Aerobic Phase Research Articles

Real-time control suitable for feed distribution strategy based on ammonia introduced in SBR sub-cycle: Field experience and validation for pilot-scale single-stage deammonification

Feed distribution based on ammonium introduced in a sequencing batch reactor (SBR) was applied to a 24 m3 single-stage deammonification to treat reject water. With field experience, the conventional SBR exhibited limited adaptability to fluctuations in influent load. This study proposed a new approach capable of coping with the influent fluctuations. The pH and alkalinity were clustered as factors that affect the NRE, which was related to the ammonium behavior in the SBR sub-cycle. To establish the real-time control, the pH value, which has the highest correlation with them, was applied. In the SBR feeding phase, their variations rather than pH values were useful in predicting the ammonium behavior. This was formulated so that the reject water in the anoxic and aerobic phases was introduced semi-continuously. In the aerobic phase, the pH was suitable for determining the partial nitritation break-point. Its efficacy was verified in a pilot. A stable NRE of 90 ± 2.1 % was achieved even though the influent nitrogen fluctuated from 508.0 to 744.9 mg/L. In addition, as the SBR parameters (HRT, aerobic cycle, and exchange ratio) were optimized in real-time, the nitrogen removal rate further improved by 0.15 kg/m3/d.

Antibiotics inhibit methanogenesis during municipal solid waste decomposition

Municipal solid waste (MSW) landfills are significant sources of antibiotics. However, the effects of antibiotics on MSW decomposition process and methanogenesis during solid waste decomposition remain insufficiently characterized. This study investigated the effects of environmentally relevant concentrations (ERCs) of antibiotics (200 μg/kg for each antibiotic) on MSW decomposition and methanogenesis in bioreactors treated with and without eight antibiotics (three tetracyclines, three sulfonamides, and two macrolides). The key phases of MSW decomposition, namely the aerobic, anaerobic acid, and methanogenic phases, were determined by analyzing the key physiochemical parameters of the leachate, including pH, chemical oxygen demand, and biochemical oxygen demand. We assessed the bacterial and archaeal compositions, along with the abundance of the gene encoding the alpha subunit of methyl-coenzyme M reductase (mcrA), during MSW decomposition using high throughput 16S ribosomal RNA (rRNA) gene sequencing and quantitative polymerase chain reactions, respectively. Our results revealed that antibiotics significantly altered the compositions of bacteria and methanogens, leading to decreased mcrA abundance and methanogenesis. Specifically, antibiotics inhibited cellulose-degrading bacteria (Firmicutes) and archaea (E2) in the anaerobic acid phase and hydrolytic bacteria (Proteobacteria) in the methanogenic phase, resulting in lower degradation of biodegradable matter than that of the biodegradation without antibiotics treatment. However, the typical MSW decomposition process indicated by the key decomposition phases was successfully separated in both bioreactors, suggesting that antibiotics did not affect overall MSW decomposition process development or the associated individual decomposition phases establishment. These findings suggest that antibiotics at ERCs may inhibit methanogenesis during MSW decomposition, thereby providing fundamental information for methane management and climate change studies.

Recovering phosphorus and lithium separately from wastewater and brine using a novel coupled biofilm-precipitation system

Phosphorus (P) and lithium (Li) are scarce resources. To address the situation of resource scarcity, a novel coupled biofilm-precipitation system was proposed to recover P and Li separately from wastewater and brine. The results indicated the denitrifying polyphosphate accumulating organisms (DPAOs) suitable for this operating process promoted their denitrifying phosphorus removal (DPR) capabilities at the aerobic phase, increasing the total P content in the biofilm (TPbiofilm) to 60.7 ± 2.7 mg/g SS. Moreover, the DPAOs performed a metabolic shift from glycogen accumulation metabolism (GAM) to polyphosphate accumulation metabolism (PAM) when TPbiofilm increased, which caused more P being released by DPAOs, and the P concentration of the enriched stream to rise to 185.8 ± 3.4 mg/L. Furthermore, the quadratic regression model was suitable for the struvite crystallization (R2 = 0.87–0.88) in the P recovery stage, and the pure struvite was obtained with a P recovery efficiency was 96.3–97.2 %. The pure lithium carbonate crystals were created with a Li recovery efficiency was 93.3–97.2 % in the Li recovery stage. Additionally, the enriched P stream was applied to natural brine, and pure struvite and lithium carbonate crystals were produced with the P and Li recovery efficiency was 94.7 % and 93.5 %, respectively. In general, using enriched P stream as P source to separate magnesium from brine and thus recover Li was a feasible option. This study provided support for the recovery of P and Li.

