Efficient and rapid capture of uranium(Ⅵ) in wastewater via multiamine modified β-cyclodextrin porous polymer

It is quite important to ensure the safety and sustainable development of nuclear energy for the treatment of radioactive wastewater. To treat radioactive wastewater efficiently and rapidly, two multi-amine β-cyclodextrin polymers(diethylenetriamine β-cyclodextrin polymer(DETA-TFCDP) and triethylenetetramine β-cyclodextrin polymer(TETA-TFCDP)) were prepared and applied to capture uranium. Results exhibited that DETA-TFCDP and TETA-TFCDP displayed the advantages of high adsorption amounts(612.2and 628.2 mg·g-1, respectively) and rapid adsorption rates, which can reach(88 ± 1)% of their equilibrium adsorption amounts in 10 min. Moreover, the adsorbent processes of DETA-TFCDP and TETATFCDP on uranium(Ⅵ) followed the Langmuir model and pseudo-second-order model, stating they were mainly chemisorption and self-endothermic. Besides, TETA-TFCDP also showed excellent selectivity in the presence of seven competing cations and could be effectively reused five times via Na2CO3as the desorption reagent. Meanwhile, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy illustrated that the enriched multi-amine groups and oxygen-containing functional groups on the surface of TETA-TFCDP were the main active sites for capturing uranium(Ⅵ). Hence, multi-amine β-cyclodextrin polymers are a highly efficient, rapid, and promising adsorbent for capturing uranium(Ⅵ)from radioactive wastewater.

An internal circulation iron-carbon micro-electrolysis reactor for aniline wastewater treatment:Parameter optimization,degradation pathways and mechanism

Aniline is a vital industrial raw material.However,highly-toxic aniline wastewater usually deteriorated effluent quality,posed a threat to human health and ecosystem safety.Therefore,this study reported a novel internal circulation iron-carbon micro-electrolysis(ICE)reactor to treat aniline wastewater.The effects of reaction time,pH,aeration rate and iron-carbon(Fe/C)ratio on the removal rate of aniline and the chemical oxygen demand were investigated using single-factor experiments.This process exhibited high aniline degradation performance of approximately 99.86% under optimal operating conditions(reaction time=20 min,pH=3,aeration rate=0.5 m3·h^(-1),and Fe/C=1:2).Based on the experimental results,the response surface method was applied to optimize the aniline removal rate.The Box–Behnken method was used to obtain the interaction effects of three main factors.The result showed that the reaction time had a dominant effect on the removal rate of aniline.The highest aniline removal rate was obtained at pH of 2,aeration rate of 0.5 m^(3)·h^(-1)and reaction time of 30 min.Under optional experimental conditions,the aniline content of effluent was reduced to 3 mg·L^(-1)and the removal rate was as high as 98.24%,within the 95% confidence interval(97.84%-99.32%)of the predicted values.The solution was treated and the reaction intermediates were identified by high-performance liquid chromatography,ultraviolet-visible spectroscopy,Fourier-transform infrared spectroscopy,gas chromatography-mass spectrometry,and ion chromatography.The main intermediates were phenol,benzoquinone,and carboxylic acid.These were used to propose the potential mechanism of aniline degradation in the ICE reactor.The results obtained in this study provide optimized conditions for the treatment of industrial wastewater containing aniline and can strengthen the understanding of the degradation mechanism of iron-carbon micro-electrolysis.

Issue of Managing Waste Computer Equipment in Conakry City (Republic of Guinea)

The digitization of administrative activities is a technique that not only optimizes resources, but also professionalizes the working methods of public and private services. This dematerialization process involves technologies based on computer equipment, which, after use, becomes cumbersome waste. The aim targeted consisted of taking stock of the management of waste computer equipment imported into the Republic of Guinea, with a view of proposing a mode of environmentally sustainable management methods in a short time. To achieve this, the data was collected through investigation methods (observations, interviews, and questionnaires). This study reveals an excess of imports of electrical and electronic equipment in general, and computer equipment in particular, over the last ten years (2009-2019), With an import rate ranging from 4.03 to 54.45%. This study demonstrated the different ways in which computer and electronic equipment of all kinds are managed, with her failings. This study demonstrated the different ways in which computer and electronic equipment of all kinds are managed, as well as their failings. For this purpose, the different ways in which electronic waste is managed by different users were identified as storage, recycling, or rejection into nature or at waste storage points, often mixed with household waste. Companies specializing in the management of this type of waste and the presence of a certain number of regulatory texts almost do not exist. One company is only for the entire country but unknown to the majority of users.

