Effluent Fractions Research Articles

Performance of up-flow anaerobic sludge blanket-membrane bioreactor (UASB-MBR) for treating rice vermicelli and flour wastewater

A laboratory-scale UASB-MBR experiment using cross-flow microfiltration was conducted to treat rice vermicelli and flour wastewater to determine the optimum operating condition and identify the fouling pattern. The chemical oxygen demand (COD) and biochemical oxygen demand (BOD5) removal were about 99 % under 0.18 g COD/g MLVSS/d of the F/M ratio. The critical pressure condition was observed in the 0.25–0.75 bars range for sludge granule concentration between 1–7 g/L, with no significant change in permeate flux when TMP was over 0.75 bars. The relaxation during filtration time allowed the minimum cake deposit on the membrane surface while soluble organic and a small fraction of UASB effluent induced internal fouling resistance. The soluble microbial product (SMP) and the extra polymeric substance (EPS) concentrations from permeate were about 7–10 times lower than those from UASB effluent. These conditions showed that the cross-flow microfiltration could successfully remove the SS from UASB effluent while allowing all sludge granules to be retained in the system.

A Critical Review of Systems for Bioremediation of Tannery Effluent with a Focus on Nitrogenous and Sulfurous Species Removal and Resource Recovery

Tanneries generate copious amounts of potentially toxic sludge and effluent from the processing of skins and hides to leather. The effluent requires remediation before discharge to protect the receiving environment. A range of physicochemical methods are used for pre- and post-treatment, but biological secondary remediation remains the most popular choice for the reduction of the organic and macronutrient fraction of tannery effluent. This review provides an update and critical discussion of biological systems used to remediate tannery effluent. While the conventional activated sludge process and similar technologies are widely used by tanneries, they have inherent problems related to poor sludge settling, low removal efficiencies, and high energy requirements. Treatment wetlands are recommended for the passive polishing step of beamhouse effluent. Hybrid systems that incorporate anoxic and/or anaerobic zones with sludge and/or effluent recycling have been shown to be effective for the removal of organics and nitrogenous species at laboratory scale, and some have been piloted. Novel systems have also been proposed for the removal and recovery of elemental sulfur and/or energy and/or process water in support of a circular economy. Full-scale studies showing successful long-term operation of such systems are now required to convince tanneries to modernize and invest in new infrastructure.

Adsorber Charge Dominates over Hydrophobic or Fluorophilic Functionalization in Influencing Adsorption of PFCA onto Polystyrene Resins

AbstractA systematic series of industrial‐relevant polystyrene‐based anion exchange resins that are functionalized with hydro‐ or fluorocarbon chains are compared regarding their adsorption behavior toward perfluorocarboxylic acids (PFCA) in respect to their charge, chain length, and type of chain. The results clearly show the dominance of electrostatic interactions in the adsorption process as uncharged adsorber materials showed no adsorption at all. In contrast, the charged adsorber materials showed in general a PFCA removal of 80% to 30% over the experiment depending on effluent fraction. Unexpectedly, for perfluorobutanoic acid (PFBA) the highest removal rate is found with consistently >90%. Despite observing significant benefits in the adsorption of PFCA for fluoroalkylated adsorbers in comparison to their non‐fluorinated counterparts, this effect of fluoroalkylation is comparatively small and can not be clearly attributed to fluorophilic interactions between the fluoroalkyl chains. These findings help clarifying that the introduction of fluorocarbon moieties in adsorber materials is not necessary in order to remove fluorocarbon molecules from the environment.

Critical fractions in reclaimed water responsible for membrane fouling: Isolation, fouling characteristics, quantitative and qualitative variations in practical application