Influence of dissolved oxygen on phosphorus removal by polyphosphate-accumulating organisms biofilm: Performance and metabolic response

The present study focused on investigating the effect of dissolved oxygen (DO) concentration on phosphorus (P) transformation and metabolism in the polyphosphate-accumulating organisms (PAOs)-biofilm system. Two biofilm sequencing batch reactors (BSBRs) with high-DO (6 mg/L, BSBR-H) versus low-DO (2 mg/L, BSBR-L) concentrations were typically operated for 90 days. Collectively, the high DO concentration in aerobic phase would force PAOs to preferentially and rapidly perform phosphate metabolism and be beneficial for them to establish the dominant ecological niche. Clear differences in stoichiometry and kinetics indicated a glycolytic pathway in BSBR-L, while it shifted to polyphosphate hydrolysis in BSBR-H. The expression of functional genes suggested that the high-affinity P transport system was mainly responsible for P transformation in BSBR-H while the low-affinity P transport system was accountable for BSBR-L. Moreover, the BSBR-H showed relatively higher abundances of Pseudomonas while Tetrasphaera were the most dominant PAOs in BSBR-L. Dechloromonas contributed substantially to poly-P metabolism by occupying the largest proportion of ppk1/2 and ppx genes in both BSBRs.

The effect of three different pre-match warm-up structures on male professional soccer players' physical fitness.

Optimizing the soccer players' match preparation is one of the most relevant concerns of coaches for strength and conditioning training. Thus, the aim of this study was to analyze the effects of three pre-match warm-up structures on the physical condition of male professional soccer players. Seventeen male professional soccer players (age: 20.9 ± 2.4 years) of one Tunisian Professional Soccer League team participated in this study. Players performed three times a typical pre-match warm-up (WU) [aerobic phase (AE); neuromuscular phase (NM); velocity phase (VL); and ball-specific phase (BS) variating the order of the included phases/exercises: WU1 (AE + BS + NM + VL); WU2 (AE + NM + VL + BS); and WU3 (AE + VL + BS + NM). After each warm-up phase, players completed the following physical fitness tests: linear sprint test, countermovement jump test, 15-m ball dribbling agility test and ball shooting test. Additionally, the rate of perceived exertion (RPE) was registered after each warm-up. The results indicated significant differences between WU1 and WU3, with better results in the ball shooting test and RPE in WU3. In addition, there were no significant differences in the other variables and between other warm-up structures. These findings could be of great interest for coaches to the strength and conditioning coaches for professional soccer teams in order to improve the players physical performance and perceived exertion.

Comparison of aerobic and anoxic-oxic sequential batch reactors for treating textile wastewater

ABSTRACT The discharge of untreated textile dyeing wastewater containing azo dyes has significant ecological consequences. The incomplete biodegradation of these dyes can produce harmful and carcinogenic aromatic amines (AAs), which pose a threat to the environment. This study evaluates the treatment of real textile dyeing wastewater containing azo dyes by two different systems: an anoxic sequential batch reactor (A/O-SBR) and an aerobic sequential batch reactor (A-SBR). The effects of hydraulic retention time (HRT) on both systems were investigated in terms of chemical oxygen demand (COD), total nitrogen (TN), color, and AAs removal. Ranging between 85% and 92%, the COD removal efficiency was almost similar in the A/O-SBR and A-SBR systems, suggesting that the aerobic phase is primarily responsible for COD removal. However, A/O-SBR showed higher removal of color (90%) than A-SBR (75%) due to the presence of an anoxic phase. HRT has a significant impact on color removal in both systems. However, there was no significant effect on COD removal when HRT exceeded 12 h. According to LC-MS/MS analysis, increasing the HRT from 12 h to 24 h increased the AAs concentration in the anoxic phase, from 253 ng/L to 261 ng/L and slightly decreased the AAs concentration in the aerobic phase from 107 ng/L to 102 ng/L. This resulted in an overall improvement in both dye and AAs removal. The presence of aerobic phase in A/O-SBR and A-SBR demonstrates strong AAs removal capacity. GC-MS/MS analysis indicated that as the HRT of A/O-SBR and A-SBR increased, the number of by-products increased.

