Analysis of a Composite Admixture Based on Ready-Mixed Concrete Waste Residuals

Reasonable treatment and utilization of waste residuals discharged during the production of ready-mixed concrete is an important problem in the cement industry.In this study,a composite admixture was prepared by using ready-mixed concrete waste residuals,furnace slag,and water granulated slag.The grinding characteristics of such material were investigated.Moreover,the effect of such admixture on cement hydration and pore structure was analyzed by X-ray diffraction,thermogravimetric-differential scanning calorimetry,scanning electron microcopy and mercury intrusion porosimetry.As shown by the results:The grinding characteristics of the waste residuals can be improved significantly by mixing them with furnace slag and water granulated slag.Furthermore,the composite admixture does not change the composition of hydration products;rather it contributes to refine the pore structure of the matrix,thus improving the mechanical properties of these cement-based materials.

Industrial wastes applications for alkalinity regulation in bauxite residue: A comprehensive review

Bauxite residue is a highly alkaline material generated from the production of alumina in which bauxite is dissolved in caustic soda.Approximately 4.4 billion tons of bauxite residues are either stockpiled or landfilled,creating environmental risks either from the generation of dust or migration of filtrates.High alkalinity is the critical factor restricting complete utilization of bauxite residues,whilst the application of alkaline regulation agents is costly and difficult to apply widely.For now,current industrial wastes,such as waste acid,ammonia nitrogen wastewater,waste gypsum and biomass,have become major problems restricting the development of the social economy.Regulation of bauxite residues alkalinity by industrial waste was proposed to achieve‘waste control by waste’with good economic and ecological benefits.This review will focus on the origin and transformation of alkalinity in bauxite residues using typical industrial waste.It will propose key research directions with an emphasis on alkaline regulation by industrial waste,whilst also providing a scientific reference point for their potential use as amendments to enhance soil formation and establish vegetation on bauxite residue disposal areas(BRDAs)following large-scale disposal.

Recycling of waste carbon residue from spent lithium-ion batteries via constant-pressure acid leaching

Waste carbon residue(WCR)was efficiently detoxicated and regenerated to high-purity graphite(PGC)used in lithium-ion batteries through the constant-pressure acid leaching technique.The leaching conditions were optimized by the combination of orthogonal and single-factor experiments.Results show that PGC with 99.5%purity is regenerated at temperature of 60℃,initial acid concentration of 12%,leaching time of 180 min,and liquid-to-solid ratio of 25:1,satisfying the requirements of commercial graphite.Meanwhile,the sodium hydroxide precipitation process was designed to recover valuable components from leachate efficiently.Ni,Co,Mn,and Al recoveries reach 96.92%,87.5%,97.83%,and 92.17%,respectively,at pH=11.Moreover,the co-product NaF can be recovered with purity over 99%via evaporative crystallization.The loss rate of fluorine is less than 0.5%,thereby eliminating the pollution risk of fluorine to the environment.The proposed process shows considerable environmental and economic benefits.

Hydrothermal Synthesis of Xonotlite-type Calcium Silicate Insulation Material Using Industrial Zirconium Waste Residue

Xonotlite-type insulation material was prepared by hydrothermal synthesis technology using industrial zirconium waste residue in this paper,and the phase analysis together with the observation of micro–morphology were also carried out by XRD,SEM and TEM.The density and thermal conductivity were measured finally.The results indicate,chlorine ion impurity contained in zirconium waste residue can be removed effectively via water washed process,and the reactive activity of silicon dioxide is almost not affected,which make it be a good substitution of silicon material for the preparation of calcium silicate insulation material by hydrothermal synthesis technique.The density and thermal conductivity of xonotlite-type calcium silicate insulation material obtained by hydrothermal synthesis technique can reach 159 kg/m3,0.049 W/（m·° C）,respectively,meeting with National Standard well,when synthesis conditions are selected as follows：Ca/Si molar ratio equal to 1,synthesis temperature at 210°C and kept for 8 hrs.It provides a new approach to realize lightweight and low thermal conductivity of calcium silicate insulation material.