Considering the different fouling characteristics between model foulants and organic components in real reclaimed water, it is of great importance to identify the critical foulants responsible for membrane fouling. This study identified and isolated the fraction with molecular weight (MW) > 100 kDa as the critical foulant in secondary effluent by MW cut-off membrane of 100 kDa with high efficiency. This fraction accounted for 92.2% membrane fouling of raw water, including 28.7%, 29.7% and 33.8% fouling contribution by subfractions with MW between 100–300, 300–500 and > 500 kDa. Specifically, the critical fraction with MW > 100 kDa were mainly distributed in two parts: < 0.22 μm and > 0.45 μm, corresponding to 41.9% and 56.9% fouling contribution of this fraction. Furthermore, both total organic carbon (TOC) and fouling potential of fraction with MW > 100 kDa were monitored, presenting about threefold increase from September to January in next year. Membrane fouling contribution of this critical fraction in raw secondary effluent were mainly distributed in 85∼95% throughout the 5 months, demonstrating its predominant fouling propensity. Moreover, the TOC concentration of fraction with MW > 100 kDa presented distinct positive correlation with the fouling potential of raw secondary effluent (R2 = 0.947), which was promising to be a surrogate for predicting membrane fouling in practical application.

The Efficiency Improvement of Electrodeposition of High-Purity Zn by a Proper Electrolyte Solution Preparation from Spent Pickling Liquor by Anion-Exchange Separation

A better procedure for recovering high-purity Zn from the SPL solution has been devised. To provide a suitable electrolyte for the efficient cathodic deposition of high-purity Zn, complete anion-exchange purification had been done by chromatographic technique. The process was then continued by galvanostatic electrodeposition to determine the efficiencies. As the SPL needs to be neutralized before any attempts of Zn electrodeposition, NaCl may provide the required source of Cl- ions for complex formation. The equilibrium studies of the anion-exchange distribution in such solutions showed similar tendencies to those already known in HCl media. The anion-exchange chromatographic separation was devised – with the finer tuning of the parameters – according to the equilibrium result, but other physical parameters were also examined for improving the efficiency of separation and the recovery of Zn. The devised anion-exchange separation in chloride media can purify the SPL, containing Zn as the valuable component and higher concentrations of Fe as the main impurity. The most important impurities (Fe, Mn, Ni, Al and Co) can be efficiently separated in a dissolved state. At the same time, Zn is sorbed in the strongly basic anion[1]exchange resin at a moderate Cl- ion concentration (~ 2 M). Stirring with Fe chips provides a reduction of iron to the Fe(II) state. The remaining problem is minor copper contamination in the same effluent fraction as Zn, which however can be eliminated by a simple additional step of cementation or directly by pre-electrolysis.

Effect of various processing methods on the numbers of Clostridium (Clostridia, Bacteria) in animal by-products

Clostridia are one of the largest genera of eubacteria living in water, soil, the intestines of humans and animals. The genus Clostridium includes both pathogenic and non-pathogenic species. Representatives of this genus occupy a leading position among all types of bacteria in producing a variety of toxins. Due to their ability to form spores, these microorganisms can survive in the most unfavorable conditions. Antibiotic-resistant Clostridia, which are released to the environment as part of farm animal manure, are of particular environmental danger. We have studied the influence of various treatment methods (aeration, acidification, and surfactant application) of the liquid fraction of pig manure effluents (ME) on the species composition and the numbers of Clostridia. Cl. septicum and Cl. perfringens were found to occupy a dominant position in the ME of manure storage baths. Both species are actively involved in the ammonification of organic compounds, releasing a wide range of volatile substances with an unpleasant odor into the environment. Most of the Clostridia were detected in biofilms formed on the surface of ME under anaerobic conditions. Such conditions are formed during storage of the liquid fraction in closed lagoons, which increases the environmental risks of the release of undesirable microorganisms into the environment. Round-the-clock aeration and acidification of ME to pH 5.5 reduce the numbers of Clostridia. Such conditions contribute to the formation of microorganism consortia with fungi to occupy a dominant position. Cl. difficile (32.52%), Cl. putrificum (31.62%) and Cl. septicum (30.72%) predominated in biofilms of acidified ME, whilst only Cl. difficile (69.98–95.26%) did in options with surfactants added. The largest relative numbers of pathogenic Cl. difficile (95.26%) were observed in the option with the addition of a cationic surfactant (benzalkonium chloride).

