Coupled Coincidence Points for Mixed Monotone Random Operators in Partially Ordered Metric Spaces

The aim of this work is to prove some coupled random coincidence theorems for a pair of compatible mixed monotone random operators satisfying weak contractive conditions. These results are some random versions and extensions of results of Karapınar et al. (2012). Our results generalize the results of Shatanawi and Mustafa (2012)

Bipolar Membrane Electrodialysis for Ammonia Recovery from Synthetic Urine: Experiments, Modeling, and Performance Analysis

Recovering nitrogen from source-separated urine is an important part of the sustainable nitrogen management. A novel bipolar membrane electrodialysis with membrane contactor (BMED–MC) process is demonstrated here for efficient recovery of ammonia from synthetic source-separated urine (∼3772 mg N L–1). In a BMED–MC process, electrically driven water dissociation in a bipolar membrane simultaneously increases the pH of the urine stream and produces an acid stream for ammonia stripping. With the increased pH of urine, ammonia transports across the gas-permeable membrane in the membrane contactor and is recovered by the acid stream as ammonium sulfate that can be directly used as fertilizer. Our results obtained using batch experiments demonstrate that the BMED–MC process can achieve 90% recovery. The average ammonia flux and the specific energy consumption can be regulated by varying the current density. At a current density of 20 mA cm–2, the energy required to achieve a 67.5% ammonia recovery in a 7 h batch mode is 92.8 MJ kg–1 N for a bench-scale system with one membrane stack and can approach 25.8 MJ kg–1 N for large-scale systems with multiple membrane stacks, with an average ammonia flux of 2.2 mol m–2 h–1. Modeling results show that a continuous BMED–MC process can achieve a 90% ammonia recovery with a lower energy consumption (i.e., 12.5 MJ kg–1 N). BMED–MC shows significant potential for ammonia recovery from source-separated urine as it is relatively energy-efficient and requires no external acid solution

Constructed wetlands as nature-based solutions for the removal of antibiotics: performance, microbial response, and emergence of antimicrobial resistance (AMR)

Antibiotics and antibiotic resistance genes (ARGs) have been regarded as emerging pollutants and pose significant threats to the aquatic environment and to human health. This study aimed to investigate the removal of nutrients, antibiotics, and the emergency of ARGs in domestic sewage by means of constructed wetlands (CWs) filled with an electroconductive media, i.e., coke. In this study, the antibiotics removal efficiencies ranged from 13% to 100%, which were significantly higher in the system filled with coke compared with the CWs filled with common quartz sand (7%~100%). Moreover, the presence of wetland plants could also significantly improve the removal of nutrients and tetracyclines. The results also demonstrated the importance of substrate selection and wetland plants in CWs on the alternation of microbial communities and structures, where the electroconductive media showed a promising effect on increasing the removal of antibiotics in CWs. In terms of the emergency of ARGs, the CWs filled with coke retained the most ARGs (10,690 copies/g) compare with the control groups (8576–7934 copies/g) in the substrate. As the accumulated ARGs could be released back to the watercourse due to the environmental/operation condition changes, the application of such an advanced substrate in CWs may pose a more significant potential threat to the environment. With these results, this study provided new insight into selection of the substrates and plants for wastewater treatment to achieve a sustainable and secure water future

Effect of Sb dopant amount on the structure and electrocatalytic capability of Ti/Sb-SnO_2 electrodes in the oxidation of 4-chlorophenol

Ti/Sb-SnO2 anodes were prepared by thermal decomposition to examine the influence of the amount of Sb dopant on the structure and electrocatalytic capability of the electrodes in the oxidation of 4-chlorophenol. The physicochemical properties of the Sb-SnO2 coating were markedly influenced by different amounts of Sb dopant. The electrodes, which contained 5% Sb dopant in the coating, presented a much more homogenous surface and much smaller mud-cracks, compared with Ti/Sb-SnO2 electrodes containing 10% or 15% Sb dopant, which exibited larger mud cracks and pores on the surface. However, the main microstructure remained unchanged with the addition of the Sb dopant. No new crystal phase was observed by X-ray diffraction (XRD). The electrochemical oxidation of 4-chlorophenol on the Ti/SnO2 electrode with 5% Sb dopant was inclined to electrochemical combustion; while for those containing more Sb dopant, intermediate species were accumulated. The electrodes with 5% Sb dopant showed the highest efficiency in the bulk electrolysis of 4-chlorophenol at a current density of 20 mA/cm(2) for 180 min; and the removal rates of 4-chlorophenol and COD were 51.0% and 48.9%, respectively

Electrochemical impedance spectroscopy and surface properties characterization of anion exchange membrane fouled by sodium dodecyl sulfate

In this study, the fouling of anion exchange membrane (AEM) in electrodialysis was investigated using sodium dodecyl sulfate (SDS) as a model foulant, and the effect of membrane cleaning on the properties of the fouled AEMs was examined further. Results showed that the severer fouling of AEM was caused by the higher concentration of SDS in the feed solution, and a dense SDS fouling layer was formed on the ARM surface, causing the obvious increase of electrical resistance and the deterioration of desalination performance. Electrochemical impedance spectroscopy (EIS) indicated the SDS fouling layer on the AEM could hinder, even restrict completely the transmembrane migration of the ions, especially at high concentration of SDS. The cleaning experiment showed the cleaning effect of ultra -pure water was similar to that of Ha solution, but was better than that of NaOH solution, in which most SDS on the fouled AEM could be removed effectively by cleaned in ultra-pure water. EIS of the fouled AEMs before and after cleaned indicated that the remaining SDS on the cleaned AEM had almost no influence on the transmembrane migration of the ions through AEM.</p