Univariate imputation method for recovering missing data in wastewater treatment process

High-quality data play a paramount role in monitoring,control,and prediction of wastewater treatment process(WWTP)and can effectively ensure the efficient and stable operation of system.Missing values seriously degrade the accuracy,reliability and completeness of the data quality due to network collapses,connection errors and data transformation failures.In these cases,it is infeasible to recover missing data depending on the correlation with other variables.To tackle this issue,a univariate imputation method(UIM)is proposed for WWTP integrating decomposition method and imputation algorithms.First,the seasonal-trend decomposition based on loess method is utilized to decompose the original time series into the seasonal,trend and remainder components to deal with the nonstationary characteristics of WWTP data.Second,the support vector regression is used to approximate the nonlinearity of the trend and remainder components respectively to provide estimates of its missing values.A self-similarity decomposition is conducted to fill the seasonal component based on its periodic pattern.Third,all the imputed results are merged to obtain the imputation result.Finally,six time series of WWTP are used to evaluate the imputation performance of the proposed UIM by comparing with existing seven methods based on two indicators.The experimental results illustrate that the proposed UIM is effective for WWTP time series under different missing ratios.Therefore,the proposed UIM is a promising method to impute WWTP time series.

Energy,exergy,economic and environmental comprehensive analysis and multi-objective optimization of a sustainable zero liquid discharge integrated process for fixed-bed coal gasification wastewater

For a long time,China's regional water resource imbalance has restricted the development of coal chemical industry,and it is imperative to achieve zero liquid discharge(ZLD).Therefore,the game relationship between technical indicators,costs and emissions in ZLD process of fixed-bed coal gasification wastewater treatment process should be explored in detail.According to the accurate model,the simulation for ZLD of fixed-bed coal gasification wastewater treatment process is established,and this process is assessed from the perspective of thermodynamics,economy,and environment.The total energy consumption of ZLD process before optimization is 4.032×10^(8)W.The results of exergy analysis show exergy destruction of ZLD process is 94.55%.For economic and environmental results,the total annual cost is 1.892×10^(7)USD·a^(-1)and the total environmental impact is 4.782×10^(-8).The total energy consumption of the optimal six-step ZLD process based on multi-objective optimization is 4.028×10^(8)W.The CO_(2)content in the treated wastewater is 0.1%.This study will have an important role in promoting the establishment of the ZLD process for coal chemistry industry.

Arsenic removal from acidic industrial wastewater by ultrasonic activated phosphorus pentasulfide

Arsenic is one of the main harmful elements in industrial wastewater.How to remove arsenic has always been one of the research hotspots in academic circles.In the process of arsenic removal by traditional sulfuration,the use of traditional sulfurizing agent will introduce new metal cations,which will affect the recycling of acid.In this study,phosphorus pentasulfide (P_(2)S_(5)) was used as sulfurizing agent,which hydrolyzed to produce H_(3)PO_(4) and H_(2)S without introducing new metal cations.The effect of ultrasound on arsenic removal by P_(2)S_(5) was studied.Under the action of ultrasound,the utilization of P_(2)S_(5) was improved and the reaction time was shortened.The effects of S/As molar ratio and reaction time on arsenic removal rate were investigated under ultrasonic conditions.Ultrasonic enhanced heat and mass transfer so that the arsenic removal rate of 94.5%could be achieved under the conditions of S/As molar ratio of 2.1:1 and reaction time of 20 min.In the first 60 min,under the same S/As molar ratio and reaction time,the ultrasonic hydrolysis efficiency of P_(2)S_(5) was higher.This is because P_(2)S_(5) forms ([(P_(2)S_(4))])^(2+)under the ultrasonic action,and the structure is damaged,which is easier to be hydrolyzed.In addition,the precipitation after arsenic removal was characterized and analyzed by X-ray diffraction,scanning electron microscope-energy dispersive spectrometer,X-ray fluorescence spectrometer and X-ray photoelectron spectroscopy.Our research avoids the introduction of metal cations in the arsenic removal process,and shortens the reaction time.