Fractionation and transport of compost‐derived dissolved organic matter fractions in saturated red soil and black soil columns

AbstractThe fractionation and transport of compost‐derived dissolved organic matter (DOMC) could affect the transport and fate of nutrients and DOM‐associated pollutants in the soil environment. In this study, the humic acid fraction of DOMC (HAC) and fulvic acid fraction of DOMC (FAC) were selected to investigate the fractionation and transport of DOMC in repacked soil columns of a red soil and a black soil under different KCl concentrations. The effluent DOMC fractions were monitored by ultraviolet (UV)‐visible (Vis) light and fluorescence spectroscopy. The results showed that the molecular weight (MW) of the effluent DOM approached that of the influent DOMC fractions with the injection of DOMC fractions. Three‐dimensional fluorescence excitation emission matrices (3D‐EEMs) coupled with parallel factor analysis resolved three fluorescent components, that is, low MW UV humic‐like substances (C1), high MW UV humic‐like substances (C2), and protein‐like substances (C3). The mobility of HAC and FAC decreased with increasing KCl concentrations (1 mM–50 mM), implying that electrostatic interaction was an important mechanism for the retention of DOMC in soil columns. The fact that the mobility of DOMC fractions in the black soil was greater than that in the red soil could be attributed to the high free Fe oxide content in the red soil. The retained DOMC fractions did not entirely desorb by the background electrolyte solution, suggesting that a part of the DOMC fractions retained in soil columns was strongly bound. These results are helpful in understanding the fractionation and transport of DOMC in soil environments.

Granular activated carbon enhances the anaerobic digestion of solid and liquid fractions of swine effluent at different mesophilic temperatures

ObjectivesThis study evaluated the effect of particle size and dosage of granular activated carbon (GAC) on methane production from the anaerobic digestion of raw effluent (RE) of swine wastewater, and the solid (SF) and liquid (LF) fractions. The effect of temperature using the selected size and dosage of GAC was also evaluated. Methods60 mL of swine wastewater were inoculated with anaerobic granular sludge and GAC at different dosages and particle size. The cultures were incubated at different temperatures at 130 rpm. The kinetic parameters from experimental data were obtained using the Gompertz model. ResultsThe cultures with the LF and GAC (75–150 μm, 15 g/L) increased 1.87-fold the methane production compared to the control without GAC. The GAC at 75–150 μm showed lower lag phases and higher Rmax than the cultures with GAC at 590–600 μm. The cumulative methane production at 45 °C with the RE + GAC was 7.4-fold higher than the control. Moreover, methane production at 45 °C significantly increased with the cultures LF + GAC (6.0-fold) and SF + GAC (2.0-fold). The highest production of volatile fatty acids and ammonium was obtained at 45 °C regardless of the substrate and the addition of GAC contributed to a higher extent than the cultures lacking GAC. In most cases, the kinetic parameters at 30 °C and 37 °C were also higher with GAC. ConclusionsGAC contributed to improving the fermentative and methanogenesis stages during the anaerobic digestion of fractions, evidenced by an improvement in the kinetic parameters.

Model-based assessment of mainstream nitrate/nitrite-dependent anaerobic methane oxidation and Anammox process in granular sludge at low temperature

The process of nitrate/nitrite-dependent anaerobic methane oxidation (n-DAMO) coupled with anaerobic ammonium oxidation (Anammox) is one of groundbreaking discoveries for nitrogen removal and methane emission reduction from wastewater simultaneously. Yet its treatment of mainstream wastewater at low temperature is still a major challenge. In this work, a one-dimensional granular sludge model incorporating Arrhenius conversion for temperature effects was constructed to depict the relationships among n-DAMO microorganisms and Anammox. The model framework was successfully evaluated with 380 days measurement data from a membrane granular sludge reactor (MGSR) operated at temperature of 20–10 °C and fed with ammonium and nitrite. The model could satisfactorily predict the kinetics of nitrogen removal rates, effluent nitrogen concentrations and biomass fractions in MGSR at varying temperatures. Despite the decrease in microbial activity of functional microorganisms, the coupled n-DAMO and Anammox process based on granule system in mainstream wastewater treatment achieved a TN removal efficiency of about 98 % and a stable nitrogen removal rate of 0.55 g L−1 d−1. The model developed is expected to facilitate fundamentally understanding the underlying mechanisms of the coupled process and provide proposals for its practical engineering application in wastewater treatment plants.