Pineapple wastewater as co-substrate in treating real alkaline, non-biodegradable textile wastewater using biogranulation technology

This study was to develop biogranules using a sequencing batch reactor (SBR) and to evaluate the effect of pineapple wastewater (PW) as a co-substrate for treating real textile wastewater (RTW). The biogranular system cycle was 24 h (2 stages of phase), with an anaerobic phase (17.8 h) followed by an aerobic phase (5.8 h) for every stage of the phase. The concentration of pineapple wastewater was the main factor studied in influencing COD and color removal efficiency. Pineapple wastewater with different concentrations (7, 5, 4, 3, and 0% v/v) makes a total volume of 3 L and causes the OLRs to vary from 2.90 to 0.23 kg COD/m3day. The system achieved 55% of average color removal and 88% of average COD removal at 7%v/v PW concentration during treatment. With the addition of PW, the removal increased significantly. The experiment on the treatment of RTW without any added nutrients proved the importance of co-substrate in dye degradation.

Effect of influent ammonia nitrogen concentration on the phosphorus removal process in the aerobic granular sludge reactor

The effects of different influent ammonia nitrogen (NH3-N) concentrations (stage I to IV: 20, 40, 60 and 80 mg/L) on the phosphorus (P) removal process were studied in an aerobic granular sludge (AGS) reactor under anaerobic/aerobic operating conditions. The phosphorous removal performance kept stable at first (stage I and II) and then significantly deteriorated at further increase of influent NH3-N concentration (stage III and IV). On the process of microbial metabolism, further increase of NH3-N aggravated the competition between phosphate accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs) for carbon sources in the anaerobic phase, and weakened the P absorption capacity of PAOs in the aerobic phase. Denitrifying phosphate accumulating organisms (DPAOs) showed higher resistance to the increase of NH3-N concentration than traditional PAOs. On the functional structure of the system, microorganisms related to phosphorus removal in the system were mainly enriched in the granules, while microorganisms with heterotrophic denitrifying function dominated the sludge flocs to obtain higher growth advantage at high ammonia nitrogen concentration. The results of this study provide more insight into the biological stability of AGS systems.

Roles of high/low nucleic acid bacteria in flocs and probing their dynamic migrations with respirogram

Bacterial migration is crucial for the stability of activated sludge but rarely reported. The static distribution was explored by changes in bacteria concentration with extracellular polymeric substances (EPS) extractions. Next, denitrification and aeration were conducted as normal running conditions for examining the bacterial migration between floc-attached and dispersed growth. Above observations were further explored by conducting copper ion (Cu2+) shock as an extreme running condition. After extracting EPS, low nucleic acid (LNA) bacteria migrated from the sludge to the supernatant primarily, and high nucleic acid (HNA) bacteria remained in the residual sludge, suggesting that HNA bacteria mainly distributed inside the sludge while LNA bacteria outside the sludge. During the denitrification process, LNA bacteria migrated out of flocs, which increased by 6.94 × 106 events/mL in the supernatant. During the feast phase of aeration, LNA bacteria grew attached to flocs, causing the increased flocs diameter from 45.60 to 47.40 μm. During the following aerobic famine phase, LNA bacteria grew dispersedly, but HNA bacteria remained unchanged. However, a further severe famine phase drove HNA bacteria to be dispersed, breaking flocs with the decreased diameter from 48.10 to 46.50 μm. When the Cu2+ shock was employed, LNA and HNA bacteria increased but the LNA/HNA ratio decreased in the supernatant, indicating more HNA bacteria migrating to the dispersed phase. From a structural perspective, HNA bacteria distributed inside the sludge and functioned as the backbone of flocs, undertaking the maintenance of flocs stability primarily; while LNA bacteria distributed outside the sludge and functioned as filling materials, having a secondary influence on flocs stability. These processes were also probed by respirogram exactly, correlating the system-scale measurement and microscale migrations and providing an early warning signal under abnormal circumstances. The processed HNA-backbone theory is promising for regulating the stability of activated sludge based on bacterial migrations.

