Real-time monitoring of the membrane biofouling based on spectroscopic analysis in a marine MBBR-MBR (moving bed biofilm reactor-membrane bioreactor) for saline wastewater treatment

Investigation of Nitrogen Removal in Flue Gas Desulfurization and Denitrification Wastewater Utilizing Halophilic Activated Sludge

In the process of flue gas desulfurization and denitrification, the generation of high-sulfate wastewater containing nitrogen is a significant challenge for biological wastewater treatment. In this study, halophilic activated sludge was inoculated in a Sequencing Batch Reactor to remove nitrogen from wastewater with a high sulfate concentration (60 g/L). With the influent concentration of 180 mg/L, the removal rate of total nitrogen was more than 96.7%. The effluent ammonium nitrogen concentration was lower than 1.94 mg/L, and the effluent nitrate nitrogen and nitrite nitrogen concentrations were even lower than 0.77 mg/L. The salt tolerance of activated sludge is mainly related to the increase in the content of ectoine in microbial cells. The Specific Nitrite Oxidation Rate is quite low, while the Specific Nitrite Reduction Rate and Specific Nitrate Reduction Rate are relatively strong. In the system, there are various nitrogen metabolic processes, including aerobic nitrification, anaerobic denitrification, and simultaneous nitrification-denitrification processes. By analyzing the nitrogen metabolic mechanisms and microbial community structure of the reaction system, dominate bacteria can be identified, such as Azoarcus, Thauera, and Halomonas, which have significant nitrogen removal capabilities.

How high salt shock affects performance and membrane fouling characteristics of a halophilic membrane bioreactor used for treating hypersaline wastewater

In the present study, the effect of short-term salt shocks (13% and 20%) on the performance of a halophilic MBR bioreactor used to treat a hypersaline (5% salt) synthetic wastewater was considered. 13% and 20% salt shocks resulted in a transient and permanent decrease in chemical oxygen demand removal efficiency, respectively which could be correlated with soluble microbial products (SMP) concentration and specific oxygen uptake rate values of the halophilic population. DNA leakage tests suggested that both 13% and 20% short-term salt shocks resulted in some cell structural damage. During both 13% and 20% salt shocks mixed liquor SMP, extracellular polymeric substances (EPS), zeta potential and endogenous respiration increased while relative hydrophobicity, EPSp/EPSc and exogenous respiration decreased; in both cases, however, the pre-shock values for these parameters were restored after the removal of the salt shock. 13% salt shock resulted in a transient increase in the membrane fouling rate and a permanent rise in total membrane resistance (Rt). On the other hand, both membrane fouling rate and Rt increased during 20% salt shock. Membrane fouling rate initially reduced after the 20% salt shock removal but after 5 days a "TMP jump" occurred. The latter was caused by the higher steady state SMPc and SMPp concentrations after removal of 20% salt shock compared to pre-shock values. This might have either resulted in a decrease in critical flux or an increase in local flux above critical flux in some parts of the membrane. The contribution of cake layer resistance to overall membrane resistance increased after the 13% and 20% salt shocks. The findings of the present study reveal the robustness of halophilic MBRs against salt shocks in the treatment of hypersaline wastewater. However, in cases of very high salt shocks, appropriate membrane fouling reduction strategies should be carried out during its operation.

Dynamic Modelling, Process Control, and Monitoring of Selected Biological and Advanced Oxidation Processes for Wastewater Treatment: A Review of Recent Developments

This review emphasizes the significance of formulating control strategies for biological and advanced oxidation process (AOP)-based wastewater treatment systems. The aim is to guarantee that the effluent quality continuously aligns with environmental regulations while operating costs are minimized. It highlights the significance of understanding the dynamic behaviour of the process in developing effective control schemes. The most common process control strategies in wastewater treatment plants (WWTPs) are explained and listed. It is emphasized that the proper control scheme should be selected based on the process dynamic behaviour and control goal. This study further discusses the challenges associated with the control of wastewater treatment processes, including inadequacies in developed models, the limitations of most control strategies to the simulation stage, the imperative requirement for real-time data, and the financial and technical intricacies associated with implementing advanced controller hardware. It is discussed that the necessity of the availability of real-time data to achieve reliable control can be achieved by implementing proper, accurate hardware sensors in suitable locations of the process or by developing and implementing soft sensors. This study recommends further investigation on available actuators and the criteria for choosing the most appropriate one to achieve robust and reliable control in WWTPs, especially for biological and AOP-based treatment approaches.