Production of Biogas from Olive Mill Waste Waters Treated by Cow Manure

The olive mill waste waters (OMWW) generated from olive oil extraction is a major environmental concern since they are characterized by their role as a pollutant (high organic and mineral matters) and their pH acid. The aim of this study was to valorize (OMWW) by anaerobic fermentation in the presence of cow manure in order to produce biogas and reduce their toxic load. Many tests were carried out by fermenting (OMWW) with polyphenols in the presence of cow manure in thermophile temperatures. The performance of this treatment was valuated through measurements of biogas production and by the determination of different parameters of fermented media (pH, volume of the biogas and polyphenols).

STUDY AND SIMULATION OF AN ACTIVATED SLUDGE TREATMENT FOR METHYL VIOLET WASTE WATER

This paper researched a promising biological treatment of methyl violet waste water by methods of activated sludge.Effects of temperature and pH were studied on this process.Kinetic equation of the substrate biodegradation was investigated in the experimental range.It was studied and simulated that flow within the bubble region of this bioreactor according to the κ ε two fluid equation.Simulation results agree well with experimental data.

Biodrying of municipal solid waste with high water content by combined hydrolytic-aerobic technology

The high water content of municipal solid waste(MSW)will reduce the effciency of mechanical sorting,consequently unfavorable for beneficial utilization.In this study,a combined hydrolytic-aerobic biodrying technology was introduced to remove water from MSW.The total water removals were proved to depend on the ventilation frequency and the temporal span in the hydrolytic stage. The ventilation frequency of 6 times/d was preferable in the hydrolytic stage.The hydrolytic span should not be prolonged more than ...

Researches on the Treatment of Phosphorous Wastewater with Oyster Shells

Based on the analysis of adsorptive features of oyster shells,the researches on the treatment of phosphorous wastewater with oyster shells and the effect of temperature on phosphorus removal were carried out.XRD was used to characterize the crystalline phases,and the main component of oyster shells was shown to be CaCO3.When the pretreatment temperature reached 800 ℃,some CaCO3 decomposed into CaO.As the temperature was further raised,CaO increased gradually.Via SEM testing,the oyster shell was a kind of natural porous materials.The pore wall partially collapsed from 550 to 900 ℃.No obvious porous structure was found at 900 ℃.However,without preheating,the oyster shell phosphorous removal material can not adsorb the phosphorus.Pretreatment made calcium activate,thus greatly increasing the absorption of phosphorus.

Study on the Genetic and Physiological Toxicity of Wastewater from a Pharmaceutical Factory Using Root Tip Micronucleus Technology of Vicia faba

ObjectiveThe aim was to assess genetic and physiological toxicity of wastewater from a pharmaceutical factory using root tip micronucleus technology of Vicia faba. MethodThe pollution of wastewater from a pharmaceutical factory was detected by using root tip micronucleus technology of Vicia faba, and the genetic and physiological toxicity of the wastewater to Vicia faba was assessed. ResultNon-processed wastewater had an extremely high level of biological toxicity; the cells were unable to live with the wastewater at a high concentration; the cells were able to grow with the wastewater at a low concentration, though the micronucleus ratio was extremely high. The processed wastewater had no significant impact on cell growth, but the micronucleus ratio was extremely high, showing that the processed water also had a high pollution index. ConclusionThe research could provide scientific references for the national treatment of wastewater from a pharmaceutical factory.

Phase equilibria for the pseudo-ternary system(NaCl+Na2SO4+H2O)of coal gasification wastewater at T=(268.15 to 373.15)K

The pseudo-ternary system(Na Cl + Na_2SO_4+ H_2O) of coal gasification wastewater was studied at T =(268.15 to 373.15) K. The solubility and density of the equilibrium liquid phase were determined by the isothermal solution saturation method. The equilibrium solids were also investigated by the Schreinemaker's method of wet residues and X-ray powder diffraction(XRD). According to the experimental data, the phase diagrams were determined. It was found that there was no significant solubility difference on the Na Cl-rich side between the ternary system(Na Cl + Na_2SO_4+ H_2O) in coal gasification wastewater and in pure water. However, the solubility on the Na_2SO_4-rich side of coal gasification wastewater was apparently higher than that of pure water. The increase in the solubility of Na_2SO_4 was most likely caused by the effects of other impurities apart from Na Cl and Na_2SO_4 in coal gasification wastewater. The measured data and phase equilibrium diagrams can provide fundamental basis for salt recovery in coal gasification wastewater.