Zeolite Synthesis under Insertion of Silica Rich Filtration Residues from Industrial Wastewater Reconditioning

Zeolite synthesis was studied using two silica rich filtration residues (FR 1 and FR 2) as Si-source and sodium aluminate in a direct synthesis at 60°C at strong alkaline conditions (8 M - 16 M NaOH). In addition to these one-pot syntheses, a two-step process was investigated. Here, an alkaline digestion of FR at 60°C was followed by gel precipitation with sodium aluminate and gel crystallization under usual conditions of 80°C - 90°C. The results show that the substitution of chemical reagent sodium silicate by a waste material like FR as Si-source is possible but requires fine tuning of the reaction conditions as zeolite crystallization is a process under kinetic control. The solubility behaviour and impurities of the inserted filtration residues strongly influenced the course of reaction. Thus zeolites like hydrosodalite or intermediate zeolite between cancrinite and sodalite, or zeolite NaA or Z-21 in cocrystallization with hydrosodalite could be observed in the one pot syntheses already in a short time interval between 1 - 4 h depending on the alkalinity. The two step process yield to zeolites NaA and NaX in very good quality. The reaction process of FR in both reaction methods was characterized by chemical analyses, X-ray powder diffraction, Fourier transform infrared spectroscopy as well as scanning electron microscopy. Surface area and water content of selected products were further characterized by the BET-method and by thermogravimetry. Summing up the results, we can show that zeolite formation from filtration residues is possible by several reaction procedures as model cases for a re-use of industrial waste materials. Beside the importance for environmental protection, the reactions are of interest for zeolite chemistry as the re-use of FR is possible under economically conditions of low energy consumption at 60°C and short reaction periods.

Co-processing Vacuum Residue with Waste Plastics in a Delayed Coking Process:Kinetics and Modeling

Thermal upgrading of vacuum residue mixed with waste plastics was studied in a laboratory scale delayed coking unit.The model of feed thermal decomposition was set up and the first order reaction kinetics was used to predict products distribution during the coking process.The distillate yield was higher(70%) for the vacuum residue/polystyrene(VR/PS) feed system and the vacuum residue/low density polyethylene(VR/LDPE) feed system.The resulted distillate yield was separated into fractions according to their boiling points,with gasoline and diesel being our fractions of concern.The activation energy was higher for gasoline production(around 60 kcal/mol) varying with the type of feed system,while it was 33 kcal/mol for diesel fraction.The regression coefficient R was 0.990.

Comprehensive Recycling Technology of Waste Residues in Zinc Hydrometallurgy

In order to improve the refining effect of zinc ore and promote the development of this industry,taking the hydrometallurgical zinc smelting process as an example,this paper first establishes a model for the recycling of waste residues in the hydrometallurgical process,proposes optimization measures based on proven comprehensive recycling technology for purifying residues to obtain higher valuable metal recovery rate,and provides reference for those in relevant fields.

A Review of Co-processing of Kitchen Waste and Municipal Residual Sludge

In this paper, the methods of kitchen waste disposal in recent years were summed up, and the advantages and disadvantages of the current treatment methods were analyzed. At the same time, it has been found that the co-processing of kitchen waste and residual sludge not only has dealt with both kitchen waste and residual sludge, but also the carbon and nitrogen ratio and moisture content of the mixture are balanced, and increases the processing efficiency significantly. It has a certain processing advantage. At present, most research is about the anaerobic digestion of kitchen waste and residual sludge, and the process is more mature, but the study of VFAs accumulation is still insufficient. Aerobic composting is still in the early stage of development, and there are few studies on it at home and abroad. Meanwhile, prospects for the kitchen waste recycling were made in this article.