Effect of inorganic salt on the removal of typical pollutants in wastewater by RuO2/TiO2 via catalytic wet air oxidation

The treatment of high-salinity and high-organic wastewater is a tough task, with the removal of organic matter and the separation of salts often mutually restricting. Catalytic wet air oxidation (CWAO) coupled desalination technology (membrane distillation (MD), membrane bioreactor (MBR), ultrafiltration (UF), nanofiltration (NF), etc.) provides an effective method to simultaneously degrade the high-salinity (via desalination) and high-organic matters (via CWAO) in wastewater. In this work, five kinds of RuO₂/TiO₂ catalysts with different calcination temperatures were prepared for CWAO of maleic acid wastewater with a theoretical chemical oxygen demand (COD) value of 20,000 mg L^-1. RuO₂/TiO₂ series catalysts demonstrated prominent salt resistance, with more than 80% TOC removal rates in the CWAO system containing 5 wt% Na₂SO₄; while RuO₂/TiO₂-350 showed the best degradation performance in both non-salinity and Na₂SO₄-containing conditions. Multiple characterization techniques, such as XRD, BET, XPS, NH₃-TPD and TEM etc., verified the physicochemical structure of RuO₂/TiO₂ catalysts, and their influence on the degradation of pollutants. The calcination temperature was found to have a direct impact on the specific surface area, pore volume, oxygen vacancies and acid sites of catalysts, which in turn affected the ultimate catalytic activity. Furthermore, we also investigated the performance of the RuO₂/TiO₂-350 catalyst for the treatment of acids, alcohols and aromatic compounds with the addition of NaCl or Na₂SO₄, proving its good universality and excellent salt resistance in saline wastewater. Meanwhile, the relationship between the structure of three types of organic compounds and the degradation effect in the CWAO system was also explored.

An overview of deploying membrane bioreactors in saline wastewater treatment from perspectives of microbial and treatment performance

The discharged saline wastewater has severely influenced the aquatic environment as the treatment performance of many wastewater treatment techniques is limited. In addition, the sources of saline wastewater are also plentiful from agricultural and various industrial fields such as food processing, tannery, pharmaceutical, etc. Although high salinity levels negatively impact the performance of both physicochemical and biological processes, membrane bioreactor (MBR) processes are considered as a potential technology to treat saline wastewater under different salinity levels depending on the adaption of the microbial community. Therefore, this study aims to systematically review the application of MBR widely used in the saline wastewater treatment from the perspectives of microbial structure and treatment efficiencies. At last, the concept of carbon dioxide capture and storage will be proposed for the MBR-treating saline wastewater technologies and considered toward the circular economy with the target of zero emission.

Impacts of bio-carriers on the characteristics of cake layer and membrane fouling in a novel hybrid membrane bioreactor for treating mariculture wastewater

Membrane fouling is generally considered as a major bottleneck to the wide application of membrane bioreactor (MBR) for high saline mariculture wastewater treatment. Though numerous researches have investigated the membrane fouling of MBR combined with bio-carriers, few studies reveal the impacts of bio-carriers on the characteristics of cake layer and the mechanism of bio-carriers alleviating membrane fouling. In this study, two systems, namely carriers-enhanced MBR (R1) and conventional MBR (R2) were parallel operated, drawing a conclusion that bio-carriers effectively improved the characteristics of cake layer, thus mitigating membrane fouling. Fluorescence excitation emission matrix (EEM) analysis indicated that bio-carriers reduced the adhesion of proteins and humic acid-like materials on membrane surface. Molecular weight (Mw) distribution suggested that soluble microbial products (SMP) with small Mw (6-20 kDa) and biopolymers in extracellular polymeric substances (EPS) (50-300 kDa) was easier to accumulate on membrane surface in R2. The above results indicated that the presence of bio-carriers could effectively reduce the attachment of these organics on membrane surface, contributing to a larger porosity of cake layer and thus mitigating membrane fouling. Meanwhile, gas chromatography-mass spectrometry (GC-MS) clarified that more components were present in R2 than R1. Moreover, the majority of compounds in the SMP were present in both systems, while only 14 compounds in the EPS were the same between R1 and R2. Noticeably, certain aromatics only existed in R2, suggesting that bio-carriers effectively reduced the accumulation of recalcitrant materials, especially aromatics. These results revealed that bio-carriers shifted the precise composition of cake layers.