Fractionation of Anaerobic Digestion Liquid Effluents through Mechanical Treatment and Filtration

Organic wastes and by-products from several activities, including food industries, farming, and animal husbandry, are a hygiene threat when aerobically decomposed. Therefore, their management is crucial for public health. In this direction, anaerobic digestion (AD) systems may be the solution by transforming waste into energy, which may decrease the environmental impact. However, their efficacy should be carefully examined. In this innovative study, we evaluated the physicochemical and microbial characteristics of liquid digestate (LD) retrieved from organic animal wastes in northern Greece using nanofiltration. Using treatment technologies, including physical (solid–liquid separation, microfiltration, and nanofiltration) and biological (anaerobic digestion), heavy metals and microbial (i.e., Salmonella spp., Escherichia coli, and Enterococcus faecalis) concentrations were reduced and nutrients were recovered. This work sets the basis for the efficient management of liquid digestate. Our method may enable the use of treated liquid digestate for unlimited irrigation water and other industrial applications of water. Apart from the sanitation process, the recovery of nutrients for soil fertilization seems to be a more sustainable way for future agricultural practices.

Trace analysis of benzophenone-type UV filters in water and their effects on human estrogen and androgen receptors

To carry out risk assessments of benzophenone-type UV filters (BPs), fast and accurate analytical methods are crucial to determine and monitor levels in the environment. This study presents an LC-MS/MS method that requires minimal sample preparation and yet can identify 10 different BPs in environmental samples such as surface or wastewater resulting in a LOQ range from 2 to 1060 ng/L. The method suitability was tested through environmental monitoring, which showed that, BP-4 is the most abundant derivative found in the surface waters of Germany, India, South Africa and Vietnam. BP-4 levels correlate with the WWTP effluent fraction of the respective river for selected samples in Germany. Peak values of 171 ng/L for 4-hydroxybenzophenone (4-OH-BP), as measured in Vietnamese surface water, already exceed the PNEC value of 80 ng/L, elevating 4-OH-BP to the status of a new pollutant that needs more frequent monitoring. Moreover, this study reveals that during biodegradation of benzophenone in river water, the transformation product 4-OH-BP is formed which contain structural alerts for estrogenic activity. By using yeast-based reporter gene assays, this study provides bio-equivalents of 9 BPs, 4-OH-BP, 2,3,4-tri-OH-BP, 4-cresol and benzoate and complements the existing structure-activities relationships of BPs and their degradation products.

Suspect Screening of Chemicals in Hospital Wastewaters Using Effect-Directed Analysis Approach as Prioritization Strategy.

The increasing number of contaminants in the environment has pushed water monitoring programs to find out the most hazardous known and unknown chemicals in the environment. Sample treatment-simplification methods and non-target screening approaches can help researchers to not overlook potential chemicals present in complex aqueous samples. In this work, an effect-directed analysis (EDA) protocol using the sea urchin embryo test (SET) as a toxicological in vivo bioassay was used as simplified strategy to identify potential unknown chemicals present in a very complex aqueous matrix such as hospital effluent. The SET bioassay was used for the first time here to evaluate potential toxic fractions in hospital effluent, which were obtained after a two-step fractionation using C18 and aminopropyl chromatographic semi-preparative columns. The unknown compounds present in the toxic fractions were identified by means of liquid chromatography coupled to a Q Exactive Orbitrap high-resolution mass spectrometer (LC-HRMS) and using a suspect analysis approach. The results were complemented by gas chromatography-mass spectrometry analysis (GC-MS) in order to identify the widest range of chemical compounds present in the sample and the toxic fractions. Using EDA as sample treatment simplification method, the number of unknown chemicals (>446 features) detected in the raw sample was narrowed down to 94 potential toxic candidates identified in the significantly toxic fractions. Among them, the presence of 25 compounds was confirmed with available chemical standards including 14 pharmaceuticals, a personal care product, six pesticides and four industrial products. The observations found in this work emphasize the difficulties in identifying potential toxicity drivers in complex water samples, as in the case of hospital wastewater.

