Real-time monitoring of biofoulants in a membrane bioreactor during saline wastewater treatment for anti-fouling strategies

A Review on Opportunities and Limitations of Membrane Bioreactor Configuration in Biofuel Production

Biofuels are a clean and renewable source of energy that has gained more attention in recent years; however, high energy input and processing cost during the production and recovery process restricted its progress. Membrane technology offers a range of energy-saving separation for product recovery and purification in biorefining along with biofuel production processes. Membrane separation techniques in combination with different biological processes increase cell concentration in the bioreactor, reduce product inhibition, decrease chemical consumption, reduce energy requirements, and further increase product concentration and productivity. Certain membrane bioreactors have evolved with the ability to deal with different biological production and separation processes to make them cost-effective, but there are certain limitations. The present review describes the advantages and limitations of membrane bioreactors to produce different biofuels with the ability to simplify upstream and downstream processes in terms of sustainability and economics.

Observation of the Intervention Effect of Biofeedback Therapy Combined With Cluster Nursing on Perioperative Constipation in Patients With Thoracolumbar Fracture

Purpose

To discuss the intervention effect of biofeedback therapy combined with cluster nursing on perioperative constipation in patients with thoracolumbar fracture.

Methods

From June 2019 to June 2020, a total of 482 patients with thoracolumbar fracture who were treated by surgery in our department were selected. The random number table method was used to divide into experimental group (n = 241) and control group (n = 241). The control group was given routine constipation care, the experimental group was given biofeedback therapy combined with cluster nursing based on the control group. The constipation score, Bristol stool scale score, the short health questionnaire (SF-36) scale score, and the satisfaction of two groups were observed.

Results

The constipation scores of the experimental group were lower than those of the control group, while the Bristol stool scale score, SF-36 score, and satisfaction degree of the experimental group were higher than those of the control group (p < 0.05).

Conclusion

Biofeedback therapy combined with cluster nursing has a good intervention effect in perioperative constipation of patients with thoracolumbar fracture, which can reduce the degree of constipation, improve stool traits, improve the quality of life, and improve the satisfaction of patients.

Analysis of the Influence of High-Dose rhGH Therapy on Serum Vitamin D and IGF-1 Levels in School-Age Children with Idiopathic Short Stature

Objective

To discuss the influence of high-dose recombinant human growth hormone (rhGH) therapy on serum vitamin D and insulin-like growth factor-1 (IGF-1) levels in school-age children with idiopathic short stature (ISS).

Method

A total of 103 school-age children with ISS were selected from June 2016 to June 2020 in our hospital. The enrolled cases were divided into the low-dose group (n = 59) and high-dose group (n = 44) according to the treatment dose of rhGH. After the treatment, the height (Ht), height standard deviation score (Ht SDS), growth velocity (GV), and other indicators were recorded. The serum 25-hydroxy vitamin D [25-(OH)D] and IGF-1 levels of the two groups were tested, and the occurrence of adverse reactions was recorded.

Results

After treatment, the high-dose group outperformed the low-dose group in various growth effect indicators such as Ht, Ht SDS, and GV (P < 0.05). After treatment, the serum 25-(OH)D of children with ISS in the two groups increased significantly, but there was no significant difference between the two groups (P > 0.05). After treatment, the serum IGF-1 of children with ISS in the two groups increased significantly, but there was no significant difference between the two groups (P > 0.05). For children with ISS, adverse reactions induced by rhGH therapy were very rare. There was no significant difference in the incidence of adverse reactions induced by different doses of rhGH in the treatment of ISS (P > 0.05).

Conclusion

rhGH has definite efficacy in the treatment of ISS children, for it can significantly increase the annual growth rate of ISS children in a dose-dependent manner. High-dose rhGH for ISS has a better therapeutic effect. At the same time, regardless of the dose level of rhGH, serum 25-(OH)D and IGF-1 levels in children with ISS were increased, with less adverse reactions and higher safety.

Data-Driven Intelligent Warning Method for Membrane Fouling

Membrane fouling has become a serious issue in membrane bioreactor (MBR) and may destroy the operation of the wastewater treatment process (WWTP). The goal of this article is to design a data-driven intelligent warning method for warning the future events of membrane fouling in MBR. The main novelties of the proposed method are threefold. First, a soft-computing model, based on the recurrent fuzzy neural network (RFNN), was proposed to identify the real-time values of membrane permeability. Second, a multistep prediction strategy was designed to predict the multiple outputs of membrane permeability accurately by decreasing the error accumulation over the predictive horizon. Third, a warning detection algorithm, using the state comprehensive evaluation (SCE) method, was developed to evaluate the pollution levels of MBR. Finally, the proposed method was inserted into a warning system to complete the predicting and warning missions and further tested in the real plants to evaluate its efficiency and effectiveness. Experimental results have verified the benefits of the proposed method.

