Removal of Acetone Vapor from Air Using a Biotrickling Filter Packed with Polymeric Bioballs

Acetone released into the atmosphere can adversely affect human health and the environment. The aim of this work was to evaluate the performance of a laboratory-scale biotrickling filter (BTF) with bioball packing material to remove acetone vapor from contaminated air. The acetone removal efficiency was investigated in two different scenarios: with and without the inoculation of microorganisms. Three strains of bacteria, Pseudomonas putida, Rhodococcus aerolatus, and Aquaspirillum annulus, were used in the BTF. In both cases, the filter units were simultaneously operated for 100 days under three different inlet acetone concentrations (0.18 ± 0.01 g/m3, 0.25 ± 0.01 g/m3, and 0.40 ± 0.02 g/m3) and two different gas flow rates (2.54 and 5.09 m3/h). The results showed that acetone removal was greater in the filter with the inoculated bacteria. In the filter operated without inoculum, the acetone removal efficiency gradually decreased with filtration time from 90.1% to 6.1%. While employing three types of bacteria in the BTF, the efficiency of acetone removal remained relatively stable and varied between 70.2% and 97.6%. The study also revealed that bioballs can be successfully used as a packing material in air biofiltration systems designed for acetone removal from the air.

Influence of Variety and Nitrogen Fertilization on the Technological Parameters of Special Malts Prepared from Naked and Hulled Oat Varieties

Grains of four naked oat varieties (Amant, Maczo, Polar and Siwek) and one hulled oat variety (Kozak) from three consecutive years (2018, 2019 and 2020), grown under three different nitrogen fertilization regimes (40, 60 and 80 kg of nitrogen per hectare) were malted and then mashed in the laboratory conditions for the first time; this was carried out to determine whether hulled and naked oat grains possess favourable properties as a raw material for the production of malt. Most of the analysed samples possess a favourable Kolbach index (39.06–46.82%), good extractivity (81.07–81.97%) and rather good saccharification time (13.33–26.67 min); however, some disadvantages of the produced malts could be pointed out. During the congress mashing, the filtration time of the worts produced from the hulled and naked oat malts was long (96.67–110 min) and the wort volume was not satisfactory (155–228.53 mL). Subsequent studies over oat malting and mashing need to be performed to maximize oat potential as the raw material for the production of the malt.

Elucidating morphological effects in membrane mineral fouling using real-time particle imaging and impedance spectroscopy

Mineral fouling is a major hindrance to high recovery effluent nanofiltration, with calcium phosphate (Ca-P) and calcium carbonate (CaCO3) the most prevalent mineral foulants. In this study, we used a novel combination of real-time in-line microscopy, electrical impedance spectroscopy (EIS), post SEM analysis, and filtration metrics (water flux and rejection) to study mineral fouling mechanisms of Ca-P and CaCO3 salts in synthetic effluent nanofiltration. We used nanofiltration (NF) polyelectrolyte multilayer (PEM) membranes, prepared by static layer-by-layer (LbL) coating of a cationic polymer - polydiallyl dimethylammonium chloride, and anionic polymer - poly styrenesulfonate (six bi-layer) on a polyethersulfone (PES) ultrafiltration (UF) membrane. Increasing permeate recovery over filtration time was simulated through additions of CaCl2 with NaHCO3 or NaH2PO4/Na2HPO4. Using the novel combination of methods, we delineated the mechanisms governing fouling development with time for both CaCO3 and Ca-P. For CaCO3, a transition from heterogeneous precipitation on the membrane surface (scaling) to particulate fouling due to bulk precipitation was identified. For Ca-P, a transition from fouling by amorphous particles to fouling by crystalline particles was identified; and this phase-change was captured in real-time images using an in-line microscope. We also found that for similar precipitation potentials measured by weight, Ca-P fouling was more detrimental to water flux (86% decrease) compared to CaCO3 (20% decrease) due to the voluminous amorphous phase. We established in-line microscopy as a new useful method to study mineral fouling, as it gives invaluable information on the suspended particles in real-time. Combining it with EIS gives complementary information on mineral accumulation on the membrane surface. Insight from this study and further use of these methods can guide future strategies towards higher effluent recovery by membrane filtration.

Brewing with 10% and 20% Malted Lentils—Trials on Laboratory and Pilot Scales

Lentils, a popular foodstuff worldwide, are gaining more interest for their use in alternative diets. In addition, we are observing an ever-growing demand for new raw materials in the malting and brewing industry and an overall rising interest in a low-gluten lifestyle. Therefore, in this study, malt was produced from green lentils and used in both laboratory- and pilot-scale brewing trials. Malted lentils were used as 10% and 20% adjuncts at the laboratory scale, following the Congress mash procedure, and the most important parameters (e.g., filtration time, pH, color, extract, fermentability) of the wort and beer samples were analyzed with a special focus on the concentrations of metal ions (Mg2+, Ca2+, Zn2+, Fe) in wort. The production of beer with lentil malt as an adjunct was then scaled up to 1 hl, and several beer parameters were analyzed, including the gluten content and foam stability. The results showed that the gluten content was decreased by circa 35% and foam stability was enhanced by approximately 6% when adding 20% lentil malt. Furthermore, the use of lentil malt reduced the filtration time by up to 17%. A trained panel evaluated the sensorial qualities of the produced beers. Overall, the use of green lentil malt shows promising results for its potential use in brewing.

