Lactic Acid Production from Kitchen Waste with a Newly Characterized Strain of Lactobacillus plantarum

To enhance the fermentative production of lactic acid (LA) from kitchen waste, a strain of high-yield lactic acid bacterium, designated as TD46, was characterized and its fermentation profiles were investigated. The strain TD46 could produce 91.34 g l–1 of LA from 100 g l–1 of glucose in 96 h of fermentation at pH 5.5~6.0 and 30 °C. On the basis of its fermentation ability to 49 carbohydrates and additional physio-biochemical tests, the strain TD46 was tentatively identified as Lactobacillus plantarum. The strain TD46 produced 28.85 g l–1 of LA from non-autoclaved kitchen waste in 48 h of fermentation at pH 5.5~6.0, which was 75.1 % higher than that of the spontaneous fermentation without inoculum (control). Meanwhile, 0.39 g g–1 of LA yield and 0.60 g l–1 h–1 of average productivity were reached, respectively. This study shows that enhancement of LA production from kitchen waste can be realized by using the high-yield strain TD46

Effect of heavy metals and surfactants on the adsorption of phenolic compounds on sediment

The effects of different heavy metals (copper and mercury), cationic surfactants cetylpyridinium chloride, anionic surfactant sodium dodecylbenzenesulfonate and the chemistry of the solution (pH value) on the adsorption of three selected phenolic compounds (2, 4-Dichlorophenol, 2, 4-Dinitro-phenol and 2, 4-Dimethyphenol) on sediment were studied. Results indicated that in the sediment-water system with phenolic compounds: (1) all of the data could be simulated by Freundlich equation; (2) the experiments studying pH effects showed that the adsorption capacity of 2, 4-Dichlorophenol and 2, 4-Dimethyphenol were quite potentia Hydrogenii dependent and increased with decrease in potentia Hydrogenii, while 2, 4-Dinitrophenol followed the different trend; (3) As the concentration increased from 0 to 0.2 mM for Cu2+, the Freundlich capacity coefficient constant varied from 62.84 to 325.1 for 2, 4-Dichlorophenol, from 13.1 to 82.179 for 2, 4-Dinitrophenol and from 29.433 to 7.976 for 2, 4-Dimethyphenol, respectively. The Freundlich capacity coefficient constant of 2, 4-Dichlorophenol, 2, 4-Dinitrophenol and 2, 4-Dimethyphenol varied from 62.84 and 421.43, 13.1 and 138.1, 29.433 and 1.381, respectively, with concentration of Hg2+ increased from 0 to 0.04 mM, respectively; (4) the adsorption of 2, 4-Dichlorophenol and 2, 4-Dimethyphenol were accentuated by cetylpyridinium chloride but suppressed by sodium dodecylbenzenesulfonate, whereas the adsorption of 2, 4-Dinitrophenol on sediment was enhanced by both cationic and anionic surfactants, effects that are consistent with electrostatic and hydrophobic interactions among ionic surfactants, phenolic compounds and sediment. The results are believed to provide a useful insight into describing the transport and fate of phenolic compounds in natural environments

Comparing the adsorption and desorption characteristics of 17α-ethinylestradiol on sludge derived from different treatment units

The adsorption and desorption behaviors of 17α-Ethinylestradiol on various sludge derived from different treatment units of a sewage treatment plant were investigated using batch equilibration experiments. The results showed that adsorption process could be well described by pseudo-second-order kinetic model and fast adsorption played a main role. Adsorption ability varied as the order of aerobic sludge ≈ anoxic sludge ≈ primary sludge> sludge cake> anaerobic sludge. Adsorption/desorption isotherms were well fitted by the modified Freundlich model, and K&apos;f values increased with the organic matter content. Thermodynamic analysis indicated that 17α-Ethinylestradiol adsorption/desorption was exothermic and conducted spontaneously. After heat-treatment for removing the organic carbon, K&apos;f values reduced by more than 78 %, but organic carbon normalized adsorption constant was 7.76-29.51 mg/g. The 17α-Ethinylestradiol adsorption capacity was found to decrease from 0.95-1.39 mg/g to 0.44-0.49 mg/g with sludge concentration increasing from 500 to 4000 mg/L, keep almost unchanged at pH 3-10 and sharply decrease when pH >10. The adsorption capacity was also found being fluctuated in the range of 2.0-3.0 mg/g when Ca2+ concentration< 0.5 mol/L and increased rapidly above 0.5 mol/L. Addition of methanol and acetonitrile could improve 17-Ethinylestradiol desorption effect, which increased with the organic solvents content, and desorption degree of acetonitrile was higher than methanol