Microplastics and Wastewater Treatment Plants—A Review

The emission of microplastics into nature poses a threat to aquatic and terrestrial ecosystems. Their penetration of the food chain presents a danger to human health as well. Wastewater treatment plants can be seen as the last barrier between microplastics and the environment. This review focuses on the impact of waste treatment plants in retaining microplastics. Studies show that no wastewater treatment method leads to a complete retention of microplastics, and so wastewater treatment plants themselves are viewed as point sources for the discharge of microplastics into the aquatic environment. Problems associated with the utilization of microplastic loaded sewage sludge are also discussed in the review.

The addition of microbes for treating textile wastewater

Some strains and culture of bacteria which are able to decolorize dyes and degrade polyvinyl alcohol(PVA) were isolated and selected. A pilot scale facultative anaerobic-aerobic biological process was applied for treatment of textile wastewater containing dyes and PVA. Activated carbon adsorption was used as a tertiary treatment stage, and residual sludge from clarifier returned to the anaerobic reactor again. The pilot test were carried out with two systems. One was inoculated by acclimated sludge, and the another was adding the mixed culture of dye-decoloring and PVA-degrading bacteria for forming biological films, the latter was observed to be more effective than the former. The test has run normally for ten months with a COD loading of 2.13 kg/m3/day, a BOD5 loading of 0.34 kg/m3/day in anaerobic reactor; a COD loading of 1.71 kg/m3/day, a BOD5 loading 0.44 kg/m3/day in aerobic reactor. The pollutants removal efficiency by adding microbes was about 20% higher than that by acclimated sludge. The average removal efficiency of COD stood about 92%, BOD5 97%, PVA 90% and decolorization 80%. The other parameters of effluent quality are also satisfactory.

Recovery of Caprolactam from Waste Water in Caprolactam Production Using Pulsed-sieve-plate Extraction Column

Recovery of caprolactam from waste water of caprolactam production factory was investigated using benzene as solvent in a small-scale pulsed-sieve-plate column. First, liquid-liquid equilibrium (LLE) data were measured, including water-caprolactam-benzene system at low caprolactam concentrations, and waste water-benzene system. Then, the operating regions and mass transfer of the pulsed-sieve-plate column were measured. Finally, the overall apparent heights of a transfer unit based on continuous phase are correlated in terms of the column operation variables.

Experimental Study of Wastewater Treatment of Reactive Dye by Phys-Chemistry Method

Wastewater, which involves easy-soluble reactive dyes, especially non-degradable dyes, is very difficult to decolor efficiently by normal processes such as coagulation process and biological treatment. The high chromaticity se- riously hinders the reuse of reactive dye waste water. In this paper, a new method by bentonite adsorption and coagulation (PAC) is employed for removing color from synthetic dye waste water which contains reactive red K-2G, K-RN blue, K-GR blue, X-3B red, K-GN orange, KB-3G yellow, K-2BP red, K-RN yellow and K-6G yellow. Bentonite pre- treated by 4% CTMAB and milled to 160 order screen is proven to the best decoloring agent. For a 100 mL reactive red K-2G sample (CODcr 400 mg/L, 25 000 chromaticity color), 0.5 g bentonite pretreated and 2.5 mL PAC is enough to decolor wastewater up to 99.92% and the sediment time is short. Non-degradable dyes such as active red X-3B and K-GN orange are declored completely as well. Raw sewage (low chromaticity color) is decolored completely at a ben-tonite dosage of 0.001g. More researches prove the high practical value of this process.