Membrane-Based Processes to Obtain High-Quality Water From Brewery Wastewater

Water reuse is a safe and often the least energy-intensive method of providing water from non-conventional sources in water stressed regions. Although public perception can be a challenge, water reuse is gaining acceptance. Recent advances in membrane technology allow for reclamation of wastewater through the production of high-quality treated water, including potable reuse. This study takes an in-depth evaluation of a combination of membrane-based tertiary processes for its application in reuse of brewery wastewater, and is one of the few studies that evaluates long-term membrane performance at the pilot-scale. Two different advanced tertiary treatment trains were tested with secondary wastewater from a brewery wastewater treatment plant (A) ultrafiltration (UF) and reverse osmosis (RO), and (B) ozonation, coagulation, microfiltration with ceramic membranes (MF) and RO. Three specific criteria were used for membrane comparison: 1) pilot plant optimisation to identify ideal operating conditions, 2) Clean-In-Place (CIP) procedures to restore permeability, and 3) final water quality obtained. Both UF and Micro-Filtration membranes were operated at increasing fluxes, filtration intervals and alternating phases of backwash (BW) and chemically enhanced backwash (CEB) to control fouling. Operation of polymeric UF membranes was optimized at a flux of 25–30 LMH with 15–20 min of filtration time to obtain longer production periods and avoid frequent CIP membrane cleaning procedures. Combination of ozone and coagulation with ceramic MF membranes resulted in high flux values up to 120 LMH with CEB:BW ratios of 1:4 to 1:10. Coagulation doses of 3–6 ppm were required to deal with the high concentrations of polyphenols (coagulation inhibitors) in the feed, but higher concentrations led to increasing fouling resistance of the MF membrane. Varying the ozone concentration stepwise from 0 to 25 mg/L had no noticeable effect on coagulation. The most effective cleaning strategy was found to be a combination of 2000 mg/L NaOCl followed by 5% HCl which enabled to recover permeability up to 400 LMH·bar−1. Both polymeric UF and ceramic MF membranes produced effluents that fulfil the limits of the national regulatory framework for reuse in industrial services (RD 1620/2007). Coupling to the RO units in both tertiary trains led to further water polishing and an improved treated water quality.

Performance evaluation of virus concentration methods for implementing SARS-CoV-2 Wastewater-based epidemiology emphasizing quick data turnaround.

Wastewater based epidemiology (WBE) has drawn significant attention as an early warning tool to detect and predict the trajectory of COVID-19 cases in a community, in conjunction with public health data. This means of monitoring for outbreaks has been used at municipal wastewater treatment centers to analyze COVID-19 trends in entire communities, as well as by universities and other community living environments to monitor COVID-19 spread in buildings. Sample concentration is crucial, especially when viral abundance in raw wastewater is below the threshold of detection by RT-qPCR analysis. We evaluated the performance of a rapid ultrafiltration-based virus concentration method using InnovaPrep Cp Select pipette tips and compared this to the established electronegative membrane filtration (EMF) method. We evaluated the sensitivity of SARS-CoV-2 quantification, surrogate virus recovery rate, and sample processing time. Results suggest that the Cp Select concentrator is more efficient at concentrating SARS-CoV-2 from wastewater compared to the EMF method. 30% of samples that tested negative when concentrated with the EMF method produced a positive signal with the Cp Select protocol. Increased recovery of the surrogate virus control using the Cp Select confirms this observation. We optimized the Cp Select protocol by adding AVL lysis buffer and sonication, to increase the recovery of virus. Sonication increased BCoV recovery by 19%, which seems to compensate for viral loss during centrifugation. Filtration time decreases by approximately 30% when using the Cp Select protocol, making this an optimal choice for building surveillance applications where a quick turnaround time is necessary.

