degrading activated sludge and o-cresol was added progressively to the ammonium feed to achieve 100 mg L(-1). The results showed that stable partial nitritation and full biodegradation of o-cresol were simultaneously maintained obtaining a suitable effluent for a subsequent anammox reactor. Moreover, two o-cresol shock-load events with concentrations of 300 and 1000 mg L(-1) were applied to assess the capabilities of the system. Despite these shock load events, the partial nitritation process was kept stable and o-cresol was totally biodegraded. Fluorescence in situ hybridization technique was used to identify the heterotrophic bacteria related to o-cresol biodegradation and the ammonia oxidising bacteria along the granules.

The chemical and petrochemical industries produce wastewaters containing ammonium and phenolic compounds. Biological treatment of these wastewaters could be problematic due to the possible inhibitory effects exerted by phenolic compounds. The feasibility of performing simultaneous nitritation and p-nitrophenol (PNP) biodegradation using a continuous aerobic granular reactor was evaluated. A nitrifying granular sludge was bioaugmented with a PNP-degrading floccular sludge, while PNP was progressively added to the feed containing a high ammonium concentration. Nitritation was sustained throughout the operational period with ca. 85% of ammonium oxidation and less than 0.3% of nitrate in the effluent. PNP biodegradation was unstable and the oxygen limiting condition was found to be the main explanation for this unsteadiness. An increase in dissolved oxygen concentration from 2.0 to 4.5 mg O2 L(-1) significantly enhanced PNP removal, achieving total elimination. Acinetobacter genus and ammonia-oxidising bacteria were the predominant bacteria species in the granular biomass.

EAU+CDS; p-Nitrophenol (PNP) is widely used as a raw material in several industries, therefore it can be released to the environment, being mandatory the treatment of the PNP-contaminated industrial wastewaters. In this sense, the influence of temperature, oxygen partial pressure, type of catalyst, pH and ionic strength on the wet air oxidation (WAO) of a highly concentrated PNP wastewater was studied. Several 480 min batch tests have been performed and four Pt and Ru-based catalysts have been tested. The PNP elimination, total organic carbon (TOC) abatement and the intermediates distribution were monitored. Moreover, respirometric screening tests were completed after each experiment to assess the biodegradability enhancement of the catalytic WAO (CWAO) treated effluents. The results showed that PNP elimination was higher than 90% in most cases, being the temperature the most important operating parameter upon CWAO. Additionally, all the catalysts showed a similar behaviour in terms of PNP and TOC conversions. Besides. CWAO increased the biodegradability by more than 50% in most of the tested conditions, being the carboxylic acid fraction the key factor to be taken into account, as the best biodegradability enhancement was observed when this fraction was the highest. The partial pressure of oxygen had a negligible effect on the biodegradability enhancement. The ionic strength influence over the CWAO was studied and even though it did not affect the CWAO performances, the presence of NaCl in the solution resulted in a decrease of the effluent biodegradability. In terms of pH, the most suitable scenario was the one with no pH adjustment. Conclusively, this work demonstrated that an integrated CWAO and biological treatment would allow an easy removal of PNP and the intermediates formed during the first step of the treatment, being the best CWAO conditions for this pre-treatment to work at 180 degrees C under stoichiometric oxygen pressure (i.e. 7.6 bar of oxygen partial pressure) with a Ru/TiO2 catalyst. (C) 2012 Elsevier B.V. All rights reserved.

BACKGROUND: Confocal laser scanning microscopy (CLSM) provides critical information of the presence of autofluorescence signals inherent to the samples under study, which may interfere with probe fluorescence. Therefore, it is important to determine the emission spectrum of the biomass autofluorescence under study in order to avoid, as much as possible, this wavelength range when selecting specific probe emissions and to modify, if necessary, the original fluorescence in situ hybridization (FISH) protocol in order to enhance probes signals. RESULTS: Microbial characterization of a p-nitrophenol-degrading activated sludge through a conventional FISH protocol was not possible because the fluorescence signal of the unlabelled cells was similar to or even higher than the signal emitted by hybridized cells, impeding the separation of the two signals and therefore, preventing biomass characterization. An optimized but simple FISH approach was developed in order to ease observation of the p-nitrophenol-degrading bacteria studied in this work. The final results allowed identification of Arthrobacter sp. (Micrococcaceae family) and genus Acinetobacter (Moraxellaceae family) in the p-nitrophenol-degrading activated sludge, whereas no hybridization was found for Pseudomonas spp. CONCLUSIONS: The hypothesis of a mixed culture following, at the same time, different degradation pathways has been confirmed through the microbial characterization of enriched p-nitrophenol-degrading activated sludge. Copyright © 2011 Society of Chemical Industry