Robust antifouling anion exchange membranes modified by graphene oxide (GO)-enhanced Co-deposition of tannic acid and polyethyleneimine

Three polyphenol-polyamine co-deposition systems containing different polyphenols (catechol (CA), gallic acid (GA) and tannic acid (TA)) and Polyethyleneimine (PEI) were established and used to construct adhesive layer on the surface of anion exchange membranes (AEMs). And graphene oxide (GO) was introduced into co-depositions to construct an antifouling modifying layer. The modified AEMs were characterized and applied in electrodialysis for antifouling experiments. The results showed that the TA-PEI-M with a large depositing amount exhibited more hydrophilic surface than those of CA-PEI-M and GA-PEI-M, but still low value in the negative charge density. The introduction of GO increased the negative charge density of membrane surface and endowed AEMs with enhanced antifouling ability significantly. Furthermore, GO-TA-PEI-M could maintain surface properties and antifouling performance after immersing in NaOH solutions, indicating good alkaline-stability. It was attributed to that the abundant phenolic groups in TA played a vital role in the formation of co-deposition layer. The abundant phenolic groups in TA could provide stronger adhesion and multiple reactive sites to generate more stable covalent structures with PEI. In addition, the hydrogel products produced by the electrostatic interaction of TA and PEI helped increase the depositing amount. This work proposed a novel approach to fabricate surface-modified antifouling AEMs with alkaline stability by polyphenol-polyamine co-deposition

Application of a pH Feedback-Controlled Substrate Feeding Method in Lactic Acid Production

Substrate concentration in lactic acid fermentation broth could not be controlled well by traditional feeding methods, including constant, intermittent, and exponential feeding methods, in fed-batch experiments. A simple feedback feeding method based on pH was proposed to control pH and substrate concentration synchronously to enhance lactic acid production in fed-batch culture. As the linear relationship between the consumption amounts of alkali and that of substrate was concluded during lactic acid fermentation, the alkali and substrate in the feeding broth were mixed together proportionally. Thus, the concentration of substrate could be controlled through the adjustment of pH automatically. In the fed-batch lactic acid fermentation with Lactobacillus lactis-11 by this method, the residual glucose concentration in fermentation broth was controlled between 4.1 and 4.9 g L-1, and the highest concentration of lactic acid, maximum cell dry weight, volumetric productivity of lactic acid, and yield were 96.3 g L-1, 4.7 g L-1, 1.9 g L-1 h(-1) and 0.99 g lactic acid per gram of glucose, respectively, compared to 82.7 g L-1, 3.31 g L-1 1.7 g L-1 h(-1) and 0.92 g lactic acid per gram of glucose in batch culture. This feeding method was simple and easily operated and could be feasible for industrial lactic acid production in the future

J. Chem. Technol. Biotechnol.

BACKGROUND: The large output of monosodium glutamate in China has produced huge amounts of isoelectric supernatant containing 40-60 g L(-1) (NH(4))(2) SO(4). With the increasing national emphasis on environmental protection and recycling, it is necessary to find a cost-effective and environment-friendly alternative to recover the (NH(4))(2)SO(4). This paper reports on investigations of the electrodialysis process for (NH(4))(2)SO(4) recovery from isoelectric supernatant pretreated by ceramic membrane. RESULTS: For ceramic membrane pretreatment, the optimal pore size chosen was 0.2 mu m. After a 250 min run, permeate flux was still maintained at 90 L m(-2) h(-1) (v = 2.8 m s(-1), Delta TMP = 0.12 MPa, concentration factor = 7). Meanwhile, the total solids and proteins content in condensed supernatant were high, up to 78 g L(-1) and 24 g L(-1), respectively, which greatly favors future cell protein harvest. With the chosen current density of 17 mA cm(-2), the energy consumption and time for six consecutive batches for electrodialysis were 2.6-2.7 kW h kg(-1) sulfate and similar to 100 min, based on similar to 80% ammonium sulfate recovery from pretreated isoelectric supernatant. CONCLUSION: Ceramic membrane pretreatment was shown to be a promising pretreatment strategy, applicable to the electrodialysis process to recover ammonium sulfate from isoelectric supernatant produced during monosodium glutamate production. (C) 2008 Society of Chemical Industry.BACKGROUND: The large output of monosodium glutamate in China has produced huge amounts of isoelectric supernatant containing 40-60 g L(-1) (NH(4))(2) SO(4). With the increasing national emphasis on environmental protection and recycling, it is necessary to find a cost-effective and environment-friendly alternative to recover the (NH(4))(2)SO(4). This paper reports on investigations of the electrodialysis process for (NH(4))(2)SO(4) recovery from isoelectric supernatant pretreated by ceramic membrane