Clinical Impact of Nurses-Physicians Collaboration Intervention on the Treatment of Immune Recurrent Spontaneous Abortion with Low-Molecular-Weight Heparin

Anticoagulation is currently the preferred and effective treatment for patients with recurrent spontaneous abortion (RSA), but, due to the prevalence of mood disorders in RSA patients and the high number of adverse effects associated with long-term medication, effective care measures are often required. In this study, 94 patients with immune-type RSA who were admitted to our hospital from January 2018 to June 2019 were selected and randomly divided into a control group and a study group of 47 patients each; both groups received low-molecular-weight heparin treatment after admission, and the control group received conventional nursing interventions during treatment, while the patients in the study group received integrated medical and nursing care interventions. Pregnancy outcomes, pre- and postintervention scores on the Self-Assessment Scale (SAS), Self-Depression Scale (SDS), and Pittsburgh Sleep Quality Index (PSQI), levels of serum gamma-interferon (IFN-γ) and interleukin-4 (IL-4) and their ratios, complications, and patient satisfaction with the intervention were observed in both groups. The results showed that the success rate of fetal preservation in the study group (89.36%) was significantly higher than that in the control group (68.09%) (P < 0.05). After treatment, SAS, SDS, and PSQI scores decreased in both groups, with the study group being lower (P < 0.05). IFN-γ and IFN-γ/IL-4 levels decreased and IL-4 levels increased in both groups after treatment, with IFN-γ and IFN-γ/IL-4 being significantly lower and IL-4 levels being significantly higher in the study group than in the control group (P < 0.05). The incidence of adverse drug reactions in the study group was significantly lower than that in the control group (P < 0.05). Patients in the study group were more satisfied with all aspects of the intervention than the control group (P < 0.05). These results suggest that nurses-physicians collaboration intervention may improve the effectiveness of low-molecular-weight heparin therapy in patients with immune-type RSA. It helps to improve patient pregnancy outcomes, mood, sleep quality, and immune function and increases patient satisfaction.

Analysis of the Curative Effect and Influencing Factors of Collagen Sponge Combined with Autologous Skin Graft in the Treatment of Deep Burn Patients

Burn is one of the common traumatic diseases in clinics. After deep burn, the complicated changes of the condition are caused by the burn wound, which ends with the repair of the wound. For patients with deep burns, whether the wound can be repaired as soon as possible is the key to the success of clinical treatment. For patients with deep burns, due to the lack of an autologous skin source, scar hyperplasia at donor site, skin graft repair at donor site, postoperative flap necrosis, and other problems in traditional surgical procedures, the method of improving function only by an autologous skin source has been unable to perform the later function reconstruction in patients with deep burns. In this study, collagen sponge combined with autologous skin graft was used to treat patients with deep burn, and the clinical efficacy of the patients was observed, and the related factors affecting the efficacy of the patients were analyzed. The results showed that collagen sponge combined with autologous skin graft was effective in the treatment of deep burn patients, and it was worth popularizing. Deep III-IV degree burns, wound infection, and hospital stay >3 months are all risk factors affecting the postoperative curative effect of patients. Therefore, in the clinical work, we should focus on patients with deep III-IV degree burns, perform surgery as soon as possible, and actively deal with wounds to prevent infection, which is beneficial to improve the curative effect.

Continuous Lumbar Plexus Block under the Guidance of the "Shamrock Method" Ultrasound: Analgesic Effects and Hemodynamic Effects after Total Knee Arthroplasty in Elderly Patients

Objective

To explore the effect of continuous lumbar plexus block guided by the “Shamrock method” on postoperative analgesia and hemodynamics in elderly patients after total knee arthroplasty (TKA).

Methods

From January 2020 to December 2020 in our hospital, 98 patients who underwent TKA were selected. Using the random number table method, the patients were divided into two groups: a continuous lumbar plexus block group (group L), with 49 patients, and a continuous femoral nerve block group (group F), with 49 patients. The onset time and maintenance time of motor and sensory nerve blocks in patients were recorded. A visual analogue scale (VAS) was applied to assess the pain severity at 6, 12, 24, and 48 h after the operation. The VAS score (FVAS) was applied to evaluate the pain severity of the patients during 24 and 48 h after the operation and knee joint functional exercise. The levels of hemodynamic indexes such as heart rate, mean arterial pressure, and oxyhemoglobin saturation and the levels of hemorheological indexes such as plasma viscosity, high and low whole blood shear viscosity, fibrinogen, and hematocrit were detected and compared between the two groups immediately after the operation and at 12 h and 48 h after the operation, respectively. The incidence of adverse reactions induced by anesthesia was counted.