Predicting Escherichia coli levels in manure using machine learning in weeping wall and mechanical liquid solid separation systems.

An increased understanding of the interaction between manure management and public and environmental health has led to the development of Alternative Dairy Effluent Management Strategies (ADEMS). The efficiency of such ADEMS can be increased using mechanical solid-liquid-separator (SLS) or gravitational Weeping-Wall (WW) solid separation systems. In this research, using pilot study data from 96 samples, the chemical, physical, biological, seasonal, and structural parameters between SLS and WW of ADEM systems were compared. Parameters including sodium, potassium, total salts, volatile solids, pH, and E. coli levels were significantly different between the SLS and WW of ADEMS. The separated solid fraction of the dairy effluents had the lowest E. coli levels, which could have beneficial downstream implications in terms of microbial pollution control. To predict effluent quality and microbial pollution risk, we used Escherichia coli as the indicator organism, and a versatile machine learning, ensemble, stacked, super-learner model called E-C-MAN (Escherichia coli-Manure) was developed. Using pilot data, the E-C-MAN model was trained, and the trained model was validated with the test dataset. These results demonstrate that the heuristic E-C-MAN ensemble model can provide a pilot framework toward predicting Escherichia coli levels in manure treated by SLS or WW systems.

Atendimento e precariedade no esgotamento sanitário em comunidades rurais do estado de Goiás, Brasil

ABSTRACT The rate of attendance to sanitary sewage services is low in rural communities, representing precarious sanitation conditions with dumping in rudimentary cesspools or in the open. Knowledge of the fractions of effluents generated and the places where they are released is important, since inadequate disposal generates public health problems and negatively impacts the environment. In this way, the objective of this work was to identify the amounts of effluent fractions generated and the deficit of sanitary sewage in rural communities in the state of Goiás. The study area included 97 rural communities, from which data were collected regarding the existence of bathrooms, alternatives and disposal sites for domestic sewage fractions, such as feces separated from urine. The results indicated an absence of a bathroom in 6.6% of the analyzed rural households, being in 2.5 and 18.2% in the households of the settlements and quilombolas, respectively, highlighting in the latter the occurrence of disposal in the open or stream in 13.7%. There was a predominant use of rudimentary cesspools to receive sewage and fecal water, while gray water from the kitchen sink and washing tanks are mainly disposed in the backyard, representing the greatest deficit in the communities. Thus, in most of the studied households there is a deficit due to lack of service, due to the release of untreated effluents into ditches/open air, mainly for gray water, and precarious service due to the unsafe disposal of treated effluents or the use of rudimentary cesspools. Few alternative technologies were found for the treatment of effluents, with ecological pit, biodigester and Tapiocanga stone pit being identified. It was concluded that the deficit of sewage in the households of the studied communities is high, due to the release of effluents without treatment and the use of rudimentary cesspools, characterized as lack of service and precarious service, respectively, observed in 84.6% of households.

Simplified engineering design towards a competitive lipid-rich effluents valorization.

Medium- and long-chain fatty acids and glycerol contained in the oily fraction of many food-industry effluents are excellent candidates to produce biobased high-value triacylglycerides (TAGs) and polyhydroxyalkanoates (PHAs). The typical process configuration for TAGs recovery from lipid-rich streams always includes two steps (culture enrichment plus storage compounds accumulation) whereas, for PHAs production, an additional pretreatment of the substrate for the obtainment of soluble volatile fatty acids (VFAs) is required. To simplify the process, substrate hydrolysis, culture enrichment, and accumulation (TAG and PHA storage) were coupled here in a single sequencing batch reactor (SBR) operated under the double growth limitation strategy (DGL) and fed in pulses with industrial waste fish oil during the whole feast phase. When the SBR was operated in 12h cycles, it was reached up to 51wt % biopolymers after only 6h of feast (TAG:PHA ratio of 50:51; 0.423 CmmolBIOP/CmmolS). Daily storage compound production was observed to be over 25% higher than the reached when enrichment and accumulation stages were carried in separate operational units. Increasing the feast phase length from 6 to 12h (18h cycle) negatively affected the DGL strategy performance and hence system storage capacity, which was recovered after also extending the famine phase in the same proportion (24h cycle). Besides, the carbon influx during the feast phase was identified as a key operational parameter controlling storage compounds production and, together with the C/N ratio, culture selection. The different cycle configurations tested clearly modulated the total fungal abundances without no significant differences in the size of the bacterial populations. Several PHA and TAG producers were found in the mixed culture although the PHA and TAG productions were poorly associated with the increased relative abundances (RAs) of specific operational taxonomic units (OTUs).

