Formation cause,composition analysis and comprehensive utilization of rare earth solid wastes

Based on practical situation of rare earth industrial chain,production process and rare earth materials that could produce solid wastes on batch were discussed.Formation cause,formation volume,composition analysis and comprehensive utilization of the solid wastes of rare earth hydrometallurgy slag,electrolysis slag,Fe-based rare earth permanent magnetic materials,Co-based rare earth permanent magnetic materials,rare earth hydrogen storage materials,rare earth polishing powders and rare earth catalysts were ...

Technology of comprehensive disposal and utilization of municipal solid waste (MSW)

The project for treating MSW of 200 tons each day was built in Yibin, Sichuan Province of China. The disposal processes are: separation and selection of usable resources; compost and fermentation of “heavy” organic waste (kitchen, garden composting rubbish); incineration of “light” waste (plastic, paper, wood and bamboo etc.) and landfill of inorganic waste. The thermal energy generated in the process can be used as 1/3 of the whole energy for drying fertilizers. In the process, there is no wastewater drainage, and air emissions can be effectively controlled by a series of measures. The sanitary and environmental indicators of disposal site meet the national standards. This project has worked well for two years. It not only disposes of and reduces the MSW, but also retrieves the resource effectively. The organic fertilizer has been applied in the ten thousand acres of fields, with productivity increase by more than 10%.

Research achievements and application in anaerobic treatment of organic solid wastes—A review

Anaerobic digestion is a good method, which possesses the optimal combination of volume reduction, probability of success and potential for resource and energy recovery. However, relatively little research has been done on the anaerobic digestion of organic solid wastes (OSW), especially in China. However, different substrates, start-up conditions, micro-organisms, processing technologies, pre-treatment methods could influence the result of anaerobic digestion. Anaerobic treatment of municipal OSW is less than that of wastewaters because some problems and obstructions need to be solved. Meanwhile, the application of anaerobic digestion of OSW is also discussed in the present paper.

CO_(2) mineralization by typical industrial solid wastes for preparing ultrafine CaCO_(3): A review

Mineral carbonation is a promising CO_(2) sequestration strategy that can utilize industrial wastes to convert CO_(2) into high-value CaCO_(3).This review summarizes the advancements in CO_(2) mineralization using typical industrial wastes to prepare ultrafine CaCO_(3).This work surveys the mechanisms of CO_(2) mineralization using these wastes and its capacities to synthesize CaCO_(3),evaluates the effects of carbonation pathways and operating parameters on the preparation of CaCO_(3),analyzes the current industrial application status and economics of this technology.Due to the large amount of impurities in solid wastes,the purity of CaCO_(3) prepared by indirect methods is greater than that prepared by direct methods.Crystalline CaCO_(3) includes three polymorphs.The polymorph of CaCO_(3) synthesized by carbonation process is determined the combined effects of various factors.These parameters essentially impact the nucleation and growth of CaCO_(3) by altering the CO_(2) supersaturation in the reaction system and the surface energy of CaCO_(3) grains.Increasing the initial pH of the solution and the CO_(2)flow rate favors the formation of vaterite,but calcite is formed under excessively high pH.Vaterite formation is favored at lower temperatures and residence time.With increased temperature and prolonged residence time,it passes through aragonite metastable phase and eventually transforms into calcite.Moreover,polymorph modifiers can decrease the surface energy of CaCO_(3) grains,facilitating the synthesis of vaterite.However,the large-scale application of this technology still faces many problems,including high costs,high energy consumption,low calcium leaching rate,low carbonation efficiency,and low product yield.Therefore,it is necessary to investigate ways to accelerate carbonation,optimize operating parameters,develop cost-effective agents,and understand the kinetics of CaCO_(3) nucleation and crystallization to obtain products with specific crystal forms.Furthermore,more studies on life cycle assessment(LCA)should be conducted to fully confirm the feasibility of the developed technologies.

