Influence of secondary treatment with CO_2 laser irradiation for mitigation site on fused silica surface

The ablation debris and raised rim, as well as residual stress and deep crater will be formed during the mitigation of damage site with a CO2 laser irradiation on fused silica surface, which greatly affects the laser damage resistance of optics. In this study, the experimental study combined with numerical simulation is utilized to investigate the effect of the secondary treatment on a mitigated site by CO2laser irradiation. The results indicate that the ablation debris and the raised rim can be completely eliminated and the depth of crater can be reduced. Notable results show that the residual stress of the mitigation site after treatment will reduce two-thirds of the original stress. Finally, the elimination and the controlling mechanism of secondary treatment on the debris and raised rim, as well as the reasons for changing the profile and stress are analyzed. The results can provide a reference for the optimization treatment of mitigation sites by CO2laser secondary treatment.

The surgical treatment of low-grade glioma with secondary epilepsy

Objective To explore the methods of surgical treatment of low-grade glioma with secondary epilepsy. Methods Video-EEG, magnetoencephalography (MEG) were performed to localizate the epileptogenic zone and domain in 13 patients,and stereotactic technology ,ultrasoumd,electrocorticogram (EcoG) were combined

One stage anterior release and posterior fusion for the treatment of irreducible atlantoaxial dislocation secondary to os odontoideum

Objective To evaluate clinical effect of the ventral release through high anterior cervical retropharyngeal approach and one stage posterior fusion for the treatment ofirreducible atlantoaxial dislocation (IAAD) secondary

Effectiveness of Centralized Wastewater Treatment Plant in Removing Emerging Contaminants: A Case Study at Kuching, Malaysia

Before the construction of the Kuching Centralized Wastewater Treatment System Package 1 (KCWTSP1), partially treated blackwater and greywater were discharged directly into natural waterways. The accumulated wastewater had polluted Sarawak river, which is regulated and cannot discharge freely into the South China Sea. The polluted Sarawak river has endangered human health, river water quality, and aquatic ecosystems. Hence, the KCWTSP1 commissioned in 2015 serves the purpose of removing pollutants from wastewater before it is discharged into natural waterways. However, the effectiveness of KCWTPP1 is unknown. This paper is aimed to discuss and review the effectiveness of KCWTPP1 in treating wastewater since its inception in 2015. From 2017 to 2020, KCWTPP1 has treated an average of 4,200,000 m3 of wastewater per year. Generally, most of the discharge effluent met Environmental Quality Act (1974) Standard A criteria, except for the oil and grease parameter. Initially, the plant could not treat suspended solids and total phosphorus, but this was greatly improved in subsequent years. Therefore, some improvements are required to treat oil and grease parameters effectively and efficiently to ensure that only Standard A effluent is discharged into the Sarawak River in the future.

Performance of a Demonstrative (Scale-Pilot) Double Advanced Oxidation Wastewater Treatment Plant to Treat Discharges from a Small Community in Morelia, Michoacán, México

This paper,reports the performance of a wastewater treatment scale-pilot plant to treat 2 GPM(Gallons per Minute)discharges with 5,205 mg/L of pollutants expressed in COD(Chemical Oxygen Demand),from“Lomas de la Maestransa”a small community in Morelia City,Michoacan,Mexico.The scale-pilot plant is a train with(1)pretreatment with a triturated pump for floating solid,(2)primary treatment with“in line”coagulation,and rapid filtration to retain suspended colloids and dissolved solids higher of 5μm diameter,(3)double advanced oxidation as secondary treatment with ozone and heterogeneous photo catalysis to oxidize volatile solids,and(4)tertiary treatment with activated carbon to retain refractory compounds.Plant performance was analyzed by a certified laboratory that belongs to Potable Water,Sewage and Sanitation Department from Morelia City Government.Results show that treated water effluent complied with the Mexican Official Standard NOM-001-SEMARNAT-1996 for discharges into national waters,with exception of fecal coliforms,since the raw water contains an average of 64,228,351 MNP/100 mL of fecal coliforms,and in spite that we obtained a 99.998%efficiency,the maximum level allowable 2,000 MPN/100 mL standard,was exceeded by 400 MPN/100 mL.After this experience,the wastewater treatment plant is equipped with a residual chlorine tank to keep a 1.5 ppm chlorine residual concentration to keep the treated water clean.This project was possible because we had the support of the Morelia Sanitation Department.