Selective recovery of Th(Ⅳ) from radioactive rare earth waste residue by utilizing MoS_(2)-modified ion-absorbed type rare earth tailings

In the process of extracting ion-absorbed rare earth ore(IREO),the production of radioactive waste is a major environmental concern.To address this issue,MoS_(2) was used to modify ion-absorbed rare earth tailings(RET) to synthesize a novel MoS_(2)@RET composite material for the effective handling of radioactive waste generated in IREO separation industry.The composite material was thoroughly characterized using various analytical techniques,including X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),thermogravimetry(TG),Fourier-transform infrared(FTIR),scanning electron microscopy(SEM),Brunaue r-Emmett-Teller(BET) and energy dispersive spectroscopy(EDS).By optimizing the operating parameters,the optimal experimental conditions were determined to be pH=3,contact time=60 min,liquid-solid ratio=6 g/L,and initial concentration=150 mg/L.The adsorption data fitted well with the pseudo second-order rate model.The thermodynamic parameters concerning the adsorption of Th(Ⅳ) were analyzed and computed.Langmuir isotherm model is a more fitting choice for the adsorption process compared to the Freundlich isotherm model.MoS_(2)@RET was used in the acid leachate of IREO waste residue,achieving the separation of Th and rare earth successfully.The mechanism of Th(Ⅳ) adsorption by MoS_(2)@RET was investigated,revealing that the adsorption process involves electrostatic interactions,chemical bonding,and redox reactions.The above research results indicate that MoS_(2)@RET composite materials have application potential in the sustainable treatment of IREO radioactive waste.

Metagenomic insights into microorganisms and antibiotic resistance genes of waste antibiotic fermentation residues along production,storage and treatment processes

Antibiotic fermentation residue(AFR)is nutrient-rich solid waste generated from fermentative antibiotic production process.It is demonstrated that AFR contains high-concentration of remaining antibiotics,and thus may promote antibiotic resistance development in receiving environment or feeding farmed animals.However,the dominate microorganisms and antibiotic resistance genes(ARGs)in AFRs have not been adequately explored,hampering understanding on the potential antibiotic resistance risk development caused by AFRs.Herein,seven kinds of representative AFRs along their production,storage,and treatment processes were collected,and multiple methods including amplicon sequencing,metagenomic sequencing,and bioinformatic approaches were adopted to explore the biological characteristics of AFRs.As expected,antibiotic fermentation producer was found as the predominant species in raw AFRs,which were collected at the outlet of fermentation tanks.However,except for producer species,more environment-derived species persisted in stored AFRs,which were temporarily stored at a semi-open space.Lactobacillus genus,classified as Firmicutes phylum and Bacilli class,became predominant bacterial taxa in stored AFRs,which might attribute to its tolerance to high concentration of antibiotics.Results from metagenomic sequencing together with assembly and binning approaches showed that these newly-colonizing species(e.g.,Lactobacillus genus)tended to carry ARGs conferring resistance to the remaining antibiotic.However,after thermal treatment,remaining antibiotic could be efficiently removed from AFRs,and microorganisms together with DNA could be strongly destroyed.In sum,the main risk from the AFRs was the remaining antibiotic,while environment-derived bacteria which tolerate extreme environment,survived in ARFs with high content antibiotics,and may carry ARGs.Thus,hydrothermal or other harmless treatment technologies are recommended to remove antibiotic content and inactivate bacteria before recycling of AFRs in pharmaceutical industry.

Assessment of the Concentration of Petroleum Hydrocarbon in Oily Wastes Residual Ash at Bodo-Ogoni Remediation Site, Nigeria