Synthesis of Activated Carbon from Polyethylene Terephthalate(PET)Plastic Waste and Its Application for Removal of Organic Dyes from Water

Synthetic plastics are often considered to be materials that cannot be broken down by natural processes.One such plastic,polyethylene terephthalate(PET),is commonly used in everyday items but when these products are discarded,they can cause serious harm to the environment and human health.In this study,PET plastic waste was used to create activated carbon using a physical activation process that involved using CO2 gas.The researchers investigated the effects of different temperatures,carbonization,and activation times on the resulting activated carbon’s surface area.The activated carbon was then analyzed using scanning electron microscopy(SEM),X-ray diffraction(XRD),FTIR,and BET.The activated carbon created from PET plastic waste showed excellent absorption properties for methylene blue in aqueous solutions across a wide range of pH levels.By creating activated carbon from plastic waste,not only are environmental issues addressed,but high-value activated carbon is produced for environmental remediation purposes.

Review of the fabrication and application of porous materials from silicon-rich industrial solid waste

Porous materials have promise as sound insulation, heat barrier, vibration attenuation, and catalysts. Most industrial solid wastes, such as tailings, coal gangue, and fly ash are rich in silicon. Additionally, a high silicon content waste is a potential raw material for the syn- thesis of silicon-based, multi-porous materials such as zeolites, mesoporous silica, glass-ceramics, and geopolymer foams. Representative sil- icon-rich industrial solid wastes (SRISWs) are the focus of this mini review of the processing and application of porous silicon materials with respect to the physical and chemical properties of the SRISW. The transformation methods of preparing porous materials from SRISWs are summarized, and their research status in micro-, meso-, and macro-scale porous materials are described. Possible problems in the application of SRISWs and in the preparation of functional porous materials are analyzed, and their development prospects are discussed. This review should provide a typical reference for the recycling and use of industrial solid wastes to develop sustainable “green materials.”

Microstructures and thermal properties of municipal solid waste incineration fly ash

To analyze the feasibility of utilization of thermal technology in fly ash treatment, thermal properties and microstructures of municipal solid waste incineration （MSW1） fly ash were studied by measuring the chemical element composition, specific surface area, pore sizes, functional groups, TEM image, mineralogy and DSC-TG curves of raw and sintered fly ash specimens. The results show that MSWI fly ash particles mostly have irregular shapes and non-typical pore structure, and the supersonic treatment improves the pore structure; MSWI fly ash consists of Such crystals as SiO2, CaSO4 and silica-aluminates, and some soluble salts like KCl and NaCl. During the sintering process, mineralogy changes largely and novel solid solutions are produced gradually with the rise of temperature. Therefore, the utilization of a proper thermal technology not only destructs those persistent organic toxicants but also stabilizes hazardous heavy metals in MSWI fly ash.

Intended process water management concept for the mechanical biological treatment of municipal solid waste

Accumulating operational experience in both aerobic and anaerobic mechanical biological waste treatment （MBT） makes it increasingly obvious that controlled water management would substantially reduce the cost of MBT and also enhance resource recovery of the organic and inorganic fraction. The MBT plant at Gescher, Germany, is used as an example in order to determine the quantity and composition of process water and leachates from intensive and subsequent rotting, pressing water from anaerobic digestion and scrubber water from acid exhaust air treatment, and hence prepare an MBT water balance. The potential of, requirements for and limits to internal process water reuse as well as the possibilities of resource recovery from scrubber water are also examined. Finally, an assimilated process water management concept with the purpose of an extensive reduction of wastewater quantity and freshwater demand is presented.

Emergy Evaluation of Treatment Methods for Solid Medical Waste in Bujumbura-Burundi

Introduction: Treatment of solid medical waste (SMW) is a complex task requiring the proper practices with specific treatment methods corresponding to each type of SMW during pretreatment and final treatment. This study targeted three treatment methods identified as the main used by the majority of health care facilities (HCFs) and treating a large amount of SMW. It aimed: 1) to evaluate the current practices by calculating the emergy investment and emergy costs that are required to treat one ton of SMW through the three treatment methods and 2) to evaluate and compare better technologies and provide policy suggestions for the final treatment of SMW in Burundi. Materials and Methods: This study used the emergy methodology to evaluate the relative efficiencies of three treatment methods used for to treat SMW in twelve HCFs in Bujumbura. Results and Conclusion: The total emergy input was 1.36E+20 seJ/yr, 3.54E+17 seJ/yr, and 1.681E+18 seJ/yr for low temperature incinerator, landfill and organic pit, respectively. Conclusion: Rapid improvement of organic pit by ensuring its maintenance, the gradual replacement of low temperature incinerator by high temperature incinerator with air control pollution and landfill by sanitary landfill are highly recommended by respecting its maintenance (fence, roof and monitoring evaluation) for reducing the risk.