Results

The onset time of motor and sensory nerve blocks in group L was lower than that in group F, and the maintenance time was higher than that in group F (P < 0.05). The VAS scores of 6, 12, 24, and 48 h after operation in group L were significantly lower than those in group F (P < 0.05). The FVAS scores of group L at 24 and 48 h after operation were significantly lower than those of group F (P < 0.05). The heart rates of the patients in the two groups were higher at 12 h and 48 h after operation than those immediately after operation (P < 0.05). The heart rates at 12 h and 48 h after operation in group L were lower than those in group F (P < 0.05). The plasma viscosity, high whole blood shear viscosity, and low whole blood shear viscosity in the group L at 12 h and 48 h after operation were lower than those in group F (P < 0.05). There was no significant difference in the incidence of local anesthetic poisoning, nausea, vomiting, urinary retention, pruritus, and other adverse reactions between the two groups (P > 0.05).

Conclusion

The “Shamrock method” ultrasound-guided continuous lumbar plexus block in elderly patients after TKA has good analgesic effect, stable hemodynamics, little influence on hemorheology, and good safety. It is of great value to enhance the surgical effect and promote postoperative rehabilitation.

Treatment of landfill leachate using single-stage anoxic moving bed biofilm reactor and aerobic membrane reactor

Landfill leachate (LFL) is one of the most serious environmental problems due to the high concentrations of toxic and hazardous matters. Although several physical, chemical, methods have been tested, biological processes and single or multiple-stage combinations of them have been receiving more attention due to their cost-effective and environmentally-friendly manner. The present work recommended coupling of conventional single-stage A/O with moving bed biofilm reactor and membrane bioreactor (AnoxMBBR/AeMBR) for LFL treatment. The system performance was evaluated for 233 d under varying nitrate concentrations (100-1000 mgNO₃^--N/L), sludge retention time (SRT) (30-90 d), and HRT (24-48 h) in AnoxMBBR, and constant SRT (infinite) and HRT (48 h) in the AeMBR. The best system performances were observed at 1000 mgNO₃^--N/L concentration, SRT of 90 d and HRT of 48 h, and the average removal efficiencies of chemical oxygen demand (COD), ammonia nitrogen (NH₄⁺-N), and nitrate‑nitrogen (NO₃^-N) were 74.2%, 99.7%, and 89.1%, respectively. Besides, the AeMBR was achieved above 99% NH₄⁺-N removal and not adversely affected by varying operation conditions of AnoxMBBR. A slight increase in selected phthalic acid ester (PAE) concentrations (diethyl phthalate (DEP), di (2-Ethylhexyl) phthalate (DEHP), diisononyl phthalate (DINP)) was detected in the AnoxMBR, and complete PAEs removal was attained in the AeMBR. Mg, Al, Si, Na, Fe was detected by SEM-EDX analyses in both biofilm of AnoxMBBR and the cake layers of AeMBR. Nitrobacter and Nitratireductor which showed a relatively high abundance played an important role in the removal of NH₄⁺-N and COD in LFL. The results confirmed that the proposed sequence is efficient for COD removal, nitrogen removal, and PAEs being an acceptable treatment for landfill leachates.

Untapped Potential of Moving Bed Biofilm Reactors with Different Biocarrier Types for Bilge Water Treatment: A Laboratory-Scale Study

Two labscale aerobic moving bed biofilm reactor (MBBR) systems, with a different type of biocarrier in each (K3 and Mutag BioChip), were operated in parallel for the treatment of real saline bilge water. During the operation, different stress conditions were applied in order to evaluate the performance of the systems: organic/hydraulic load shock (chemical oxygen demand (COD): 9 g L−1; hydraulic retention time (HRT): 48–72 h) and salinity shock (salinity: 40 ppt). At the same time, the microbiome in the biofilm and suspended biomass was monitored through 16S rRNA gene analysis in order to describe the changes in the microbial community. The dominant classes were Alphaproteobacteria (families Rhodospirillaceae and Rhodobacteraceae) and Bacteroidia (family Lentimicrobiaceae), being recorded at high relative abundance in all MBBRs. The structure of the biofilm was examined and visualized with scanning electron microscopy (SEM) analysis. Both systems exhibited competent performance, reaching up to 86% removal of COD under high organic loading conditions (COD: 9 g L−1). In the system in which K3 biocarriers were used, the attached and suspended biomass demonstrated a similar trend regarding the changes observed in the microbial communities. In the bioreactor filled with K3 biocarriers, higher concentration of biomass was observed. Biofilm developed on Mutag BioChip biocarriers presented lower biodiversity, while the few species identified in the raw wastewater were not dominant in the bioreactors. Through energy-dispersive X-ray (EDX) analysis of the biofilm, the presence of calcium carbonate was discovered, indicating that biomineralization occurred.