Hydrocarbon wastes generated from remediation activities contain Total Petroleum Hydrocarbon (TPH), Polyaromatic Hydrocarbon (PAH) and Heavy Metals whose respective concentrations are yet to be determined. There is limited available literature particularly in Nigeria, on whether the concentration of these wastes after treatment exceeds permissible limits. The present work aims to determine the concentration of petroleum hydrocarbon in the residual ash from the treated (incinerated) oily wastes from the Bodo-Ogoni remediation activities. Oily wastes residual ash samples were collected from six treatment sites, each divided into four replicates in a Completely Randomized Design. A total of twenty-four residual ash samples were collected and taken to National Oil Spill Detection and Response Agency (NOSDRA) Reference Laboratory, Port Harcourt for extraction. The concentration of TPH, PAH and heavy metals in untreated hydrocarbon wastes were also determined and used for the control experiment. The extracts were analyzed using AGILENT 7890A-GC and Atomic Absorption Spectrophotometer (AAS) modelled 240FS, manufactured in USA. The results show six residual pollutants;Cadmium, Lead, Zinc, Manganese, TPH and PAH below the Nigeria Department of Petroleum Resources (DPR) Intervention Level but exceeded the DPR Target Level for TPH and PAH. The descending order of concentration of PAH obtained from the treatment sites gwere;1.24 + 2.4 mg/kg (Paschal), 4.76 + 7.48 mg/kg (ITS), 10.46 + 14.68 mg/kg (TMCH) and 16.14 + 6.36 mg/kg (Mosab). Similarly, the concentration of TPH was 320.18 + 355.13 mg/kg (TMCH), 463.25 + 205.29 mg/kg (ICREN) and 501.11 + 300.79 mg/kg (Networld) against TPH 12,000 mg/kg, PAH 23 mg/kg, Cadmium 0.15 mg/kg, Lead 0.59 mg/kg, Zinc 3.45 mg/kg and Manganese 2.8 mg/kg (untreated wastes). Two treatment sites only recorded concentration of heavy metals, while four reformed inefficiently and couldn’t detect the concentration of some residual pollutants in the ash samples and consequently, recorded below detectable level (BDL). Statistical analysis showed a significant difference (P 0.05) between heavy metal content across sites and their target values. The results showed that the remediation activities had a strong impact on the concentration of TPH and PAH, and a weak impact on the concentration of heavy metals in the treated oily wastes. The implications of the results are discussed.

Advances in Research on Comprehensive Utilization of Tea Waste

China is a big producer and consumer of tea. A huge amount of tea waste is produced in China every year, resulting in environmental pollution and enormous natural resources waste. From the perspective of utilization way, this pa- per summarized the research progresses in tea waste as a raw material for ex- tracting active ingredients and preparing absorbent, activated carbon, bio-organic fer- tilizer, animal feed and nutrients for edible fungi cultivation. In addition, the develop- ment trend of comprehensive utilization of tea waste was prospected. It is found that the comprehensive utilization of tea waste using a variety of techniques can im- prove the utilization efficiency of tea waste and reduce production costs. Finally, a simple and practical comprehensive utilization program was proposed to provide a reference for practical application.

Development of Soda Residue Concrete Expansion Agent

A new type of concrete expansion agent has been successfully developed for the first time in the world by utilizing an industrial waste residue soda residue and an industrial wasteliquor.Adding 3%-6% of the agent into Portland cement enables a shrinkage compensating concrete to be prepared.Mortar and concrete containing this expansion agent have better shrinkage compensating and mechanical properties.The raw materials component,production process,technical properties,micro analysis of mortar made with this expansion agent,mechanism of expansion and research results are described in this article.The experimental results show that the new type of concrete expansion agent accords with the standard and its main mineral component is xCaO ySO 3 zAl 2O 3.

Biodegradation of Medicinal Plants Waste in an Anaerobic Digestion Reactor for Biogas Production