Analysis of the biodegradation performance and biofouling in a halophilic MBBR-MBR to improve the treatment of disinfected saline wastewater

Disinfectant-containing wastewaters have been generated from many places, including marine industries. The synthetic NaClO-containing wastewaters have been effectively treated in a saline MBBR-MBR (moving bed biofilm reactor & membrane bioreactor) system containing marine microorganisms. A low concentration of NaCl (below 100 mg/L) is not enough to kill the microorganisms, but can affect their bioactivity and induce membrane biofouling. A linear relationship has been obtained for the half-life of membrane biofouling as a function of the NaClO concentration (10-100 mg/L): [half-life] = 25-0.12 × [NaClO concentration]. The COD and NH₃-N removals are the highest at a salinity of 30 g/L for the marine bioreactors. The behaviour of the typical biofoulants, measured real-timely by fluorescence spectroscopy, can indicate the levels of membrane biofouling and microbial activity, responding to the NaClO and NaCl influences. Based on the behaviour of biofoulants, this work has also proposed a novel strategy of biofoulants monitoring for membrane antifouling, where antifouling responses can be carried out when the concentration of biofoulants significantly increases.

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.

A critical review on saline wastewater treatment by membrane bioreactor (MBR) from a microbial perspective

This work has reviewed from a microbial perspective and listed the typical studies on MBR techniques for saline wastewater treatments. When the salinity of influent is lower than 10 g/L NaCl, conventional MBR can be easily applied with adjusted operating conditions. For better biodegradation and anti-fouling ability at higher salinities (10-100 g/L), modified and hybrid MBR systems may need to be wisely designed according to the change in the microbial community and contents of EPS/SMP. To treat hypersaline wastewaters with salinities of up to 100 g/L NaCl, inoculation of halophilic bacteria has been applied in MBR works. Microbial community structures in some typical works have been discussed from a microbial perspective to benefit the identification and isolation of halophilic bacteria for future works. The following aspects are also suggested in future MBR research for saline wastewater treatment: (1) The structure design of MBR and the manufacture of advanced membranes; (2) The maintenance of the microbial biodiversity for anti-membrane fouling; (3) The metabolic mechanism for halophilic (or salt-tolerant) microorganisms against salinity shocks; (4) The revolution stage and process of microorganisms during saline wastewater treatment in MBR; (5) The effects of characteristics (cell structure, shape and metabolic pathways) of microorganisms on the salt tolerance; (6) Applying halophilic microorganisms for salinities over 150 g/L NaCl.

Enhanced removal mechanism of iron carbon micro-electrolysis constructed wetland on C, N, and P in salty permitted effluent of wastewater treatment plant

In this study, the combination of a constructed wetland (CW) with iron-carbon (Fe-C) system was used to enhance the simultaneous removal of carbon, nitrogen and phosphorus in salty permitted effluent of wastewater treatment plant (SPE-WTP). The removal mechanism of Fe-C micro-electrolysis CWs with different salinity (0.027, 0.308, and 0.511%) for treating SPE-WTP was investigated, including chemical oxygen demand (COD), phosphorus and nitrogen removal, the mass balance, as well as the changes in the microbial community structure. The results showed the salinity has a certain influence on the contaminant removals, and can enhance nitrogen removal under certain conditions. When the salinity increased from 0.308% to 0.511%, the removal of COD decreased from 68.20% to 62.69%, whereas the removal of total nitrogen (TN) increased from 72.02% to 81.21% in the ICCW-p system (including P. australis as the plant and gravel doped with 3% iron-carbon as the matrix). Microbial degradation, including the electrochemical effect (the degradation by iron-carbon micro-electrolysis) was the main N removal pathway in the ICCW-p system. The ICCW-p system always achieved higher removal rates (such as 81.21% TN and 62.69% COD removals at 0.511% salinity) than that in ICCW-n system (without plants and gravel doped with 3% iron-carbon as the matrix, 63.76% TN and 56.31% COD removals, respectively) and CW-n (without plants and gravel as the matrix, 14.90% TN and 22.39% COD removals, respectively). In addition, high-throughput sequencing analysis revealed that high salinity increased the abundance of N-removing bacteria in the ICCW-p system. Furthermore, with the introduction of iron-carbon in CWs, the removal methods in ICCW-p were diverse, which has enough ability to resist the impact of salinity. Fe electrolysis produced different valence states that acted as carriers for electron transport and accelerated the efficiency of biological and chemical reactions, which enhanced the simultaneous removal of carbon, nitrogen and phosphorus.

Mechanistic insights into alginate fouling caused by calcium ions based on terahertz time-domain spectra analyses and DFT calculations

Fouling mechanisms underlying the filtration behaviors of alginate solution caused by calcium addition were investigated by Terahertz time-domain spectroscopy (THz-TDS) and density functional theory (DFT) techniques. Filtration tests showed that specific filtration resistance (SFR) of alginate solution (0.75 g L^-1) monotonously increased with calcium addition at a relatively low range of calcium concentration (0-1.0 mM), and SFR (2.61 × 10¹⁵ m kg^-1) of alginate solution with 1.0 mM calcium addition was extremely high as compared with sludge suspension. Characterizations by X-ray photoelectric spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and Thermogravimetric analysis (TGA) showed that the composition of functional groups, elements and thermal stability of alginate was not apparently affected by calcium concentration. Howbeit, THz-TDS spectra showed that calcium addition caused structural variation of alginate polymer in solution. DTF calculation results showed that initial binding of alginate chains induced by calcium ions preferentially occurred in intermolecular other than intramolecular, and moreover, the two alginate chains bridged by a calcium atom tend to stretch in a tetrahedron structure (cross to each other) other than parallel to each other. According to these results, "chemical potential gap" depicted by Flory-Huggins theory was suggested to be responsible for the filtration behaviors of alginate solution caused by calcium addition. This study provided the mechanistic insights into membrane fouling.