Food waste valorization into bioenergy and bioproducts through a cascade combination of bioprocesses using anaerobic open mixed cultures

This study assessed a strategy for food waste (FW) valorization into multiple products by applying a cascade combination of only two anaerobic processes using open mixed cultures. FWs were firstly subjected to an anaerobic fermentation (AF) to generate an effluent rich in valuable bioproducts. The remaining solid fraction of AF effluent was further valorized into biogas via conventional anaerobic digestion (AD). The operational conditions imposed in AF (55 °C, pH 5.8 and 20.1 d hydraulic retention time) and FW composition promoted a microbial community with high hydrolytic and acidogenic activity that maximized FWs fermentation, resulting in three bioproducts in one single process. pH was a key factor in the microbiome enrichment with Thermoanaerobacterium (63.2% relative abundance). Thermoanaerobacterium was the main bacteria enabling FWs valorization into the three valuable metabolites with remarkable high efficiency, reaching 51.3% bioconversion into SCFAs, 22.8 g L−1 ethanol and 157 L H2 kg VSfed−1. The subsequent AD of the remaining solid fraction resulted in 288.5 L CH4 kg VSfed−1, allowing a final total carbohydrate recovery higher than 80%. This multiproduct strategy enabled FWs valorization by attaining both bioproducts (SCFAs and ethanol) and energy streams (H2 and methane) from a single waste, establishing a groundwork for using open mixed anaerobic cultures for clean and sustainable production of a wide range of added-value compounds.

In vitro assessment of pancreatic hormone secretion from isolated porcine islets.

The potential use of porcine islets for transplantation in humans has triggered interest in understanding porcine islet physiology. However, the number of studies dedicated to this topic has remained limited, as most islet physiologists prefer to use the less time-consuming rodent model or the more clinically relevant human islet. An often-overlooked aspect of pig islet physiology is its alpha cell activity and regulation of its glucagon secretion. In vitro islet perifusion is a reliable method to study the dynamics of hormone secretion in response to different stimuli. We thus used this method to quantify and study glucagon secretion from pig islets. Pancreatic islets were isolated from 20 neonatal (14 to 21-day old) and 5 adult (>2 years) pigs and cultured in appropriate media. Islet perifusion experiments were performed 8 to 10 days post-isolation for neonatal islets and 1 to 2 days post-isolation for adult islets. Insulin and glucagon were quantified in perifusion effluent fractions as well as in islet extracts by RIA. Increasing glucose concentration from 1 mM to 15 mM markedly inhibited glucagon secretion independently of animal age. Interestingly, the effect of high glucose was more drastic on glucagon secretion compared to its effect on insulin secretion. In vivo, glucose injection during IVGTT initiated a quick (2-10 minutes) 3-fold decrease of plasmatic glucagon whereas the increase of plasmatic insulin took 20 minutes to become significant. These results suggest that regulation of glucagon secretion significantly contributes to glucose homeostasis in pigs and might compensate for the mild changes in insulin secretion in response to changes in glucose concentration.

Application of Quantum Cascade Laser-Infrared Spectroscopy and Chemometrics for In-Line Discrimination of Coeluting Proteins from Preparative Size Exclusion Chromatography.