Glycyrrhiza glabra,Mint,Cuminum cyminum,Lavender and Arctium medicinal are considered as edible plants with therapeutic properties and as medicinal plants in Iran.After extraction process of medicinal plants,residual wastes are not suitable for animal feed and are considered as waste and as an environmental threat.At present there is no proper management of waste of these plants and they are burned or buried.The present study discusses the possibility of biogas production from Glycyrrhiza Glabra Waste(GGW),Mentha Waste(MW),Cuminum Cyminum Waste(CCW),Lavender Waste(LW)and Arctium Waste(AW).250 g of these plants with TS of 10%were digested in the batch type reactors at the temperature of 35℃.The highest biogas production rate were observed to be 13611 mL and 13471 mL for CCW and GGW(10%TS),respectively.While the maximum methane was related to GGW with a value of 9041 mL(10%TS).The highest specific biogas and methane production were related to CCW with value of 247.4 mL.(g.VS)-1 and 65.1 mL.(g.VS)-1,respectively.As an important result,it was obvious that in lignocellulose materials,it cannot be concluded that the materials with similar ratio of C/N has the similar digestion and biogas production ability.

Optimization of hydrothermal pretreatment for co-utilization of xylose and glucose of cassava anaerobic residue for producing ethanol

The development of a process that could recover biofuel from industrial cellulose waste can not only reduce the negative environmental impacts by using fossil fuels, but also bring a green idea for the waste’s disposing. In this study, hydrothermal pretreatment was optimized for cassava anaerobic residue, a cellulosic waste from cassava ethanol industry, to co-utilize xylose and glucose for producing bioethanol. The effect of the main pretreatment conditions, namely, temperature, solid content and time, was explored for the highest recovery of xylose in prehydrolysate and glucose in enzymatic hydrolysate. The single factor experiment results showed that the conditions for maximum xylose recovery in prehydrolysate and glucose recovery in enzymatic hydrolysate were 60℃, 75 min, 10% solids and 160℃, 75 min, 10% solids, respectively. Whereafter, response surface methodology(RSM) was applied to further optimize the pretreatment conditions for the maximum theoretical ethanol production through utilizing both xylose and glucose. A treatment at 163℃, for 59 min and with 9.5%solids was found optimal, with the highest ethanol production of 20.2 mg·g^-1 raw material. Furthermore, in order to assess the impacts of the pretreatment on cassava anaerobic residue, the changes in crystallinity and morphology for untreated and pretreated solids were investigated.

Preparation of colloidal Sb_2O_5 from arsenic-alkali residue

The stable colloidal antimony pentoxide was prepared by oxidation of the mixture of Sb2O3 and Sb2O5 obtained from arsenic-alkali residue by hydrometallurgical process, with hydrogen peroxide as oxidant and phosphoric acid as stabilizer. Effects of main factors were investigated. The theories on thermodynamics, kinetics and electrical double layer（EDL） were used to analyze the experimental phenomena and results. The results show that no aging time is the most beneficial to forming colloid, when molar ratio of phosphoric acid to antimony is in the range from （0.8） to 1.0 and 1.0 to 1.3, the particle sizes of sol with the concentration of 10% and 15% antimony pentoxide by mass are both smaller. With increasing concentration of the mixture of antimony oxide from 10% to 20%, the reaction time decreases from 90 to about 30min, but the optimized range of molar ratio of H3PO4 to antimony increases. The reaction temperature is not the main factor on particle size with the existence of H3PO4 in the temperature range from 60 to 90℃.

The Application of Ultrasonic in the Refining of Waste Silk Material

The treatment effect of ultrasonic on waste silk material was studied in this paper. The results show that Ultrasonic can emulsify the pupal fat and accelerate the dissolving of sericin. For high pupal fat containing material, high temperature, high pH value and long time which may result in damage to silk fibre are not required and different levels of sericin can be kept according to requirement in ultrasonic refining. In addition, silk fibres are swollen and the breaking elongation of silk fibre is increased on prolonged ultrasonic treatment. But the breaking tenacity is damaged slightly.