Development of yeast aerobic granules for long-term continuous bioethanol production from rice straw hydrolysate

For the first time application of aerobic granulation technology has been demonstrated for bioethanol production. A reactor was fabricated for ethanol production from rice straw hydrolysate (RSH) using Saccharomyces cerevisiae aerobic granules. The yeast granules were developed within 4–6 days by alternate aerobic mixing phase and settling phase without airflow of 8 h and 4 h, respectively. These yeast granules were found to produce ethanol (34.42 g/L) from pure glucose (80 g/L). A column filter was designed using activated charcoal, silica, cotton, and concrete aggregate to eliminate toxic impurities from RSH. Compared to unfiltered RSH, the filtered one was found to be more effective in ethanol production. A maximum of 16.18 g/L ethanol was produced from filtered RSH containing 10 g/L reducing sugar supplemented with pure glucose (40 g/L). It was possible to continuously run the process for more than 60 days. This study for the first time demonstrates continuous bioethanol production for an extended period by repeated use of yeast in the form of novel aerobic granules. This new concept has the potential to improve bioethanol production efficiencies of existing biorefineries.

Comparative metagenomics and microbial dynamics of jute retting environment.

Jute, eco-friendly natural fiber, depends on conventional water-based microbial retting process that suffers from the production of low-quality fiber, restricting its diversified applications. The efficiency of water retting of jute depends on plant polysaccharide fermenting pectinolytic microorganisms. Understanding the phase difference in retting microbial community composition is crucial to provide knowledge on the functions of each member of microbiota for the improvement of retting and fiber quality. The retting microbiota profiling of jute was commonly performed previously using only one retting phase with culture-dependent methods which has limited coverage and accuracy. Here, for the first we have analyzed jute retting water through WGS metagenome approach in three phases (pre-retting, aerobic retting, and anaerobic retting phases) and characterized the microbial communities both culturable and non-culturable along with their dynamics with the fluctuation of oxygen availability. Our analysis revealed a total of 25.99 × 104 unknown proteins (13.75%), 16.18 × 105 annotated proteins (86.08%), and 32.68 × 102 ribosomal RNA (0.17%) in the pre-retting phase, 15.12 × 104 unknown proteins (8.53%), 16.18 × 105 annotated proteins (91.25%), and 38.62 × 102 ribosomal RNA (0.22%) in the aerobic retting phase, and 22.68 × 102 ribosomal RNA and 80.14 × 104 (99.72%) annotated protein in the anaerobic retting phase. Taxonomically, we identified 53 different phylotypes in the retting environment, with Proteobacteria being the dominant taxa comprising over 60% of the population. We have identified 915 genera from Archaea, Viruses, Bacteria, and Eukaryota in the retting habitat, with anaerobic or facultative anaerobic pectinolytic microflora being enriched in the anoxic, nutrient-rich retting niche, such as Aeromonas (7%), Bacteroides (3%), Clostridium (6%), Desulfovibrio (4%), Acinetobacter (4%), Enterobacter (1%), Prevotella (2%), Acidovorax (3%), Bacillus (1%), Burkholderia (1%), Dechloromonas (2%), Caulobacter (1%) and Pseudomonas (7%). We observed an increase in the expression of 30 different KO functional level 3 pathways in the final retting stage compared to the middle and pre-retting stages. The main functional differences among the retting phases were found to be related to nutrient absorption and bacterial colonization. These findings reveal the bacterial groups that are involved in fiber retting different phases and will facilitate to develop future phase-specific microbial consortia for the improvement of jute retting process.