Biodegradation performance and biofouling control of a halophilic biocarriers-MBR in saline pharmaceutical (ampicillin-containing) wastewater treatment

This work develops a halophilic biocarriers-MBR for saline pharmaceutical wastewater treatment. The system has effectively treated the ampicillin-containing saline wastewater for 32 days, when the ampicillin concentration is lower than 20 mg/L. The system can tolerate the saline organic wastewater with a reasonable biodegradability (removals of COD over 75%) when the ampicillin concentration is 50 mg/L. The system has a bad performance in biodegradation (COD removals around 60-70%) and fouled within 16 days at a high ampicillin concentration of 100 mg/L. At high transmembrane pressures over 30 KPa, some ampicillin molecules may permeate through the membrane causing decreases in the ampicillin removal. The concentrations of protein and carbohydrate in EPS and SMP have increased over time and with increasing the ampicillin concentration. The method of biofouling control in MBR for the ampicillin situations has been proposed based on monitoring the concentrations of EPS and SMP. The drying-assisted monitoring of membrane biofoulants has showed a better efficiency than the monitoring of transmembrane pressure for membrane anti-biofouling in the treatment of pharmaceutical saline wastewaters where a spectroscopic detection can be hardly applied. This work may benefit relative research works for the control of biodegradation performance and membrane biofouling to better treat saline pharmaceutical wastewaters.

Fate and role of fluorescence moieties in extracellular polymeric substances during biological wastewater treatment: A review

In biological wastewater treatment systems, extracellular polymeric substances (EPS) are continuously excreted as a response to environmental changes and substrate conditions. It could severely affect the treatment efficacy such as membrane fouling, dewaterability and the formation of carcinogenic disinfection by-products (DBPs). The heterogeneous dissolved organic matter (DOM) with varying size and chemical nature constitute a primary proportion of EPS. In the last few decades, fluorescence spectroscopy has received increasing attention for characterizing these organic substances due to the attractive features of this low-cost spectroscopic approach, including easy sample handling, rapid, non-destructive and highly sensitive nature. In this review, we summarize the application of fluorescence spectroscopy for characterizing EPS and provide the potential implications for online monitoring of water quality along with its limitations. We also link the dynamics of fluorescent dissolved organic matter (FDOM) in EPS with operational and environmental changes in wastewater treatment systems as well as their associations with metal binding, membrane fouling, adsorption, toxicity, and dewaterability. The multiple modes of exploration of fluorescence spectra, such as synchronous spectra with or without coupling with two-dimensional correlation spectroscopy (2D-COS), excitation-emission matrix (EEM) deconvoluted fluorescence regional integration (FRI), and parallel factor analysis (PARAFAC) are also discussed. The potential fluorescence indicators to depict the composition and bulk characteristics of EPS are also of interest. Further studies are highly recommended to expand the application of fluorescence spectroscopy paired with appropriate supplementary techniques to fully unravel the underlying mechanisms associated with EPS.

Enhanced removal of copper by electroflocculation and electroreduction in a novel bioelectrochemical system assisted microelectrolysis

The idea is immensely attractive if copper ions can be completely removed in wastewater. In this study, a novel bioelectrochemical system assisted microelectrolysis was developed for the enhanced removal of copper. One abandoned aluminium was used as anode and graphite/activated carbon as biological anode, and a bifunctional catalytic conductive membrane as cathode. Under the combined action of electroreduction and electroflocculation, copper ions directly pumped into the cathode chamber were efficiently treated, and organic matter was synchronously removed (Copper ions >99.9%, TOC >98.2%, COD >97.9%, NH₄⁺-N >94.5% and TP >94.9%). The reactions of primary batteries and microelectrolysis in anode chamber significantly enhanced the self-production capacity of BES (maximum power density of 2250 mW m^-3 at current density 10.65 mA m^-2, maximum cell voltage of 1.4 V). The results confirmed the application potential of bioelectrochemical system assisted microelectrolysis for the removal of copper.