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.

Optimization of Hydrothermal Treatment Parameters to Produce Chlorine-Free Alternative Solid Fuel from Plastic-Contained Municipal Solid Waste

An experimental study of the treatment of plastic-contained Japanese MSW （municipal solid waste） employing 1 ton capacity hydrothermal reactor to produce chlorine-free solid fuel has been performed. The system applies medium-pressure saturated steam at about 2 MPa in a stirred reactor for certain holding period. It was shown that the products exhibited organic chlorine conversion into inorganic chlorine, which can then be water washed. To obtain an optimal operating condition, the temperature and holding period was integrated into one parameter called RS （reaction severity）. It was found that to convert 75% organic chlorine in the MSW, the optimum RS number correlates to an operating temperature of about 225℃ and holding period of 90 min, or 235 ℃ for 60 min. Since hydrothermal treatment is a batch process, a shorter holding period is preferable to increase the number of batches and indirectly increase its processing capacity.

Oyster Shell Recycling and Bone Waste Treatment Using Plasma Pyrolysis

Investigations on the recycling plasma pyrolysis technique are presented in 25 kW was employed for the experiments. of oyster shells and bone waste treatment using the this paper. A arc based plasma torch operated at Fresh oyster shells were recycled using the plasma torch to convert them to a useful product such as CaO. Bone waste was treated to remove the infectious organic part and to vitrify the inorganic part. The time required for treatment in both cases was significantly short. Significant reduction in the weight of the samples was observed in both cases.

Thermodynamic Analysis of the Gasification of Municipal Solid Waste

This work aims to understand the gasification performance of municipal solid waste （MSW） by means of thermodynamic analysis. Thermodynamic analysis is based on the assumption that the gasification reactions take place at the thermodynamic equilibrium condition, without regard to the reactor and process characteristics. First, model components of MSW including food, green wastes, paper, textiles, rubber, chlorine-free plastic, and polyvinyl chloride were chosen as the feedstock of a steam gasification process, with the steam temperature ranging from 973 K to 2273 K and the steam-to-MSW ratio （STMR） ranging from 1 to 5. It was found that the effect of the STMR on the gasification performance was almost the same as that of the steam temperature. All the differences among the seven types of MSW were caused by the variation of their compositions. Next, the gasification of actual MSW was analyzed using this thermodynamic equilibrium model. It was possible to count the inorganic components of actual MSW as silicon dioxide or aluminum oxide for the purpose of simplification, due to the fact that the inorganic components mainly affected the reactor temperature. A detailed comparison was made of the composition of the gaseous products obtained using steam, hydrogen, and air gasifying agents to provide basic knowledge regarding the appropriate choice of gasifying agent in MSW treatment upon demand.

Analysis and Economic Evaluation of Hourly Operation Strategy Based on MSW Classification and LNG Multi-Generation System

In this study,a model of combined cooling,heating and power system with municipal solid waste(MSW)and liquefied natural gas(LNG)as energy sources was proposed and developed based on the energy demand of a large community,andMSW was classified and utilized.The systemoperated by determining power by heating load,and measures were taken to reduce operating costs by purchasing and selling LNG,natural gas(NG),cooling,heating,and power.Based on this system model,three operation strategies were proposed based on whether MSW was classified and the length of kitchen waste fermentation time,and each strategy was simulated hourly throughout the year.The results showed that the strategy of MSW classified and centralized fermentation of kitchen waste in summer(i.e.,strategy 3)required the least total amount of LNG for the whole year,which was 47701.77 t.In terms of total annual cost expenditure,strategy 3 had the best overall economy,with the lowest total annual expenditure of 2.7730×108 RMB at LNG and NG unit prices of 4 and 4.2 RMB/kg,respectively.The lower heating value of biogas produced by fermentation of kitchen waste from MSW being classified was higher than that of MSW before being classified,so the average annual thermal economy of the operating strategy of MSW being classified was better than that of MSW not being classified.Among the strategies in which MSW was classified and utilized,strategy 3 could better meet the load demand of users in the corresponding season,and thus this strategy had better thermal economy than the strategy of year-round fermentation of kitchen waste(i.e.,strategy 2).The hourly analysis data showed that the net electrical efficiency of the system varies in the same trend as the cooling,heating and power loads in all seasons,while the relationship between the energy utilization efficiency and load varied from season to season.This study can provide guidance for the practical application of MSW being classified in the system.