Understanding the impacts of intermittent electro field on the bioelectrochemical aniline degradation system: Performance, microbial community and functional enzyme

On account of the lack of a sustainable electron donor source and the inhibitory effect of aniline on denitrogenation make it tough to achieve simultaneous removal of aniline and nitrogen. Herein, the strategy of adjusting electric field mode was applied to the electro-enhanced sequential batch reactors (E-SBRs: R1 (continuous ON), R2 (2 h-ON/2 h-OFF), R3 (12 h-ON/12 h-OFF), R4 (in the aerobic phase ON), R5 (in the anoxic phase ON)) to treat aniline wastewater. Aniline removal rate reached approximately 99% in the five systems. Decreasing electrical stimulation interval from 12 to 2 h significantly improved the electron utilization efficiency for aniline degradation and nitrogen metabolism. The total nitrogen removal was achieved from 70.31% to 75.63%. Meanwhile, the hydrogenotrophic denitrifiers of Hydrogenophaga, Thauera, and Rhodospirillales, enriched in reactors of minor electrical stimulation interval. Accordingly, the expression of functional enzyme related to electron transport was incremental with the proper electrical stimulation frequency.

Nanoporous Gold: From Structure Evolution to Functional Properties in Catalysis and Electrochemistry.

Nanoporous gold (NPG) is characterized by a bicontinuous network of nanometer-sized metallic struts and interconnected pores formed spontaneously by oxidative dissolution of the less noble element from gold alloys. The resulting material exhibits decent catalytic activity for low-temperature, aerobic total as well as partial oxidation reactions, the oxidative coupling of methanol to methyl formate being the prototypical example. This review not only provides a critical discussion of ways to tune the morphology and composition of this material and its implication for catalysis and electrocatalysis, but will also exemplarily review the current mechanistic understanding of the partial oxidation of methanol using information from quantum chemical studies, model studies on single-crystal surfaces, gas phase catalysis, aerobic liquid phase oxidation, and electrocatalysis. In this respect, a particular focus will be on mechanistic aspects not well understood, yet. Apart from the mechanistic aspects of catalysis, best practice examples with respect to material preparation and characterization will be discussed. These can improve the reproducibility of the materials property such as the catalytic activity and selectivity as well as the scope of reactions being identified as the main challenges for a broader application of NPG in target-oriented organic synthesis.

Catalytic potential of sustainable dinuclear (Cu2+ and ZrO2+) metal organic incorporated frameworks with comprehensive biological studies

BackgroundThe high coordination ability of dihydrazone derivatives with metals of different valents, new homo dinuclear complexes of low and high valent ions of Cu2+ and ZrO2+ (CuLss and ZrOLss, respectively) were constructed via their coordination with diisatin succinyldihydrazone ligand (H2Lss). In which, the structure confirmation of H2Lss and its MLss complexes were achieved by different distinguished spectral tools. MethodsThe two novel MLss complexes were constructed by 2: 1 molar amounts of M2+ (Cu2+ or ZrO2+) ion to the H2Lss mole in DMF. Their catalytic action was examined under aerobic and homogeneous phase in the productive benzyl alcohol redox protocol within an aqueous H2O2. The antimicrobial and anticancer activities of H2Lss, CuLss and ZrOLss were investigated. In addition, their interaction with calf thymus DNA (ctDNA) was studied through spectrophotometric and viscometric techniques. The significant findingsAppreciable productivity was recognized with the yielded amounts of benzaldehyde (the corresponded selective oxide product) with both catalysts. However, CuLss represents more classified action by 92% yielding of benzaldehyde (for about 5 h at reaction temperature 60 °C with 0.005 mmol of its loaded amount), whereas, ZrOLss showed less efficacy with 87% (for 3 h at temperature of the reaction 70 °C with 0.005 mmol loaded amount). The catalytic progress referred to the nature of metal ion, which could be interpreted in the catalytic mechanism, i.e. the oxygen transfer pathway. The two MLss complexes exhibited more significant inhibiting affect against the bacterial and fungal strains and as well as the cancer cell lines than those of the free H2Lss, pointing to the function of M2+ ion in their MLss complexes. CuLss showed more interaction potential with ctDNA more than that of ZrOLss according to the Kb, the binding constants, (= 16.51 and 14.37 × 107 mol−1.dm3), also on the derived values of the Gibbs’ free energy values (ΔGb≠ = -46.39 and -45.61 kJ.mol−1), respectively, however, both CuLss and VOLss exhibited higher reactivity over their H2Lss (Kb = 10.87 × 107 mol−1.dm3 and ΔGb≠ = -43.75 kJ.mol−1) referring to the type and nature of interaction depending on the M2+ ion to progress their reactivity towards ctDNA.