An external-cavity quantum cascade laser (EC-QCL)-based flow-through mid-infrared (IR) spectrometer was placed in line with a preparative size exclusion chromatography system to demonstrate real-time analysis of protein elutions with strongly overlapping chromatographic peaks. Two different case studies involving three and four model proteins were performed under typical lab-scale purification conditions. The large optical path length (25 μm), high signal-to-noise ratios, and wide spectral coverage (1350 to 1750 cm–1) of the QCL-IR spectrometer allow for robust spectra acquisition across both the amide I and II bands. Chemometric analysis by self-modeling mixture analysis and multivariate curve resolution enabled accurate quantitation and structural fingerprinting across the protein elution transient. The acquired concentration profiles were found to be in excellent agreement with the off-line high-performance liquid chromatography reference analytics performed on the collected effluent fractions. These results demonstrate that QCL-IR detectors can be used effectively for in-line, real-time analysis of protein elutions, providing critical quality attribute data that are typically only accessible through time-consuming and resource-intensive off-line methods.

Hydrodynamic cavitation pre-treatment of urban waste: Integration with acidogenic fermentation, PHAs synthesis and anaerobic digestion processes

Urban waste can be valorized within a biorefinery approach, producing platform chemicals, biopolymers and energy. In this framework, hydrodynamic cavitation (HC) is a promising pre-treatment for improving biodegradability due to its high effectiveness and low cost. This paper deals with the effect of HC pre-treatment on the acidogenic co-fermentation process of thickened sewage sludge from a WWTP and seasonal vegetable waste from a wholesale market. Specifically, HC was assessed by testing two sets of parameters (i.e., treatment time of 30 and 50 min; vacuum pressure 1.4 and 2.0 bar; applied power 8 and 17 kW) to determine its effectiveness as a pre-treatment of the mixture. The highest increase in sCOD (+83%) and VFAs (from 1.93 to 17.29 gCODVFA L−1) was gained after 50 min of cavitation. Fermentations were conducted with not cavitated and cavitated mixtures at 37 °C on 4 L reactors in batch mode, then switched to semi-continuous with OLR of 8 kgTVS m-3 d−1 and HRT of 5–6.6 d. Good VFAs concentrations (12.94–18.27 gCODVFA L−1) and yields (0.44–0.53 gCODVFA gVS(0)−1) were obtained, which could be enhanced by pre-treatment optimization and pH control. The organic acid rich broth obtained was then assessed as a substrate for PHAs storage by C. necator. It yielded 0.37 g g−1 of polyhydroxybutyrate, such biopolymer resulted to have analogous physicochemical characteristics of commercial equivalent. The only generated side-stream would be the solid-rich fraction of the fermented effluent, which valorization was assessed through BMP tests, showing a higher SGP of 0.42 Nm3 kgTVS−1 for the cavitated.

Combination of chromatographic and spectroscopic characterization based on primitive ultraviolet absorbance detection to fulfill advanced monitoring of dissolved organic matter in municipal wastewater treatment plant

Effective and affordable monitoring tool for dissolved organic matter (DOM) in municipal wastewater treatment plant (WWTP) is in great need. In this study, high-performance size exclusion chromatography (HPSEC) with ultraviolet absorbance (UVA) detection and ultraviolet (UV) spectrometry were complementarily combined for advanced characterization of DOM in a municipal WWTP. DOM in different process units were chromatographically characterized mainly by UVA at 210 nm (UVA210), 254 nm (UVA254), UVA ratio index (URI, UVA210/UVA254). Differential and derivative UV spectrometry were also used for DOM characterization. HPSEC URI chromatographic analyses helped to acquire rich chemical information of DOM components with primitive UVA detection. Influent HPSEC fractions Ⅰ, Ⅳ, Ⅴ− 2, which were proved to consist of protein and polysaccharides, low molecular weight organic acids and hydrophobic organics respectively, were readily removable. HPSEC fractions Ⅱ and Ⅲ were proved to contain mostly recalcitrant humic substances (HS). Effluent HPSEC fraction Ⅴ− 1 contained nonbiodegradable saturated organics. UV spectrometry complemented HPSEC characterization by revealing that saturated organics generated during sand filtration and second derivative peak height at 295 nm (SDPH295) could be surrogate for biodegradable organics concentration in influent. Measures for DOM control optimization of this WWTP were proposed based on the DOM characteristics revealed. This study proved practicability of achieving advanced DOM monitoring with cheap and convenient but primitive chromatographic and spectroscopic characterization with UVA detection which may provide basis for developing applicable equipment for organic pollutants monitoring of municipal WWTP.