Monitoring of 943 organic micropollutants in wastewater from municipal wastewater treatment plants with secondary and advanced treatment processes

To perform a systematic survey on the occurrence and removal of micropollutants during municipal wastewater treatment, 943 semi-volatile organic chemicals in 32 wastewater samples including influents of secondary treatments, secondary effluents and final effluents（effluents of advanced treatments）, which were collected from seven full-scale municipal wastewater treatment plants（MWTPs） in China, were examined by gas chromatography-mass spectrometry（GC-MS） coupled with an automated identification and quantification system with a database（AIQS-DB）. In total, 196 and 145 chemicals were detected in secondary and final effluents, respectively. The majority of the total concentrations（average removal efficiency, 87.0%±5.9%） of the micropollutants were removed during secondary treatments. However, advanced treatments achieved different micropollutant removal extents from secondary effluents depending on the different treatment processes employed. Highly variable removal efficiencies of total concentrations（32.7%–99.3%） were observed among the different advanced processes. Among them,ozonation-based processes could remove 70.0%–80.9% of the total concentrations of studied micropollutants. The potentially harmful micropollutants, based on their detection frequency and concentration in secondary and final effluents, were polycyclic aromatic hydrocarbons（PAHs）（2-methylnaphthalene, fluoranthene, pyrene, naphthalene and phenanthrene）, phosphorus flame retardants（tributyl phosphate（TBP）, tris（2-chloroethyl）phosphate（TCEP） and tris（1,3-dichloro-2-propyl） phosphate（TDCP））, phthalates（bis（2-ethylhexyl）phthalate（DEHP））, benzothiazoles（benzothiazole,2-（methylthio）-benzothiazol, and 2（3H）-benzothiazolone） and phenol. This study indicated that the presence of considerable amounts of micropollutants in secondary effluent creates the need for suitable advanced treatment before their reuse.

Health Risks of Trace Metals in Wastewater-Fed Fishes:A Case Study

In this study,the usage wastewater from secondary treatment in feeding fishes of Carassius gibelio species and suitability of the fishes for human food were evaluated.The metals(Ag,Al,As and B)in treated effluent and skeleton,skin,eyes and brain tissues of fishes were examined seasonally.It was found that treated effluent was not suitable for irrigation and aquaculture in terms of Al according to the Turkish standard values.According to annual averages the size order of Ag and B concentrations were skeleton>skin>eyes>brain and skeleton>skin>brain>eye respectively.Also,skin>brain>eyes>skeleton was for As and Al.TF(Transfer Factor)values of all metals examined were determined as>1 in the four tissues and the metals caused bioaccumulation because of treated effluent.Concentrations in muscles were found 7 to 6227 times higher than in water.The size order of TF and BCF(Bio-concentration Factor)values in skin and eye tissue were the same and it was Ag>Al>As>B.It was Ag>Al>As>B in skeleton,Al>As>Ag>B in brain.HQ(Hazard Quotient)of Al in all tissues had carcinogenic risk level.

Secondary Austenite Morphologies in Fusion Zone of Welded Joint after Postweld Heat Treatment with a Continuous Wave Laser

In order to improve the weldability of duplex stainless steels,obtaining more secondary austenite in the weld metal is an effective way.Therefore,optimizing the secondary austenite by changing its morphology,volume fraction and stability may be expected to enhance the ductility of the weld.The secondary austenite morphologies in the fusion zone of the laser continuously heat treated welds of 2205 duplex stainless steel were investigated.The secondary austenite morphologies were found to be influenced by different laser power level.The secondary austenite with penniform,freely grown and dendritic shape appeared in the course of 4,6 and 8 kW continuous heat treatment,respectively.It was found that there were three kinds of morphologies of secondary austenite in the fusion zone treated by different power,i.e.,widmannst¨atten austenite,grain boundary austenite and intragranular austenite.The results demonstrated that the mechanism of the secondary austenite formation was a displacement mechanism during the initial austenite lath formation and a diffusion mechanism during cooling.The nitrides provided the nitrogen for the transformation and at the same time acted as nucleation sites for the secondary austenite.

Removal efficiencies of natural and synthetic progesterones in hospital wastewater treated by different disinfection processes

Progesterones are ubiquitous in hospital wastewater(HWW)with concentrations much higher than those of estrogens and androgens.To ensure that these water systems are safe to use,disinfection is crucial during HWW treatment by providing"front line"defense against biological contaminations.Here,five disinfection processes,namely,chlorine(Cl_(2)),chlorine dioxide(ClO_(2)),ozone(O_(3)),ultraviolet(UV)),and UV/chlorine(UV/Cl_(2)),were selected to investigate their removal efficiencies for progesterones in primary filtration and secondary biological treatment effluents.There were 61 natural and synthetic progesterones detected in HWW,with the natural progesterones being the main components with a concentration of 845.51 ng/L and contributing to 75.08%of the total proge-sterones.The primary filtration treatment presented insignificant removal effects on the progesterones,while the secondary biological treatment significantly reduced the progesterone content by biode-gradation.The order of removal efficiencies of total progesterones by different disinfection processes was UV/Cl_(2)>Cl_(2)>O_(3)>ClO_(2)>UV.UV/Cl_(2)showed the highest removal efficiency against progesterones mainly due to the activation of Cl_(2)by ultraviolet(UV)photolysis,which helps open the heterocyclic,aromatic,and phenolic rings,thus accelerating progesterone degradation.In addition,the removal efficiencies of natural progesterones in the five disinfection processes were higher than those of synthetic progesterones(progesterone derivatives,19-nortestosterone derivatives,and 17α-hydroxyprogesterone derivatives).