Integration of EBPR with mainstream anammox process to treat real municipal wastewater: Process performance and microbiology

The mainstream application of anaerobic ammonium oxidation (anammox) for sustainable N removal remains a challenge. Similarly, with recent additional stringent regulations for P discharges, it is imperative to integrate N with P removal. This research studied integrated fixed film activated sludge (IFAS) technology to simultaneously remove N and P in real municipal wastewater by combining biofilm anammox with flocculent activated sludge for enhanced biological P removal (EBPR). This technology was assessed in a sequencing batch reactor (SBR) operated as a conventional A2O (anaerobic-anoxic-oxic) process with a hydraulic retention time of 8.8 h. After a steady state operation was reached, robust reactor performance was obtained with average TIN and P removal efficiencies of 91.3 ± 4.1% and 98.4 ± 2.4%, respectively. The average TIN removal rate recorded over the last 100 d of reactor operation was 118 mg/L·d, which is a reasonable number for mainstream applications. The activity of denitrifying polyphosphate accumulating organisms (DPAOs) accounted for nearly 15.9% of P-uptake during the anoxic phase. DPAOs and canonical denitrifiers removed approximately 5.9 mg TIN/L in the anoxic phase. Batch activity assays, which showed that nearly 44.5% of TIN were removed by the biofilms during the aerobic phase. The functional gene expression data also confirmed anammox activities. The IFAS configuration of the SBR allowed operation at a low solid retention time (SRT) of 5-d without washing out biofilm ammonium-oxidizing and anammox bacteria. The low SRT, combined with low dissolved oxygen and intermittent aeration, provided a selective pressure to washout nitrite-oxidizing bacteria and glycogen-accumulating organisms, as relative abundances of

Enhancing phosphorus removal of photogranules by incorporating polyphosphate accumulating organisms

Photogranules are a novel wastewater treatment technology that can utilize the sun's energy to treat water with lower energy input and have great potential for nutrient recovery applications. They have been proven to efficiently remove nitrogen and carbon but show lower conversion rates for phosphorus compared to established treatment systems, such as aerobic granular sludge. In this study, we successfully introduced polyphosphate accumulating organisms (PAOs) to an established photogranular culture. We operated photobioreactors in sequencing batch mode with six cycles per day and alternating anaerobic (dark) and aerobic (light) phases. We were able to increase phosphorus removal/recovery by 6 times from 5.4 to 30 mg/L/d while maintaining similar nitrogen and carbon removal compared to photogranules without PAOs. To maintain PAOs activity, alternating anaerobic feast and aerobic famine conditions were required. In future applications, where aerobic conditions are dependent on in-situ oxygenation via photosynthesis, the process will rely on sunlight availability. Therefore, we investigated the feasibility of the process under diurnal cycles with a 12-h anaerobic phase during nighttime and six short cycles during the 12 h daytime. The 12-h anaerobic phase had no adverse effect on the PAOs and phototrophs. Due to the extension of one anaerobic phase to 12 h the six aerobic phases were shortened by 47% and consequently decreased the light hours per day. This resulted in a decrease of phototrophs, which reduced nitrogen removal and biomass productivity up to 30%. Finally, we discuss and suggest strategies to apply PAO-enriched photogranules at large-scale.

Microbial community-based production of single cell protein from soybean-processing wastewater of variable chemical composition

The use of food-processing wastewaters to produce microbial biomass-derived single cell protein (SCP) is a sustainable way to meet the global food demand. Microbial community-based approaches to SCP production have the potential benefits of lower costs and greater resource recovery compared to pure cultures, yet they have received scarce attention. Here, SCP production from soybean-processing wastewaters using their existent microbial communities was evaluated. Six sequencing batch reactors of 4.5-L working volume were operated at 30 °C for 34 d in cycles consisting of 3-h anaerobic and 9-h aerobic phases. Four reactors received no microbial inoculum and the remaining two were amended with 1.5 L of a mixed culture from a prior SCP production cycle. Reactors produced more SCP when fed with wastewaters of higher soluble total Kjeldahl nitrogen (sTKN) content. The protein yield in biomass ranged from 0.53 to 3.13 g protein/g sTKN, with a maximum protein content of 50 %. The average removal of soluble chemical oxygen demand (sCOD) and soluble total nitrogen (sTN) was 92 % and 73 %, respectively. Distinct microbial genera were enriched in all six bioreactors, with Azospirillum, Rhodobacter, Lactococcus, and Novosphingobium dominating. The study showed that constituents in soybean wastewater can be converted to SCP and demonstrated the effect of variable influent wastewater composition on SCP production.

