Enhanced Purification and Disinfection of Restaurant Wastewater by Electro-coagulation Coupled with an Electro-oxidation Process: From Lab Scale to Field Scale

Several Covid-19 infection events have been reported in restaurant and food-processing factory scenarios. To block the transmission of waterborne pathogens and protect human’s safety, it is urgent to take action for the purification and disinfection of restaurant wastewater. Considering the requirement of restaurant wastewater treatment technology, such as limited spaces, low capital cost, simple to operate, and high efficiency, an integrated electro-coagulation (EC) and electro-oxidation (EO) process was put forward. The lab-scale system treatment results illustrated that the composition of restaurant wastewater underwent significant changes. The chemical oxygen demand value decreased from 1680 to 344 mg/L. Total phosphate, total nitrogen, suspended solids, petroleum, animal fat and vegetable oils, and anionic surfactants achieved a distinct decrease. Moreover, the removal of Escherichia coli and Phi6 illustrated the satisfactory disinfection performance of the EC–EO system. The acute toxicity of the EC–EO effluent was reduced compared to that of raw wastewater. Comparing the results of EC treatment with EO treatment, the EC process provided more significant contributions to the purification and disinfection of wastewater than the EO process. The oxidants generated in the EO process would ensure the residual purification and disinfection performance through the long sewer pipe. The physical–chemical parameters and disinfection performances of the field-scale EC–EO system met the requirement of “Wastewater quality standards for discharge to municipal sewers-GB/T 31962-2015”. However, a certain amount of disinfectant byproducts were formed in the effluent. Moreover, the techno-economic analysis further illustrated the feasibility of the integrated EC–EO system for the purification and disinfection of restaurant wastewater

Effect of Tm3+ concentration on the emission wavelength shift in Tm3+-doped silica microsphere lasers

In this work, a Tm3+-doped solgel silica microsphere lasing at 2.0 mu m is reported. Microspheres with different Tm3+ concentrations are fabricated by overlaying different Tm3+ concentration solgel solutions on the surface of a pure silica microsphere resonator and then annealing the sample with a CO2 laser. Based on a traditional fiber taper-microsphere coupling method, single and multimode microsphere lasing in the wavelength range 1.8-2.0 mu m is observed if an 808 nm laser diode is used as a pump source. A relatively low threshold pumping power of 1.2 mW is achieved using this arrangement. This solgel method allows for an easy varying of the Tm3+ doping concentration. The observed laser output shifts to longer wavelengths when the Tm3+ doping concentration increases. This has been explained by the larger Tm absorption at shorter wavelengths. The ability to fabricate solgel co-doped silica glass microlasers represents a new generation of low threshold and compact infrared laser sources for use as miniaturized photonic components for a wide range of applications, including gas sensing and medical surgery. (c) 2018 Optical Society of America

A Tm3+-Ho3+ codoped tellurite glass microsphere laser in the 1.47 μm wavelength region

In this Letter, a Tm-3(+)-Ho3+ codoped tellurite glass microsphere laser in the 1.47 mu m wavelength region is described. Using a traditional tapered microfiber-microsphere coupling method, multimode and single-mode lasing around the wavelength of 1.47 mu m is observed using an 802 nm laser diode as a pump source. This Tm3+-Ho3+ codoped tellurite glass microsphere laser can be used in near-infrared telecommunications, biomedical, and astrophysical applications. (C) 2019 Optical Society of Americ

Up-conversion luminescence and C-band laser in Er3+-doped fluorozirconate glass microsphere resonator

Up-conversion luminescence and C-band microsphere laser output is reported for an Er3+-doped ZrF4-BaF2-YF3-AlF3 (ZBYA) fluorozirconate glass microsphere. The microsphere was fabricated by heating a ZBYA glass filament using a CO2 laser beam. The fabrication process accurately and repeatably produces microspheres of 68 μm diameter. The input and output laser light was coupled to the microsphere using a tapered optical fiber. The coupling position between the tapered fiber and microsphere was adjusted using a sophisticated three-dimensional translation stage. The up-conversion luminescence emission, single-mode and multi-mode laser at C-band (1530 to 1565 nm) were observed when pumped using a 980 nm laser

An in-fibre whispering-gallery modes microsphere resonator based integrated device

A novel in-fiber whispering-gallery mode (WGM) microsphere resonator-based integrated device is reported. It is fabricated by placing a silica microsphere into an embedded dual-core hollow fiber (EDCHF). Using a fiber tapering method, a silica microsphere can be placed and fixed in the transition section of the hollow core of the EDCHF. The transmitted light from the tapered-input single-mode fiber is coupled into the embedded silica microsphere via the two suspended fiber cores, and hence effectively excites the WGMs. A Q-factor of 5.54 × 103 is achieved over the wavelength range of 1100–1300 nm. The polarization and temperature dependence of the in-fiber WGM microsphere resonator device is also investigated experimentally. This integrated photonics device provides greatly improved mechanical stability, compared with the traditional tapered fiber-coupled WGM microresonator devices. Additional advantages include ease of fabrication, compact structure, and low cost. This novel in-fiberWGMresonator integrated device is ideally positioned to access a wide range of potential applications in optical sensing and microcavity lasing