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.

Treatment of Bone Waste Using Thermal Plasma Technology

Daily meat consumption produces a lot of bone waste, and dumped bone waste without treatment would result in environmental hazards. Conventional treatment methods of waste bones have some disadvantages. Herein, an investigation of bone waste treated using thermal plasma technology is presented. A high-temperature plasma torch operated at 25.2 kW was used to treat bone waste for seven minutes. The bone waste was finally changed into vitric matter and lost 2/3 of its weight after the treatment. The process was highly efficient, economical, convenient, and fuel-free. This method could be used as an alternative for disposal of bone waste, small infectious animals, hazardous hospital waste, etc.

Study of Biological Methods in Landfill Leachate Treatment

Landfill leachate is mainly the result of precipitation of water into the layers of buried waste, and biochemical reactions of waste that has dangerous substances and pollutants that lead to the contamination of surface and groundwater resources. Therefore, it must be collected and treated properly. The investigation of various biological methods in leachate treatment, their advantages and disadvantages, and their effect on reduction of COD (chemical oxygen demand) are the objectives of this study. Reviewed processes include anaerobic and aerobic sequencing batch reactor, up-flow anaerobic sludge blanket, moving-bed biofilm reactor, membrane bioreactor, and aerated lagoons, lead to reduction of biodegradability pollutants in different circumstances. The present study has indicated that the most and the least reduction of COD has been through aerated lagoon (95%) and moving-bed biofilm reactor (8%), respectively.

Resourceful Utilization of Tannery Wastewater

Leather industry is an important light industry in China.Leather making requires a series of chemical treatment.Degreasing,unhairing and chrome tanning wastewaters are the main portions of tannery wastewater.Reclaiming and reusing these wastewaters can eliminate 80% of COD,75% of BOD,95% of chromium and 93% of sulfuret,furthermore reduce environment impact,decrease treatment costs,save chemicals and water.Some application methods of wastewater reclamation and reuse for different operations were reported.The suitable reclamation and reuse technologies can enable leather making processes more rational,and realize the recovery and recycle of several chemicals in the tannery.Resourceful utilization of tannery wastewater should mate with renovating production technology,updating equipment,and must be guaranteed sufficiently by environmental protection measures.

Modeling Municipal Solid Waste Management in Africa: Case Study of Matadi, the Democratic Republic of Congo

The purpose of this article is to present the key elements for best performance and profitability of Municipal Solid Waste (MSW) management in a low-income city. The research provides an overview of methods and models for integrated planning of a two-phase program: MSW collection and transportation, and MSW treatment. We present the case study of Matadi (the Democratic Republic of Congo) that has a low level of the MSW management compared to other African cities. We develop a spreadsheet model for collection and transportation of MSW which is relevant for low-income cities and enables determining the waste collection fee. A CDM decay model is used to predict the GHG emissions in disposal site. The MSW treatment plant in case of Matadi is evaluated. For the anaerobic digestion technology selected as appropriate for this plant, the key factors that ensure profitability of the plant are as follows: tipping fee from the municipality (19% of total revenue), amount of carbon credits which can sum up to 16% of the total revenue, expansion of waste collection range from 25 to 50 km. The methods of this study can be used for solving waste problem in other low-income cities where the budget for municipal services is scanty, particularly when starting from a very low level of MSW management.

Recent Advances in the Synthesis of Zeolites from Solid Wastes

With the rapid development of industrialization,it is inevitable to produce solid wastes in the fields of energy petrochemical industry.However,the storage and utilization of these solid wastes have become a considerable challenge.Due to the main element composition of these solid wastes including silicon and aluminum,it has attracted extensive attention for synthesizing zeolites.This review summarized the properties of major solid wastes including coal fly ash,coal gangue,spent fluid catalytic cracking(FCC)catalyst,lithium slag,bauxite residue,and waste glass.Then,the preparation of LTA,FAU,ZSM-5,SSZ-13,Beta,and MOR zeolites from these solid wastes were introduced.Finally,the current challenges and perspectives were discussed.