Turnover of the extracellular polymeric matrix of granules performing biological phosphate removal

Polyphosphate accumulating organisms (PAOs) are responsible for enhanced biological phosphate removal (EBPR) from wastewater, where they grow embedded in a matrix of extracellular polymeric substances (EPS). EPSs comprise a mixture of biopolymers like polysaccharides or (glyco)proteins. Despite previous studies, little is known about the dynamics of EPS in mixed cultures, and their production by PAOs and potential consumption by flanking microbes. EPSs are biodegradable and have been suggested to be a substrate for other organisms in the community. Studying EPS turnover can help elucidate their biosynthesis and biodegradation cycles. We analyzed the turnover of proteins and polysaccharides in the EPS of an enrichment culture of PAOs relative to the turnover of internal proteins. An anaerobic-aerobic sequencing batch reactor (SBR) simulating EBPR conditions was operated to enrich for PAOs. After achieving a stable culture, carbon source was switched to uniformly 13C-labeled acetate. Samples were collected at the end of each aerobic phase. EPSs were extracted by alkaline treatment. 13C enrichment in proteins and sugars (after hydrolysis of polysaccharides) in the extracted EPS were measured by mass spectrometry. The average turnover rate of sugars and proteins (0.167 and 0.192 d−1 respectively) was higher than the expected value based on the solid removal rate (0.132 d−1), and no significant difference was observed between intracellular and extracellular proteins. This indicates that EPS from the PAO enriched community is not selectively degraded by flanking populations under stable EBPR process conditions. Instead, we observed general decay of biomass, which corresponds to a value of 0.048 d−1.Key Points• Proteins showed a higher turnover rate than carbohydrates.• Turnover of EPS was similar to the turnover of intracellular proteins.• EPS is not preferentially consumed by flanking populations.

Remedial trial of sequential anoxic/oxic chemico-biological treatment for decontamination of extreme hexachlorocyclohexane concentrations in polluted soil.

During production of γ-hexachlorocyclohexane (γ-HCH), thousands of tons of other isomers were synthesized as byproducts, and after dumping represent sources of contamination for the environment. Several microbes have the potential for aerobic and anaerobic degradation of HCHs, and zero-valent iron is an effective remediation agent for abiotic dechlorination of HCHs, whereas the combination of the processes has not yet been explored. In this study, a sequence of anoxic/oxic chemico-biological treatments for the degradation of HCHs in a real extremely contaminated soil (10-30g/kg) was applied. Approximately 1500kg of the soil was employed, and various combinations of reducing and oxygen-releasing chemicals were used for setting up the aerobic and anaerobic phases. The best results were obtained with mZVI/nZVI, grass cuttings, and oxygen-releasing compounds. In this case, 80 % removal of HCHs was achieved in 129 days, and 98 % degradation was achieved after 1106 days. The analysis of HCHs and their transformation products proved active degradation when slight accumulation of the transformation product during the anaerobic phase was followed by aerobic degradation. The results document that switching between aerobic and anaerobic phases, together with the addition of grass, also created suitable conditions for the biodegradation of HCHs and monochlorobenzene/benzene by microbes.

ANÁLISE DE DESEMPENHO DO REATOR ANAERÓBIO DE CIRCULAÇÃO INTERNA NO TRATAMENTO DE EFLUENTES EM UMA INDÚSTRIA DE BEBIDAS

The most used wastewater treatment process in the beverage industry consists of the following steps: preliminary treatment, where coarse solids are removed, secondary treatment (anaerobic phase), responsible for the degradation of most of the organic load of the effluent, and tertiary treatment ( aerobic phase), which serves as an after-treatment, removing pollutants that remain after the anaerobic phase. In this treatment process, the secondary treatment (anaerobic phase) is the step that most contributes to the removal of pollutants from the effluent, therefore, the objective of this study is to analyze the performance of the anaerobic reactor with internal circulation in the treatment of effluents from a large industry of beverages, producer of soft drinks.