An Assessment of the Potential Use of Forest Residues for the Production of Bio-Oils in the Urban-Rural Interface of Louisiana

Louisiana is endowed with forest resources. Forest wastes generated after thinning, land clearing, and logging operations, such as wood debris, tree trimmings, barks, sawdust, wood chips, and black liquor, among others, can serve as potential fuels for energy production in Louisiana. This paper aims to evaluate the potential annual volumes of forest wastes established on detailed and existing data on the forest structure in the rural-urban interface of Louisiana. It also demonstrates the state’s prospects of utilizing forest wastes to produce bio-oils. The data specific to the study was deduced from secondary data sources to obtain the annual average total residue production in Louisiana and estimate the number of logging residues available for procurement for bioenergy production. The total biomass production per year was modeled versus years by polynomial regression curve fitting using Microsoft Excel. Results of the model show that the cumulative annual total biomass production for 2025 and 2030 in Louisiana is projected to be 80000000 Bone Dry Ton (BDT) and 16000000 (BDT) respectively. The findings of the study depict that Louisiana has a massive biomass supply from forest wastes for bioenergy production. Thus, the potential for Louisiana to become an influential player in the production of bio-based products from forest residues is evident. The author recommends that future research can use Geographic Information Systems (GIS) to create maps displaying the potential locations and utilization centers of forest wastes for bioenergy production in the state.

Rapid conversion of alkaline bauxite residue through co-pyrolysis with waste biomass and its revegetation potential

The extreme alkalinity of bauxite residue(BR)leads to difficulty with its reuse.Alkaline leachate and dust generation during the stacking process can pollute surrounding soil,air and water.In this work,co-pyrolysis of bauxite residue and sawdust was applied to rapidly produce a soil-like matrix that met the conditions for plant growth as demonstrated by ryegrass pot experiments.The present study aimed to characterize the detailed changes in physicochemical,mineral weathering,and microbial communities of the pyrolyzed BR with different ratios of saw dust after plant colonization for 2 months.With increasing sawdust addition during co-pyrolysis,the pH of BR decreased from 11.21 to 8.16,the fraction of macro-aggregates 0.25-2 mm in the water-stable agglomerates increased by 29.3%,and the organic carbon concentration increased from 12.5 to 320 mg/kg,whilst facilitating the degree of humification,which were all beneficial to its revegetation performance.The backscattered electron-scanning electron microscope-energy-dispersive X-ray spectrometry(BSE-SEM-EDS)results confirmed the occurrence of sodalite and calcite weathering on aggregate surfaces,and X-ray photoelectron spectroscopy(XPS)results of surface Al and Si compounds identified that some weathering products were clay minerals such as kaolinite.Furthermore,bacterial community composition and structure shifted towards typical soil taxonomic groups.These results demonstrate soil development of treated BR at an early stage.The technique is a combination of alkalinity regulation and agglomerate construction,which accelerates soil formation of BR,thus proving highly promising for potential application as an artificial soil substitute.

Shearing-force-driven delamination of waste residue into oxidatively stable MXene composites for high-performance Si anode

The low yield of MXene is normally related to the delaminating step,contributing to the key technical challenges in moving toward industrial applications.Here,a shearing-force-driven strategy is proposed for re-exfoliating waste MXene residue to prepare oxidatively stable MXene composites in a low-cost manner,where the strong shear stress in the assisted solvent,such as carbon nanotubes(CNTs),chitosan(CS),and polyacrylamide(PAM)aqueous solutions,acts on the surface of MXene(Ti_(3)C_(2)T_(x))through coordination between hydroxyl and Ti atoms,resulting in a rapid and efficient exfoliation of waste Ti_(3)C_(2)T_(x)residue under stirring.Furthermore,this formed coordinate bond helps to stabilize the low-valent Ti atoms on the surface of MXene,thereby enhancing the oxidative stability of Ti_(3)C_(2)T_(x).Besides,the CNT@MXene composite is selected to construct a free-standing membrane to encapsulate Si nanoparticles,achieving a high and reversible capacity after 50 cycles.This work supports the concept of valorizing waste and adopts a fluid shear forceassisted method to re-exfoliate waste residues,which greatly reduces the cost of processing and improves the chemical stability of MXene.More importantly,this work has uncovered a new direction for the commercialization of MXene composites and has significantly improved the realworld applications of MXene-based materials.