Graphitic biochar catalysts from anaerobic digestion sludge for nonradical degradation of micropollutants and disinfection

The peroxydisulfate (PDS) -based advanced oxidation processes (AOPs) is a promising technology for wastewater treatment and the efficiency primarily depends on the high-performance catalysts. Therefore, it is necessary to develop a green and low-cost biomaterial for PDS activation to drive such a process. In this study, biochar catalysts were produced via pyrolysis of anaerobic digestion sludge (ADS) as effective PDS activators. The biochar derived from ADS (ADSBC) yielded large specific surface areas, a high degree of graphitization and good conductivity, which can be used for effectively oxidizing various pollutants including dyes, estrogens and sulfonamides with PDS in broad pH and temperature ranges. It is showed that PDS activated by ADSBC 1000 can completely remove sulfathiazole in 90 min much higher than that of ADSBC 400 (20.25%). Moreover, the biochar produced under high pyrolysis temperature shows great stability and low biotoxicity due to the limited metals leaching and eliminated persistent free radicals as well as dissolved organic matter. The mechanism of the ADSBCs/PDS system was critically discussed via selectively radical screening tests, solvent exchange (H₂O to D₂O), selectivity to pollutants and electrochemical analysis. These results revealed that the organics were decomposed by a nonradical pathway via electron transfer rather than relying on free radicals or singlet oxygen. More importantly, the biochar-based nonradical oxidation system can leveraged for inactivation of Escherichia coli (E. coli) and diverse bacteria in both simulated and real wastewater. Therefore, this work not only provides an approach to reuse the sludge residue to prepare graphitic biochar catalysts as PDS activators for decontamination of emerging micropollutants, but also expands the practical application of advanced carbocatalysis for bacteria inactivation by nonradical oxidation in real wastewater.Yi-di Chen, Xiaoguang Duan, Chaofan Zhang, Shaobin Wang, Nan-qi Ren, Shih-Hsin H

Advanced oxidation processes for water disinfection: Features, mechanisms and prospects

Available online 25 December 2020The disinfection of microbial pathogens plays an important role in control of waterborne diseases and health issues. Recently, advanced oxidation processes (AOPs) are applied as powerful and effective technologies for wastewater purification and pathogen elimination. This review will showcase the recent endeavors in the fields and provide a comprehensive understanding of pathogens inactivation by diverse AOPs (i.e., Fenton processes, photocatalysis, electrochemical advanced oxidation processes (EAOPs), sonolysis, ozonation, and persulfate-based AOPs). The mechanisms of AOPs-based disinfection include the destruction of cell envelope, enzymes, and intracellular substances via diverse reactive oxygen species (ROS). The primary ROS are HO·, SO4•−, O2•−, 1O2, and O3, which exhibit different oxidative capacities, and can react with cell envelope to destroy the permeability of cell membrane. Specifically, this review emphasizes on the performances and mechanisms of different AOPs systems in microbial inactivation as well as perspectives in practical applications of disinfection in terms of feasibility, operating cost, and sustainability.Yi-di Chen, Xiaoguang Duan, Xu Zhou, Rupeng Wang, Shaobin Wang, Nan-qi Ren, Shih-Hsin H

Urinary bisphenol a concentrations and their implications for human exposure in several Asian countries

Bisphenol A (BPA) is an industrial chemical used in the manufacture of polycarbonate plastics and epoxy resins. Due to the potential of this compound to disrupt normal endocrinal functions, concerns over human exposure to BPA have been raised. Although several studies have reported human exposure to BPA in Western nations, little is known about exposure in Asian countries. In this study, we determined total urinary BPA concentrations (free plus conjugated) in 296 urine samples (male/female: 153/143) collected from the general population in seven Asian countries, China, India, Japan, Korea, Kuwait, Malaysia, and Vietnam, using high-performance liquid chromatography (HPLC) tandem mass spectrometry (MS/MS). On the basis of urinary BPA concentrations, we estimated the total daily intake. The results indicated that BPA was detected in 94.3 of the samples analyzed, at concentrations ranging from = 50 years), the highest median concentration of BPA was found in urine samples from the age group of <= 19 years. There was no significant difference in BPA concentrations between genders (male and female) or domicile of residence (rural and urban). The estimated median daily intakes of BPA for the populations in Kuwait, Korea, India, China, Vietnam, Malaysia, and Japan were 5.19, 3.69, 2.90, 2.13, 2.01, 1.80, and 1.61 mu g/day, respectively. The estimated daily intake of BPA in the seven Asian countries was significantly lower than the tolerable daily intake recommended by the U.S. Environmental Protection Agency. This is the first study to document the occurrence of and human exposure to BPA in several Asian countries