High-strength ammonium wastewaters containing phenolic compounds are generated by several industries. A possible solution for these industrial wastewaters could be the combination of an advanced oxidation process with a biological nitrogen removal process via nitrite. Therefore, knowledge of the interactions between both treatment steps is needed, in particular for the potential inhibitory effect of quinone-like intermediates from the oxidation of phenolic compounds (hydroquinone, catechol and p-benzoquinone) over partial nitrification. In this sense, the aim of this work was to study the impact of quinone-like compounds over an activated sludge enriched in ammonium-oxidising bacteria (AOB) by means of respirometry and titrimetry. The results show that nitrification was progressively inhibited as quinone-like compounds concentration was increased, with IC(50) values at 1h of exposure time of 3.1+/-0.5, 11+/-1 and 2.8+/-0.4mgL(-1) for hydroquinone, catechol and p-benzoquinone, respectively. Also, it was established that exposure time between quinone-like compounds and the enriched AOB sludge was a crucial factor when dealing with inhibition.

La importancia de la evaluación institucional del profesorado viene determinada en la medida que genera cambios positivos en la calidad educativa, es decir, cuando resulta útil y funcional para generar un proceso de auto-reflexión del profesor y de la propia institución sobre la práctica docente. La información generada debería ser utilizada para la mejora continua del proceso educativo, de tal manera que su alcance y consecuencias deberían ser evidentes para toda la comunidad universitaria. Por consiguiente, debe de ser un punto de inflexión que muestre y evalúe la diversidad de formas y estrategias de enseñar, de aprender y de evaluar, así como también debe servir como plataforma para compartir reflexiones y experiencias sobre la calidad educativa y sobre las propuestas de mejora integral del proceso entorno a temas e inquietudes sobre el ejercicio de la práctica docente. En este sentido, el portafolio docente se constituye como una herramienta que representa una oportunidad para repensar y evaluar la docencia del profesorado, ya que facilita la autogestión, la autorregulación, el aprendizaje continuo, la autovaloración y la planificación del trabajo futuro. Es por tanto, una herramienta idónea para la reflexión del profesorado sobre su práctica docente. En este marco y como miembros del Grupo de interés (Gi) en Portafolios Docentes (Gi-PD) de la Universidad Autónoma de Barcelona (UAB) formado por profesores e investigadores de diversas facultades y departamentos de dicha Universidad, se considera de suma relevancia dedicar un espacio de este monográfico al portafolio docente, haciendo hincapié en su posible incidencia en la evaluación institucional y en la mejora de la calidad educativa._____________________________________________________The importance of the institutional evaluation is determined by the ability to generate positive changes into the educational quality, i.e. when is so useful and functional that serves to generate self-reflection and awareness about teaching practise, from both, the professor and the own institution. The information generated in this process must help for the continuous improvement of the educative process, in such a way that its results and consequences become evident for all the university community. Therefore, it must of be an inflexion point that shows and evaluates the diversity of forms and strategies used for teaching, for learning and for evaluating, as well as it should become in a platform for sharing reflections and experiences over the educational quality and for making proposals for the integral improvement of all the process. In this sense, the teaching portfolio is an opportunity to rethink and to evaluate teaching, because, it eases self-management, self-regulation, continuous learning, self-assessment and self-planning of the future work. It is, therefore, a suitable tool for the reflection of the teaching staff about their educational practice. In this frame, and being members of the Group of Interest (Gi) in Teaching Portfolios (Gi-PD) of the Universitat Autònoma de Barcelona (UAB) composed by professors and researchers of diverse faculties and departments of this University, considers of extreme relevance to dedicate a space of this monographic to the Teaching Portfolio insisting on its possible incidence in the institutional evaluation and in the improvement of the educational quality.

Nowadays, there are increasingly stringent regulations requiring more and more treatment of industrial effluents to generate product waters which could be easily reused or disposed of to the environment without any harmful effects. Therefore, different advanced oxidation processes were investigated as suitable precursors for the biological treatment of industrial effluents containing phenol. Wet air oxidation and Fenton process were tested batch wise, while catalytic wet air oxidation and H2O2-promoted catalytic wet air oxidation processes were studied in a trickle bed reactor, the last two using over activated carbon as catalyst. Effluent characterisation was made by means of substrate conversion (using high liquid performance chromatography), chemical oxygen demand and total organic carbon. Biodegradation parameters (i.e. maximum oxygen uptake rate and oxygen consumption) were obtained from respirometric tests using activated sludge from an urban biological wastewater treatment plant (WWTP). The main goal was to find the proper conditions in terms of biodegradability enhancement, so that these phenolic effluents could be successfully treated in an urban biological WWTP. Results show promising research ways for the development of efficient coupled processes for the treatment of wastewater containing toxic or biologically non-degradable compounds.