Recycling water glass from wet reclamation sewage of waste sodium silicate-bonded sand

Wet reclamation of waste sodium silicate-bonded sand produces much alkaline sewage and causes pollution. Recycling water glass from wet reclamation sewage of the waste sodium silicate-bonded sand can solve pollution issues and generate economic benefits. In this work, the wet reclamation sewage was filtered, and the filtrate was causticized with a quicklime powder to produce a lye. The effects of causticization temperature, causticization time, and the amount of quicklime powder on the causticization rate were studied. The lye was used to dissolve the silica in the filtration residue to prepare a sodium silicate solution. The effects of the mass of filtration residue, dissolution temperature, and dissolution time on sodium silicate modulus were studied. Finally, the recycled water glass was obtained by concentrating the sodium silicate solution, and the bonding strength of the recycled water glass was tested. The results showed that the causticization rate could be improved by increasing the amount of quicklime powder, causticization temperature, and causticization time, and the highest causticization rate was above 92%. Amorphous silica in the filtration residue dissolved in the lye. Increasing the amount of the filtration residue, dissolution temperature, and dissolution time could improve the sodium silicate modulus. The bonding strength of the recycled water glass was close to that of commercial water glass. The recycled water glass could be used as a substitute for the commercial water glass.

Adsorption of oil from waste water by coal:characteristics and mechanism

The work described here was focused on exploring the potential application of coal to purification of oily waste water.Coal was added to oily waste water as an adsorbent and then removed through a flotation process.This allowed economical and highly efficient separation of oil from the waste water.The absorption time,coal type,coal particle size distribution,pH value and oil concentration were investigated.The results indicate that oil absorption by a coal increases for a period of 1.5 h and then gradually tends toward an equilibrium value.It appears that the absorption capacity of anthracite is more than that of lean coal or lignite,given the same coal particle size distribution.The absorption capacity of a coarse coal fraction is less than that of finer coal,given the same of coal type.The absorption capacity of anthracite decreases slightly as the pH increases from 4 to 9.The adsorption of oil on anthracite follows the Freundlich isothermal adsorption law:given initial oil concentrations of 160.5 or 1023.6 mg/L the absorption capacity was 23.8 or 840.0 mg/g.The absorption mechanism consists of two kinds of absorption,a physical process assisted by a chemical one.

Studies on Feasibility of Reverse Osmosis (Membrane) Technology for Treatment of Tannery Wastewater

Tanneries reusing wastewater by combination of conventional and advanced Reverse Osmosis (RO) treatment technologies were assessed for technical and economic viabilities. Conventional treatment methods such as neutralization, clari-flocculation and biological processes are followed to clean the effluents before feeding to RO membrane modules. The characteristics of untreated composite effluents such as pH, biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), total dissolved solids (TDS), and total chromium were in the range of 4.00-4.60, 680-3600 mg/L, 1698-7546 mg/L, 980-1480 mg/L, 4200-14500 mg/L, and 26.4-190 mg/L, respectively. Inorganic ions like Ca2+, Na+, Cl– and SO42– were found more in the wastewaters. Conventional treatments significantly removed the organic pollutants however failed to remove dissolved inorganic salts. Membrane technology removed the salts as well as remaining organic pollutants and the product water is reused in the process. The studied tanneries (5 numbers) have achieved 93-98%, 92-99% and 91-96% removal of TDS, sodium and chloride, respectively. Seventy to eighty five percentage of wastewater was recovered and recycled in the industrial processes. The rejects are subject to either solar evaporation system or Multiple Effect Evaporation (MEE) technology. The resulting salts are collected in polythene bags and disposed into scientifically managed secured land fill (SLF) site. The cost of wastewater treatment for operation and maintenances of RO including the pre-treatments (conventional methods) is INR 100-110 m-3.

Structure Characterization and Dephosphorization Effect Analysis of Oyster Shell-silica Micropowder Waste Water Dephosphorization Materials

In this work,the effects of pH value of waste water and initial concentration of phosphorus on dephosphorization materials were investigated.The materials were prepared by shaping,sintering and hydrothermal reshaping oyster shell and silica micro-powder.Different concentrations of phosphorus-contained waste water were simulated with potassium dihydrogen phosphate solution,the effect of dephosphorization was tested with phosphomolybdenum blue spectrophotometer method,and the crystal phase and microstructure of materials were characterized by XRD and SEM methods. It was indicated that dephosphorization was completed in 6 h when the initial phosphorus concentration in waste water was lower than 15 mg/L, and the dephosphorization time prolonged as the increase of phosphorus concentration. It was observed that the pH value of waste water influenced dephosphorization significantly, and neutral subalkalic environment favored dephosphorization. When the pH value was 11, the efficiency of dephosphozation was the greatest. For waste water with an initial concentration of 20 mg/L, the dephosphozation rate is close to 100% in8 h.