KINETICS OF GRINDING OF VEGETABLE RAW MATERIALS DURING ELECTRIC DISCHARGE EXTRACTION

The influence of the degree of grinding of the particles of growing raw materials during electric discharge extraction on the quality of the obtained extracts was studied. Each discharge during electro-discharge extraction contributes to the grinding of a part of the raw material, which is confirmed by granulometric analysis. The particle size of the raw material should be controlled, since excessive grinding of the extracts results in cloudy, difficult to clarify and poorly filtered. The design of the extraction chamber is proposed, in which the grounded electrode is made in the form of a perforated plate, called a false bottom, with the optimal size of the holes and their density, which eliminates the over-grinding of the raw material particles, which leads to the production of turbid and difficult-to-filter extracts. Since the extraction of raw materials is carried out at a certain ratio of solid-liquid phases, the volume of the chamber from the sieve to the bottom does not significantly affect the kinetics of the extraction process itself, since it is intended for collecting the smallest particles of processed raw materials, the mass of which does not exceed 15-16% of the loaded mass of raw materials. The device of the extraction chamber, due to the high turbulence and intensive mixing of the suspension under the action of cavitation and shock waves initiated by the discharge in the liquid, allows you to remove small particles of raw materials less than 1 mm in size from the working area of the chamber. The results of the study show that the extraction of target components from various raw materials using a chamber with a false bottom can significantly reduce the content of the smallest particles of raw materials in the extract. It facilitates the filtration of the extract, reduces the filtration time, significantly reduces the likelihood of turbidity of the solution due to suspension, which improves the quality of the extract. Experimental studies of the developed electric discharge chamber with a false bottom, conducted with various types of plant raw materials, confirm the effectiveness of extraction in the chamber of the proposed design.

Study of Head Loss in Rapid Filtration with four River Sands

In this work, we studied the filtration behavior, with regard to the head loss, of four calibrated Togo Rivers sands compared to that of a reference filter sand imported from Europe. The objective is to determine the suitability of local rivers sands as filter sands for water treatment plants. The sands were successively loaded into a filtration pilot and subjected, during at least 20 hours, to the filtration of water whose turbidity was maintained at around 20 NTU. The results show that the average deviations of the head loss profiles as a function of depth, calculated in relation to the head loss recorded on the reference sand, at the same filtration time t=20h, are small and vary from 2 cm to 8 cm. In the same way, the curves of the head loss as a function of time are quite close to the one observed for the reference sand. Examination of the clogging front after 20 hours of filtration reveals that the progression is either the same or greater and reached 20 cm in depth at the same time. This study can be extended to other rivers sand samples and by varying the turbidity and the filtration rate. Doi: 10.28991/cej-2021-03091682 Full Text: PDF

Thermal Annealing Surface Modification: Effect on Surface and Performance of Electrospun Nylon 6,6 Nanofiber Membrane for Wastewater Treatment

As the forefront in fiber materials development, electrospun nanofiber membrane (NFM) is potentially reliable for wastewater treatment due to its excellent properties for instance; large surface area, high porosity, tuneable pore size, and has great flux as compared to other conventional membranes. However, fouling issue will lead to degradation of membrane performance. Fouling issue can be alleviated by applying membrane surface modification. In this study, thermal annealing is applied onto nylon 6,6 nanofiber membrane with three different temperatures (60°C, 80°C and 120°C). Results show that annealing causes membrane shrinkage and reduction of membrane fiber diameter where the fiber reduced from 138.5 nm to 108.5 nm when annealed at 120°C. The optimum annealing temperature for the membrane was found to be at 60˚C as the membrane shows the highest flux at 1200 L/m2.h at 75 minutes filtration time and took longer time to get fouled (>75 minutes) compared with un-annealed membrane (55 minutes). Nylon 6,6 nanofiber membrane is also proven to give more than 90% of COD and turbidity rejection.

Concentration Polarization Enabled Reactive Coating of Nanofiltration Membranes with Zwitterionic Hydrogel

In this study, the bottleneck challenge of membrane fouling is addressed via establishing a scalable concentration polarization (CP) enabled and surface-selective hydrogel coating using zwitterionic cross-linkable macromolecules as building blocks. First, a novel methacrylate-based copolymer with sulfobetain and methacrylate side groups was prepared in a simple three-step synthesis. Polymer gelation initiated by a redox initiator system (ammonium persulfate and tetramethylethylenediamine) for radical cross-linking was studied in bulk in order to identify minimum (“critical”) concentrations to obtain a hydrogel. In situ reactive coating of a polyamide nanofiltration membrane was achieved via filtration of a mixture of the reactive compounds, utilizing CP to meet critical gelation conditions solely within the boundary layer. Because the feasibility was studied and demonstrated in dead-end filtration mode, the variable extent of CP was estimated in the frame of the film model, with an iterative calculation using experimental data as input. This allowed to discuss the influence of parameters such as solution composition or filtration rate on the actual polymer concentration and resulting hydrogel formation at the membrane surface. The zwitterionic hydrogel-coated membranes exhibited lower surface charge and higher flux during protein filtration, both compared to pristine membranes. Salt rejection was found to remain unchanged. Results further reveal that the hydrogel coating thickness and consequently the reduction in membrane permeance due to the coating can be tuned by variation of filtration time and polymer feed concentration, illustrating the novel modification method’s promising potential for scale-up to real applications.